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2022,50(6):1-8 DOI: 10.3876/j.issn.1000-1980.2022.06.001
Abstract:
The surface water Subei Plain was polluted eriously, and the deep confined groundwater becomes the main exploitation aquifer, but high-water levels areas still exist after the extensive groundwater extraction. In order to investigate the cause of this phenomenon, the hydrogen and oxygen isotopes as well as water chemistry of river water and groundwater in Lianyungang,Huaian, Yangzhou, Taizhou and Yancheng were sampled and analyzed. The results showed that the hydrogen and oxygen isotopes of confined water in the Subei Plain are depleted relative to the surface water and the shallow groundwater, rather than from local infiltration of precipitation and recharge of the upper aquifer by transgressive flow. The recharge source is characterized by the obvious isotope depletion. Tritium dating data indicates that the groundwater receives modern precipitation recharge and apparent tritium from nuclear testing has been detected in the confined water. The large amount of metasilicic acid in the deep groundwater indicates that the groundwater water-rock reaction is dominated by the silicate reaction. Because multiple volcanic eruptions have occurred since the Pliocene in the northern Jiangsu area, the area of occult basalt beneath the Quaternary strata may be the main aquifer where deep groundwater reacted with water-rock to produce the metasilicic acid, and these metasilicic acid-rich groundwater then transported through the faults to the Quaternary confined aquifer.
The surface water Subei Plain was polluted eriously, and the deep confined groundwater becomes the main exploitation aquifer, but high-water levels areas still exist after the extensive groundwater extraction. In order to investigate the cause of this phenomenon, the hydrogen and oxygen isotopes as well as water chemistry of river water and groundwater in Lianyungang,Huaian, Yangzhou, Taizhou and Yancheng were sampled and analyzed. The results showed that the hydrogen and oxygen isotopes of confined water in the Subei Plain are depleted relative to the surface water and the shallow groundwater, rather than from local infiltration of precipitation and recharge of the upper aquifer by transgressive flow. The recharge source is characterized by the obvious isotope depletion. Tritium dating data indicates that the groundwater receives modern precipitation recharge and apparent tritium from nuclear testing has been detected in the confined water. The large amount of metasilicic acid in the deep groundwater indicates that the groundwater water-rock reaction is dominated by the silicate reaction. Because multiple volcanic eruptions have occurred since the Pliocene in the northern Jiangsu area, the area of occult basalt beneath the Quaternary strata may be the main aquifer where deep groundwater reacted with water-rock to produce the metasilicic acid, and these metasilicic acid-rich groundwater then transported through the faults to the Quaternary confined aquifer.
2022,50(6):9-17 DOI: 10.3876/j.issn.1000-1980.2022.06.002
Abstract:
In order to deeply understand the chemical evolution of groundwater and scientifically guide the groundwater resource management in the alpine region, this study took the Golmud River Watershed as the typical alpine watershed, investigated the groundwater chemistry and explored the influencing factors in 2019. Meanwhile, the groundwater quality in the snowmelt, wet season and dry season was evaluated using the entropy water quality index, Durov diagram and sodium sorption ratio, and potential risks posed by nitrate and fluoride in the groundwater to human health were assessed using the mathematical model of health risk assessment. Hydro chemical results showed that chemical type of groundwater had little change with periods but varied greatly in space: HCO-3 type for phreatic groundwater in the mountain area, Cl- type for phreatic groundwater in the plain area and HCO-3 type for confined groundwater in the plain area. The high ion concentrations of groundwater occurred mainly in the overflow zone of plain. Phreatic groundwater chemistry was mainly affected by the fertilizer use of spring tillage during the snowmelt season, by the industrial wastewater and domestic sewage discharge during the dry season, and by the water-rock interaction during the wet season. The results of water quality assessment indicated that shallow groundwater was not mostly suitable for irrigation in the watershed, and some was not suitable for drinking in the plain. The health risk evaluation found that the non-carcinogenic risk of fluoride was greater than that of nitrate to human health, and has already endangered children, and the non-carcinogenic risks of fluoride and nitrate were severer to human health during the dry period than other periods. Therefore, it is currently urgent to reduce the anthropogenic input such as domestic sewage, industrial discharge and agricultural discharge to protect the groundwater quality in the watershed.
In order to deeply understand the chemical evolution of groundwater and scientifically guide the groundwater resource management in the alpine region, this study took the Golmud River Watershed as the typical alpine watershed, investigated the groundwater chemistry and explored the influencing factors in 2019. Meanwhile, the groundwater quality in the snowmelt, wet season and dry season was evaluated using the entropy water quality index, Durov diagram and sodium sorption ratio, and potential risks posed by nitrate and fluoride in the groundwater to human health were assessed using the mathematical model of health risk assessment. Hydro chemical results showed that chemical type of groundwater had little change with periods but varied greatly in space: HCO-3 type for phreatic groundwater in the mountain area, Cl- type for phreatic groundwater in the plain area and HCO-3 type for confined groundwater in the plain area. The high ion concentrations of groundwater occurred mainly in the overflow zone of plain. Phreatic groundwater chemistry was mainly affected by the fertilizer use of spring tillage during the snowmelt season, by the industrial wastewater and domestic sewage discharge during the dry season, and by the water-rock interaction during the wet season. The results of water quality assessment indicated that shallow groundwater was not mostly suitable for irrigation in the watershed, and some was not suitable for drinking in the plain. The health risk evaluation found that the non-carcinogenic risk of fluoride was greater than that of nitrate to human health, and has already endangered children, and the non-carcinogenic risks of fluoride and nitrate were severer to human health during the dry period than other periods. Therefore, it is currently urgent to reduce the anthropogenic input such as domestic sewage, industrial discharge and agricultural discharge to protect the groundwater quality in the watershed.
2022,50(6):18-24, 137 DOI: 10.3876/j.issn.1000-1980.2022.06.003
Abstract:
In order to improve the refined management and planning of the Yangtze River shoreline, the definition method for the shoreline protection scope of the lower reaches of the Yangtze River is preliminary explored in this paper. Referring to the Yangtze River Protection Law as well as the relevant literatures, standards and regulations, a defining and planning method for the shoreline protection scope of the lower reaches of the Yangtze River is proposed. In this method, both the shoreline administration scope for hydrological departments and a “shoreline-riparian zone-buffer zone” based protection scope are considered comprehensively. For the riparian zone and buffer zone, they can be obtained in consideration with ecology and hydrological functions of shorelines and utilization modes of hinterland areas. Based on the Yangtze River coastline in the Yangzhou section, the application analysis of the proposed definition method indicates that this method has a good correlation with the current shoreline management methods and shows good operability. The proposed methods can provide a support for the formulation of the shoreline protection plan for the lower reaches of the Yangtze River.
In order to improve the refined management and planning of the Yangtze River shoreline, the definition method for the shoreline protection scope of the lower reaches of the Yangtze River is preliminary explored in this paper. Referring to the Yangtze River Protection Law as well as the relevant literatures, standards and regulations, a defining and planning method for the shoreline protection scope of the lower reaches of the Yangtze River is proposed. In this method, both the shoreline administration scope for hydrological departments and a “shoreline-riparian zone-buffer zone” based protection scope are considered comprehensively. For the riparian zone and buffer zone, they can be obtained in consideration with ecology and hydrological functions of shorelines and utilization modes of hinterland areas. Based on the Yangtze River coastline in the Yangzhou section, the application analysis of the proposed definition method indicates that this method has a good correlation with the current shoreline management methods and shows good operability. The proposed methods can provide a support for the formulation of the shoreline protection plan for the lower reaches of the Yangtze River.
2022,50(6):25-32, 122 DOI: 10.3876/j.issn.1000-1980.2022.06.004
Abstract:
In order to improve the applicability of Grid-Xin’anjiang model (Grid-XAJ)in flood simulation and forecasting of the semi-arid and semi-humid areas, the dominant runoff generation mechanism of the basin grid in the process of runoff generation was dynamically identified by determining the relationship between rainfall and soil moisture in this study. The Grid-Xin’anjiang and saturation-infiltration double excess distributed model (Grid-XAJ-SIDE)was constructed based on the dynamic combination of saturation-excess and infiltration-excess runoff. The semi-arid Suide Watershed was selected for comparing the simulation results of the Grid-XAJ-SIDE, the Grid-XAJ and the Grid-GA models. The results show that the qualified rate of runoff simulation of the three models in the Suide watershed are all above 80.0%. Compared with the Grid-XAJ (53.0%)and Grid-GA (40.0%)models, the Grid-XAJ-SIDE (66.7%)model has a higher qualified rate for the flood peak simulation. Meanwhile, the Grid-XAJ-SIDE model can capture the control effects of rainfall and soil water content on the spatio-temporal distribution of runoff generation.
In order to improve the applicability of Grid-Xin’anjiang model (Grid-XAJ)in flood simulation and forecasting of the semi-arid and semi-humid areas, the dominant runoff generation mechanism of the basin grid in the process of runoff generation was dynamically identified by determining the relationship between rainfall and soil moisture in this study. The Grid-Xin’anjiang and saturation-infiltration double excess distributed model (Grid-XAJ-SIDE)was constructed based on the dynamic combination of saturation-excess and infiltration-excess runoff. The semi-arid Suide Watershed was selected for comparing the simulation results of the Grid-XAJ-SIDE, the Grid-XAJ and the Grid-GA models. The results show that the qualified rate of runoff simulation of the three models in the Suide watershed are all above 80.0%. Compared with the Grid-XAJ (53.0%)and Grid-GA (40.0%)models, the Grid-XAJ-SIDE (66.7%)model has a higher qualified rate for the flood peak simulation. Meanwhile, the Grid-XAJ-SIDE model can capture the control effects of rainfall and soil water content on the spatio-temporal distribution of runoff generation.
2022,50(6):33-39, 57 DOI: 10.3876/j.issn.1000-1980.2022.06.005
Abstract:
The segmental Muskingum method,the Muskingum-Cunge (MC) algorithm with variable parameters and the Muskingum-Cunge-Todini (MCT) variable parameter method which reflecting the shape and hydraulic characteristics of the river cross-section were respectively used to study channel flow confluence for the Yuanling station-Wangjiahe station section inYuanshui Basin. The application effect of the routing method with distributed parameters in real river channel is discussed. The results show that the segmental Muskingum method,MC algorithm and MCT variable parameter method can all simulate pushing and tampering of flood in the river channel with high simulation accuracy,and the deterministic coefficients of MC algorithm and MCT variable parameter method are more accurate and stable than segmental Muskingum method. The MC algorithm and MCT variable parameter method improve the parameter characteristics of segmental Muskingum method well,and the MCT variable parameter method solves the problem of the inconsistency between the storage capacity and the steady state of MC algorithm. On the whole,the three methods have strong adaptability and reliability for flood frocast,and provide a new method for real-time flood forecast.
The segmental Muskingum method,the Muskingum-Cunge (MC) algorithm with variable parameters and the Muskingum-Cunge-Todini (MCT) variable parameter method which reflecting the shape and hydraulic characteristics of the river cross-section were respectively used to study channel flow confluence for the Yuanling station-Wangjiahe station section inYuanshui Basin. The application effect of the routing method with distributed parameters in real river channel is discussed. The results show that the segmental Muskingum method,MC algorithm and MCT variable parameter method can all simulate pushing and tampering of flood in the river channel with high simulation accuracy,and the deterministic coefficients of MC algorithm and MCT variable parameter method are more accurate and stable than segmental Muskingum method. The MC algorithm and MCT variable parameter method improve the parameter characteristics of segmental Muskingum method well,and the MCT variable parameter method solves the problem of the inconsistency between the storage capacity and the steady state of MC algorithm. On the whole,the three methods have strong adaptability and reliability for flood frocast,and provide a new method for real-time flood forecast.
2022,50(6):40-46 DOI: 10.3876/j.issn.1000-1980.2022.06.006
Abstract:
Considering that satellite retrieved soil moisture (SRSM) products have relatively coarser spatiotemporal resolutions and, therefore, cannot meet the demand of flood forecasting in small and medium-sized watersheds, this study takes the Qinhuai River Basin as the research area to develope a method to merge three SRSM products and further downscale it to a finer resolution. The merged product was obtained based on three SRSM products, i.e., the SMOS, SMAP and AMSR2 products, via an assembling average method. The downscaling procedure was implemented to obtain the fine-scale soil moisture based on the relationship of topographic wetness index and soil moisture. The results showed that the RMSE of merged product is lower than that of original SRSM product. Besides, the merged product is close to the observations regarding both daily and seasonal average values. The method proposed in this paper can overcome the disadvantages of a single SRSM product, such as large time interval and lower precision, with a potential of worldwide applicability.
Considering that satellite retrieved soil moisture (SRSM) products have relatively coarser spatiotemporal resolutions and, therefore, cannot meet the demand of flood forecasting in small and medium-sized watersheds, this study takes the Qinhuai River Basin as the research area to develope a method to merge three SRSM products and further downscale it to a finer resolution. The merged product was obtained based on three SRSM products, i.e., the SMOS, SMAP and AMSR2 products, via an assembling average method. The downscaling procedure was implemented to obtain the fine-scale soil moisture based on the relationship of topographic wetness index and soil moisture. The results showed that the RMSE of merged product is lower than that of original SRSM product. Besides, the merged product is close to the observations regarding both daily and seasonal average values. The method proposed in this paper can overcome the disadvantages of a single SRSM product, such as large time interval and lower precision, with a potential of worldwide applicability.
2022,50(6):47-57 DOI: 10.3876/j.issn.1000-1980.2022.06.007
Abstract:
In order to illustrate the structural adaptability, precision and accuracy of different PM correction models in wheat fields of Yongnian District of Handan City, the field evapotranspiration during key growth stages (from April to May) of winter wheat was simulated respectively through PM-1, PM-2 and PM-3, and simulation results were compared with the water balance results. The results show that the simulated evapotranspiration precision of PM-1 is the highest, of which the corresponding R 2 and GPI values are 0.773 and 3.105 respectively; the precision of PM-3 is the lowest, of which the corresponding R 2 and GPI are 0.701 and -2.904 respectively. The temporal distribution equilibrium of PM-1 simulated evapotranspiration is the best and that of PM-2 is the worst. These PM correction models have their own advantages and limitations, and PM-1 is more suitable for the evapotranspiration simulation of Yongnian District. The results can supply reference to the disclosure of wheat-fields evapotranspiration law in key growth stages and provide basis for the inversion and revision of remote sensing evapotranspiration in large scale.
In order to illustrate the structural adaptability, precision and accuracy of different PM correction models in wheat fields of Yongnian District of Handan City, the field evapotranspiration during key growth stages (from April to May) of winter wheat was simulated respectively through PM-1, PM-2 and PM-3, and simulation results were compared with the water balance results. The results show that the simulated evapotranspiration precision of PM-1 is the highest, of which the corresponding R 2 and GPI values are 0.773 and 3.105 respectively; the precision of PM-3 is the lowest, of which the corresponding R 2 and GPI are 0.701 and -2.904 respectively. The temporal distribution equilibrium of PM-1 simulated evapotranspiration is the best and that of PM-2 is the worst. These PM correction models have their own advantages and limitations, and PM-1 is more suitable for the evapotranspiration simulation of Yongnian District. The results can supply reference to the disclosure of wheat-fields evapotranspiration law in key growth stages and provide basis for the inversion and revision of remote sensing evapotranspiration in large scale.
2022,50(6):58-65 DOI: 10.3876/j.issn.1000-1980.2022.06.008
Abstract:
In order to study the response characteristics of surface current to the changing wind field and the effect of wind field and surface current on the cyanobacteria migration in the Lake Taihu, systematic field observation was carried out. In this study, the surface current was observed by the GPS particle tracers, while the characteristics of surface current and the accumulation process of cyanobacteria blooms in the Lake Taihu under varying wind condition were analyzed by combining the variation characteristics of wind field and remote sensing map. The results show that the wind is the main driving force of surface current in the Lake Taihu. However, due to the influence of topographic characteristics, shoreline characteristics and et al, the response of surface current to the wind field in different water areas is not completely consistent. The surface currents of the Lake Taihu under the influence of wind field have wide spatial differences, which is the dominant factor leading to different concentrations of cyanobacteria in different areas during the migration process, and this phenomenon is one of the important reasons for the regional cyanobacteria bloom. The process of wind field, surface current and cyanobacteria migration and aggregation are a response system of successive conduction. The current field under the influence of suitable wind field is an important external factor to promote the large area of cyanobacteria blooms in a short time.
In order to study the response characteristics of surface current to the changing wind field and the effect of wind field and surface current on the cyanobacteria migration in the Lake Taihu, systematic field observation was carried out. In this study, the surface current was observed by the GPS particle tracers, while the characteristics of surface current and the accumulation process of cyanobacteria blooms in the Lake Taihu under varying wind condition were analyzed by combining the variation characteristics of wind field and remote sensing map. The results show that the wind is the main driving force of surface current in the Lake Taihu. However, due to the influence of topographic characteristics, shoreline characteristics and et al, the response of surface current to the wind field in different water areas is not completely consistent. The surface currents of the Lake Taihu under the influence of wind field have wide spatial differences, which is the dominant factor leading to different concentrations of cyanobacteria in different areas during the migration process, and this phenomenon is one of the important reasons for the regional cyanobacteria bloom. The process of wind field, surface current and cyanobacteria migration and aggregation are a response system of successive conduction. The current field under the influence of suitable wind field is an important external factor to promote the large area of cyanobacteria blooms in a short time.
Characteristics of microbial community on leaf surface of submerged plants in different water bodies
2022,50(6):66-74 DOI: 10.3876/j.issn.1000-1980.2022.06.009
Abstract:
Submerged plants, such as the Hydrilla verticillata, Vallisneria natans , Elodea nuttallii and Potamogeton crispus L , were selected as the research objects. This study used the scanning electron microscopy, fluorescence microscopy and 16S rRNA high-throughput sequencing technology to explore the bacterial community structure and influencing factors attached to the leaf surface of submerged plants in different habitats. The results show that the composition of algae attached to the leaf surface of submerged plants is significantly different from that in the environmental water body. Different submerged plants have different density of microorganisms on the leaf surface, and the density of microorganisms attached to the surface of lake samples are lower than the river samples. α-Proteobacteria, β-Proteobacteria and γ-Proteobacteria are the main bacterial classes in the biofilm on the leaves of submerged plants. These classes have the function of degrading pollutants and purifying water bodies. Redundant analysis shows that the concentration of nutrients in the water body has a great influence on the microbial community structure on the leaf surface of submerged plants.
Submerged plants, such as the Hydrilla verticillata, Vallisneria natans , Elodea nuttallii and Potamogeton crispus L , were selected as the research objects. This study used the scanning electron microscopy, fluorescence microscopy and 16S rRNA high-throughput sequencing technology to explore the bacterial community structure and influencing factors attached to the leaf surface of submerged plants in different habitats. The results show that the composition of algae attached to the leaf surface of submerged plants is significantly different from that in the environmental water body. Different submerged plants have different density of microorganisms on the leaf surface, and the density of microorganisms attached to the surface of lake samples are lower than the river samples. α-Proteobacteria, β-Proteobacteria and γ-Proteobacteria are the main bacterial classes in the biofilm on the leaves of submerged plants. These classes have the function of degrading pollutants and purifying water bodies. Redundant analysis shows that the concentration of nutrients in the water body has a great influence on the microbial community structure on the leaf surface of submerged plants.
2022,50(6):75-84 DOI: 10.3876/j.issn.1000-1980.2022.06.010
Abstract:
In this study, the ciprofloxacin (CFC) and copper (Cu) were selected as the target pollutants, indoor culture experiments were designed, and the interaction relationship between microbial communities and antibiotic resistance genes (ARGs)under ciprofloxacin and copper co-contamination in river sediments was explored using high throughput 16S rRNA sequencing and quantitative PCR. The results showed that the ARGs abundance, microbial community composition and functions were significantly different among different experimental groups (CFC contamination, Cu contamination and co-contamination). The total relative abundance of ARGs of each sample showed an increasing trend first, and then it decreased at the end of culture experiment. Co-occurrence network analysis suggested that intI 1 was associated with 3 types of ARGs and 8 bacterial communities, regarded as a bridge between ARGs and microbial community. Meanwhile, the bacteria that belonged to Proteobacteria, Acidobacteria, Firmicutes, Bacteroidetes and Chloroflexi was considered as the potential ARGs hosts in the aquatic environment. Based on the partial redundancy analysis, the microbial community had the highest overall interpretation rate (49.77%) for the change of ARGs abundance among MGEs, microbial communities, pollutants and other factors. At last, the path analysis showed that CFC and Cu pollutants indirectly affect the spread and diffusion of ARGs mainly through microbial communities.
In this study, the ciprofloxacin (CFC) and copper (Cu) were selected as the target pollutants, indoor culture experiments were designed, and the interaction relationship between microbial communities and antibiotic resistance genes (ARGs)under ciprofloxacin and copper co-contamination in river sediments was explored using high throughput 16S rRNA sequencing and quantitative PCR. The results showed that the ARGs abundance, microbial community composition and functions were significantly different among different experimental groups (CFC contamination, Cu contamination and co-contamination). The total relative abundance of ARGs of each sample showed an increasing trend first, and then it decreased at the end of culture experiment. Co-occurrence network analysis suggested that intI 1 was associated with 3 types of ARGs and 8 bacterial communities, regarded as a bridge between ARGs and microbial community. Meanwhile, the bacteria that belonged to Proteobacteria, Acidobacteria, Firmicutes, Bacteroidetes and Chloroflexi was considered as the potential ARGs hosts in the aquatic environment. Based on the partial redundancy analysis, the microbial community had the highest overall interpretation rate (49.77%) for the change of ARGs abundance among MGEs, microbial communities, pollutants and other factors. At last, the path analysis showed that CFC and Cu pollutants indirectly affect the spread and diffusion of ARGs mainly through microbial communities.
2022,50(6):85-91 DOI: 10.3876/j.issn.1000-1980.2022.06.011
Abstract:
The stress state and the variation law of velocity in the falling process of rock breaking hammer are studied according to the immersed tunnel foundation trench in the Shenzhen-Zhongshan passage project. The FEM method is used to simulate the process of rock drilling, study the damage development characteristics of rock and analyze the influence law of water depth, impact velocity and drilling times on the rock failure and damage development. The results show that during the falling process, the velocity of rock breaking hammer increases linearly first, then decreases gradually, and finally tends to a stable ending velocity. The speed of the hammer decreases and the damage accumulates in the process of drilling. In addition, the water depth is negatively correlated with the rock damage, while the impact velocity and impact times are positively correlated with the rock damage.
The stress state and the variation law of velocity in the falling process of rock breaking hammer are studied according to the immersed tunnel foundation trench in the Shenzhen-Zhongshan passage project. The FEM method is used to simulate the process of rock drilling, study the damage development characteristics of rock and analyze the influence law of water depth, impact velocity and drilling times on the rock failure and damage development. The results show that during the falling process, the velocity of rock breaking hammer increases linearly first, then decreases gradually, and finally tends to a stable ending velocity. The speed of the hammer decreases and the damage accumulates in the process of drilling. In addition, the water depth is negatively correlated with the rock damage, while the impact velocity and impact times are positively correlated with the rock damage.
2022,50(6):92-100 DOI: 10.3876/j.issn.1000-1980.2022.06.012
Abstract:
Asymmetric excavation has become increasingly common with the development of construction and the progressive collapse caused by the local component failure has attracted many attentions. Aiming at this problem, the three-dimensional finite element software PLAXIS 3D is adopted to analyze the response of the whole retaining system to the asymmetric excavation after local component failure through the method of removing component. The results show that when the braces fail, the earth pressure of piles decreases in the failed area because of the unloading effect but is opposite in the adjacent area. Meanwhile, the moments of piles near intact braces increase greatly. The earth pressure and moment of piles on the same side of the failed piles increase greatly, while on the opposite side they decrease as piles get failed. Piles on the deep side push piles on the shallow side through braces, but the displacement reverses when piles on the deep side failed. The value of soil settlement on the shallow side is less than that on the deep side and increases with the increasing number of failed piles, but the range of settlement almost keeps unchanged. Earth pressure variation coefficient and moment transfer coefficient get surge when the depth difference increases. In addition, the change of depth boundary line has little effect on the earth pressure and pile moment. Finally, a design method is proposed to improve the redundancy of supporting structure through enlarging the reinforcement moment of piles.
Asymmetric excavation has become increasingly common with the development of construction and the progressive collapse caused by the local component failure has attracted many attentions. Aiming at this problem, the three-dimensional finite element software PLAXIS 3D is adopted to analyze the response of the whole retaining system to the asymmetric excavation after local component failure through the method of removing component. The results show that when the braces fail, the earth pressure of piles decreases in the failed area because of the unloading effect but is opposite in the adjacent area. Meanwhile, the moments of piles near intact braces increase greatly. The earth pressure and moment of piles on the same side of the failed piles increase greatly, while on the opposite side they decrease as piles get failed. Piles on the deep side push piles on the shallow side through braces, but the displacement reverses when piles on the deep side failed. The value of soil settlement on the shallow side is less than that on the deep side and increases with the increasing number of failed piles, but the range of settlement almost keeps unchanged. Earth pressure variation coefficient and moment transfer coefficient get surge when the depth difference increases. In addition, the change of depth boundary line has little effect on the earth pressure and pile moment. Finally, a design method is proposed to improve the redundancy of supporting structure through enlarging the reinforcement moment of piles.
2022,50(6):101-107 DOI: 10.3876/j.issn.1000-1980.2022.06.013
Abstract:
In order to explore the permeability characteristics of soilbags infilled with expansive soils, a large-scale permeability-test model box was developed. The permeability test was carried out according to the arrangement pattern of soilbags, water flow direction, water head and interlayer filling conditions. The experimental result showed that the horizontal permeability coefficient is greater than the vertical permeability coefficient. The infiltration water could be quickly discharged along the gap between the horizontal layers of soilbags, so that it was not easy to infiltrate into the compacted underlying layer of the expansive soil canal slopes. After filling the gaps between bags with expansive soils, the vertical permeability coefficient changed slightly, while the horizontal permeability coefficient decreased obviously. The permeability of soilbags infilled with expansive soils mainly depends on the size of the gaps. The effect of the soilbag arrangement on the permeability is essentially attributed to the changing of the gap number and shape. In practical, it is expected to provide more preferential flow paths along the horizontal direction if no compacted soils are infilled inside the gaps between soilbags during the actual construction conditions.
In order to explore the permeability characteristics of soilbags infilled with expansive soils, a large-scale permeability-test model box was developed. The permeability test was carried out according to the arrangement pattern of soilbags, water flow direction, water head and interlayer filling conditions. The experimental result showed that the horizontal permeability coefficient is greater than the vertical permeability coefficient. The infiltration water could be quickly discharged along the gap between the horizontal layers of soilbags, so that it was not easy to infiltrate into the compacted underlying layer of the expansive soil canal slopes. After filling the gaps between bags with expansive soils, the vertical permeability coefficient changed slightly, while the horizontal permeability coefficient decreased obviously. The permeability of soilbags infilled with expansive soils mainly depends on the size of the gaps. The effect of the soilbag arrangement on the permeability is essentially attributed to the changing of the gap number and shape. In practical, it is expected to provide more preferential flow paths along the horizontal direction if no compacted soils are infilled inside the gaps between soilbags during the actual construction conditions.
2022,50(6):108-113 DOI: 10.3876/j.issn.1000-1980.2022.06.014
Abstract:
Using the discrete element method (DEM), a series of numerical simulations of elastic wave propagation are carried out on the particle models of pure soil foundation and soil foundation containing a single-layered soilbag. The influence of the soilbag in the foundation on the elastic wave velocity and the damping of foundation is studied. Numerical simulation results show that the existence of soilbag in the foundation slightly reduces the elastic wave velocity and reduces the quality factor Q of the foundation. The change laws of elastic P-wave velocity and S-wave velocity are roughly the same when they pass through the soilbag. Under the condition of 100.kPa confining pressure and 500.Hz elastic wave input, the attenuation effect of a soilbag on the elastic wave is mainly concentrated when passing through the upper and lower geosynthetic interface.
Using the discrete element method (DEM), a series of numerical simulations of elastic wave propagation are carried out on the particle models of pure soil foundation and soil foundation containing a single-layered soilbag. The influence of the soilbag in the foundation on the elastic wave velocity and the damping of foundation is studied. Numerical simulation results show that the existence of soilbag in the foundation slightly reduces the elastic wave velocity and reduces the quality factor Q of the foundation. The change laws of elastic P-wave velocity and S-wave velocity are roughly the same when they pass through the soilbag. Under the condition of 100.kPa confining pressure and 500.Hz elastic wave input, the attenuation effect of a soilbag on the elastic wave is mainly concentrated when passing through the upper and lower geosynthetic interface.
2022,50(6):114-122 DOI: 10.3876/j.issn.1000-1980.2022.06.015
Abstract:
In order to solve the problem that the cement concrete of the airport pavement is easy to produce early micro cracks during the construction period and bring potential safety hazards to the aircraft operation during the service period, this study proposed a method to strengthen the surface performance of the airport pavement by laying fiber mesh in the concrete surface mortar layer. Carbon fiber, aramid fiber and basalt fiber mesh were selected as reinforcement materials to characterize the early cracking resistance of concrete with the early cracking performance of mortar. The effects of water cement ratio, cement sand ratio, fineness modulus and fiber mesh on the early cracking resistance of cement mortar in high temperature and multi wind simulation environment were studied. The results show that the early cracking resistance of cement mortar is the best when the water cement ratio is 0.43, the cement sand ratio is 0.47 and the fineness modulus is 3.4, and when the fiber mesh is basalt fiber with a grid size of 3 mm ×3 mm, the strengthening effect of early cracking resistance is the best.
In order to solve the problem that the cement concrete of the airport pavement is easy to produce early micro cracks during the construction period and bring potential safety hazards to the aircraft operation during the service period, this study proposed a method to strengthen the surface performance of the airport pavement by laying fiber mesh in the concrete surface mortar layer. Carbon fiber, aramid fiber and basalt fiber mesh were selected as reinforcement materials to characterize the early cracking resistance of concrete with the early cracking performance of mortar. The effects of water cement ratio, cement sand ratio, fineness modulus and fiber mesh on the early cracking resistance of cement mortar in high temperature and multi wind simulation environment were studied. The results show that the early cracking resistance of cement mortar is the best when the water cement ratio is 0.43, the cement sand ratio is 0.47 and the fineness modulus is 3.4, and when the fiber mesh is basalt fiber with a grid size of 3 mm ×3 mm, the strengthening effect of early cracking resistance is the best.
2022,50(6):123-129 DOI: 10.3876/j.issn.1000-1980.2022.06.016
Abstract:
The traditional method to determine the soil moisture content and dry density, which uses the oven drying combined with the cutting-ring, has the problems of long testing period and sampling disturbance, thus a rapid non-destructive testing method was proposed based on the frequency domain reflectometry (FDR) technology in this study. Firstly, based on the relationships of dielectric constant and bulk electrical conductivity with the soil moisture content and dry density, and by using the fitting relationship of dielectric constant and bulk electrical conductivity, the solving equations for soil moisture content and dry density were derived. After that, both the calibration test and model test that simulated the layered filling construction were conducted to verify the applicability of the proposed method. It is found that the proposed mothed to detect the soil moisture content and dry density is feasible with high accuracy.
The traditional method to determine the soil moisture content and dry density, which uses the oven drying combined with the cutting-ring, has the problems of long testing period and sampling disturbance, thus a rapid non-destructive testing method was proposed based on the frequency domain reflectometry (FDR) technology in this study. Firstly, based on the relationships of dielectric constant and bulk electrical conductivity with the soil moisture content and dry density, and by using the fitting relationship of dielectric constant and bulk electrical conductivity, the solving equations for soil moisture content and dry density were derived. After that, both the calibration test and model test that simulated the layered filling construction were conducted to verify the applicability of the proposed method. It is found that the proposed mothed to detect the soil moisture content and dry density is feasible with high accuracy.
2022,50(6):130-137 DOI: 10.3876/j.issn.1000-1980.2022.06.017
Abstract:
The bending characteristics of drainage plate in super soft foundation and its influence are studied by the theoretical calculation and the model test. Based on the utilization of waste materials, a new type of ribbed structure is proposed, and its bending resistance is theoretically and experimentally analyzed. The results show that the P cr of Euler critical force is very small, and the water flow of Z bend is obviously smaller than that of S bend. When the bending rate increases from 10% to 20%, the vacuum degree of drainage plate core will decrease by 3 to 8 kPa, while the vacuum degree of drainage plate core will decrease by 34 to 46 kPa when the bending rate increases from 20% to 30%. The influence of bending rate on the vacuum degree of plate core and the excess pore pressure of soil is nonlinear. The influence degree is obviously intensified when the bending rate reaches 30%. Based on the idea of waste utilization, the ribbed plate structure is proposed, and the section bending stiffness of ribbed plate structure is 8 times that of the common plate, and the bending resistance of plate body could be increased several times. After reinforcement, the cross-plate strength of dredger fill reaches 16-23 kPa, and the characteristic value of the bearing capacity of mud surface foundation reaches 60-63 kPa, with basically erect plate body after excavation. The ribbed drainage board plays a certain role in enhancing the bending resistance of drainage plate and improving the drainage consolidation effect.
The bending characteristics of drainage plate in super soft foundation and its influence are studied by the theoretical calculation and the model test. Based on the utilization of waste materials, a new type of ribbed structure is proposed, and its bending resistance is theoretically and experimentally analyzed. The results show that the P cr of Euler critical force is very small, and the water flow of Z bend is obviously smaller than that of S bend. When the bending rate increases from 10% to 20%, the vacuum degree of drainage plate core will decrease by 3 to 8 kPa, while the vacuum degree of drainage plate core will decrease by 34 to 46 kPa when the bending rate increases from 20% to 30%. The influence of bending rate on the vacuum degree of plate core and the excess pore pressure of soil is nonlinear. The influence degree is obviously intensified when the bending rate reaches 30%. Based on the idea of waste utilization, the ribbed plate structure is proposed, and the section bending stiffness of ribbed plate structure is 8 times that of the common plate, and the bending resistance of plate body could be increased several times. After reinforcement, the cross-plate strength of dredger fill reaches 16-23 kPa, and the characteristic value of the bearing capacity of mud surface foundation reaches 60-63 kPa, with basically erect plate body after excavation. The ribbed drainage board plays a certain role in enhancing the bending resistance of drainage plate and improving the drainage consolidation effect.
2022,50(6):138-143 DOI: 10.3876/j.issn.1000-1980.2022.06.018
Abstract:
In order to solve the defects of relying on the engineering experience, difficult maintenance and reducing the efficiency of the turbine in the traditional layout scheme of the water supply cooler in the secondary circulation technology of the hydropower station, this paper proposes an optimization method for the layout scheme of tail water coolers based on computational fluid dynamics(CFD) through the steady-state numerical simulation of three-dimensional flow in the tailrace. By analyzing the spatial distribution characteristics of multiple physical quantities such as streamlines, flow velocity, turbulent kinetic energy and other physical quantities of the flow field in the area where the cooler is to be installed on the platform above the draft tube in the simulation results, the location with a higher flow velocity from the cooler is selected as the appropriate installation position. The three-dimensional flow domain of the complex tailrace channel considering the geometric model of the actual cooler is established for the numerical simulation and verification to check the rationality of the layout. The simulation and verification results show that this scheme not only meets the cooling requirements of the cooler, but also facilitates the maintenance and avoids any impact on the operation of the unit.
In order to solve the defects of relying on the engineering experience, difficult maintenance and reducing the efficiency of the turbine in the traditional layout scheme of the water supply cooler in the secondary circulation technology of the hydropower station, this paper proposes an optimization method for the layout scheme of tail water coolers based on computational fluid dynamics(CFD) through the steady-state numerical simulation of three-dimensional flow in the tailrace. By analyzing the spatial distribution characteristics of multiple physical quantities such as streamlines, flow velocity, turbulent kinetic energy and other physical quantities of the flow field in the area where the cooler is to be installed on the platform above the draft tube in the simulation results, the location with a higher flow velocity from the cooler is selected as the appropriate installation position. The three-dimensional flow domain of the complex tailrace channel considering the geometric model of the actual cooler is established for the numerical simulation and verification to check the rationality of the layout. The simulation and verification results show that this scheme not only meets the cooling requirements of the cooler, but also facilitates the maintenance and avoids any impact on the operation of the unit.
2022,50(6):144-151 DOI: 10.3876/j.issn.1000-1980.2022.06.019
Abstract:
In order to improve the efficiency of cable force measurement in the long-span cable-stayed bridge, a cable force measurement method based on the microwave interferometric radar is proposed and the measurement results are compared with those of JMM-268 and DaspBCF. Firstly, the displacements of cables of the bridge were measured by the IBIS-S radar system. Then, based on the collected displacement information, fast Fourier transform (FFT) algorithm was adopted to obtain the frequency spectrum as well as the fundamental frequency of the target cables. Finally, the forces of multiple cables were identified by the oscillating frequency technique. The test results show that: the dynamic information of multiple cables can be measured by the microwave interferometric radar simultaneously with high efficiency; test method that transmits the radar wave from bottom to top can greatly avoid the influence of noise; relative errors between the cable forces calculated by data measured with radar and conventional accelerometers are less than 2.2%, which proves that the test results are reliable. The cable force measurement method in this paper is of high efficiency and easy to operate, which is worth promotion.
In order to improve the efficiency of cable force measurement in the long-span cable-stayed bridge, a cable force measurement method based on the microwave interferometric radar is proposed and the measurement results are compared with those of JMM-268 and DaspBCF. Firstly, the displacements of cables of the bridge were measured by the IBIS-S radar system. Then, based on the collected displacement information, fast Fourier transform (FFT) algorithm was adopted to obtain the frequency spectrum as well as the fundamental frequency of the target cables. Finally, the forces of multiple cables were identified by the oscillating frequency technique. The test results show that: the dynamic information of multiple cables can be measured by the microwave interferometric radar simultaneously with high efficiency; test method that transmits the radar wave from bottom to top can greatly avoid the influence of noise; relative errors between the cable forces calculated by data measured with radar and conventional accelerometers are less than 2.2%, which proves that the test results are reliable. The cable force measurement method in this paper is of high efficiency and easy to operate, which is worth promotion.
2022,50(6):152-158 DOI: 10.3876/j.issn.1000-1980.2022.06.020
Abstract:
To effectively suppress the overvoltage of HVDC receiving end system caused by the fault elimination, a coordinated control strategy of synchronous condenser and inverter side extinction angle is proposed. A reactive power regulator (QPC) is added to the conventional control system with a fixed extinction angle at the inverter side for realizing the reactive power control of the converter station by adjusting extinction angle at the inverter side, and at the same time coordinating the reactive power regulator parameters of both the synchronous condenser and the DC control system. The numerical simulation model of HVDC system with the synchronous condenser is built based on the PSCAD/EMTDC environment. The simulation results show that the coordinated control method can effectively reduce the overvoltage of HVDC receiving end system after the accident occurrence and speed up the recovery time of the AC system voltage.
To effectively suppress the overvoltage of HVDC receiving end system caused by the fault elimination, a coordinated control strategy of synchronous condenser and inverter side extinction angle is proposed. A reactive power regulator (QPC) is added to the conventional control system with a fixed extinction angle at the inverter side for realizing the reactive power control of the converter station by adjusting extinction angle at the inverter side, and at the same time coordinating the reactive power regulator parameters of both the synchronous condenser and the DC control system. The numerical simulation model of HVDC system with the synchronous condenser is built based on the PSCAD/EMTDC environment. The simulation results show that the coordinated control method can effectively reduce the overvoltage of HVDC receiving end system after the accident occurrence and speed up the recovery time of the AC system voltage.
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2018,46(2):128-133, DOI: 10.3876/j.issn.1000-1980.2018.02.005
Abstract:
To improve the operational safety of earth rockfill dam, a longitudinal reinforcement is proposed. This rigid structure has triple functions as the seepage controlling, stress resistance and deformation resistance. Based on the classical mechanics, its anti-seepage effect, anti-deformation ability and the capacity to withstand external force is quantitatively analyzed. In addition, the quantitative relationships between the reinforcement thickness and the downstream water level, as well as the material properties of the rockfill dam are derived. For the theoretical derivation, the reinforced body is regarded as a fixed-end beam, loaded by water pressures from upstream and downstream, the active earth pressure from rockfill and the vertical drag force due to the differential settlement between core walls and rockfill. The top displacement together with the rotation angle and the bottom stress of the fixed end are derived from the deformation differential equation and validated through designing reviews. Subsequently, the construction method of buried steel pipe, which is adopted to perform the base grouting and also to meet the strength requirements, is put forward. The proposed method plays an important guiding role in rehabilitating and reinforcing the dangerous earth rockfill dams, as well as the design and construction of new dams.
To improve the operational safety of earth rockfill dam, a longitudinal reinforcement is proposed. This rigid structure has triple functions as the seepage controlling, stress resistance and deformation resistance. Based on the classical mechanics, its anti-seepage effect, anti-deformation ability and the capacity to withstand external force is quantitatively analyzed. In addition, the quantitative relationships between the reinforcement thickness and the downstream water level, as well as the material properties of the rockfill dam are derived. For the theoretical derivation, the reinforced body is regarded as a fixed-end beam, loaded by water pressures from upstream and downstream, the active earth pressure from rockfill and the vertical drag force due to the differential settlement between core walls and rockfill. The top displacement together with the rotation angle and the bottom stress of the fixed end are derived from the deformation differential equation and validated through designing reviews. Subsequently, the construction method of buried steel pipe, which is adopted to perform the base grouting and also to meet the strength requirements, is put forward. The proposed method plays an important guiding role in rehabilitating and reinforcing the dangerous earth rockfill dams, as well as the design and construction of new dams.
2019,47(1):1-6, DOI: 10.3876/j.issn.1000-1980.2019.01.001
Abstract:
To improve the accuracy of flood forecasting, 13 flood events between 2000 and 2017 were selected from the sections of Lutaizi and Lubeng, and the Xin’anjiang three-source model(XAJ model)was used to simulate the flood events. The Lutaizi basin can be divided into 9 natural sub-basins and the Lubeng basin can be divided into 4 natural sub-basins. Then, the XAJ model was calibrated for these basins. The node generalizability was carried out in the mainstream section of the Huaihe River with flood diversion and flood retarding areas. Combined with the diversion ratio method and the Muskingen method, the simulation method of flood diversion was established, and fairly good forecasting results were obtained. The research results show that: for the relative error of flood volume, the qualified rates of Lutaizi and Lubeng region are both up to 100%, and the Lutaizi reached a qualified rate of 100% in the flood peak, while the Lubeng region reached 92. 3%. In two floods in 2003 and 2007, the relative error and the certainty coefficient of flood peak have been significantly improved.
To improve the accuracy of flood forecasting, 13 flood events between 2000 and 2017 were selected from the sections of Lutaizi and Lubeng, and the Xin’anjiang three-source model(XAJ model)was used to simulate the flood events. The Lutaizi basin can be divided into 9 natural sub-basins and the Lubeng basin can be divided into 4 natural sub-basins. Then, the XAJ model was calibrated for these basins. The node generalizability was carried out in the mainstream section of the Huaihe River with flood diversion and flood retarding areas. Combined with the diversion ratio method and the Muskingen method, the simulation method of flood diversion was established, and fairly good forecasting results were obtained. The research results show that: for the relative error of flood volume, the qualified rates of Lutaizi and Lubeng region are both up to 100%, and the Lutaizi reached a qualified rate of 100% in the flood peak, while the Lubeng region reached 92. 3%. In two floods in 2003 and 2007, the relative error and the certainty coefficient of flood peak have been significantly improved.
2020,48(1):1-7, DOI: 10.3876/j.issn.1000-1980.2020.01.001
Abstract:
Based on the development of hydrology science and the basic framework of physical and virtual water coupled flow theory, this study indicated that the process hydrology is an interdiscipline that can reveal the coupled flow law and associated effects of physical and virtual water in complicated system. In addition, this study makes a detailed analysis of the scientific connotation, main characteristics, framework, discipline basis, method system and core tasks of process hydrology. Given the theoretical value and practical significance of process hydrology, it can be concluded that the development of process hydrology can provide measures and new views to cope with new challenges in hydrology that the sustainable developments of nature, economy and society faces.
Based on the development of hydrology science and the basic framework of physical and virtual water coupled flow theory, this study indicated that the process hydrology is an interdiscipline that can reveal the coupled flow law and associated effects of physical and virtual water in complicated system. In addition, this study makes a detailed analysis of the scientific connotation, main characteristics, framework, discipline basis, method system and core tasks of process hydrology. Given the theoretical value and practical significance of process hydrology, it can be concluded that the development of process hydrology can provide measures and new views to cope with new challenges in hydrology that the sustainable developments of nature, economy and society faces.
2021,49(1):1-6, DOI: 10. 3876/ j. issn.1000-1980.2021.01.001
Abstract:
This study introduces the basic situation of China‘s small and medium-sized rivers and flood disasters, and then key difficulties as well as urgent scientific and technological problems in the flood prevention of small and medium-sized rivers were analyzed. Thereafter, the study puts forward the strategy and measures for the flood forecasting and early warning of small and medium- sized rivers. Besides, prospects for the future forecasting, risk early warning, and refined risk management concepts and practices are also proposed. It will realize the change from the hydrological element forecasting to the flood impact forecasting, from the flood threshold-based warning to the flood risk warning, from the " prediction-response" emergency disposal to the grid refinement risk management, from the monitoring data provision to the information product service, in which the development level of the hydrological modernization is continuously improved.
This study introduces the basic situation of China‘s small and medium-sized rivers and flood disasters, and then key difficulties as well as urgent scientific and technological problems in the flood prevention of small and medium-sized rivers were analyzed. Thereafter, the study puts forward the strategy and measures for the flood forecasting and early warning of small and medium- sized rivers. Besides, prospects for the future forecasting, risk early warning, and refined risk management concepts and practices are also proposed. It will realize the change from the hydrological element forecasting to the flood impact forecasting, from the flood threshold-based warning to the flood risk warning, from the " prediction-response" emergency disposal to the grid refinement risk management, from the monitoring data provision to the information product service, in which the development level of the hydrological modernization is continuously improved.
2020,48(1):22-28, DOI: 10.3876/j.issn.1000-1980.2020.01.004
Abstract:
This study reviewed the environmental behavior of microplastics(including the adsorption of organic pollutants and the release of organic additives after entering water), and the interaction between microplastics and organic pollutants after entering into water body, including its mechanism, influencing factors and biological toxicity. It also analyzed the deficiencies of current researches, and believed that, in order to provide theoretical basis for further study on the behavior and function of microplastics, it is necessary to expand the research on the interaction between microplastics and organic pollutants, such as strengthening the research in the freshwater environment, establishing systematic research system, and paying attention to the effect of biofilm
This study reviewed the environmental behavior of microplastics(including the adsorption of organic pollutants and the release of organic additives after entering water), and the interaction between microplastics and organic pollutants after entering into water body, including its mechanism, influencing factors and biological toxicity. It also analyzed the deficiencies of current researches, and believed that, in order to provide theoretical basis for further study on the behavior and function of microplastics, it is necessary to expand the research on the interaction between microplastics and organic pollutants, such as strengthening the research in the freshwater environment, establishing systematic research system, and paying attention to the effect of biofilm
2020,48(2):95-101, DOI: 10.3876/j.issn.1000-1980.2020.02.001
Abstract:
Although the Piecewise Muskingum method for river flood calculation has been widely used in China, the major limitation that hinders the further application of the Piecewise Muskingum method within distributed models still needs to be addressed. This method with empirical parameters cannot consider the impact of changing river cross-section characteristics and hydraulic roughness on the flood computation. In this study, the Muskingum-Cunge-Todini variable parameter method and the non-linear reservoir method, which could consider the channel cross-section geometry and hydraulic roughness, were used in the river flood calculation in the middle part of Huaihe river, from Wujiadu to Xiaoliuxiang, and the middle part of Hutuo River, from Huangbizhuang to Beizhongshan. In addition, the river flood calculation with the Piecewise Muskingum method also has been conducted as a comparison. Initial tests indicate that the Muskingum-Cunge-Todini variable parameter method and the non-linear reservoir method have high simulation accuracy in the studied cases. The correct rate of flood peak is above 86%, and the coefficient of certainty is greater than 0. 8. This study can provide references for the flood calculation considering the change of the channel cross section and hydraulic roughness characteristics.
Although the Piecewise Muskingum method for river flood calculation has been widely used in China, the major limitation that hinders the further application of the Piecewise Muskingum method within distributed models still needs to be addressed. This method with empirical parameters cannot consider the impact of changing river cross-section characteristics and hydraulic roughness on the flood computation. In this study, the Muskingum-Cunge-Todini variable parameter method and the non-linear reservoir method, which could consider the channel cross-section geometry and hydraulic roughness, were used in the river flood calculation in the middle part of Huaihe river, from Wujiadu to Xiaoliuxiang, and the middle part of Hutuo River, from Huangbizhuang to Beizhongshan. In addition, the river flood calculation with the Piecewise Muskingum method also has been conducted as a comparison. Initial tests indicate that the Muskingum-Cunge-Todini variable parameter method and the non-linear reservoir method have high simulation accuracy in the studied cases. The correct rate of flood peak is above 86%, and the coefficient of certainty is greater than 0. 8. This study can provide references for the flood calculation considering the change of the channel cross section and hydraulic roughness characteristics.
2019,47(1):7-12, DOI: 10.3876/j.issn.1000-1980.2019.01.002
Abstract:
In order to make full use of the continues pumping test data to estimate the hydraulic conductivity(K), the transmissivity(T)and the storage coefficient(μ*)of different head depression cones in a confined aquifer, a dimensionless analytical solution of drawdown transients with variable pumping rates was derived based on the Theis formula and the principle of superposition. Furthermore, a new type curve method was proposed. The in-situ pumping test was conducted to obtain the drawdown record perturbed by stepwise rates. Then, the drawdown curve was used to match the corresponding type curve. After that, this method selects one match point and records its coordinate values on both the type curve and the real drawdown curve. By substituting these recorded values into related formulas, the hydraulic parameters of the confined aquifer can be determined. This method was applied to a field pumping test conducted at a southern highway in Wuxi, Jiangsu Province, China. The type curve matching process is implemented in stages. Field test results reveal that the hydraulic conductivity of the confined aquifer with the 2-3 silt layer are 5. 12×10-4 cm/s, 2. 54×10-3 cm/s and 2. 83×10-3 cm/s respectively, which are corresponding to three-stage stepwise pumping rates.
In order to make full use of the continues pumping test data to estimate the hydraulic conductivity(K), the transmissivity(T)and the storage coefficient(μ*)of different head depression cones in a confined aquifer, a dimensionless analytical solution of drawdown transients with variable pumping rates was derived based on the Theis formula and the principle of superposition. Furthermore, a new type curve method was proposed. The in-situ pumping test was conducted to obtain the drawdown record perturbed by stepwise rates. Then, the drawdown curve was used to match the corresponding type curve. After that, this method selects one match point and records its coordinate values on both the type curve and the real drawdown curve. By substituting these recorded values into related formulas, the hydraulic parameters of the confined aquifer can be determined. This method was applied to a field pumping test conducted at a southern highway in Wuxi, Jiangsu Province, China. The type curve matching process is implemented in stages. Field test results reveal that the hydraulic conductivity of the confined aquifer with the 2-3 silt layer are 5. 12×10-4 cm/s, 2. 54×10-3 cm/s and 2. 83×10-3 cm/s respectively, which are corresponding to three-stage stepwise pumping rates.
2017,45(3):277-282, DOI: 10.3876/j.issn.1000-1980.2017.03.014
Abstract:
It is necessary to monitor the state of ZnO arresters to guarantee their safe operation. In order to select a best way to monitor the state of arresters, the advantages, disadvantages, and application of each monitoring method were analyzed. The results show that the harmonic analysis method is the most effective method. The properties of the harmonic analysis method in practical application could be improved by modifying the resistive leakage current and selecting an appropriate window function when conducting fast discrete Fourier transform on the collected signals. Through review of monitoring technologies in China and abroad, it can be found that in the future, the overall development trend of online monitoring methods of ZnO arresters is to develop fully automatic and multi-functional integrated online insulation monitoring systems.
It is necessary to monitor the state of ZnO arresters to guarantee their safe operation. In order to select a best way to monitor the state of arresters, the advantages, disadvantages, and application of each monitoring method were analyzed. The results show that the harmonic analysis method is the most effective method. The properties of the harmonic analysis method in practical application could be improved by modifying the resistive leakage current and selecting an appropriate window function when conducting fast discrete Fourier transform on the collected signals. Through review of monitoring technologies in China and abroad, it can be found that in the future, the overall development trend of online monitoring methods of ZnO arresters is to develop fully automatic and multi-functional integrated online insulation monitoring systems.
2020,48(3):189-194, DOI: 10.3876/j.issn.1000-1980.2020.03.001
Abstract:
On the basis of the original Xin’anjiang model, this study solved the matching problem between sub-catchment and grid channel, and enabled the model to calculate channel routing according to actual river conditions. A hybrid rainfall-runoff model(named XAJ-DCH)was further proposed by coupling the XAJ model with diffusion wave method and Muskingum-Cunge-Todini(MCT)method by accounting for the lateral inflow. The flood prediction capabilities of the traditional XAJ model and the XAJ-DCH model were compared at hourly scale for the Chengcun catchment. The performance of both models is comparable and satisfactory, and thus, the rationality of the new model is verified. By improving the channel routing method in the Xin’anjiang model, the spatiotemporal variability can be further considered. Furthermore, compared with the Xin’anjiang model, the XAJ-DCH model can not only be used to simulate the discharge at the outlet station, but also to predict the water level and discharge of the interior station in the catchment. In addition, the diffusion wave method was introduced into the XAJ-DCH model, which can improve the prediction accuracy in hydraulically mild slope area by accounting for the backwater effects.
On the basis of the original Xin’anjiang model, this study solved the matching problem between sub-catchment and grid channel, and enabled the model to calculate channel routing according to actual river conditions. A hybrid rainfall-runoff model(named XAJ-DCH)was further proposed by coupling the XAJ model with diffusion wave method and Muskingum-Cunge-Todini(MCT)method by accounting for the lateral inflow. The flood prediction capabilities of the traditional XAJ model and the XAJ-DCH model were compared at hourly scale for the Chengcun catchment. The performance of both models is comparable and satisfactory, and thus, the rationality of the new model is verified. By improving the channel routing method in the Xin’anjiang model, the spatiotemporal variability can be further considered. Furthermore, compared with the Xin’anjiang model, the XAJ-DCH model can not only be used to simulate the discharge at the outlet station, but also to predict the water level and discharge of the interior station in the catchment. In addition, the diffusion wave method was introduced into the XAJ-DCH model, which can improve the prediction accuracy in hydraulically mild slope area by accounting for the backwater effects.
2015,43(5):384-394, DOI: 10.3876/j.issn.1000-1980.2015.05.002
Abstract:
Water resources constraints constitute a significant bottleneck in China. The origins of water are worth further research, as they relate to the Earth’s formation, the origins of the water globe, and the issue of deep water. First, we attempt to divide the hydrosphere into several belts and focus on the complex interaction between spherical layers. Then, water resources development issues are discussed, the concept of the comprehensive effect and related evaluation of the evolution of an entire basin is developed based on the spherical layer movement, and the evolution of the middle reaches of the Yellow River, the middle and upper reaches of the Yangtze River, and the inland river basin is analyzed based on this concept. Water resources development should consider three properties: limits, relativity, and ecology, as well as the instructive observation that water can carry a boat and also overturn a boat. The comprehensive development and utilization of water from six different sources, including rainwater, river water, lake water, groundwater, reservoir water, and sea water, are examined. We also discuss prevention and mitigation of six types of disasters related to the six water sources: flooding, waterlogging, drought, storm surges, geological disasters, and water pollution. It is pointed out that segmented control of water quality in the reservoir area, comprehensive development of surface water and groundwater, and construction of underground reservoirs are important. Finally, some suggestions for water resources development and disaster prevention are proposed: cooperation between multiple departments and multiple disciplines, implementation of water-saving measures, construction of an enhanced water resources network, determination of demand according to provision, and improvement of an investigation system for evaluation and development.
Water resources constraints constitute a significant bottleneck in China. The origins of water are worth further research, as they relate to the Earth’s formation, the origins of the water globe, and the issue of deep water. First, we attempt to divide the hydrosphere into several belts and focus on the complex interaction between spherical layers. Then, water resources development issues are discussed, the concept of the comprehensive effect and related evaluation of the evolution of an entire basin is developed based on the spherical layer movement, and the evolution of the middle reaches of the Yellow River, the middle and upper reaches of the Yangtze River, and the inland river basin is analyzed based on this concept. Water resources development should consider three properties: limits, relativity, and ecology, as well as the instructive observation that water can carry a boat and also overturn a boat. The comprehensive development and utilization of water from six different sources, including rainwater, river water, lake water, groundwater, reservoir water, and sea water, are examined. We also discuss prevention and mitigation of six types of disasters related to the six water sources: flooding, waterlogging, drought, storm surges, geological disasters, and water pollution. It is pointed out that segmented control of water quality in the reservoir area, comprehensive development of surface water and groundwater, and construction of underground reservoirs are important. Finally, some suggestions for water resources development and disaster prevention are proposed: cooperation between multiple departments and multiple disciplines, implementation of water-saving measures, construction of an enhanced water resources network, determination of demand according to provision, and improvement of an investigation system for evaluation and development.
2020,48(4):377-384, DOI: 10.3876/j.issn.1000-1980.2020.04.013
Abstract:
Firstly, the necessity of power electronization is explained from the development history of the power electronics and the challenges in power generation, transmission, distribution, and consumption. Secondly, the driving factors of power electronization, such as politics, economy, and technology, are elaborated in three aspects, including energy security and political construction, the resource and environmental benefits, and the transformation of power generation, transmission, distribution and consumption. Finally, the development trends and main restrictive factors of power electronization in power system are analyzed, and related study directions are summarized to provide some references and suggestions for future study.
Firstly, the necessity of power electronization is explained from the development history of the power electronics and the challenges in power generation, transmission, distribution, and consumption. Secondly, the driving factors of power electronization, such as politics, economy, and technology, are elaborated in three aspects, including energy security and political construction, the resource and environmental benefits, and the transformation of power generation, transmission, distribution and consumption. Finally, the development trends and main restrictive factors of power electronization in power system are analyzed, and related study directions are summarized to provide some references and suggestions for future study.
2020,48(2):102-108, DOI: 10.3876/j.issn.1000-1980.2020.02.002
Abstract:
In order to obtain the characteristics of wind field and flow field as well as the influence of different types of wind fields on the flow field of Taihu Lake, 6 acoustic doppler current profilers(ADCP)and 4 meteorological stations were set up in different areas of Taihu Lake, and the synchronous data of flow field and wind field were obtained. The results show the floolwing: (a)The spatial distribution of wind field in Taihu Lake was not uniform, the wind speed varied greatly among 4 stations, and the difference of wind direction was expanded along with the decrease of wind speed. (b)The flow field in Taihu Lake had obvious characteristics of wind-generated flow. When the average wind speed was greater than 6. 7 m/s, there was a counterclockwise circulation that appeared in the western lake area, and there was no obvious flow stratification during this period. When the average wind speed was less than 3. 8 m/s, the circulation in the west fade away. However, the flow stratification was obviously developed, the current direction of each layer was relatively stable but different, and the compensation flow developed. (c)According to the observed data, the percentage of current speed less than 10 cm/s was more than 90%, and the current speed can reach 20 cm/s under strong wind conditions.
In order to obtain the characteristics of wind field and flow field as well as the influence of different types of wind fields on the flow field of Taihu Lake, 6 acoustic doppler current profilers(ADCP)and 4 meteorological stations were set up in different areas of Taihu Lake, and the synchronous data of flow field and wind field were obtained. The results show the floolwing: (a)The spatial distribution of wind field in Taihu Lake was not uniform, the wind speed varied greatly among 4 stations, and the difference of wind direction was expanded along with the decrease of wind speed. (b)The flow field in Taihu Lake had obvious characteristics of wind-generated flow. When the average wind speed was greater than 6. 7 m/s, there was a counterclockwise circulation that appeared in the western lake area, and there was no obvious flow stratification during this period. When the average wind speed was less than 3. 8 m/s, the circulation in the west fade away. However, the flow stratification was obviously developed, the current direction of each layer was relatively stable but different, and the compensation flow developed. (c)According to the observed data, the percentage of current speed less than 10 cm/s was more than 90%, and the current speed can reach 20 cm/s under strong wind conditions.
Journal information
- Competent unit：
Ministry of Education, P. R.China
- Organizers：
Hohai University
- Editor-in-chief：
TANG Hongwu
- Address：
1 Xikang Road, Nanjing 210098, P.R. China
- Postcode：
210098
- Phone：
86-25-83786343
- Email：
xb@hhu.edu.cn
- CN：
32-1117/TV
- ISSN：
1000-1980
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