Abstract:The technological progress of geotube engineering in China was demonstrated through reviewing the representative geotube dams since 1980s. The development of project design, process equipment and technical measures was analyzed and the results of fundamental research for engineering applications were also summarized. Taken the widely used high strength elliptical geotubes abroad as reference, simplified ordinary strength flat geotubes were developed in China. They have been important components in the construction of huge infrastructures such as fresh water reservoirs in estuaries, deep-draft channel improvement, harbors, airports, dikes in coastal areas, wave breakers, beach reclamation, etc. The regions of geotube dam construction range from intertidal zones to complex areas with deep tidal currents. The construction operation of geotube dams has been changed mainly from manpower to equipment and until recently underwater construction in complex deep-water regions can be accomplished by multi-integrated equipment. The encircled area by geotube dams is becoming larger and super large closure gaps can be closed successfully.

Abstract:In order to obtain the deformation and stability characteristics of the uncovered flat geotubes structure under wave action, the wave force exerted on the flat geotubes was analyzed. By introducing a deformation indicator, the geotubes dam stability formula considering the tube deformation was derived in the case of sliding instability and overturning instability. Based on the instability forms and the corresponding deformation parameters obtained from the model test, the effect of deformation on wave force and gravity force in the case of sliding instability and the corresponding torque in the case of overturning instability was discussed respectively. The stability formula considering the geotubes deformation can be further improved if the deformation indicator is calculated. This formula fully considers the geotubes deformation characteristics caused by wave force and it has universal applicability.

Abstract:The slow dewatering speed of geotextile tubes filled with high clay(silt)particle-content soil generally cannot meet the requirement of the limited construction period in the coastal and estuarine areas of China. A preliminary method of actively discharging the surface muddy water in geotubes to improve the dewatering speed was proposed based on the hanging bag tests and settlement tests of filling slurry. The feasibility and actual results of the new dewatering method has been verified by both laboratory model tests and large-scale field model tests. Based on the test results and the field engineering experience, an efficient construction technology that can actively discharge muddy water with alternately filling and discharging techniques to accelerate dewatering speed of geotextile tubes filled with high clay(silt)particle-content soil was generalized. The specific procedure and construction steps were also provided.

Abstract:To study the problem of sand erosion through seams between geotubes, erosion stability of the backfill sand inside the dam core was carried out by a self-developed experimental apparatus. The physical model test was performed in unidirectional flow conditions and wave conditions. The transport characteristics of sand particles and scouring stability were analyzed. Experimental results show that in the condition of unidirectional flow, the process and mechanism of sand particle erosion has a “groove type” characteristic. In the condition of wave flow, arch-like structures will appear, form and collapse and correspondingly the erosion process can be divided into three stages of lashing, arching and stability. The critical length of the sand pile inside the seams between tubes was chosen as a criterion parameter to determine the erosion stability of seams between geotubes. The scouring stability in wave flow conditions can be determined by comparing the length of the seam between geotubes and the length of the sand pile inside the seam in real engineering works.

Abstract:For the problem of sand erosion from the side walls of punctured geotubes, a set of experimental apparatus was developed to study the erosion stability along seams between tubes of a punctured geotube dam. Based on the experiments in both unidirectional flow and wave flow conditions, characteristics of erosion process and sand transport in the seams between geotubes were summarized. The impact of breakage on the scouring stability in unidirectional flow conditions was also analyzed. The results show that scouring stability in the seams between geotubes in unidirectional flow conditions is related to the threshold velocity of the sand particles with the maximum diameter, velocity magnitudes inside the seam and the extent of the breakage. Scouring instability can easily occur in the case of larger breakage, higher flow velocity and lower threshold velocity of sand particles. In wave flow conditions, the critical peak water pressure is selected as a criterion parameter to determine the stability of seams between punctured geotubes. The scouring stability in wave flow conditions for real engineering works can be determined by comparing the peak water pressure in the seams with the critical value.

Abstract:To improve the construction technology of geotube engineering in China, design for informatization construction technology in geotube embankment engineering and its preliminary practices was strated from the aspect of information collection, information analysis and processing, information feedback, control and decision. According to the characteristics and monitoring principles of geotube embankment, wave parameters, tidal level, surface flow velocity, wind speed, foundation deformation and foundation seepage are selected as the monitoring indicators. The corresponding monitoring equipment, site deployment methods and installation schemes are proposed based on the selected monitoring indicators. The calculation programs of safety construction of geotube embankments are presented respectively for each monitoring indicator. In addition, the common problems and corresponding solutions in the construction of geotube projects are presented, which can be used to build an expert system. Information technology can provide technical support for the construction safety and quality control of geotube engineering.

Abstract:For the situation that the placement of bevel dumped geocontainers cannot be accurately predicted in estuarine and coastal engineering, theoretical computational formulas of the settling coordinates were presented through force analysis of the dumped geocontainers. Experimental study was carried out in a flume based on the construction parameters in practical engineering. Settling characteristics of the geocontainer were investigated under the condition of various water depth and flow velocities and thus empirical formulas of the drag coefficients were obtained. The comparison between experiment and calculation shows that the calculated trajectories of the geocontainer agree well with the experimental ones in shallow water. Geocontainers are more likely to rotate under the condition of deep water, which causes a slight increase in the dispersion of horizontal settling distance. For the geocontainers widely used in practical projects with 8m in the perimeter of sand-filling opening, 62 m in length and 78.54% of the filling ratio, the horizontal and vertical drag coefficients of the geocontainer range from 0. 30 to 4.27 and 0.84 to 2.53 respectively.

Abstract:Based on the entropy weighting method, a comprehensive assessment system for the relationship between scientific and technological innovation and water use efficiency was constructed. The indexes of innovation and water use efficiency were calculated for Anhui Province as an example. By use of SPSS19. 0, the marginal contribution of scientific and technological innovation to water use efficiency were calculated based on the canonical correlation analysis and partial least-squares regression analysis method. The path analysis method was adopted to investigate the direct and indirect effects of scientific and technological innovation on water use efficiency. The results show that the scientific and technological innovation index of Anhui Province jumped from 0.0129 in 2005 to 0.9742 in 2014, while the water use efficiency index rose from 0. 4616 in 2005 to 0.8558 in 2014, indicating a synthetic evolution. The total elasticity coefficient of scientific and technological innovation to the marginal effect of water use efficiency is 0.09799, among which, the direct elasticity coefficient is 0.065253 and the indirect elasticity coefficient is 0.032737. The indirect elasticity coefficients of economic growth, regulation policy and industrial structure are 0.02583, 0.00754 and 0.00027 respectively. Based on the research results, the policy suggestions are proposed to improve water use efficiency.

Abstract:The development of hydropower resources and the construction of water storage facilities in major countries was analyzed, especially for developed countries. Based on the persisting track of the achievements and data for hydropower resources at home and abroad, the hydropower development level in China was assessed from an international perspective. The present study shows that China has the largest hydropower resources reserves in the world and the annual energy production is also in the top of the world. The economic development degree of hydropower in 2013 is 52%, which is lower than that in main developed countries(higher than 70%). The hydropower development degree in China is slightly lower than that in countries with moderate human development index of 0.7~0.8. Some total quantity indicators in the development and utilization of water resources in China lead the world, but the degree of development and utilization and the degree of socio-economic matching is still lower compared with developed countries.

Abstract:To carry out frequency analysis for the Manas River in Xinjiang based on the nearly 60 years runoff sequence, a mixed distribution model and a conditional probability distribution model were constructed using the Mann-Kendall test and t-test. The results shows that the annual runoff series of the Manas River in 1956~2014 have great variations and the year 1995 is the sequence variation year. In the upper part of the fitted curve, the mixed distribution and the conditional probability distribution are similar, but big difference exists compared the P-III distribution. In the middle of the fitted curve, the fitting effect of the mixed distribution is better than both conditional probability distribution and P-III distribution. In the lower part of the fitted curve, the fitting effects of all the three distributions are pretty good, and there is no obvious fluctuations. Through the K-S test analysis and comparing the values of OLS, ABS and AIC, the mixed distribution model is more suitable for frequency analysis of the annual runoff in the Manas River Basin.

Abstract:Coastal vegetation can function as the energy attenuator for solitary waves and the primary objective of the present study is to explore the performance of roots, stems, canopies and distribution densities on the height decay of a solitary wave passing through a vegetation belt. If the wave nonlinearity is greater than 0.11, the wave height attenuation induced by stems is not consistent with power or exponential laws. The trends of wave height decay induced by roots and stems are similar to that of pure stems when the submergence ratios are equal to 0.67. If the submergence ratios are less than 0.67 and the wave nonlinearity is not less than 0.30, the wave height attenuation under the effects of stems and canopies fits well to power or exponential laws. Under non-submerged conditions, the intensities of wave height attenuation affected by the vegetation belt decrease and the boundary effects of the vegetation belt become weaker as the distribution densities decease. Compared with roots and stems, the characteristics of solitary wave height attenuation can be efficiently influenced by canopies. In addition to the effects of roots, stems, canopies and distribution densities, the characteristics of wave height attenuation is related to the submergence ratio and solitary wave nonlinearity.

Abstract:To explore the practical application modes of underground reservoir system engineering in sponge city construction, the concepts, classifications and engineering practice on underground reservoirs at home and abroad were reviewed. The connotation and request of a sponge city, the advantages of underground reservoirs in sponge city construction and the basic principles of regulation, purification and water cycle path were presented. The feasibility of underground reservoir system in the application of sponge city construction was also demonstrated. Based on the key principles in sponge city construction, such as infiltration, detention, storage, purifying, and drainage, an overall structure of an underground reservoir system engineering was designed. The overall structure consists of eight systems, including surface water impoundment, land rainwater collection, recharge, groundwater storage, water intaking, water discharge, wastewater discharge and treatment, and central monitoring projects.

Abstract:In order to study the landslide failure of rock slopes induced by rock landslide surges in the Three Gorges Reservoir Region, physical model tests of rock landslide in Wanzhou port have been designed as the prototype. The influences of landslide volumes, inclination angles of the slip surface and three different slope soil particle diameters were studied in the experiment. The scouring depthsand the overallerosion characteristics of slopesin the range of 15 m below and above static water level have been analyzed. The results show that the maximum scouring depths are in positive correlation with the width and thickness of the landslide mass. For large volume of landslide mass, the scouring depth can reach its maxima if the inclination angle of the slip face is 40° while for relatively smaller volume of landslide mass, the inclination angle is 60°. The suggested scope for bank protection is in the range of 7 m below and above static water level. The empirical formula for the maximum erosion depth of bank slope was obtained based on experimental data.