Abstract:In this paper,the characteristics and the development status of rockfill dam with surface impermeable geomembrane (i.e., membrane faced rockfill dam,MFRD) during half a century is summed up and.the technology status and constructing requirement on MFRD in China is analyzed. The overall advantage of MFRD is that it is impermeable, suitable to differential deformation, brief to construct and cheap. Due to overseas protection of patents, unlike the concrete faced rockfill dam and the roller compacted concrete dam, the technology of MFRD lacks of wide dissemination and application. Since the first MFRD was built elsewhere, no high MFRD has ever been constructed in China. For the demand of clean energy of hydropower and conditions of ecological environment, MFRD is required to play an important role, and corresponding technology of design and analysis on MFRD demand further studies as well as a systematic and deeper integration. Recent preliminary studies on the result of key technology of MFRD are summarized, which include mechanism of anchoring influence at perimeter of MFRD and eliminating approach, biaxial tensile mechanical property of geomembrane used as surface barrier of high rockfill dam, analysis of stress and deformation characteristics of geomembrane surface barrier for rockfill dam, experimental research on engineering property of non-granular cushion for geomembrane surface barrier of high rockfill dam, and probabilistic analysis of geomembrane puncture on rockfill dam surface.

Abstract:A key technology issue firstly faced in studding and designing membrane faced rockfill dam (MFRD) is that at perimeter of surface membrane, under definite depth of water, “anchorages of surface membrane” are formed and then “anchoring influences”, affecting the safety of faced membrane, are produced. Based on material test and structure analysis, the forming mechanism of anchoring influence is analyzed and the necessary and sufficient conditions of anchoring influence formed are proposed. After designing structure experiment model of anchoring influence at perimeter of surface membrane on MFRD, it is proved by preliminary experiment that anchoring influence cannot be avoid if surface membrane is placed on dam according to traditional way. Based on a full consideration of construction technology and sufficient conditions of anchoring influence formed, the idea of eliminating anchoring influence under the condition of no damage of surface, one should increasing the initial gauge length between anchorages of surface membrane in order to substitute geometry deformation for the material deformation between anchorages of surface membrane during dam displacement. The approach of design is that the paving line of surface membrane is high to anchoring line, thus the paving line of surface membrane goes back to anchoring line after displacement of the dam surface.

Abstract:The geomembrane impervious barrier of hydraulic structure engineering is usually designed on basis of results of uniaxial tensile test. But geomembrane is actually in plain stress state in practical project. The principal stresses are in biaxial stress state. Two self-developed biaxial tensile devices and corresponding test methods were employed to investigate the mechanical property of geomembrane which is used as the surface barrier of high rock-fill dam. Several groups of tests with different biaxial tensile conditions were carried out for several geomembrane usually used in rock-fill dam. Then the experimental results were analyzed in contrast to that of conventional uniaxial tension tests. The mechanical property include tension strength, elongation, elastic modulus, Poisson’s ratio and true stress-strain relationship under different biaxial tension states were obtained. That revealed the stress-deformation properties and failure mechanism of geomembrane in actual working condition for rock-fill dam. The test results can provide some theoretical foundations and basis for the design and numerical analysis of geomembrane surface barrier of rock-fill dam.

Abstract:In the current state, the numerical computation and structural analysis of earth-rock dam impermeable structure present shortcomings. In this paper, we modified and improved the traditional Finite Element Method (FEM) model by using a new linkage unit to simulate the interfacial shear characteristics between the lower cushion and geomembrane. Additionally we improved the geomembrane finite element analysis accuracy without additional FEM overall size, which can greatly improve the computational efficiency. We successfully simulated the geomembrane force-deformation characteristics at anchoring points for the possible anchoring effect of geomembrane impermeable structure around dam face through adding three-dimensional spring unit at anchor points. The results show that impermeable geomembrane at the top of earth-rock dam face suffered smaller tension, but at the anchoring points at the bottom, it suffered lager tension, so it is prone to tensile crack.

Abstract:For the high rockfill dam built on the foundation of large overburden depth, the traditional cushion materials cannot maintain the stability of geomembrane surface barrier and satisfy the requirement of adaptability to dam deformation. Laboratory experiments such as: permeability test, compressive strength test, flexural property test, interface direct test, and structural model test were carried to evaluate the permeability, basic mechanical property, interface strength, and adaptability to deformation of new porous cushion material (polymer permeable concrete). Additionally, comparative tests and analysis of traditional cushion material-non-fine concrete-were also conducted. The test results show that polymer permeable concrete not only has high mechanical strength and water permeability, but also has lower elasticity modulus and obvious toughness. It is indicated that polymer permeable concrete has stronger adaptability to flexural deformation compared to non-fine concrete. It is concluded that the polymer permeable concrete is a better alternative to the traditional cushion material of geomembrane surface barrier for high rockfill dam built on thick foundation.

Abstract:For the randomness and disordered issues of the contact status of earth-rock dam geomembrane and granular cushion, combined with the relationship between the mechanical strength of geomembrane and ability to resist bursting and piercing, a calculation method of probability of bursting and piercing in local geomembrane under simplified conditions is established. Also, this paper analyzed the relation between different granular size and pressures of granular cushion and bursting and piercing probability of local geomembrane. Considering a certain earth-rock dam with impermeable membrane as an example, this paper provided probability distribution of the safety of impermeable membrane structure under overall geomembrane force-deformation condition. The results show that: the greater the pressure, the larger the particle size, the higher the possibility of bursting and piercing of geomembrane, and due to the uncertain imbalance force direction of the local geomembrane, the mentioned relationship presents two functions.

Abstract:Engineering of drainage and water log prevention is an important measure to prevent and mitigate the flood disasters. The scale of the engineering is mainly restricted by rain flood variation within the project life period and the level of economic and social development. This paper discusses the characteristics of the changes of city rainwater, the causes of flood disaster and disaster prevention and reduction principle of different types of engineering measures. Additionally, it also explains the concept of disaster probability and design standard and presents the hydrological calculation task about planning and designing of engineering of drainage and water log prevention in urban areas. By doing it so, it discusses the rainstorm intensity formula, design rainstorm hydrograph and other problems, which are involved in city design storm. Finally, it is described the principle and method of confirming design flood from design storm.

Abstract:This paper analyzes the total water control targets in states (cites) in order to implement the general requirements of the most stringent water management system. Based on the current situation of water supply pattern in Yunnan Province, combined with the water project construction planning, a model for water resource system simulation is developed with water resources configuration management tool MIKE BASIN. Additionally, it is also presented the water allocation among various sectors and states (cites), and water-supply pattern among the various water projects in 2020 and 2030. To 2030 target year, through promoting construction of water-saving society, water projects, Water Diversion of the Central Yunnan and other projects, ecological and socio-economic water demand will be satisfied, in line with total water control and water efficiency control constraints.

Abstract:This paper introduces the collection of essays forToward a Sustainable Water Future: Visions for 2050, which is organized by Environmental and Water Resources Institute (EWRI) of the American Society of Civil Engineers (ASCE). These essays, written by 52 American scientists, analyzed and described development road of water resources and environment in science and engineering technology aspects. There are three parts in the collection: Planning and Policy, Education, Science and Technology.

Abstract:In this paper, we analyze the function of the levee road in order to ensure that it meets the actual needs of the development process. Levee road can be divided into four categories: flood control road, comprehensive road, traffic road, and landscape road. These four categories are proposed according to the main functions of the levee road, the level of levee project, the location where roads lie, and the relationship between it and local road network. Additionally, regarding to the level of dike and traffic volume, the levee road construction’s standards can be divided into two or three levels. Finally, we proposed a classification and grading system of levee road.

Abstract:The composite lining canal is a kind of lining form which combine compound geomembrane and concrete lining structure. In order to improve the performance of the canal of antifreezing expansion damage, aimed at the lining trapezoidal canal with arc-bottom, the friction of the compound geomembrane and the concrete lining structure are considered. By analyzing the damage mechanism of frostheaving on the concrete lining of the channel with arc-bottom section, it has been indicated that the slope lining is seen as a cantilever beam under the function of frost-heaving force, frozen force and the friction. Further, it has been found that the slope lining plate and the bottom lining plate are combined deformation members under the loads of bending and compressing. The mechanics models of frost-heaving damage of composite lining canal with arc-bottom are built. The internal forces of the canal slope lining plate and the canal bottom lining plate with arc-bottom are solved and the thickness of the lining plates are assessed. Compared with the concrete canal, the tangential force of constraint of the lining canal is reduced by adding the compound geomembrane because of a number of allowable displacements of frost heave. The stress condition of the lining structure itself is improved, and the distribution of the frost-heave capacity is more balanced. These have played an important role in anti-freezing expansion damage and have disclosed the mechanism of frost-heaving damage. Compared with the trapezoidal canal, the integration of the lining canal with arc-bottom combined with the slope lining plate and the bottom lining plate is better because of its antiarching effect is obvious and it’s of more benefit to anti-freezing expansion damage. To sum up, this study provides some theory basis for the technology of anti-freezing expansion damage of the compound lining canal.

Abstract:We applied saturated and unsaturated theory to establish a three dimensional finite element model (FEM), based on a proposed concrete faced sand-gravel dam, aiming to simulate the seepage field of the dam and its foundation under the condition of slab joint local failure. The different length, width, and position of the slab joint local failure were combined in the simulation condition. Overall, the results showed that a single local failure of slab joint had large influence on the local seepage field around the slab joint failure and little influence on the entire seepage field. Additionally, the saturated field is enlarged by the increase of length and width of the slab joint failure and the decrease of the position, besides the seepage field is affected mostly by the position and minimally by the width. The results also revealed that the great increase of the saturated surface was caused by the slab joint full-length failure under the action of superhigh-head. Thus, these factors should be taken into consideration during the design in order to avoid large-scale failure of slab joint.

Abstract:In the present paper we improve the method to calculate socketed depth of large diameter soft rock socketed piles in water project, and explore the relationship between the socketed depth and influencing parameters. Assuming that the rock resistance of rock-socketed pile side is linear distributed and the rock failure criteria matches with the two parabolic Mohr criterions, it is possible to derive the rock-socketed pile’s calculation model on the basis of rock-socketed pile subjected to normal stress and tangential shear stress. Hence, the minimum depth analytical solution can be given by hydrostatic equilibrium. By using a laboratory model test and a practical project to verify the method, results show that: socket length increases with the increase of the horizontal force and continuously decreases with the increase of the pile diameter and rock uniaxial compressive strength. However, when the rock uniaxial compressive strength increases to a certain value, the rock-socketed depth shows a slight decreasing trend. Additionally, the overburden pressure has little effect on the rock-socketed depth.

Abstract:Due to some deficiencies in the combination rule of D-S evidence theory, some dynamic signatures for damage location are determined according to the vibration characteristics of guide wall structure induced by flood discharge. The responses measured from health state and damage state are utilized to respectively calculate these dynamic signatures, which are applied to preliminary judgment of damage location. And the identification results are regarded as evidences for fusion decision to decide the damage location by using the improved D-S evidence theory. The results demonstrate that the accurate decision can be obtained based on few evidences by utilizing the method proposed, the errors originated from sensor and noise are avoided, and the influence on final fusion decision of the wrong evidence is effectively reduced. The method based on dynamic signatures and improved D-S evidence theory is applicable to damage localization.

Abstract:Based on the normal operation charts of cascade reservoirs, we proposed a mathematical model of optimal operation chart aiming to reach at the maximum value of annual average electricity generation. In this regard, we suggested a solving algorithm to reduce dimensionalities based on multiple iterations as follow: reduce spatial multi-reservoir dimensionality by iteration in reservoir turns; reduce multi-curve dimensionality by iteration in rule curve turns; and reduce multi-state dimensionality of rule curve with progressive optimality algorithm. Overall, results based on experiments considering Wananxi-Baisha cascade reservoirs as a case studies show that this optimum method provides optimal operation charts of cascade reservoirs in rational form as well as significant increases in electricity generation of the reservoir group while compared with traditional method.

Abstract:Surrounding rock stability and lining structure stress in acute angle region of reinforced concrete bifurcation is complex. Based on the practice of a certain pumped-storage power station, three-dimensional numerical model of the diversion bifurcation is proposed and the acute angle of bifurcation is optimized. By using finite element method (FEM) comparative analysis of stress and deformation of lining structure as well as the surrounding rock stability before and after optimization of different round radius have been performed. Numerical results show that after optimization, the range of plastic zone increases during construction period and the plastic concentration of surrounding rock slows down while the deformation of surrounding rock increases slightly because span at bifurcation point increases. The stress concentration of bifurcation and rebar reduce during operation period, thus the stress distributes more uniform. The bifurcation lining mainly endures compressive stress during overhaul period and the degree of local compressive stress concentration reduces with proper optimization, which has little effect on deformation. Thus, if surrounding rock is stable, one should reduce excavation and choose proper round radius, which is conducive to surrounding rock stability and lining structure stress.