| Earth-rock dam is one of the most oldest dam types which is still current in the world, has a long historical source. According to statistics that there are 29000 earth-rockfill dam in the World,15000 earth-rockfill dam in China. Earth-rock dam has many advantages, such as dam body foundation codition is low, its construction process is simple, strong adaptability, the test behaved very well, reliable operation and long life, simple management. To become most widely used dam types which is still current in the world. Because dam Material of earth-rockfill dam is soil material, stone, sandy gravel, or soil-aggregate mixture, its permeability coefficient is relatively great. So anti-seepage of earth-rock dam become the key design of engineering design and engineering construction, the anti-seepage measures of earth-rock dam has been a important research topic.Geomembrane as a new type impervious body, compared with the traditional impervious body of earth-rock dam, impervious body of geomembrane has its own advantages. But with development and wide application of the impervious body of geomembrane, there emerge some engineering problems. This is mainly because it is not clear about engineering characteristics of geomembrane. So it is quite clear to know that engineering characteristics of geomembrane, this paper adopts experimental study, numerical calculation and theoretical analysis, three methods to study engineering characteristics of geomembrane.Experimental study includes two parts. First, friction characteristics between composite geomembrane and structural plane of coarse-grained materials by using of TZY-1 earthwork synthetic material detenninator. Through friction test, the friction angle and cohesion between composite geomembrane and structural plane of dry coarse-grained materials are 26.7°and 15.9kPa; when coarse-grained materials moisture content is 3%, the friction angle is 27.59°, cohesion is 16.76kPa; when coarse-grained materials moisture content is 6%, the friction angle is 28.87°, cohesion is 23.95kPa; when coarse-grained materials moisture content is 8.5%, the friction angle is 32.32°, cohesion is 26.14kPa; Secondly, friction angle between composite geomembrane and structural plane of coarse-grained materials by using of friction angle determinator of unbulk solid material. the friction angle between composite geomembrane and coarse-grained materials of different moisture contents(dry,3%,6%,8.5%). the friction angle is respectively 30.4°,31.5°,32.5°,34.3°. The friction angle is increased with coarse-grained materials of different moisture contents increase.Numerical calculation includes two parts. First, mechanical properties of core earth and rock dams with composite geomembrane by using of finite difference. Combined with practical work, discussed on structure design of core earth and rock dams with composite geomembrane, analysis and calculation the stress and strain of dam body and composite geomembrane in every case, and summarize in variation of the stress and strain of dam body and composite geomembrane. Secondly, mechanical properties and stability against sliding of slope-wall rock dam with composite geomembrane by using of finite element method. Discussed on structure design of slope-wall rock dam with composite geomembrane, calculation the stress and strain of dam body and composite geomembrane, through analysis calculation results, to get variation of the stress and strain of dam body and composite geomembrane. For analysis stability against sliding of slope-wall rock dam with geomembrane, still adopting finite element method. At first analysis stability against sliding mechanism of slope-wall rockfill dam with geomembrane, based on calculation, top interface of impervious body of geomembrane is weak of sliding surface, embodies a kind characteristics of soften interface. The calculation results consistent with experimental study results.Theoretical analysis includes two parts:anti-crack analysis of impervious body of geomembrane in partial of reservoir area, and seepage stability analysis of impervious body of geomembrane in large scale of reservoir area. For anti-crack analysis of impervious body of geomembrane, at first analysis of mechanism of crack resistance and divided into two aspects:mechanism of crack resistance of geomembrane in overhead state and mechanism of crack resistance of geomembrane in not overhead state. Analysis force condition of geomembrane in two aspects, and derived differential control equation of geomembrane in two aspects, at the same time, analysis influence factorst of ear strength.Through experimental study, numerical calculation and theoretical analysis, The change law of stress and strain and constitutive relation of friction between composite geomembrane and structural plane of coarse-grained materials were summarized. To get mechanical properties of core earth and rockfill dams with composite geomembrane and slope-wall rockfill dam with composite geomembrane. To get anti-cracking characteristicsget of impervious body of geomembrane in partial of reservoir area. To get seepage properties of impervious body of geomembrane in large scale of reservoir area. Study on Engineering Properties of impervious body of geomembrane, has established the important theoretical foundation to practical application of geomembrane.For percolation estimate analysis of impervious body of geomembrane in large scale of reservoir area, infiltration capacity of impervious body of geomembrane were divided into infiltration capacity and seepage amount, analysis permeation mechanism of impervious body of geomembrane in large scale of reservoir area. Combined with practical work, accordance with principle of water balance, estimation seepage amount of impervious body of geomembrane in large scale of reservoir area. Accordance with Darcy law, calculation permeability coefficient of impervious body of geomembranes, to get Seepage regulation of impervious body of geomembrane in large scale. Seepage amount of impervious body of geomembrane reduces to 10"7cm/s～10-cm/s from 10-12cm/s～10-13cm/s.
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