Abstract
Based on the direct shear test results of interface between a composite geomembrane and cushion material, nonlinear elastic, perfectly plastic model was used to describe the interface behaviors. The interface model was incorporated into the Geogrid element of a fast Lagrange analysis of continua in three dimensions (FLAC3D) procedure through a user-defined program in the FISH. Then a geomembrane surfaced rock-fill dam on thick pervious foundation was numerically analyzed using the incorporated model. The numerical results showed that only small tension deformation can be found in the most area of geomembrane on the dam surface. However, large tension deformation of geomembrane appeared close to the anchorage in the peripheral zone of the barrier. The anchorage structure of geomembrane in this area should be carefully designed to avoid tension failure of geomembrane.
Highlights
Due to better characteristics in watertight, stronger ability to adapt differential deformation, shorter construction period and lower cost than traditional barriers such as compacted clay, cement concrete and asphalt concrete as water tightness of earth and rock fill dam, geomembrane surfaced rock-fill dam is especially suited to be constructed on thick pervious foundation[1]
It is revealed from the distribution of principal stresses and strains of geomembrane obtained by numerical analysis that, the stress and strain values of geomembrane at the dam surface is small and its distribution is even, the maximum tensile strain on the dam is only 0.25%; but serious stress concentration of geomembrane appears at the bank slope and near the dam toe, and the principal strain values are larger
The interface model incorporated into Geogrid element in FLAC3D is employed in the numerical analysis of stress-deformation behavior of geomembrane surfaced high rockfill dam built on thick pervious foundation
Summary
Due to better characteristics in watertight, stronger ability to adapt differential deformation, shorter construction period and lower cost than traditional barriers such as compacted clay, cement concrete and asphalt concrete as water tightness of earth and rock fill dam, geomembrane surfaced rock-fill dam is especially suited to be constructed on thick pervious foundation[1]. The stress-deformation behavior of geomembrane surface barrier is important guarantee for security of the whole dam seepage prevention system. The key of the numerical analysis of geomembrane barrier is how to simulate the mechanical behavior of flexible geomembrane and geomembranecushions interaction. No reasonable unified calculating model has been developed to simulate the interaction of the geomembrane and cushion materials yet. The differences in elasticity modulus of geomembrane and cushion like soils are large and materials on both sides of the interface will experience discontinuous deformation like dislocation and slippage under load, larger shear stress is generated on the interface. The issue whether the simulation method for interaction between geomembrane and soil is proper directly affects the reliability of stress-deformation calculated results of geomembrane in working state
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