Numerical simulation of experimentally shear-tested contact specimens from existing dam joints

Abstract

This paper first proposes an original procedure to implement three-dimensional (3D) surfaces of rough existing unbonded contact specimens, i.e. fully open with no chemical bond, into non-linear finite element models to numerically simulate shear tests conducted under Constant Normal Load (CNL) conditions. The developed procedure is applied to 18 contact specimens drilled from concrete, concrete-rock, and rock joints of existing dams. A total of 83 finite element models of the contact interfaces are generated and the results of the numerical simulations are analyzed and validated against corresponding experimental findings. Sensitivity analyses are conducted and highlight, among other things, that the geometric resolution must be selected with caution and that mismatch due to initially unmated conditions or differences between the geometries of the lower and upper contact faces must be considered. A practical non-linear shear strength criterion is also proposed and compared to numerical results. The results presented confirm the major role of roughness and matching properties in the shear response of dam joints. Finally, values of apparent cohesion and friction angle are suggested and applied to dam stability assessment while accounting for joint roughness and matching properties to emphasize the efficiency and relevance of such practice.