Physical modelling of initial seepage failure process

Abstract

Seepage failure is one of the main factors of earth-rock dam break. The identification of piping behaviour, the calculation of critical hydraulic gradients and the applicability of controlling measures are more concerned in the current studies. Meanwhile, it is significantly essential to identify the gradual change accurately in the seepage process from initial deformation to complete failure in order to reduce the break risk and promote dam safety. In this paper, a physical modelling has been conducted to analyse the mechanics of the seepage failure process with several representative grading soil samples including sandy gravels, fine-grained sands and silty clay. By analysing the seepage gradient, permeability, porosity and the penetration rate, seepage failure process observed in the laboratory tests show four stages, that is, incubation, formation, evolution and destruction. The experimental results show that sandy gravel still maintains stability in the process of destruction when the increasing seepage gradient is not enough to affect the soil skeleton stability. However, the stability of fine-grained sands gets worse after the seepage process of evolution, and silty clay gets unstable at the beginning of the process of formation.