Seepage Piping Evolution Characteristics in Bimsoils -An Experimental Study

Piping is a kind of seepage failure mode that commonly occurs under the influence of seepage force in soil materials. Many studies have been done to study the characteristics of piping for soil materials, however, the initiation and development mechanism of piping in bimsoils is poorly understood. In this work, an experimental program was set for investigating the evolution process of piping, in a self-developed servo-controlled flow–erosion–stress coupled testing system. All the studied samples with rock block percentage (RBP) of 30%, 40%, 50%, 60%, and 70%, were produced as a cylindrical shape(50 mm diameter and 100 mm height) by compaction tests with different hammer strike counts to roughly insure the same void ratio. The results show that the amount of rock blocks in bimsoil samples significantly influenced the initiation and development of piping. Furthermore, the stress state has a crucial influence on the critical hydraulic gradient, seepage velocity, permeability, erosion, and migration of soil particles. Moreover, interactions among soil matrix, rock blocks, and rock–soil interfaces control the seepage stability of the bimsoil sample