Flume tests and corresponding numerical simulation of hydraulic/mechanical behavior of Tangjiashan landslide dam subjected to seepage loading

Abstract

Landslide dams (LDs) are usually composed of natural debris materials and normally exhibit heterogeneous strata along both the depth and run-out directions. In addition, LDs usually have weaker structures than undisturbed ground and are more vulnerable to seepage loading. Considering that the surface layer of naturally packed LD materials is mostly in an unsaturated state, it is undoubtedly important to investigate the hydraulic/mechanical behavior of LDs with heterogeneous strata subjected to seepage loading. In this paper, a systematic flume test program was firstly conducted, in which the Tangjiashan LD was carefully referenced for its model design. Three different water level rising rates and two different stratal arrangements were considered in the flume tests. Then, soil-water-air coupled finite element analyses were conducted to simulate the flume tests, and all the material parameters of the LD materials were carefully determined based on the results of element tests. A comparison of the test and calculated results showed the possibility of using the proposed numerical method to predict the occurrence of dam breaching and to estimate the risk of LD failure. Moreover, the hydraulic/mechanical behavior of the LD materials and the heterogeneous strata of the LD were proven to be very important to the stability of the LD. Finally, from an engineering viewpoint, the possibility of utilizing a naturally formed LD, and not destroying it after its formation, is also discussed.