MODEL TEST RESEARCH ON RAINFALL-TYPE LOESS LANDSLIDE UNDER PRESET JOINT CONDITIONS

Landslide disasters occur frequently in China's loess plateau. Most of landslides are related to rainfall. The joint is also one of the important factors leading to the occurrence of loess landslides. In order to further reveal the influence of joints on loess landslides, this paper takes loess joints as the starting point of research. It is based on fieldwork and carries out a large-scale physical model test of artificial rainfall-induced landslides with preset joints. It carries out the real-time monitoring of the stage changes of soil water content and pore water pressure with the rainfall process. It analyses the expansion and evolution law of joints and fissures in the slope, as well as the trend of slope displacement and deformation. It reveals the potential mechanism of the existence of joints for inducing landslides and the law of slope response. The test results show the follows. The joints have obvious accelerating and promoting effects on the infiltration of rainwater inside the slope. The model slopes on the preset joint side have a faster and larger increase in the water content of the soil, comparing to the side without joints and have a wider range of influence. The opening degree of the joints crack in the middle of the model slope is the largest. The opening degree of the crack of the side slope with joints is about twice as large as that of the side without joints. The increase in pore water pressure on the side with joints is relatively large when the landslide occurs. The sensitivity and variation range of soil moisture content to rainfall is inversely proportional to the depth of burial. The response of moisture content in the superficial part of the slope body is quickly and fluctuates greatly while in the deep part it is opposite. The research results can provide experimental basis and theoretical reference for further clarifying the cause and failure mechanism of loess landslides.