Abstract
A large number of deposit landslides are induced by rainfall, and those with different weak layers may be subject to catastrophic failure. This research investigates the rainfall infiltration effect on the stability of deposit landslides with a weak layer at different slope angles. Four rainfall physical model tests were conducted with fixed double penetration artificial rainfall technique and dynamic sensor technologies by using the rainfall test methods as modified in the paper. Deformation and mechanics parameters, as well as water content parameters in the key position in the deposit landslide, were monitored by means of various displacement monitoring sensors, dynamic soil pressure sensors, pore water pressure (PWP) monitoring sensors, and water content sensors. The results show that, under the same rainfall conditions, the rule of displacement and mechanical changes of deposit slope with different angles are similar, that the displacement, soil pressure, and PWP are characterized by two stages of rising and falling, and that the displacement of deposit slope with weak layer remains creep after rainfall. In addition, the displacement at the rear edge of the slope with a small angle is larger than that at the front of the steep slope, but the displacement in the front of the slope is opposite. Furthermore, the slope with a smaller angle is prone to form a tensile crack in the back of the slope, and its deformation and failure have the characteristics of a progressive and thrust-type landslide. While the failure in front of a steep slope (slope angle more than 60°) occurred first, the slope failure was characterized by sudden and retrogressive modes. The mathematical analysis of the model is also conducted which shows that deformation and failure can be divided into three stages, i.e., creep inoculation, accumulation uplift, and speed-up sliding. The test results can provide a reference for the investigation, design, and assessment of similar deposit slopes.
Highlights
Rainfall infiltration has a great influence on the stability of deposit slopes, especially the deposit slope with weak layers, which is prone to landslide [1]. ese rainfallinduced deposit landslides with weak layers pose a lot of threats to the masses in mountainous areas due to their strong concealment and complex formation mechanism [2,3,4,5,6]
According to the model test and numerical analysis, it is concluded that two stages of displacement and three failure stages exist in deposit landslide with a weak layer with each having a special characteristic
Under the condition of the same rainfall, the displacement and soil pressure change in the trailing edge at 30° or 45° slope is greater than displacement and soil pressure in the front of the slope, and it has the characteristics of creep and retrogressive
Summary
Rainfall infiltration has a great influence on the stability of deposit slopes, especially the deposit slope with weak layers, which is prone to landslide [1]. ese rainfallinduced deposit landslides with weak layers pose a lot of threats to the masses in mountainous areas due to their strong concealment and complex formation mechanism [2,3,4,5,6]. Tian et al [16] conducted experimental analysis on the displacement field deformation of loose deposit slope by using centrifugal rainfall simulation equipment, and Jeong et al [17] and Sun et al [18] analyzed the landslide of soil deep foundation with numerical analysis and physical modeling test. Is landslide is mainly characterized by a three-layer structure: the sliding bed composed of carboniferous limestone and sandstone, the slide zones composed of silty clay, and the sliding body mainly composed of gravel deposit Another typical feature is that there are three transverse landslide cracks in the back of the slope. In order to measure the mechanical and deformation parameters of the landslide with special geological structure, three strata of the artificial rainfall simulation test model and four angle slope models are developed, and several monitors are set in the different positions of the slide zone and main body. Rainfall is the causal factor of this landslide, and mudding of the slide zone soil is the main failure reason of the Nanheng landslide, which is a kind of planar landslide in the deep layer (see Figure 1)
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