Abstract
Granite residual soil landslides are widely distributed in southeastern Guangxi province, China. They are posing a huge threat to local communities and hindering social and economic development. To understand the failure mode of the landslide can provide a scientific basis for early warning and prevention. In this study, it conducted artificial flume model tests to investigate the failure mode of granite residual soil landslide. The macroscopic phenomena of landslides in the flume were summarized. The changes of soil moisture content along with pore water pressure were analyzed. And the differences and commonness in the initiation patterns of landslides were discussed. The results had four aspects. (1) There were significant similarities in the phenomenon of slope failures. In the beginning of the artificial rain, slopes were infiltrated, following by the slope toe soil softened and slipped. Another similar pattern was that continuous rainfall could cause soil crusts and runoff on the slope surface. Short-term low-lying areas and interlocking ditches would appear due to surface runoff and rainwater erosion. (2) The increase of initial dry density enhanced the permeability resistance of rainwater to the residual soil, which led to a delay in the response time of water content and pore water pressure, and a decrease in pore water pressure. Moreover, the fluctuation characteristics of pore water pressure may be related to the type of soil shear deformation. (3) The starting time of a landslide was delayed as the initial dry density and slope angle increased, but it was shortened due to the increase in rainfall intensity. Meanwhile, the initiation pattern changed from a sudden sliding type to a progressive failure type due to the increase of initial dry density. (4) The failure process of the granite residual soil landslide could be classified into five stages: rainwater infiltration, soil sliding at the slope toe, the occurrence of surface runoff and erosion, the formation of a steep free face, and the upper soil sliding. Above research results can provide valuable references for the prevention and warning of granite residual soil landslide in southeast Guangxi.
Highlights
1 Introduction Rainfall-induced landslides are the most common geohazards in the tropical and subtropical areas covered by granite residual soil, such as Brazil (Lacerda, 2007; Coutinho et al, 2019), Singapore (Rezaur et al, 2003; Rahardjo et al, 2008; Harianto et al, 2012; Zhai et al, 2016; Zhang et al, 2019), 40 Malaysia (Rahman et al, 2018), Korea (Kim et al, 2004; Pham et al, 2019), the southern (Jiao et al, 2005; Luo et al, 2021; Liu et al, 2021; Liu et al, 2020a; Liu et al, 2020b) and southeastern China (Xia et al, 2019; Yao et al, 2021; Shu et al, 2021; Zhao et al, 2021)
235 Figure 6 Slope after soil sliding in six sets of tests. (a) Test 1. (b) Test 2. (c) Test 3. (d) Test 4. (e) Test 5. (f) Test 6. 3.2 Volume moisture content Because the change characteristics of the volume moisture content (VMC) at A and B are similar, this paper only shows the VMC at four position B, C, D, E
In order to discuss the relationship between landslide failure, soil moisture content and pore water pressure, this paper only shows the pore water pressure (PWP) at three positions (C, D, E) closely related to landslide
Summary
Rainfall-induced landslides are the most common geohazards in the tropical and subtropical areas covered by granite residual soil, such as Brazil (Lacerda, 2007; Coutinho et al, 2019), Singapore (Rezaur et al, 2003; Rahardjo et al, 2008; Harianto et al, 2012; Zhai et al, 2016; Zhang et al, 2019), 40 Malaysia (Rahman et al, 2018), Korea (Kim et al, 2004; Pham et al, 2019), the southern (Jiao et al, 2005; Luo et al, 2021; Liu et al, 2021; Liu et al, 2020a; Liu et al, 2020b) and southeastern China (Xia et al, 2019; Yao et al, 2021; Shu et al, 2021; Zhao et al, 2021). Hot and rainy climatic conditions have caused strong weathering of the surface 45 granite, giving birth to tens of thousands of residual soil. This provides a superior environment for the formation of landslides. The southeastern Guangxi has been threatened by granite residual soil landslides for a long time. Granite residual soil is extremely sensitive to rainfall, and is easy to disintegrate and soften, which will induce large-scale landslides (Dahal et al, 2008; Liu et al, 2020a; Zhang and Tang, 2013). Shallow landslides are the main type (Rahardjo et al, 2008; Kim et al, 2004), they still have the characteristics of high frequency (Kim et al, 2015), 55 suddenness and mass occurrence
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