The Effect of Rainfall, Soil Type and Slope on the Processes and Mechanism of Rainfall-Induced Landslide

Abstract

Landslides are serious geological hazards that become a disaster worldwide, causing a large number of casualties and economic losses every year. There are many factors affecting landslide susceptibility, such as rainfall, soil and slope. Each of them has an important role in the process of slope losing stability. In this paper, the effects of rainfall intensity, rainfall pattern, slope gradient and soil type on landslide susceptibility are studied. In the process of rainfall-induced landslide, the relevant physical quantities of soil changes continuously. Their values and processes are closely related to the time of landslide occurrence. Hence, the variation of soil volumetric water content, matrix suction, pore water pressure and total stress throughout the rainfall are measured. As the results, soil type, slope gradient and rainfall intensity have a large influence on landslide susceptibility. The occurrence of landslides has a prerequisite that the slope is greater than or equal to 15°. The rainfall intensity needs to be not less than 80 mm/h. The difference of rainfall pattern also affects the landslide susceptibility. The rainfall pattern with rainfall intensity peak at the later stage is more likely to induce landslide. Coarser soils with gravels are prone to landslides when other conditions are the same. Steeper slopes, stronger rainfall, and coarser soils can all increase the amount of sediment yield.

Water Distribution Characteristics of Slopes Based on the High-Density Electrical Method

“…It is described in detail below. The selected soil had a particle density of 2.75 g/cm 3 and a natural moisture content of 7.4%. After air drying, grinding, screening and heat drying, the treated soil was stored in a sealed bag.…”

“…where ρ w g/cm 3 is the wet density of the specimen; ρ d g/cm 3 is the dry density of the specimen; and ρ wat g/cm 3 is the density of the water. S r (%) is the saturation of the specimen, and can be used to describe the volumetric water content ω, which can be expressed as…”

“…The material of the landslide body was the same as the material used in the resistivity test, and the initial material parameters were the density γ of 1.7 g/cm 3 and moisture content ω of 15%. The tamping method was used to build the landslide model with respect to operability.…”

“…Landslide body 15% 1.7 g/cm 3 Soil moisture sensors were installed in the landslide model, and Figure 7 illustrates the soil moisture pressure sensors arranged in four sections. The high-density resistivity method, the main measurement method in this experiment, was applied to the landslide model, and electrode bars were inserted into the surface of the landslide with a horizontal interval of 0.2 m. The sensors and measuring equipment used are shown in Figure 8.…”

“…Hydrodynamic landslides are slope geotechnical instability hazards driven by hydrodynamic factors, such as glacial snow melting, rainfall, water level changes, surface runoff and groundwater activities [1][2][3][4][5]. Water plays a key role, not only in the shape, movement and disaster-causing processes of landslides, but also in hydrodynamic response, which is closely related to the occurrence of landslide hazards.…”