Shear behavior of sliding zone soil of loess landslides via ring shear tests in the South Jingyang Plateau

Abstract

Since the 1970s, a large number of loess collapses and landslides have occurred in the Loess Plateau of China due to water diversion and irrigation projects. A large amount of ancient landslide deposits are accumulated at the foot of the tableland, which is likely to slide again in the case of a rapid increase in short-term rainfall or long-term irrigation. The weak characteristics of the sliding zone soil often become the key factor affecting the revival of old landslides. To explore the effects of water content and shear rate on shear behavior of the sliding zone soil, a series of ring shear tests were conducted on reconstituted loess in the South Jingyang Plateau. Experimental results suggest that under the condition of normal consolidation, the soil sample with the optimum moisture content has the highest shear strength. The increase in the shear rate effectively reduces the strength of the soil. Because of the high shear rate, the pore water that cannot be dissipated and fine particles accumulated at the shear plane form a weak base (slurry making theory), which cannot be easily stopped once the landslides start, leading to high-speed and long-distance landslides. In addition, the changes in the soil particles and pores were observed using a scanning electron microscope (SEM), and the observations were consistent with macroscopic results. From these studies, we come to the conclusion that the motion mechanism of reactivated landslide was associated with the interaction of water content and shear rate, which reduces the shear strength of the displaced materials to a great extent.

Factors Affecting the Stability of Loess Landslides: A Review

“…These include porosity analysis [34][35][36][37], fracture structure assessment [8,15,[38][39][40], landslide geometry evaluation [4,8,36], and investigation of subsurface geological conditions [8,15,17,22,23]. The techniques used include electrical testing [8,20,23,30,34,36], seismic testing [35,[41][42][43][44][45][46][47][48][49][50][51][52][53], mechanical testing [13][14][15]18,19,22,37,38], and borehole data analysis [9,31,43,47,53,…”

“…Alternatively, slope stability has been evaluated by examining the relationship between the changes in water content, loess particles, porosity, and peak shear strength [13][14][15]. Water infiltration along fractures increases soil water content, leading to reduced effective stress and reduced shear strength [16][17][18][19][20]. Vertical liquefaction during landslide shearing is a major cause of landslides according to Coulomb mechanics [21][22][23].…”

Experimental investigation into the physical properties of mixed soil within sliding zones and landslide slip zone evolution process analysis

“…Sun et al (Sun et al 2023) employed physical model experiments to assess the influence of water content on the strength, deformation parameters, and stability of sliding zone soil, concluding that tension-shear failure primarily characterizes the destruction of reservoir bank landslides. Zhu et al (Zhu et al 2022) conducted circumferential shear tests to analyze the shear properties of sliding zone soil in loess areas, revealing dynamic changes in soil water content during the shear process, which, in turn, affected shear strength parameters. Sattler et al (Sattler et al 2021) evaluated the impact of changes in matrix suction within sliding zone soil on slope stability and deformation via field monitoring and numerical calculations.…”

Study on the Mechanical Characteristics of Large Shear Deformation of Lightweight Soil Solidified by Blowing and Filling with High Moisture Content

“…Wang et al [12] employed ring shear tests to investigate the behavior of landslide soil under environmental factors like rainfall. Zhu et al [13] investigated the impact of moisture content on the comprehensive strength in ring shear experiments of loess. They also analyzed the particle movement mechanism of the soil using scanning electron microscopy.…”