Stress–Strain Strength Characteristics of Undisturbed Granite Residual Soil Considering Different Patterns of Variation of Mean Effective Stress

Abstract

Granite residual soil is one of the most frequently encountered problem soils in tropical regions, whose mechanical behavior heavily depends on the pattern of variation of mean effective stress (p’) during shearing, which can be classified into three categories: increasing-p’, constant-p’, and decreasing-p’. Unfortunately, so far, the stress–strain strength characteristics of granite residual soils have been studied mainly under increasing-p’ stress paths, although it is very likely to encounter stress paths with decreasing p’ in practice, especially in excavation engineering. Moreover, most pertinent research has focused on remolded granite residual soils, whereas undisturbed specimens have not yet received enough attention. In this paper, stress path triaxial tests considering different patterns of variation of mean effective stress were conducted on an undisturbed granite residual soil. Subsequently, a variable termed loading angle was introduced to quantitatively represent stress path. The influences of stress path on the Mohr–Coulomb strength parameters, deformation characteristics, ductility, and shearing stiffness were analyzed, with an emphasis on the role of pattern of variation of mean effective stress. The experimental results show that friction angle of the soil increases while cohesion decreases with the increase in loading angle. The increase in loading angle leads to less volume contraction and smaller failure strain. During shearing, the soil exhibited a less brittle response under stress paths with smaller loading angles. The initial secant shear modulus first decreased and then increased as the loading angle increased, with the minimum shearing stiffness occurring at a certain loading angle lying between 90° and 123.7°.

Failure mode of rainfall-induced landslide of granite residual soil, southeastern Guangxi Province, China

“…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, 2008Rahardjo et al, , 2012Zhai et al, 2016;Zhang et al, 2019), Malaysia (Rahman et al, 2018), Korea (Kim et al, 2004;Pham et al, 2019), southern (Jiao et al, 2005;Fan et al, 2018;Luo et al, 2021;Liu et al, 2020aLiu et al, , b, 2021 and southeastern China (Xia et al, 2019;Yao et al, 2021;Shu et al, 2021;Zhao et al, 2021). Guangxi is located in southeastern China, where granite is concentrated in the southeast and landslides occur frequently (Liao et al, 2019).…”

“…Rainfall-triggered mechanisms focus on completely weathered granite fill slope in Hong Kong SAR, China. They are static liquefaction (Chen et al, 2004) and the transition from slide to flow due to localized transient pore water pressure (Take et al, 2004). However, static liquefaction is impossible due to an unsaturated condition.…”

“…However, static liquefaction is impossible due to an unsaturated condition. Instead, local transient pore water pressure can induce the initially slip, which further triggers the high-speed slide (Take et al, 2004). Another finding is that the initial dry density (Mukhlisin et al, 2008) and slope angle (Liu et al, 2020a, b) can affect the water permeability and control the formation of landslides (Xu et al, 2018).…”

Description of Limit States in the Subsurface Layer of Loosened Subsoil in View of Critical State Soil Mechanics

“…Nowadays, numerical analyses play an increasingly important role in designing and assessing the construction structure and phenomena occurring in subsoil [ 25 , 26 , 27 ]. For example, Shu et al [ 25 ] used different constitutive models to recreate undisturbed subsoils’ stress–strain strength characteristics.…”

“…Nowadays, numerical analyses play an increasingly important role in designing and assessing the construction structure and phenomena occurring in subsoil [ 25 , 26 , 27 ]. For example, Shu et al [ 25 ] used different constitutive models to recreate undisturbed subsoils’ stress–strain strength characteristics. Kadela and Fedorowicz [ 26 , 27 ] and Kadela [ 28 ] used the MCC model to recreate the subsoil behaviour of the road pavement-subsoil system under the real load from the vehicle wheels.…”