Abstract
Loess landslides induced by rainfall and traffic load are significant hazards during the construction and operation of highways in many loess-covered areas. Studies of the deformation and stability of loess slopes with seepage fissures are limited. In the study, a case study of the Yangpoyao loess slope with seepage fissures in China’s Loess Plateau was conducted to reveal the deformation development mechanism and assess the landslide hazards of such fissured loess slopes. First, the hydraulic-mechanical properties of the Q2 loess were investigated through experiments, and the mathematical expressions of the relationships between various mechanical parameters and water content were fitted, indicating that the mechanical parameters, such as cohesion, angle of internal friction, and deformation modulus, vary in a quasi-linear manner with the water content. Then, a new numerical method was proposed to simulate the mechanical behaviours of the loess considering its water sensitivity and transverse isotropy, where the water sensitivity was considered through the implementation of the mathematical expressions of the hydraulic-mechanical relationships, and the transverse isotropy was considered by the modified constitutive model that combined the logics of transversely elastic model and a ubiquitous-joint model. Finally, the deformation development mechanism of the fissured loess slope under rainfall and traffic load was revealed by using the proposed method. The roles of the rainfall and traffic load in the fissure propagation and deformation development process of the slope were explored, and some stabilisation measures are recommended for the prevention of its failure. The proposed method and findings arising therefrom may provide references for future studies of the stability and landslide hazard assessment of fissured loess slopes.
Highlights
Loess covers 6.31 × 105 km2 of China and is widely distributed in several provinces Xinjiang, Ningxia, Gansu, Shaanxi, and Shanxi of the country (Derbyshire, 2001; Liu, 2002)
Based on the analysis of the simulation and field monitoring results, some stabilisation treatments are recommended for the prevention of fissured loess slope failure
The fissure-deformation development process is an important stage of the failure evolution process of loess slopes under rainfall and traffic load, and understanding the mechanism of fissuredeformation development is key to the hazard assessment and prevention of slope failures
Summary
Loess covers 6.31 × 105 km of China and is widely distributed in several provinces Xinjiang, Ningxia, Gansu, Shaanxi, and Shanxi of the country (Derbyshire, 2001; Liu, 2002). The loess has high void ratios and well-developed vertical joints (Zhang et al, 1988; Derbyshire et al, 1998), featuring a remarkably collapsibility and transverse isotropy (Jiang et al, 2014; Xu and Coop, 2016). As such distinctive soil structure facilitate water infiltration, it is very common to see seepage fissures on loess slopes (Jin et al, 2012; Krzeminska et al, 2013; Pu et al, 2020; Chang et al, 2021). Previous studies on rainfall-induced landslides of fissured loess slopes have generally discovered that the failure process of the slopes can be divided into three stages: water infiltration, fissure-deformation development, and sliding (Wang et al, 2017; Zhuang et al, 2018), where the fissure-deformation development stage is of most importance in the formation of loess landslides (Jin et al, 2012; Wang J. et al, 2018; Chen et al, 2018)
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