sliding zone
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2022 ◽  
Vol 9 ◽  
Author(s):  
Chunyan Bao ◽  
Lingtao Zhan ◽  
Yingjie Xia ◽  
Yongliang Huang ◽  
Zhenxing Zhao

The creep slope is a dynamic development process, from stable deformation to instability failure. For the slope with sliding zone, it generally creeps along the sliding zone. If the sliding zone controlling the slope sliding does not have obvious displacement, and the slope has unexpected instability without warning, the harm and potential safety hazard are often much greater than the visible creep. Studying the development trend of this kind of landslide is of great significance to slope treatment and landslide early warning. Taking Xiashan village landslide in Huishan Town, Xinchang County, Zhejiang Province as an example, the landslide point was determined by numerical simulation in 2006. Generally, the landslide is a typical long-term slow deformation towards the free direction. Based on a new round of investigation and monitoring, this paper shows that there are signs of creeping on the surface of the landslide since 2003, and there is no creep on the deep sliding surface. The joint fissures in the landslide area are relatively developed, and rainfall infiltration will soften the soft rock and soil layer and greatly reduce its stability. This paper collects and arranges the rainfall data of the landslide area in recent 30 years, constructs the slope finite element model considering rainfall conditions through ANSYS finite element software, and carries out numerical simulation stability analysis. The results show that if cracks appear below or above the slope’s sliding surface, or are artificially damaged, the sliding surface may develop into weak cracks. Then, the plastic zone of penetration is offset; In the case of heavy rain, the slope can unload itself under the action of rainfall. At this time, the slope was unstable and the landslide happened suddenly.


2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Qiong Chen ◽  
Deshan Cui ◽  
Yu Chen ◽  
Xianyu Tao ◽  
Wei Xiang

Earthquakes or cyclic loadings cause significant changes in the strength characteristics of soil. These changes, especially for sliding zone soil, can lead to catastrophic landslides. Taking into account this characteristic, this paper investigates the effects of prior cyclic loading on the consolidated undrained triaxial compression strength of sliding zone soil with the KTL triaxial automated system. Our experimental results indicate that the prior cyclic loading has a significant effect on the strength behaviour of saturated sliding zone soil. Under different confining pressures, cycle periods, and number of cycles, the samples exhibit the characteristics of strain-hardening. Deviatoric stress under cyclic loading condition is smaller than that with monotonic loading condition under different confining pressures, cycle periods, and number of cycles. As the confining pressure and cycle period increase, the failure stress ratio decreases. The axial strain exhibits a steep rise first and then stays stable under a cycle period of 90 s, while the axial strain shows a linear increase with an increase in the number of cycles under a cycle period of 10 s under confining pressures of 100 kPa and 400 kPa, respectively. The logarithmic relation correlates well with the failure stress ratio in the cyclic loading tests, which preliminary validates the applicability of logarithmic relation for sliding zone soil influenced by prior cyclic loading, providing a theoretical basis and guidance for the further understanding of strength characteristics of sliding zone soil.


2021 ◽  
Author(s):  
Yuntao Zhou ◽  
Xiaoyan Zhao ◽  
Jiajia Zhang ◽  
Minghui Meng

Abstract Identification of the locking segments is crucial for assessing the potential runout risk and the overall stability of the high-locality landslide. However, during the field investigation, it is difficult to identify the locking segments before landslide failure due to their concealment. Tizicao landslide, a high-locality landslide, is used as the field example for the locking segments identification analysis in this study. Based on the geomorphology and spatial-temporal deformation in the landslide, the identification characteristics of the locking segments of the landslide are analyzed macroscopically, and the location and area of the locking segments are determined based on the analysis results. The field investigation methods are used to verify the identification results, including the monitoring of surface and deep displacement, geological borehole drilling, and oblique photography using drones. The results show that the locking segment of the Tizicao landslide lies at the southern slope toe, which covers an area of about 4.69 × 104 m2, accounting for 15.2% of the total area of the landslide. The significant different developmental characteristics are observed in respect of the surface displacement, deep displacement, surface crack, and sliding zone soil between locking and non-locking segments. It is concluded that the formation and evolution of the locking rock masses in the Tizicao landslide are closely related to the development of local folds and S-shaped river valleys, differential unloading due to river cutting, and earthquake-induced damage to rock masses in the landslide area.


2021 ◽  
Author(s):  
Wenyue Che ◽  
Jin Liu ◽  
Jianbing Peng ◽  
Zhongjie Fan ◽  
Yuxia Bai ◽  
...  

Abstract Many landslides are induced by excavation activities in the loess region. In this article, a loess – paleosol slope model was built and tested under 80 g centrifugal environment. Three certain angle excavations were simulated by manipulator movement. The mini pressure sensor and PIV system were utilized to monitor experimental process respectively. It can be found that the slope from excavation to failure, is liable to form the deep and shallow two sliding surfaces. The distance perpendicular to slope surface was measured as 9.6 cm for the deeper sliding surface, and 4.2 cm for the shallower one. Both of sliding surfaces are caused by the interaction of tensile failure and shear failure, specifically presented as the tensile failure concentrating on the upper part and the shear failure on the lower part. The loess slope can be split into three zones by response of excavation unloading (i.e., the sliding zone, the influenced zone and the uninfluenced zone). The failure pattern belongs to a retrogressive type with the bulging front edge and tension cracking trailing edge. The causes of the fractures on the slope top can be divided into different sections. The fracture near the slope top is induced by tension and shear force. But the fracture away from slope top is only induced by tension. In addition, the plastic zone development distribution of simulation has a good consistency with the centrifugal model deformation zoning diagram. These results can provide guidance for excavation activities in loess – paleosol slopes.


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