Analysis of Genetic Mechanism and Failure Mode of a Large Paleo-landslide in Sichuan-Tibet Railway Transportation Corridor

doi:10.19657/j.geoscience.1000-8527.2021.017

Abstract

Abstract:

Sichuan-Tibet railway is vulnerable to serious geological hazards, especially where the topography is complex and tectonic activities are intense. The reactivation of paleo-landslides is one of the serious threats to the construction and operation of the railway. A paleo-landslide is located in the Kangding city, only one hundred meters away from the proposed Sichuan-Tibet railway. On the basis of the analysis of characteristics and formation mechanism using engineering geological mapping and exploration drilling, this study predicts its potential failure mode. The results are listed as follows. The large-scale paleo-landslide mainly slides along the bedrock-overburden discontinuity with strong partial deformation and develops multi-level tensile cracks. The stability scale is stable in the natural and rainy condition, but becomes unstable when earthquake occurs. The potential landslide failure sites are the trailing edges of gravel soil in the middle of the slope, while the potential sliding surface is the interface between the debris rock soil and the fully-weathered rock body.

Key words: Sichuan-Tibet railway, paleo-landslide, failure mode, formation and evolution, alpine area

CLC Number:

P642

WANG Jiazhu, GAO Yanchao, RAN Tao, TIE Yongbo, ZHANG Fan. Analysis of Genetic Mechanism and Failure Mode of a Large Paleo-landslide in Sichuan-Tibet Railway Transportation Corridor[J]. Geoscience, 2021, 35(01): 18-25.

Figures/Tables 8

Fig.1 Geological structure and full view of the paleo-landslide in Kangding, Sichuan

Fig.2 Engineering geologic plane of the paleo-landslide

Fig.3 Deformation and failure characteristics of the paleo-landslide

Fig.4 Engineering geologic profile of 1-1' (a) and its FEM model (b)

Table 1 Physical and mechanical parameters of the rock and soil

岩土材料	密度/ (kg/m³)	弹性模量 /MPa	泊松比	黏聚力 /MPa	内摩擦角 / (°)
碎块石土	2 100	350	0.30	0.05	38
卵砾质粉质黏土	2 000	300	0.32	0.1	37
全风化岩体	2 200	500	0.28	0.2	40
强风化岩体	2 300	2 000	0.25	1	45
弱风化岩体	2 600	5 000	0.23	2	55

Fig.5 Stability of profile 1-1'

Fig.6 Slope displacement maps of profile 1-1' under natural and rain condition

Fig.7 Numerical simulation results of profile 1-1' under earthquake condition

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