Analysis of an anti-dip landslide triggered by the 2008 Wenchuan earthquake in China

Runqiu Huang,Min Lee Lee,Yanrong Li,Nengpan Ju,Guo Li,Jianjun Zhao

doi:10.1007/s11069-013-0671-5

Abstract

The Guantan landslide, with a total displaced mass of about 468 × 104 m3, was triggered by the 2008 Wenchuan earthquake and succeeding rainfall in Jushui Town, Sichuan Province, China. The landslide occurred on an anti-dip hard rock slope with a weak rock founding stratum of 200 m in thickness. To investigate the failure mechanism of the Guantan landslide, dynamic behaviors of hard and soft rock slopes were investigated by means of large scale shaking table tests. The laboratory models attempted to simulate the field geological conditions of the Guantan landslide. Sinusoidal waves and actual seismic waves measured from the Wenchuan Earthquake were applied on the slope models under 37 loading configurations. The experimental results indicated that deformation mainly developed at a shallow depth in the upper part of the hard rock slope and in the upper (near the crest) and lower (near the toe) parts of the soft rock slope. An equation for predicting the depth of sliding plane was proposed based on the location of the maximum horizontal acceleration. Finally, it was concluded that the failure process of the Guantan landslide occurred in three stages: (1) toppling failure caused by compression of the underlying soft rock strata, (2) formation of crushed hard rock and sliding surface in soft rock as the result of seismic shocks, particularly in the horizontal direction, and (3) aftershock rainfall accelerates the process of mass movement along the sliding plane.

Highlights

A disastrous earthquake with a magnitude of 8.0 (MS) struck Wenchuan, Sichuan Province, China on May 12, 2008, at 14:28
Initial investigation of the landslides triggered by the Wenchuan earthquake indicated that most of the large scale landslides on anti-dip slopes were characterized by post-seismic deformation (Huang et al 2012), among which the Guantan landslide was a typical landslide of the kind (Zhao et al 2010)
The Guantan landslide is a typical example of earthquake-induced landslide on an anti-dip slope with a weak founding stratum

Summary

Introduction

A disastrous earthquake with a magnitude of 8.0 (MS) struck Wenchuan, Sichuan Province, China on May 12, 2008, at 14:28. Based on case studies of the Xikou and Touzhai landslides, Huang (2012) proposed a conceptual model to explain failure mechanisms of anti-dip slopes found on soft rock strata He suggested that the mechanism is analogous to the collapse of a retaining wall in which the rigid mass in the middle or front part of the slope behaves like a ‘‘retaining wall’’. Xu et al (2011) concluded that the anti-dip slopes under seismic loadings failed by mechanisms of tension-cracking–shearing-sliding, while Huang et al (2011a, b) described this mechanism as shattering-tension-sliding Both of the geological models proposed by Huang et al (2011a, b) and Xu et al (2011) were derived based on general characteristics of main scarps of a number of landslides triggered by the Wenchuan earthquake. This observation implied that the failure mechanism of the Guantan landslide could be similar to the ‘‘retaining wall’’ collapse mechanism as proposed by Huang (2012)

Methods

Results

Discussion

Conclusion