Dynamic Process and Mechanism of the Catastrophic Taihongcun Landslide Triggered by the 2008 Wenchuan Earthquake Based on Field Investigations and Discrete Element Method Simulations

Xingtao Zhou,Xiaohui Xue,Pengfei Wei,Lihua Li,Xiaodong Fu

doi:10.3389/feart.2021.710031

Abstract

The Taihongcun landslide, which was a remarkable geological disaster triggered by the 2008 Wenchuan earthquake, had a volume of about 2 × 106 m3 and killed about 23 people. Through detailed field investigations, basic information of topography, geological structure and stratigraphy for the landslide were acquired and key kinetic characteristics of the landslide were identified. On the basis of filed investigations, 2D numerical models with discrete element method (DEM) were established to simulate the kinematics and failure process of the landslide. To ensure the validity of the dynamic calculations, the free-field boundary condition was developed and introduced intro the DEM models. According to filed investigations and DEM simulations, the dynamic processes of the Taihongcun landslide can be divided into four phases: fragmentation, projection motion, scraping, and granular debris flow and accumulation. In addition, the parameter analysis showed that the particle bond strength had a significant influence on the runout distance and landslide debris morphology. Finally, the possible mechanism of the Taihongcun landslide was determined: a rock mass of poor quality provided the lithological basis for this landslide formation; a joint set J1 in the back scarp and a weak interlayer of carbonaceous slate and shale between the upper sliding mass and the bedrock formed the rupture boundaries of the upper source area; a strong seismic ground motion was the external excitation that triggered the destructive landslide event; additionally, hypermobility was caused by the high elevation and topographical conditions of the landslide.

Highlights

On May 12, 2008, a magnitude Mw 7.9 earthquake occurred in the Longmenshan Mountains tectonic zone of Sichuan Province, China
Based on the two-dimensional code PFC2D, discrete element method (DEM) models were used to investigate the kinematical process and failure mechanism of the Taihongcun landslide triggered by the 2008 Wenchuan earthquake
According to field investigations and numerical simulations, a possible mechanism of the Taihongcun landslide was determined: the rock mass in the study area was of poor quality and was vulnerable to weathering, which provided the lithological basis for this landslide formation; the joint set J1, which steeply dips outward in the residual slope, and the weak interlayer, which was comprised of carbonaceous slate and shale, formed the rupture boundary of the upper source area; the strong seismic ground motion was an external excitation that triggered the destructive landslide event; the high elevation and topographical conditions provided the bases for hypermobility

Summary

INTRODUCTION

On May 12, 2008, a magnitude Mw 7.9 earthquake occurred in the Longmenshan Mountains tectonic zone of Sichuan Province, China. Huang et al (2012), Tang et al (2013), Zhou et al (2013), Yuan et al (2014), and Deng et al (2017) developed 2D DEM models to simulate the dynamic process of landslides triggered by earthquakes and explore their seismic failure mechanism. In their simulations, the sliding surface and bedrock were represented by wall elements, and the seismic ground motion histories were applied to the wall boundaries. Based on the two-dimensional code PFC2D, DEM models were used to investigate the kinematical process and failure mechanism of the Taihongcun landslide triggered by the 2008 Wenchuan earthquake

Element Method

CONCLUSION

ETHICS STATEMENT