Initiation mechanism of Jiweishan high-speed rockslide in Chongqing, China
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Initiation mechanism of Jiweishan high‑speed rockslide in Chongqing, China Zhiming Zhao1 · Lijun Deng2 Received: 15 October 2018 / Accepted: 2 July 2020 © Springer Nature B.V. 2020
Abstract A rockslide of 5.0-million-m3 volume occurred on June 5, 2009, in Jiweishan, Chongqing, China. The field investigation indicates that the kinetic process of the Jiweishan rockslide was divided into four stages: the initiation of ejection, flying and scraping, colliding and direction altering, and stopping and accumulating. The rock mass had been considered stable according to the principle of statics. To investigate the possible initiation mechanism, the present research proposes a new initiation model that considers the vibration effects as a shaking force (F), which acts against the rockslide mass in the direction normal to the rupture surface at the same instant when the brittle limestone is ruptured. The amplitude of F was best estimated as ||𝜏 ⋅ AF || , where τ and AF are the shear stress and area of the rupture surface, respectively; under this model, the initial ejection direction agrees very well with the observed direction. The movement characteristics of the slide were later identified by assuming a variety of friction angles (at 0°, 5°, 10°, and 15°) at the weak slip surface. It is observed that when the friction angle ranged from 0° to 5°, the velocity of the rockslide reached 68.3–79.2 m/s and the rockslide mass could fly to the observed scraping area. Furthermore, the velocity and duration at each moving stage were estimated, using the assumptions in the shaking force and friction angle. Results show that the total travel time of Jiweishan rockslide was 66.8–78.6 s, which is close to 60 s as estimated by eyewitnesses and the seismic wave records. Keywords Jiweishan rockslide · Initiation mechanism · Shaking force · Movement
1 Introduction Large-scale rockslides have resulted in huge casualties and economic losses in many regions of the Earth, such as Vajont (Skempton 1966; Müller 1968), Yigong (Xu et al. 2012), Daguangbao (Cui et al. 2018), Touzhai (Xing et al. 2016) and Maoxian (Yin * Zhiming Zhao [email protected] 1
Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu, Sichuan, China
2
Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada
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Vol.:(0123456789)
Natural Hazards
et al. 2017). Researchers (e.g., Yin et al. 2011; Hunter and Fell 2002; Huang et al. 2012, 2013) investigated the failure mechanisms of large-scale rockslides, while the common approaches are geological investigation, physical model testing, monitoring, and numerical modeling. In recent years, many research projects have determined the characteristics of large high-speed rockslides in terms of their topography, material, triggering factors, volume, and initial posture (Hungr and Evans 2004; Zou et al. 2017a). Some of these studies assumed an intact rock bridge failure, which subsequently results in the catastrophic failure with a high velo
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