Centrifuge modeling of layered rock slopes susceptible to block-flexure toppling failure
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ORIGINAL PAPER
Centrifuge modeling of layered rock slopes susceptible to block-flexure toppling failure Haina Zhang 1,2 & Congxin Chen 1,2 & Yun Zheng 1,2 & Qunqun Yu 3 & Wei Zhang 1,2 Received: 8 May 2019 / Accepted: 8 April 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Block-flexure toppling failure is a widespread issue in natural and excavated rock slopes. The aim of this paper was to elucidate the failure mechanism of block-flexure toppling failure using a centrifuge model. The artificial rock and a slope model were prepared. A series of mechanical tests (i.e., uniaxial compression tests, direct shear tests, and three-point bending tests) were then conducted to research the properties of the artificial rock. Three kinds of measurement methods (laser displacement meters (LDMs), digital image correlation (DIC), and fiber Bragg gratings (FBGs)) were used to acquire detailed information on the deformation and failure process associated with block-flexure toppling failure. The results of our test show that block-flexure toppling failure occurs instantaneously and that the total failure surface is stepped. More explicitly, the preceding section of the failure surface is a flat plane perpendicular to the joints that dip steeply into the face in front of the slope crest. The rear of the failure surface begins to become stepped and the heights of the steps are mainly controlled by the spacing of cross joints. The deformation and failure zone can be divided into three subzones: a toppling failure zone, a crack zone, and a deformation zone. The tensile stress in the continuous columns shows a distribution that is similar to a triangle. That is, the value of the tensile stress on the top of each column is approximately zero and gradually increases with the burial depth of the column. The tensile stress in the columns at the back of the slope is less than that in the face of the slope. Keywords Rock slope . Block-flexure toppling failure . Centrifuge model . Failure mode . Fiber Bragg grating sensor
Introduction Toppling failure is one of the most common modes of instability in both natural and excavated layered rock slopes (Muller 1968; Wyllie 1980; Alejano and Alonso 2005, Alejano et al. 2015, Gu and Huang 2016; Amini et al. 2018; Zheng et al. 2019). From the mechanistic perspective, Goodman and Bray (1976) classified toppling failures into three main types, i.e., block toppling, flexural toppling, and block-flexure toppling.
* Yun Zheng [email protected] 1
State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, Hubei, China
2
University of Chinese Academy of Sciences, Beijing 100049, China
3
School of Civil Engineering and Architecture, Anhui University of Science and Technology, Huainan 232001, Anhui, China
Block toppling failure occurs in rock slopes with two sets of orthogonal joints. One set of parallel joints dip steeply into the slope face and the other set, which have a gentler dip a
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