Calculating the Permanent Displacement of a Rock Slope Based on the Shear Characteristics of a Structural Plane Under Cy
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ORIGINAL PAPER
Calculating the Permanent Displacement of a Rock Slope Based on the Shear Characteristics of a Structural Plane Under Cyclic Loading Shan Dong1 · Wenkai Feng1 · Yibo Yin1 · Rui Hu1 · Hongchuan Dai1 · Guoqiang Zhang1 Received: 1 November 2019 / Accepted: 26 June 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract When a rock mass shears along a structural plane, the shear resistance of the structural plane is affected by the structural plane undulations and by the friction between the contact regions. During an earthquake, the seismic load (composed of the cyclic and dynamic loads) produces a dynamic deterioration of the mechanical properties of the structural plane, which is mainly reflected as follows: (1) under cyclic shear of the seismic load, the undulant angle αk decreases. (2) Under the dynamic load, the frictional coefficient of the structural surface is reduced. The dilatancy angle is generally used instead of the undulant angle. When calculating rock slope stability, the frictional angle is equivalent to the sum of the basic frictional angle and the undulant angle. In this study, the equations for calculating the dilatancy angle of a structural plane under cyclic shear loading are determined based on cyclic shear tests of a split structural plane. The basic frictional angle for calculating the cyclic shear is also determined, based on previous research. Furthermore, according to the dynamic model of a rock slope, a method to calculate the permanent displacement of the rock slope is proposed, considering the effect of structural plane deterioration. We found that the effect of structural plane deterioration under a seismic load directly affects the stability and permanent displacement of the rock slope. The feasibility and engineering practicalities of this method are also verified by comparing the proposed method with previously developed methods. Keywords Rock mass structural plane · Deterioration effect · Permanent displacement · Rock slope stability List of Symbols Rh Maximum height of the surface roughness profile Rp Maximum contour peak height Rv Maximum contour valley depth SA Contour area ratio At Developed contour surface area An Sampling area Ac Structural surface contact area JMC Joint Matching Coefficient αi Average shear dilatancy angle i Cyclic shear times σc Intact rock strength α0 Initial undulant angle φi Basic frictional angle φ0 Initial basic frictional angle φr Residual basic frictional angle * Wenkai Feng [email protected] 1
State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, CN, China
αr Residual undulant angle 𝜑∗s Residual equivalent friction angle C Cohesion M Mass of the landslide Β Dip angle of the sliding surface ü g Seismic acceleration θ Angle between the direction of the earthquake motion and the horizontal direction Fs Safety factor φb Basic frictional angle αk Undulant angle αd Dilatancy angle JRC Roughness coefficient ay Critic
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