The Deformation Modes of Rock Slopes due to Excavation in Mountain-Type Mines

Abstract

This paper discusses an investigation of mining-induced elastic deformation of a cut rock slope formed in a mountain-type mine using a two-dimensional finite element method. The horizontal elastic deformation mechanism is discussed, including the effects of the Poisson's ratio, slope angle and progression of the excavation. The results show a clear dependence of the deformation modes characterized by extension, contraction or shear distortion of rock mass, on these three effects, in which the direction of rock movement at the surface due to excavation was opposite. Four effects contribute to the deformation mechanism in mountain-type mines: the Poisson effect (PE), the distributed load effect (DLE), bending effects and shear distortion. Forward surface displacement of the cut rock slope was found to occur during the early stages of excavation due to the release of horizontal compressive stresses due to bending effects around the middle of the mountaintop. As the excavation progresses, forward or backward horizontal surface displacement was found to occur due to PE or DLE, respectively, which depends on the Poisson's ratio in the subsequent stages of excavation. Asymmetric stress release due to excavation affects the horizontal deformation of the mountain, and induces a moment enhancing the backward displacement due to shear distortion. It should be noted that the direction of the surface displacement of the rock slope could change from forward to backward as the excavation progresses, even though the rock slope may be stable. This is very important in the interpretation of surface displacement monitoring using the Automated Polar System and/or Global Positioning System. In the interpretation of the internal displacement measured using extensometers, we should consider extension during the early stages of excavation, followed by slight contraction during the latter stages, as a sign of a stable cut rock slope in a mountain type mine.

Creep characteristics and discharge optimization of overlying river inner dump: A case study of Yuanbaoshan open-pit coal mine in China

“…The inner dump has a loose structure and poor overall stability. It is prone to instability and damage especially under the action of overlying loads, seriously threatening the safe production of the mining area [ [1] , [2] , [3] ]. The overlying river is a typical overlying load, which can accelerate the creep rate of the internal dumpsite and easily induce landslide disasters [ 4 , 5 ].…”

Analysis of Re-Tensioning Time of Anchor Cable Based on New Prestress Loss Model

“…During the construction of highways and railways, slope excavation will not only change the original stress state of a slope, but also accelerate the weathering speed of new exposed rock mass [1][2][3][4]; therefore, it is necessary to support the excavated slope along the road to improve the stability of the excavated slope, so as to ensure the operation safety of the road. There are many kinds of slope support methods, commonly used slope support structures include retaining wall [5][6][7], anti-slide pile [8,9], prestressed anchor rod [10,11] and prestressed anchor cable [12,13], among them, the prestressed anchor cable has been widely used in slope support engineering due to its advantages of reliable strength, simple construction and economic benefits.…”