逆层岩质边坡地震动力破坏过程FLAC/PFC~(2D)耦合数值模拟分析
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摘要
建立含有非贯通层面和正交次级节理的逆层岩质边坡FLAC/PFC2D耦合计算模型,进行地震动力破坏过程模拟试验,研究了逆层岩质边坡地震动力破坏机理。试验结果证明,在地震动力破坏过程中,边坡内部层面主要产生剪切破坏,少量张拉破坏集中于逆层边坡顶部位置并且总是发生在坡体已经产生动力失稳之后,因此层面的抗拉强度并不影响逆层边坡的地震动力稳定性。坡顶正交次级节理只能产生张拉破坏,形成宏观的岩层倾倒趋势,而坡底的正交次级节理既会产生张拉破坏,也会产生剪切破坏,破坏面滑动趋势明显。动力响应坡顶放大效应和破坏面发育位置深度导致坡顶岩体的张拉倾倒早于坡底岩体的剪切滑动,与逆层边坡静力倾倒破坏顺序相反。
This paper presents FLAC / PFC2 Dhybrid numerical models for a typical toppling rock slope with intermittent bedding planes and orthogonal secondary rock joints inside. The seismically induced failure processes of the slope are simulated and analysed. The simulation results reveal that the rock bedding plane generally fails in shear during the dynamic failure process. Very few tensile failure of the bedding plane can occur on the top of the slope. But the tensile failure always appears after the collapse of the whole slope. Therefore the tensile strength of the beddings cannot serve to affect the actual dynamic stability of the slope in a whole. Secondary rock joints on the top of slope can only fail in tension,resulting rock layer toppling. The joints on the bottom of the slope can fail both in tension and shear,inducing shearing displacement along the penetrating joint surfaces. Moreover,the jointfailure at the top of slope always occurs before the joint failure at the bottom,which is completely opposite to the classic failure sequence of toppling rock slope on static condition. This difference may be due to the dynamic amplification effect on the crest of slope and the difference on position and depth for failing secondary rock joints on the top and on the bottom.
This paper presents FLAC / PFC2 Dhybrid numerical models for a typical toppling rock slope with intermittent bedding planes and orthogonal secondary rock joints inside. The seismically induced failure processes of the slope are simulated and analysed. The simulation results reveal that the rock bedding plane generally fails in shear during the dynamic failure process. Very few tensile failure of the bedding plane can occur on the top of the slope. But the tensile failure always appears after the collapse of the whole slope. Therefore the tensile strength of the beddings cannot serve to affect the actual dynamic stability of the slope in a whole. Secondary rock joints on the top of slope can only fail in tension,resulting rock layer toppling. The joints on the bottom of the slope can fail both in tension and shear,inducing shearing displacement along the penetrating joint surfaces. Moreover,the jointfailure at the top of slope always occurs before the joint failure at the bottom,which is completely opposite to the classic failure sequence of toppling rock slope on static condition. This difference may be due to the dynamic amplification effect on the crest of slope and the difference on position and depth for failing secondary rock joints on the top and on the bottom.
引文
[1]Zhang J H,Chen Z Y,Wang X G.Centrifuge modeling of rock slopes susceptible to block toppling[J].Rock Mechanics and Rock Engineering,2007,40(4):363~382.
[2]Zhang G,Zhao Y,Shi G H,et al.Toppling failure simulation of rock slopes by numerical manifold method[J].Chinese Journal of Geotechnical Engineering,2007,29(6):800~805.
[3]Adhikary D P,Dyskin A V,Jewell R J,et al.A study of the mechanism of flexural toppling failure of rock slopes[J].Rock Mechanics and Rock Engineering,1997,30(2):75~93.
[4]左保成,陈从新,刘小巍,等.反倾岩质边坡破坏机理模型试验研究[J].岩石力学与工程学报,2005,24(19):3505~3511.Zuo Baocheng,Chen Congxin,Liu Xiaowei,et al.Modeling experiment study on failure mechanism of counter-tilt rock slope[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(19):3505~3511.
[5]Bray J W,Goodman R E.The theory of base friction models[J].International Journal of Rock Mechanics and Mining Sciences&Geomechanics Abstracts,1981,18(6):453~468.
[6]Itasca.PFC2DManuals[M].Minneapolis,USA:HC Itasca Company,2011.
[2]Zhang G,Zhao Y,Shi G H,et al.Toppling failure simulation of rock slopes by numerical manifold method[J].Chinese Journal of Geotechnical Engineering,2007,29(6):800~805.
[3]Adhikary D P,Dyskin A V,Jewell R J,et al.A study of the mechanism of flexural toppling failure of rock slopes[J].Rock Mechanics and Rock Engineering,1997,30(2):75~93.
[4]左保成,陈从新,刘小巍,等.反倾岩质边坡破坏机理模型试验研究[J].岩石力学与工程学报,2005,24(19):3505~3511.Zuo Baocheng,Chen Congxin,Liu Xiaowei,et al.Modeling experiment study on failure mechanism of counter-tilt rock slope[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(19):3505~3511.
[5]Bray J W,Goodman R E.The theory of base friction models[J].International Journal of Rock Mechanics and Mining Sciences&Geomechanics Abstracts,1981,18(6):453~468.
[6]Itasca.PFC2DManuals[M].Minneapolis,USA:HC Itasca Company,2011.
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