考虑环境劣化非贯通节理岩体的直剪试验离散元模拟
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摘要
非贯通节理岩体的强度特性是大型边坡、隧道等工程安全性的重要影响因素。随着酸雨、河流污染等对岩石环境劣化程度的加剧,考虑环境劣化因素对非贯通节理岩体强度的影响很有必要。采用离散元法,基于已有的胶结接触模型,将岩体因环境作用而劣化等效为岩石试样质量损失不断加剧的过程,最后等效为颗粒和颗粒之间的物质不断溶蚀的过程,由此建立考虑环境劣化的微观接触模型并将其植入离散元软件中,模拟分析了不同环境劣化程度的非贯通节理岩体在不同连通率和不同法向应力下的直剪试验。结果表明:不同环境劣化程度非贯通节理岩体剪切应力-位移曲线趋势一致;随环境劣化程度的加深,节理岩体的破坏形式以拉裂纹为主转变为以剪切裂纹为主;环境劣化使得节理岩体直剪试验起裂应力降低,且环境劣化程度的加深会导致非贯通节理岩体的凝聚力降低及内摩擦角减小,表现为峰值剪切强度降低。
The strength property of the intermittent jointed rock mass is an important factor which affects the safety of large slope and tunnels.With the increasing degree of environmental degradation induced by the acid rain,pollution and other factors,it is necessary to study its influence on the mechanical properties of intermittent jointed rock mass.Based on the existing bond contact model,a novel bond contact model,in which the process of environmental degradation was simplified ultimately as the constantly dissolution of bond between the particles,was established and implemented into a commercial distinct element code.Then,a series of direct shear tests with different connectivity rates and normal stresses under various degree of environmental degradation was conducted in DEM.The results imply that there is a similar tendency of shear stress-displacement curves obtained from intermittent jointed rock mass samples with varying degree of environmental degradation.And with the increasing of environmental degradation degree,the main failure mode of intermittent jointed rock mass changes from tensile crack to shear crack.In addition,the initiation stress,the cohesion and internal friction angle of non-penetrating jointed rock mass are reduced with the increasing of environmental degradation degree.
The strength property of the intermittent jointed rock mass is an important factor which affects the safety of large slope and tunnels.With the increasing degree of environmental degradation induced by the acid rain,pollution and other factors,it is necessary to study its influence on the mechanical properties of intermittent jointed rock mass.Based on the existing bond contact model,a novel bond contact model,in which the process of environmental degradation was simplified ultimately as the constantly dissolution of bond between the particles,was established and implemented into a commercial distinct element code.Then,a series of direct shear tests with different connectivity rates and normal stresses under various degree of environmental degradation was conducted in DEM.The results imply that there is a similar tendency of shear stress-displacement curves obtained from intermittent jointed rock mass samples with varying degree of environmental degradation.And with the increasing of environmental degradation degree,the main failure mode of intermittent jointed rock mass changes from tensile crack to shear crack.In addition,the initiation stress,the cohesion and internal friction angle of non-penetrating jointed rock mass are reduced with the increasing of environmental degradation degree.
引文
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[23]GEHLE C,KUTTER H K.Breakage and shear behaviour of intermittent rock joints[J].International Journal of Rock Mechanics&Mining Sciences,2003,40(5):687-700.
[24]唐志成,夏才初,丁增志.非贯通类节理岩体剪切变形规律分析[J].岩土力学,2011,32(8):2344-2358.TANG Zhi-cheng,XIA Cai-chu,DING Zeng-zhi.Analysis of shear deformation law for intermittent jointed rock mass[J].Rock and Soil Mechanics,2011,32(8):2344-2358.
[2]LAJTAI E Z.Shear strength of weakness planes in rock[J].International Journal of Rock Mechanics&Mining Sciences&Geomechanics Abstracts,1969,6(5):499-515.
[3]LAJTAI E Z.Strength of discontinuous rocks in direct shear[J].Géotechnique,1969,19(2):218-233.
[4]白世伟,任伟中,丰定祥,等.共面闭合断续节理岩体强度特性直剪试验研究[J].岩土力学,1999,20(2):10-16.BAI Shi-wei,REN Wei-zhong,FENG Ding-xiang,et al.Research on the strength behaviour of rock containing coplanar close intermittent joints by direct shear test[J].Rock and Soil Mechanics,1999,20(2):10-16.
[5]任伟中,白世伟,丰定祥.平面应力条件下闭合断续节理岩体力学特性实验研究[J].实验力学,1999,14(4):520-527.REN Wei-zhong,BAI Shi-wei,FENG Ding-xiang.An experimental study on the mechanical characteristics of rockmass containing close intermittent joints under plane stress condition[J].Experimental Mechanics,1999,14(4):520-527.
[6]刘远明,夏才初.共面闭合非贯通节理岩体贯通机制和破坏强度准则研究[J].岩石力学与工程学报,2006,25(10):2086-2091.LIU Yuan-ming,XIA Cai-chu.Study on fracture mechanism and criteria of failure strength of rock mass containing coplanar close discontinuous joints under direct shear[J].Journal of Rock Mechanics and Engineering,2006,25(10):2086-2091.
[7]刘远明,夏才初.基于岩桥力学性质弱化机制的非贯通节理岩体直剪试验研究[J].岩石力学与工程学报,2010,29(7):1467-1472.LIU Yuan-ming,XIA Cai-chu.Research on rock mass containing discontinuous joints by direct shear test based on weakening mechanism of rock bridge mechanical properties[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(7):1467-1472.
[8]JIANG M J,YAN H B,ZHU H H,et al.Modeling shear behavior and strain localization in cemented sands by two-dimensional distinct element method analyses[J].Computers and Geotechnics,2011,(1):14-29.
[9]JIANG M J,ZHU H H,LI X.Strain localization analyses of idealized sands in biaxial tests by distinct element method[J].Frontiers of Architecture&Civil Engineering in China,2010,4(2):208-222.
[10]JIANG M J,CHEN H,CROSTA G B.Numerical modeling of rock mechanical behavior and fracture propagation by a new bond contact model[J].International Journal of Rock Mechanics and Mining Sciences,2015.
[11]CUNDALL P A,STRACK O D L.Discrete numerical model for granular assemblies[J].Géotechnique,1979,29(1):47-65.
[12]蒋明镜,金树楼,张宁.不同胶结尺寸的粒间胶结强度统一表达式[J].岩土力学,2015,36(9):2451-2466.JIANG Ming-jing,JIN Shu-lou,ZHANG Ning.Uniform formulation for bonding strength of cemented granules of different bond sizes[J].Rock and Soil Mechanics,2015,36(9):2451-2466.
[13]JIANG M J,YU H S,LEROUEIL S.A simple and efficient approach to capturing bonding effect in naturally microstructured sands by discrete element method[J].International Journal for Numerical Methods in Engineering,2007,69(6):1158-1193.
[14]蒋明镜,周雅萍,陈贺.不同胶结厚度下粒间胶结力学特性的试验研究[J].岩土力学,2013,34(5):1264-1273.JIANG Ming-jing,ZHOU Ya-ping,CHEN He.Experimental study of mechanical behaviors of bonded granules under different bond thicknesses[J].Rock and Soil Mechanics,2013,34(5):1264-1273.
[15]周雅萍,蒋明镜,陈贺.变胶结厚度下胶结颗粒微观模型的初步研究[J].地下空间与工程学报,2011,7(5):890-894.ZHOU Ya-ping,JIANG Ming-jing,CHEN He.Experimental investigation on micro-mechanical model of bonded granules with different bond thicknesses[J].Chinese Journal of Underground Space and Engineering,2011,7(5):890-894.
[16]蒋明镜,张宁,金树楼.不同胶结宽度粒间胶结特性试验研究[J].岩土力学,2015,36(4):928-936.JIANG Ming-jing,ZHANG Ning,JIN Shu-lou.Experimental study of mechanical behaviors of bonded granules with different bond widths[J].Rock and Soil Mechanics,2015,(4):928-936.
[17]蒋明镜,陈贺,刘芳.岩石微观胶结模型及离散元数值仿真方法初探[J].岩石力学与工程学报,2013,32(1):15-23.JIANG Ming-jing,CHEN He,LIU Fang.A microscopic bond model for rock and preliminary study of numerical simulation method by distinct element method[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(1):15-23.
[18]蒋明镜,陈贺,张宁,等.含双裂隙岩石裂纹演化机制的离散元数值分析[J].岩土力学,2014,35(11):3529-3288.JIANG Ming-jing,CHEN He,ZHANG Ning,et al.Distinct element numerical analysis of crack evolution in rocks containing pre-existing double flaw[J].Rock and Soil Mechanics,2014,35(11):3529-3288.
[19]YESILOGLU-GULTEKIN N,GOKCEOGLU C,SEZER E A.Prediction of uniaxial compressive strength of granitic rocks by various nonlinear tools and comparison of their performances[J].International Journal of Rock Mechanics&Mining Sciences,2013,62(9):113-122.
[20]CIANTIA M O,CASTELLANZA R,CLAUDIO D P.Chemo-mechanical weathering of calcarenites:Experiments&theory[M].[S.l.]:[s.n.],2013.
[21]JIANG M J,KONRAD J M,LEROUEIL S.An efficient technique for generating homogeneous specimens for DEM studies[J].Computers and Geotechnics,2003,30(7):579-597.
[22]汪小刚,贾志欣,张发明,等.岩体结构面网络模拟原理及其工程应用[M].中国水利水电出版社,2010.WANG Xiao-gang,JIA Zhi-xin,ZHANG Fa-ming,et al.The theory of joint network simulation and its application[M].Beijing:China Water&Power Press,2010.
[23]GEHLE C,KUTTER H K.Breakage and shear behaviour of intermittent rock joints[J].International Journal of Rock Mechanics&Mining Sciences,2003,40(5):687-700.
[24]唐志成,夏才初,丁增志.非贯通类节理岩体剪切变形规律分析[J].岩土力学,2011,32(8):2344-2358.TANG Zhi-cheng,XIA Cai-chu,DING Zeng-zhi.Analysis of shear deformation law for intermittent jointed rock mass[J].Rock and Soil Mechanics,2011,32(8):2344-2358.