锚索应力增量法评价边坡稳定性
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摘要
预应力锚索加固后,边坡岩体的力学性能得到改善,从而使其受力状态发生变化,此时如仍按一般边坡稳定性评价方法评价并不是很合理。因此,提出采用支护结构的受力特性来表征加固后边坡的稳定性,具体是指用预应力锚索在各工况下产生变形所引起的应力增量与允许应力增量的差值,将该差值与允许应力增量的比值来表示边坡的稳定性。某水电站左岸坝轴线边坡天然岸坡高、自然坡角大、片麻理陡倾岸外,与片麻理垂直的陡倾裂隙和平缓裂隙是控制边坡稳定性的主要因素,结合现场地质资料和监测数据,利用离散化有限元软件FINAL建立左岸边坡开挖变形分析模型。对比研究3种工况下不同预应力锚索加固设计方案的边坡稳定性,得出暴雨工况为最危险工况,然后分析了最危险工况下不同加固方案时的变形、位移及应力,所得结果与边坡稳定系数法得到的边坡稳定性状况一致。研究结果对该电站左岸坝轴线边坡后续加固有一定的参考作用。
After the pre-stressed anchor cable is reinforced, the mechanical property of slope rock mass is improved so as to lead to change of stress state. It will not be very reasonable if evaluation is made according to the normal stability of slope at this moment. Hence, in this paper, the mechanical properties of supporting structure are proposed and adopted to represent the stability of slope after reinforcement. Specifically, the difference value between the stress increment and the permissible stress increment caused by deformation of pre-stressed anchor cable under various working conditions is used, that is, the stability of slope can be indicated with the specific value of the difference value and permissible stress increment. The slope of axis of dam on the left bank of a certain hydropower station has features of high natural bank, large natural angle of repose and gneissic schistosity steep dip off the shore. Also, the steep dip crack and the flat crack perpendicular to gneissic schistosity are the main factors controlling the stability of slope. In this paper, the deformation analysis model of excavation of slope on the left bank is built through combination of site geological data, monitoring data and investigation conditions and utilization of discretization finite element software FINAL. A comparative study is made on the stability of slope of different design schemes of pre-stressed anchor cable reinforcement under three types of working conditions. The stability coefficient of slope is calculated by using the safety stability coefficient equation proposed in this paper to come to a conclusion that the working conditions of storm rainfall are the most dangerous working conditions. Then the deformation field, displacement field and stress field under the most dangerous working conditions are analyzed. The research findings have some reference value for subsequent reinforcement of the slope of the dam axis of the left bank.
After the pre-stressed anchor cable is reinforced, the mechanical property of slope rock mass is improved so as to lead to change of stress state. It will not be very reasonable if evaluation is made according to the normal stability of slope at this moment. Hence, in this paper, the mechanical properties of supporting structure are proposed and adopted to represent the stability of slope after reinforcement. Specifically, the difference value between the stress increment and the permissible stress increment caused by deformation of pre-stressed anchor cable under various working conditions is used, that is, the stability of slope can be indicated with the specific value of the difference value and permissible stress increment. The slope of axis of dam on the left bank of a certain hydropower station has features of high natural bank, large natural angle of repose and gneissic schistosity steep dip off the shore. Also, the steep dip crack and the flat crack perpendicular to gneissic schistosity are the main factors controlling the stability of slope. In this paper, the deformation analysis model of excavation of slope on the left bank is built through combination of site geological data, monitoring data and investigation conditions and utilization of discretization finite element software FINAL. A comparative study is made on the stability of slope of different design schemes of pre-stressed anchor cable reinforcement under three types of working conditions. The stability coefficient of slope is calculated by using the safety stability coefficient equation proposed in this paper to come to a conclusion that the working conditions of storm rainfall are the most dangerous working conditions. Then the deformation field, displacement field and stress field under the most dangerous working conditions are analyzed. The research findings have some reference value for subsequent reinforcement of the slope of the dam axis of the left bank.
引文
[1] 何满潮,景海河,孙晓明.软岩工程力学[M].北京:科学出版社,2002.(HE Manchao,JING Haihe,SUN Xiaoming.Soft rock engineering mechanics[M].Beijing:Science Press,2002.(in Chinese))
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[3] 张晗旭.关于预应力锚索加固效应研究的几点看法[J].河海大学学报,1999,27(4):93-96.(ZHANG Hanxu.Comments on the study of reinforcing effect of prestressed anchored steel rope[J].Journal of Hohai University,1999,27(4):93-96.(in Chinese))
[4] 徐年丰,陈胜宏.我国岩土预应力锚索加固技术的发展与存在的问题[J].水利水电快报,2001,22(10):20-23.(XU Nianfeng,CHEN Shenghong.The development and existing problems of reinforcement technology of geotechnical prestressed anchorage cable in China[J].Express Water Resources and Hydropower Information,2001,22(10):20-23.(in Chinese))
[5] 吴茂明,阮含婷,刘鹭.预应力锚索在岩土边坡工程治理中的应用[J].岩土工程学报,2010,32(增刊1):324-326.(WU Maoming,RUAN Hanting,LIU Lu.Application of prestressed anchor cables in treatment of geotechnical slopes[J].Chinese Journal of Geotechnical Engineering,2010,32(Suppl1):324-326.(in Chinese))
[6] 叶海林,郑颖人,李安洪,等.地震作用下边坡预应力锚索振动台试验研究[J].岩石力学与工程学报,2012,31(增刊1):2847-2854.(YE Hailin,ZHENG Yingren,LI Anhong,et al.Shaking table test studies of prestressed anchor cable of slope under earthquake[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(Suppl1):2847-2854.(in Chinese))
[7] 郑文博,庄晓莹,蔡永昌,等.地震作用下预应力锚索对岩石边坡稳定性影响的模拟方法及锚索优化研究[J].岩土工程学报,2012,34(9):1668-1676.(ZHENG Wenbo,ZHUANG Xiaoying,CAI Yongchang,et al.Modeling of prestressed anchors in rock slope under earthquake and optimization of anchor arrangement[J].Chinese Journal of Geotechnical Engineering,2012,34(9):1668-1676.(in Chinese))
[8] 赵炼恒,罗强,李亮,等.基于失稳状态耗能最小原理的预应力锚索加固边坡稳定性上限解析[J].岩土力学,2013,34(2):426-432.(ZHAO Lianheng,LUO Qiang,LI Liang,et al.Energy analysis method for slopes reinforcing with prestressed anchor cables based on minimum energy principle of instability state[J].Rock and Soil Mechanics,2013,34(2):426-432.(in Chinese))
[9] AMINI M,MAJDI A,VESHADI M A.Stability analysis of rock slopes against block-flexure toppling failure[J].Rock Mechanics and Rock Engineering,2012,45(4):519-532.
[10] 李宁,张鹏,于冲.边坡预应力锚索加固的数值模拟方法研究[J].岩石力学与工程学报,2007,26(2):254-261.(LI Ning,ZHANG Peng,YU Chong.Research on method of numerical simulation of prestressed anchor cable in slope[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(2):254-261.(in Chinese))
[11] 庄晓莹,蔡永昌,朱合华.锚固边坡稳定性分析有限元模型及锚固效应的探讨[J].岩土工程学报,2008,30(7):1099-1104.(ZHUANG Xiaoying,CAI Yongchang,ZHU Hehua.FEM modeling method for anchored slope stability analysis and discussions on anchoring effect[J].Chinese Journal of Geotechnical Engineering,2008,30(7):1099-1104.(in Chinese))
[12] DAWSON E M,ROTH W H,DRESCHER A.Slope stability analysis by strength reduction[J].Geotechnique,1999,49(6):835-840.
[2] 程良奎.岩土锚固的现状与发展[J].土木工程学报,2001,34(3):7-12,34.(CHENG Liankui.Present status and development of ground anchorages[J].China Civil Engineering Journal,2000,34(3):7-12,34.(in Chinese))
[3] 张晗旭.关于预应力锚索加固效应研究的几点看法[J].河海大学学报,1999,27(4):93-96.(ZHANG Hanxu.Comments on the study of reinforcing effect of prestressed anchored steel rope[J].Journal of Hohai University,1999,27(4):93-96.(in Chinese))
[4] 徐年丰,陈胜宏.我国岩土预应力锚索加固技术的发展与存在的问题[J].水利水电快报,2001,22(10):20-23.(XU Nianfeng,CHEN Shenghong.The development and existing problems of reinforcement technology of geotechnical prestressed anchorage cable in China[J].Express Water Resources and Hydropower Information,2001,22(10):20-23.(in Chinese))
[5] 吴茂明,阮含婷,刘鹭.预应力锚索在岩土边坡工程治理中的应用[J].岩土工程学报,2010,32(增刊1):324-326.(WU Maoming,RUAN Hanting,LIU Lu.Application of prestressed anchor cables in treatment of geotechnical slopes[J].Chinese Journal of Geotechnical Engineering,2010,32(Suppl1):324-326.(in Chinese))
[6] 叶海林,郑颖人,李安洪,等.地震作用下边坡预应力锚索振动台试验研究[J].岩石力学与工程学报,2012,31(增刊1):2847-2854.(YE Hailin,ZHENG Yingren,LI Anhong,et al.Shaking table test studies of prestressed anchor cable of slope under earthquake[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(Suppl1):2847-2854.(in Chinese))
[7] 郑文博,庄晓莹,蔡永昌,等.地震作用下预应力锚索对岩石边坡稳定性影响的模拟方法及锚索优化研究[J].岩土工程学报,2012,34(9):1668-1676.(ZHENG Wenbo,ZHUANG Xiaoying,CAI Yongchang,et al.Modeling of prestressed anchors in rock slope under earthquake and optimization of anchor arrangement[J].Chinese Journal of Geotechnical Engineering,2012,34(9):1668-1676.(in Chinese))
[8] 赵炼恒,罗强,李亮,等.基于失稳状态耗能最小原理的预应力锚索加固边坡稳定性上限解析[J].岩土力学,2013,34(2):426-432.(ZHAO Lianheng,LUO Qiang,LI Liang,et al.Energy analysis method for slopes reinforcing with prestressed anchor cables based on minimum energy principle of instability state[J].Rock and Soil Mechanics,2013,34(2):426-432.(in Chinese))
[9] AMINI M,MAJDI A,VESHADI M A.Stability analysis of rock slopes against block-flexure toppling failure[J].Rock Mechanics and Rock Engineering,2012,45(4):519-532.
[10] 李宁,张鹏,于冲.边坡预应力锚索加固的数值模拟方法研究[J].岩石力学与工程学报,2007,26(2):254-261.(LI Ning,ZHANG Peng,YU Chong.Research on method of numerical simulation of prestressed anchor cable in slope[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(2):254-261.(in Chinese))
[11] 庄晓莹,蔡永昌,朱合华.锚固边坡稳定性分析有限元模型及锚固效应的探讨[J].岩土工程学报,2008,30(7):1099-1104.(ZHUANG Xiaoying,CAI Yongchang,ZHU Hehua.FEM modeling method for anchored slope stability analysis and discussions on anchoring effect[J].Chinese Journal of Geotechnical Engineering,2008,30(7):1099-1104.(in Chinese))
[12] DAWSON E M,ROTH W H,DRESCHER A.Slope stability analysis by strength reduction[J].Geotechnique,1999,49(6):835-840.
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