深部硬岩开挖隧洞围岩稳定性数值模拟
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摘要
通过RFPA方法考虑岩石材料的细观非均匀特性,对深埋硬岩隧洞全断面一次开挖和分断面多次开挖进行数值模拟分析,直观呈现隧道围岩破裂面位置与形态渐进破坏诱致失稳的演化全过程,并与现场破坏情况对比研究,旨在揭示两种不同施工过程中应力演化、位移扩展、能量释放多个特征方面对围岩稳定性的影响及其破坏机制。数值模拟结果表明,隧洞围岩稳定性采用分断面多次开挖优于全断面一次开挖方式,为应对1#引水隧洞TBM掘进到锦屏山核部强岩爆风险,排引2#横通道往西洞段采用钻爆法超前实施导洞方案为最佳。虽然分断面开挖可以显著地降低围岩破坏风险,但不能彻底排除多次扩挖过程中围岩大塌方的情况,则建议这些洞段直接钻爆扩挖到位,让TBM步进安全通过为宜。同时深埋硬岩"城门型"隧道的破坏机制是来自侧壁破坏为主而拱形部位不存在压力拱破坏,与浅埋隧道的破坏在拱顶的破坏机制有明显区别,对认识隧道破坏机制有重要意义。
The RFPA code was used to consider the heterogeneous characteristics of rock material at mesoscopic level,numerical analysis was carried out to simulate the full-face excavation and multi-stage excavation in deep hard rock tunnel. The progressive failure induced instability of the whole evolution process was reproduced directly for rupture position and morphology of the tunnel surrounding rock,the results were investigated by comparing with the filed destruction. In order to reveal the impact of the stability of surrounding rock and its failure mechanism of two different construction methods including more features of stress evolution,displacement expansion,energy release.The numerical simulation results show that the stability of surrounding rock of tunnel excavation section repeatedly is better than that of full face excavation,in response to prepare for strong rock burst risk in the core of the Jinping Mountain due to TBM driving in 1# diversion tunnel,the optimal drilling and blasting method is adopted to carry pilot tunnel ahead of Section excavation to the west of 2# drainage and diversion cross tunnel. Although the stability risk of surrounding rock can be reduced significantly with comparison of that of full section excavation,but great collapse of surrounding rock can not be completely removed due to the rock dug repeatedly,it is suggested that tunnel section is finally completed by drilling and blasting excavation,let TBM machine pass through the tunnel safely. At the same time,the failure mechanism of the deep buried hard rock for the rectangular tunnel with arch crown is damaged mainly from the side wall,but there is no pressure arch destruction in the arch. It is of great significance to understand the tunnel failure mechanism.
The RFPA code was used to consider the heterogeneous characteristics of rock material at mesoscopic level,numerical analysis was carried out to simulate the full-face excavation and multi-stage excavation in deep hard rock tunnel. The progressive failure induced instability of the whole evolution process was reproduced directly for rupture position and morphology of the tunnel surrounding rock,the results were investigated by comparing with the filed destruction. In order to reveal the impact of the stability of surrounding rock and its failure mechanism of two different construction methods including more features of stress evolution,displacement expansion,energy release.The numerical simulation results show that the stability of surrounding rock of tunnel excavation section repeatedly is better than that of full face excavation,in response to prepare for strong rock burst risk in the core of the Jinping Mountain due to TBM driving in 1# diversion tunnel,the optimal drilling and blasting method is adopted to carry pilot tunnel ahead of Section excavation to the west of 2# drainage and diversion cross tunnel. Although the stability risk of surrounding rock can be reduced significantly with comparison of that of full section excavation,but great collapse of surrounding rock can not be completely removed due to the rock dug repeatedly,it is suggested that tunnel section is finally completed by drilling and blasting excavation,let TBM machine pass through the tunnel safely. At the same time,the failure mechanism of the deep buried hard rock for the rectangular tunnel with arch crown is damaged mainly from the side wall,but there is no pressure arch destruction in the arch. It is of great significance to understand the tunnel failure mechanism.
引文
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[16]张黎明,郑颖人,有限元强度折减法在公路隧道中的应用探讨[J].岩土力学,2007,28(1):97-101.
[17]郑颖人,胡文清,王敬林.强度折减有限元法及其在隧道和地下硐室工程中的应用[A]//中国土木工程学会第十一届隧道及地下工程分会第十三届年会论文集[C].2004:239-243.
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[19]唐春安,李连崇,李常文,等.岩土工程稳定性分析RFPA强度折减法[J].岩石力学与工程学报,2006,25(8):1522-1530.
[20]朱万成,唐春安,杨天鸿,等.岩石破裂过程分析(RFPA2D)系统的细观单元本构关系及验证[J].岩石力学与工程学报,2003,22(1):24-29.
[2]任旭华,李同春,陈祥荣.锦屏二级水电站深埋引水隧洞衬砌及围岩结构分析[J].岩石力学与工程学报,2001,20(1):16-19.
[3]于本福,闫相祯,杨秀娟.基于突变理论的水封储油洞室稳定性分析[J].地下空间与工程学报,2016,12(6):1570-1576.
[4]冯夏庭,马平波.基于数据挖掘的地下硐室围岩稳定性判别[J].岩石力学与工程学报,2001,20(3):306-309.
[5]曾开华,鞠海燕,张常光.深埋圆形隧道弹塑性位移统一解及其比较分析[J].岩土力学,2011,32(5):1315-1319.
[6]徐栓强,俞茂宏,胡小荣.基于双剪统一强度理论的地下圆形洞室稳定性的研究[J].煤炭学报,2003,28(5):522-526.
[7]蒋斌松,张强,贺永年,等.深部圆形巷道破裂围岩的弹塑性分析[J].岩石力学与工程学报,2007,26(5):982-986.
[8]Zienkiewicz O C,Humpheson C,Lewis R W.Associated and non-associated viscoplasticity and plasticity in soil mechanics[J].Geotechnique,1975,25(4):671-689.
[9]Naylor D J.Finite elements and slope stability[A]//Numerical Methods in Geomechanics,Proceedings of the NATO Advanced Study Institute[C].Lisbon,Portugal,1981:229-244.
[10]Dawson E M,Roth W H,Drescher A.Slope stability analysis by strength reduction[J].Geotechnique,1999,49(6):835-840.
[11]Donald I B,Giam S K.Application of the nodal displacement method to slope stability analysis[A]//Proceedings of the 5th Australia-New Zealand Conference on Geomechanics[C].Sydney,Australia,1988:456–460.
[12]Duncan J M.State of the art:limit equilibrium and finite element analysis of slopes[J].Journal of Geotechnical and Geoenvironmental Engineering,1996,122(7):577-569.
[13]Griffiths D V,Lane P A.Slope stability analysis by finite elements[J].Geotechnique,1999,49(3):387-403.
[14]Matsui T,San K C.Finite element slope stability analysis by shear strength reduction technique[J].Soils and Foundations,1992,32(1):59-70.
[15]Ugai K,Leshchinsky D.Three-dimensional limit equilibrium and finite element analyses:a comparison of results[J].Soils and Foundations,1995,35(4):1-7.
[16]张黎明,郑颖人,有限元强度折减法在公路隧道中的应用探讨[J].岩土力学,2007,28(1):97-101.
[17]郑颖人,胡文清,王敬林.强度折减有限元法及其在隧道和地下硐室工程中的应用[A]//中国土木工程学会第十一届隧道及地下工程分会第十三届年会论文集[C].2004:239-243.
[18]郑颖人,赵尚毅.有限元极限分析法发展及其在岩土工程中的应用[J].中国工程科学,2006,8(12):39-61.
[19]唐春安,李连崇,李常文,等.岩土工程稳定性分析RFPA强度折减法[J].岩石力学与工程学报,2006,25(8):1522-1530.
[20]朱万成,唐春安,杨天鸿,等.岩石破裂过程分析(RFPA2D)系统的细观单元本构关系及验证[J].岩石力学与工程学报,2003,22(1):24-29.