浅埋地铁隧道施工影响下含空洞地层的变形特征分析
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摘要
地层空洞的存在使得隧道结构周围的地层环境变得更为复杂,在地铁隧道施工的影响下极易引起地表沉降加剧甚至地表坍塌。针对V级围岩地铁隧道,采用三维模型试验和数值模拟研究了不同位置地层空洞对地表沉降的影响规律以及空洞的变形特征,同时通过修正后的Peck公式对试验结果进行拟合分析。研究结果表明:空洞的存在使得地层损失加剧,地表沉降槽深度和宽度均有所增大,沉降槽曲线整体向空洞一侧偏移,通过修正后的Peck公式能较好地拟合出沉降曲线形态;从地表整体沉降形状上看,空洞上方一定范围内地表沉降较大,地表会出现明显的沉降盆形态;综合考虑空洞对地表沉降槽宽度和深度以及地层损失率的影响,认为空洞位于隧道斜上方是最不利位置,在施工过程中对这一方位地层空洞应重点关注;不同方位空洞的变形模式不同,主要表现为立式椭球体和卧式椭球体等变形模式。
The existence of the ground voids makes the ground conditions around the tunnel more complex, which may increase the ground surface settlement and even induce collapse during shallow metro tunneling. Concerning the metro tunnels in the surrounding rock grade V, a series of model tests and 3 D numerical simulations are conducted to investigate the characteristics of the void deformation and the impact of different void positions on the ground surface settlement. Besides, an improved Peck formula is proposed to perform the curve-fitting analysis on the model test results. The main conclusions are as follows: the ground voids increase the ground loss, depth and width of settlement trough of the ground surface, and the settlement trough moves towards the ground voids. The curve-fitting results of the improved Peck formula correspond well with those of the model tests and numerical simulations. Furthermore, from an overall perspective of the settlement trough shape of the ground surface, the ground surface settlements are relatively larger within a certain range above the void, and a basin-shaped groove occurs on the ground surface. Considering the overall influences of the ground loss, depth and width of settlement trough, the void locating on the inclined top of the tunnel is the worst position for the tunnel construction, in which case the engineers should pay more attention to monitoring of the ground movement. According to the results of the numerical simulations, the void deformation modes are different with different positions of the void, and the main deformation modes are vertical ellipsoid and horizontal ellipsoid.
The existence of the ground voids makes the ground conditions around the tunnel more complex, which may increase the ground surface settlement and even induce collapse during shallow metro tunneling. Concerning the metro tunnels in the surrounding rock grade V, a series of model tests and 3 D numerical simulations are conducted to investigate the characteristics of the void deformation and the impact of different void positions on the ground surface settlement. Besides, an improved Peck formula is proposed to perform the curve-fitting analysis on the model test results. The main conclusions are as follows: the ground voids increase the ground loss, depth and width of settlement trough of the ground surface, and the settlement trough moves towards the ground voids. The curve-fitting results of the improved Peck formula correspond well with those of the model tests and numerical simulations. Furthermore, from an overall perspective of the settlement trough shape of the ground surface, the ground surface settlements are relatively larger within a certain range above the void, and a basin-shaped groove occurs on the ground surface. Considering the overall influences of the ground loss, depth and width of settlement trough, the void locating on the inclined top of the tunnel is the worst position for the tunnel construction, in which case the engineers should pay more attention to monitoring of the ground movement. According to the results of the numerical simulations, the void deformation modes are different with different positions of the void, and the main deformation modes are vertical ellipsoid and horizontal ellipsoid.
引文
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[12]莫阳春.高水压充填型岩溶隧道稳定性研究[D].成都:西南交通大学,2009.(MO Yang-chun.Research on stability of tunnels with high water pressure filled karst caves[D].Chengdu:Southwest Jiaotong University,2009.(in Chinese))
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[14]李贺.浅埋隧道施工影响下含空洞地层失稳破坏模式及演化规律[D].北京:北京交通大学,2013.(LI He.Instability mode and corresponding evolution law of the ground with voids induced by shallow tunnelling[D].Beijing:Beijing Jiaotong University,2013.(in Chinese))
[15]余乐.城市地层不同形态空洞失稳破坏机制的试验研究[D].北京:北京交通大学,2013.(YU Le.Test study on failure mechanism of underground cavity in different forms in urban strata[D].Beijing:Beijing Jiaotong University,2013.(in Chinese))
[16]李倩倩.复杂城市地层的细观结构稳定性及其变形效应[D].北京:北京交通大学,2015.(LI Qian-qian.Stability and deformation effect of defects in complicated strata[D].Beijing:Beijing Jiaotong University,2015.(in Chinese))
[17]李倩倩,张顶立,张成平,等.不同埋深下暗挖隧道施工的地层响应[J].北京交通大学学报,2013,37(1):27-33.(LI Qian-qian,ZHANG Ding-li,ZHANG Cheng-ping,et al.Study on ground response caused by undercutting subway tunnel under different overburden depths[J].Journal of Beijing Jiaotong University,2013,37(1):27-33.(in Chinese))
[18]张成平,张旭,李贺,等.浅埋隧道施工扰动下含空洞地层破坏演化规律试验研究[J].岩土工程学报,2016,38(2):263-270.(ZHANG Cheng-ping,ZHANG Xu,LI He,et al.Model tests on failure laws of ground with voids induced by shallow tunnelling[J].Chinese Journal of Geotechnical Engineering,2016,38(2):263-270.(in Chinese))
[19]袁文忠.相似理论与静力学模型试验[M].成都:西南交通大学出版社,1998.(YUAN Wen-zhong.Simulation theory and statics model test[M].Chengdu:Southwest Jiaotong University Press,1998.(in Chinese))
[20]王戍平.破碎围岩隧道的模拟试验研究[D].杭州:浙江大学,2004.(Model test study on the tunnel within cracked surrounding rocks[D].Hangzhou:Zhejiang University,2004.(in Chinese))
[21]PECK R B.Deep excavations and tunneling in soft ground[C]//Proceedings of the 7th International Conference on Soil Mechanics and Foundation Engineering.Mexico City,1969.
[2]张成平,张顶立,王梦恕,等.城市隧道施工诱发的地面塌陷灾变机制及其控制[J].岩土力学,2010,31(增刊1):303-309.(ZHANG Cheng-ping,ZHANG Ding-li,WANGMeng-shu,et al.Catastrophe mechanism and control technology of ground collapse induced by urban tunneling[J].Rock and Soil Mechanics,2010,31(S1):303-309.(in Chinese))
[3]苗宇宽,郭景力.地质雷达在城市道路地下空洞勘察中的应用[J].矿产勘查,2008,11(9):85-88.(MIAO Yu-kuan,GUO Jing-li.Application of geological radar in underground voids exploration of urban roads[J].Geotechnical Engineering World,2008,11(9):85-88.(in Chinese))
[4]薛建,曾昭发,王者江,等.探地雷达在城市地铁沿线空洞探测中的技术方法[J].物探与化探,2010,34(5):617-621.(XUE Jian,ZHEN Zhao-fa,WANG Zhe-jiang,et al.The technical methods for applying GPR to underground cavity detection along the subway[J].Geophysical&Geochemical Exploration,2010,34(5):617-621.(in Chinese))
[5]吴梦军.岩溶地区公路隧道围岩稳定性研究[D].重庆:重庆交通大学,2003.(WU Meng-jun.Study on stability of surrounding rock of highway tunnel in karst area[D].Chongqing:Chongqing Jiaotong University,2003.(in Chinese))
[6]吴梦军,许锡宾,刘绪华,等.岩溶对公路隧道围岩稳定性的影响研究[J].地下空间,2003,23(1):59-63.(WUMeng-jun,XU Xi-bin,LIU Xu-hua,et al.Study on effect of karst to surrounding rock stability of highway tunnel[J].Underground Space,2003,23(1):59-63.(in Chinese))
[7]吴梦军,许锡宾,赵明阶,等.岩溶地区公路隧道施工力学响应研究[J].岩石力学与工程学报,2004(9):1525-1529.(WU Meng-jun,XU Xi-bin,ZHAO Ming-jie,et al.Construction mechanics response study of highway tunnel in karst region[J].Chinese Journal of Rock Mechanics and Engineering,2004(9):1525-1529.(in Chinese))
[8]吴梦军,赵明阶,刘绪华,等.岩溶区公路隧道围岩稳定性模型试验研究[C]//中国岩石力学与工程学会第七次学术大会论文集.北京,2002.(WU Meng-jun,ZHAO Ming-jie,LIU Xu-hua,et al.Test research on model of surrounding rock stability on highway tunnel in karst area[C]//The Seventh Academic Conference of Rock Mechanic and Engineering in China.Beijing,2002.(in Chinese))
[9]赵明阶,敖建华,刘绪华,等.岩溶尺寸对隧道围岩稳定性影响的模型试验研究[J].岩石力学与工程学报,2004,23(2):213-217.(ZHAO Ming-jie,AO Jian-hua,LIUXu-hua,et al.Model testing research on influence of karst cave size on stability of surrounding rock masses during tunnel construction[J].Chinese Journal of Rock Mechenics and Engineering,2004,23(2):213-217.(in Chinese))
[10]赵明阶,徐容,刘绪华,等.隧道顶部溶洞影响围岩稳定性的模型试验研究[J].地下空间.2003,23(2):153-157.(ZHAO Ming-jie,XU Rong,LIU xu-hua,et al.A model test study on influence of top karst cave on stability of the surrounding rock-mass during tunnel construction[J].Underground Space,·2003,23(2):153-157.(in Chinese))
[11]赵明阶,徐容,许锡宾.岩溶区全断面开挖隧道围岩变形特性模拟[J].同济大学学报(自然科学版),2004,32(6):710-715.(ZHAO Ming-jie,XU Rong,XU Xi-bin.Deformation modeling of surrounding rock during full-face excavation of tunnel in karst regions[J].Journal of Tongji University(Natural Science Edition),2004,32(6):710-715.(in Chinese))
[12]莫阳春.高水压充填型岩溶隧道稳定性研究[D].成都:西南交通大学,2009.(MO Yang-chun.Research on stability of tunnels with high water pressure filled karst caves[D].Chengdu:Southwest Jiaotong University,2009.(in Chinese))
[13]何岳.地层空洞影响下城市隧道施工引起的地层变形规律及控制技术研究[D].北京:北京交通大学,2012.(HEYue.Study on ground deformation discipline and control techniques of subway tunnel excavation under the influence of strata defect[D].Beijing:Beijing Jiaotong University,2012.(in Chinese))
[14]李贺.浅埋隧道施工影响下含空洞地层失稳破坏模式及演化规律[D].北京:北京交通大学,2013.(LI He.Instability mode and corresponding evolution law of the ground with voids induced by shallow tunnelling[D].Beijing:Beijing Jiaotong University,2013.(in Chinese))
[15]余乐.城市地层不同形态空洞失稳破坏机制的试验研究[D].北京:北京交通大学,2013.(YU Le.Test study on failure mechanism of underground cavity in different forms in urban strata[D].Beijing:Beijing Jiaotong University,2013.(in Chinese))
[16]李倩倩.复杂城市地层的细观结构稳定性及其变形效应[D].北京:北京交通大学,2015.(LI Qian-qian.Stability and deformation effect of defects in complicated strata[D].Beijing:Beijing Jiaotong University,2015.(in Chinese))
[17]李倩倩,张顶立,张成平,等.不同埋深下暗挖隧道施工的地层响应[J].北京交通大学学报,2013,37(1):27-33.(LI Qian-qian,ZHANG Ding-li,ZHANG Cheng-ping,et al.Study on ground response caused by undercutting subway tunnel under different overburden depths[J].Journal of Beijing Jiaotong University,2013,37(1):27-33.(in Chinese))
[18]张成平,张旭,李贺,等.浅埋隧道施工扰动下含空洞地层破坏演化规律试验研究[J].岩土工程学报,2016,38(2):263-270.(ZHANG Cheng-ping,ZHANG Xu,LI He,et al.Model tests on failure laws of ground with voids induced by shallow tunnelling[J].Chinese Journal of Geotechnical Engineering,2016,38(2):263-270.(in Chinese))
[19]袁文忠.相似理论与静力学模型试验[M].成都:西南交通大学出版社,1998.(YUAN Wen-zhong.Simulation theory and statics model test[M].Chengdu:Southwest Jiaotong University Press,1998.(in Chinese))
[20]王戍平.破碎围岩隧道的模拟试验研究[D].杭州:浙江大学,2004.(Model test study on the tunnel within cracked surrounding rocks[D].Hangzhou:Zhejiang University,2004.(in Chinese))
[21]PECK R B.Deep excavations and tunneling in soft ground[C]//Proceedings of the 7th International Conference on Soil Mechanics and Foundation Engineering.Mexico City,1969.