车站基坑揭露断层带注浆加固效果数值模拟研究
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摘要
为研究注浆对明挖基坑揭露断层带的加固效果,以南京地铁上元门车站基坑工程为背景,考虑基坑开挖过程中渗流场与围岩应力场的相互耦合作用,建立相应的有限元分析模型,对软弱破碎层、注浆加固带、基坑地下连续墙以及围岩所组成的耦合系统进行模拟,研究注浆加固前后围岩渗流场、位移场以及应力场的特征,最终获得基坑地下连续墙的水平位移、基坑外地表沉降、围岩塑性区分布、基坑内围岩变形以及基坑内涌水量变化规律。研究结果表明:1)通过对基坑底部断层带的注浆加固,基坑侧向位移及基坑外地表沉降均得到有效控制,相比于注浆加固前,其最大水平位移和地表累计沉降量减小50%以上,满足工程要求; 2)基坑底部区域内塑性区范围明显减少,基坑外塑性区扩散也得到有效抑制; 3)基坑底部断层带注浆改变了渗流场分布,有效降低了基坑涌水量,基坑治理区域涌水量由最初的94 m3/h逐渐减小到4 m3/h,堵水率达96%; 4)注浆结束后现场钻孔取芯率达到75%～80%,开挖揭露大量劈裂作用形成的浆脉,验证了注浆可有效治理明挖基坑所揭露的软弱断层破碎带。
In order to study the reinforcement effect of grouting on the exposed fault zone of open-cut foundation pit,taking the the foundation pit project of Nanjing Metro Shangyuanmen Station as an example,the coupling interaction between seepage field and surrounding rock stress field in excavation process is considered. The corresponding finite element analysis model is established to simulate the coupling system consisting of soft broken layer, grouting reinforcement zone, foundation pit retaining wall and surrounding rock. The characteristics of seepage field,displacement field and stress field of surrounding rock before and after grouting are studied. Finally,the horizontal displacement at the retaining wall of the foundation pit,the surface settlement outside the foundation pit,the distribution of the plastic zone of surrounding rock,the deformation of surrounding rock in the foundation pit and the variation rule of the water inflow in the foundation pit are obtained. The results show that:( 1) Both lateral displacement and ground subsidence of the foundation pit are effectively controlled by grouting reinforcement of fault zone at the bottom of foundation pit. Compared with that before grouting, the maximum horizontal displacement and the accumulated settlement of ground surface are reduced by more than 50%,which can meet the engineering requirements;( 2) The range of plastic zone in the bottom of foundation pit is obviously reduced,and the diffusion of plastic zone outside the foundation pit is restrained effectively;( 3) Grouting in the fault zone of the bottom of foundation pit has changed the distribution of seepage field and effectively reduced the water inflow of foundation pit. The water gushing amount of the foundation pit is gradually reduced from the original 94 m3/h to 4 m3/h,and the water reduction rate is 96%;( 4) The coring rate of site drilling is 75%-80% after the grouting. The excavation reveals a large number of veins formed by splitting,which proves that the grouting can effectively control the weak fault fracture zone exposed by the open excavation foundation pit.
In order to study the reinforcement effect of grouting on the exposed fault zone of open-cut foundation pit,taking the the foundation pit project of Nanjing Metro Shangyuanmen Station as an example,the coupling interaction between seepage field and surrounding rock stress field in excavation process is considered. The corresponding finite element analysis model is established to simulate the coupling system consisting of soft broken layer, grouting reinforcement zone, foundation pit retaining wall and surrounding rock. The characteristics of seepage field,displacement field and stress field of surrounding rock before and after grouting are studied. Finally,the horizontal displacement at the retaining wall of the foundation pit,the surface settlement outside the foundation pit,the distribution of the plastic zone of surrounding rock,the deformation of surrounding rock in the foundation pit and the variation rule of the water inflow in the foundation pit are obtained. The results show that:( 1) Both lateral displacement and ground subsidence of the foundation pit are effectively controlled by grouting reinforcement of fault zone at the bottom of foundation pit. Compared with that before grouting, the maximum horizontal displacement and the accumulated settlement of ground surface are reduced by more than 50%,which can meet the engineering requirements;( 2) The range of plastic zone in the bottom of foundation pit is obviously reduced,and the diffusion of plastic zone outside the foundation pit is restrained effectively;( 3) Grouting in the fault zone of the bottom of foundation pit has changed the distribution of seepage field and effectively reduced the water inflow of foundation pit. The water gushing amount of the foundation pit is gradually reduced from the original 94 m3/h to 4 m3/h,and the water reduction rate is 96%;( 4) The coring rate of site drilling is 75%-80% after the grouting. The excavation reveals a large number of veins formed by splitting,which proves that the grouting can effectively control the weak fault fracture zone exposed by the open excavation foundation pit.
引文
[1] LI Shucai,LIU Rentai,ZHANG Qingsong,et al. Protectionagainst water or mud inrush in tunnels by grouting:a review[J]. Journal of Rock Mechanics and GeotechnicalEngineering,2016,8(5):753.
[2]邝建政,昝月稳,王杰,等.岩土工程注浆理论与工程实例[M].北京:科学出版社,2001.KUANG Jianzheng,ZAN Yuewen,WANG Jie,et al. Theoryand project example of grout in geotechnical engineering[M]. Beijing:Science Press,2001.
[3]张庆松,韩伟伟,李术才,等.灰岩角砾岩破碎带涌水综合注浆治理[J].岩石力学与工程学报,2012,31(12):2412.ZHANG Qingsong, HAN Weiwei, LI Shucai, et al.Comprehensive grouting treatment for water gushing analysisin limestone breccias fracture zone[J]. Chinese Journal ofRock Mechanics and Engineering,2012,31(12):2412.
[4]李术才,张伟杰,张庆松,等.富水断裂带优势劈裂注浆机制及注浆控制方法研究[J].岩土力学,2014(3):744.LI Shucai, ZHANG Weijie, ZHANG Qingsong, et al.Research on advantage-fracture grouting mechanism andcontrolled grouting method in water-rich fault zone[J]. Rockand Soil Mechanics,2014(3):744.
[5]孙锋,陈铁林,张顶立,等.基于宾汉体浆液的海底隧道劈裂注浆机制研究[J].北京交通大学学报,2009,33(4):1.SUN Feng,CHEN Tielin,ZHANG Dingli,et al. Study onfracture grouting mechanism in subsea tunnel based onBingham fluids[J]. Journal of Beijing Jiaotong University,2009,33(4):1.
[6]张忠苗,邹健.桩底劈裂注浆扩散半径和注浆压力研究[J].岩土工程学报,2008,30(2):181.ZHANG Zhongmiao, ZOU Jian. Penetration radius andgrouting pressure in fracture grouting[J]. Chinese Journal ofGeotechnical Engineering,2008,30(2):181.
[7]孙锋,张顶立,陈铁林.基于流体时变性的隧道劈裂注浆机制研究[J].岩土工程学报,2011,33(1):88.SUN Feng,ZHANG Dingli,CHEN Tielin. Fracture groutingmechanism in tunnels based on time-dependent behaviors ofgrout[J]. Chinese Journal of Geotechnical Engineering,2011,33(1):88.
[8]李鹏,张庆松,张霄,等.非均质断层介质单双液加固特性对比[J].应用基础与工程科学学报,2016,24(4):840.LI Peng, ZHANG Qingsong, ZHANG Xiao, et al.Comparison research on reinforcement characteristics ofcement slurry and C-S slurry for inhomogeneous faultmedium[J]. Journal of Basic Science and Engineering,2016,24(4):840.
[9]张庆松,李鹏,张霄,等.隧道断层泥注浆加固机制模型试验研究[J].岩石力学与工程学报,2015,34(5):924.ZHANG Qingsong,LI Peng,ZHANG Xiao,et al. Modeltest on grouting strengthening mechanism for fault gouge oftunnel[J]. Chinese Journal of Rock Mechanics andEngineering,2015,34(5):924.
[10]张伟杰,李术才,魏久传,等.富水破碎岩体帷幕注浆模型试验研究[J].岩土工程学报,2015,37(9):1627.ZHANG Weijie,LI Shucai,WEI Jiuchuan,et al. Modeltests on curtain grouting in water-rich broken rock mass[J]. Chinese Journal of Geotechnical Engineering,2015,37(9):1627.
[11]张伟杰,李术才,魏久传,等.破碎围岩注浆加固体开挖稳定性及水压超载试验研究[J].中南大学学报(自然科学版),2016,47(6):2083.ZHANG Weijie, LI Shucai, WEI Jiuchuan, et al.Excavation stability and hydraulic overload test of groutingbody in fractured zone[J]. Journal of Central SouthUniversity(Science and Technology),2016,47(6):2083.
[12]李志鹏.断层软弱介质注浆扩散加固机制及工程应用[D].济南:山东大学,2015.LI Zhipeng. Mechanism of grouting spread andreinforcement on soft medium in fault and its application[D]. Jinan:Shandong University,2015.
[2]邝建政,昝月稳,王杰,等.岩土工程注浆理论与工程实例[M].北京:科学出版社,2001.KUANG Jianzheng,ZAN Yuewen,WANG Jie,et al. Theoryand project example of grout in geotechnical engineering[M]. Beijing:Science Press,2001.
[3]张庆松,韩伟伟,李术才,等.灰岩角砾岩破碎带涌水综合注浆治理[J].岩石力学与工程学报,2012,31(12):2412.ZHANG Qingsong, HAN Weiwei, LI Shucai, et al.Comprehensive grouting treatment for water gushing analysisin limestone breccias fracture zone[J]. Chinese Journal ofRock Mechanics and Engineering,2012,31(12):2412.
[4]李术才,张伟杰,张庆松,等.富水断裂带优势劈裂注浆机制及注浆控制方法研究[J].岩土力学,2014(3):744.LI Shucai, ZHANG Weijie, ZHANG Qingsong, et al.Research on advantage-fracture grouting mechanism andcontrolled grouting method in water-rich fault zone[J]. Rockand Soil Mechanics,2014(3):744.
[5]孙锋,陈铁林,张顶立,等.基于宾汉体浆液的海底隧道劈裂注浆机制研究[J].北京交通大学学报,2009,33(4):1.SUN Feng,CHEN Tielin,ZHANG Dingli,et al. Study onfracture grouting mechanism in subsea tunnel based onBingham fluids[J]. Journal of Beijing Jiaotong University,2009,33(4):1.
[6]张忠苗,邹健.桩底劈裂注浆扩散半径和注浆压力研究[J].岩土工程学报,2008,30(2):181.ZHANG Zhongmiao, ZOU Jian. Penetration radius andgrouting pressure in fracture grouting[J]. Chinese Journal ofGeotechnical Engineering,2008,30(2):181.
[7]孙锋,张顶立,陈铁林.基于流体时变性的隧道劈裂注浆机制研究[J].岩土工程学报,2011,33(1):88.SUN Feng,ZHANG Dingli,CHEN Tielin. Fracture groutingmechanism in tunnels based on time-dependent behaviors ofgrout[J]. Chinese Journal of Geotechnical Engineering,2011,33(1):88.
[8]李鹏,张庆松,张霄,等.非均质断层介质单双液加固特性对比[J].应用基础与工程科学学报,2016,24(4):840.LI Peng, ZHANG Qingsong, ZHANG Xiao, et al.Comparison research on reinforcement characteristics ofcement slurry and C-S slurry for inhomogeneous faultmedium[J]. Journal of Basic Science and Engineering,2016,24(4):840.
[9]张庆松,李鹏,张霄,等.隧道断层泥注浆加固机制模型试验研究[J].岩石力学与工程学报,2015,34(5):924.ZHANG Qingsong,LI Peng,ZHANG Xiao,et al. Modeltest on grouting strengthening mechanism for fault gouge oftunnel[J]. Chinese Journal of Rock Mechanics andEngineering,2015,34(5):924.
[10]张伟杰,李术才,魏久传,等.富水破碎岩体帷幕注浆模型试验研究[J].岩土工程学报,2015,37(9):1627.ZHANG Weijie,LI Shucai,WEI Jiuchuan,et al. Modeltests on curtain grouting in water-rich broken rock mass[J]. Chinese Journal of Geotechnical Engineering,2015,37(9):1627.
[11]张伟杰,李术才,魏久传,等.破碎围岩注浆加固体开挖稳定性及水压超载试验研究[J].中南大学学报(自然科学版),2016,47(6):2083.ZHANG Weijie, LI Shucai, WEI Jiuchuan, et al.Excavation stability and hydraulic overload test of groutingbody in fractured zone[J]. Journal of Central SouthUniversity(Science and Technology),2016,47(6):2083.
[12]李志鹏.断层软弱介质注浆扩散加固机制及工程应用[D].济南:山东大学,2015.LI Zhipeng. Mechanism of grouting spread andreinforcement on soft medium in fault and its application[D]. Jinan:Shandong University,2015.
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