基坑开挖卸荷对下卧隧道压力拱的影响研究  

Research on the Influence of Foundation Pit Excavation Unloading on the Pressure Arch of Underlying Tunnel

作　　者：张文正[1] 李星 汪洋[1] 薛尚铃[1] Zhang Wenzheng;Li Xing;Wang Yang;Xue Shangling(CISDI Engineering Co.Ltd.,Chongqing 400013,P.R.China)

机构地区：[1]中冶赛迪工程技术股份有限公司,重庆400013

出　　处：《地下空间与工程学报》2024年第5期1686-1694,1716,共10页Chinese Journal of Underground Space and Engineering

基　　金：重庆市技术创新与应用发展专项(cstc2020jscx-msxmX0130);中冶赛迪集团有限公司科技项目(90150774)。

摘　　要：城市地下空间的开发与利用日益增多,运营的城市隧道周边不可避免地需要开挖,而隧道上方基坑的开挖卸荷对既有隧道压力拱的形成存在较大影响。针对前人研究,总结了基坑开挖3种卸荷比模型,并依据压力拱内外边界判别方法,通过数值模拟研究了基坑开挖卸荷对下卧隧道压力拱形成的影响作用。结果表明:隧道拱顶岩土体受到上方基坑两侧岩土体侧压力的综合作用,相较于一维卸荷比N 1,二维卸荷比N 2与压力拱边界的相关性更为显著。基于基坑开挖对下卧隧道压力拱形成的影响分析,提出了基坑开挖卸荷的工程影响分区,即一般影响区、次要影响区、显著影响区、强烈影响区;基坑开挖宽度L不大于D且基坑开挖深度h小于0.15H时,视为一般影响区;基坑开挖宽度L不大于D且基坑开挖深度h介于0.15H与0.225H之间时,视为显著影响区;基坑开挖宽度L大于D且其二维卸荷比N 2小于0.33时,视为次要影响区;基坑开挖的二维卸荷比N 2不小于0.33时,视为强烈影响区。With the increasing development and utilization of urban underground space,it is inevitable to excavate around the urban operational tunnels.The excavation and unloading of the foundation pit above the tunnel has a great influence on the formation of the pressure arch of the existing tunnel.Based on previous studies,three unloading ratio models for excavation of foundation pits are summarized,and a method for judging the inner and outer boundaries of the pressure arch is provided.The effect of excavation and unloading of foundation pit on the formation of pressure arch of underlying tunnel is studied by numerical simulation.The results show that:The tunnel vault rock and soil are subjected to the combined effect of the lateral pressure of the rock and soil on both sides of the foundation pit above.Compared with the one-dimensional unloading ratio N1,the correlation between the two-dimensional unloading ratio N2 and the boundary of the pressure arch is more significant.Based on the analysis of the impact of foundation pit excavation on the formation of the pressure arch of the underlying tunnel,the engineering impact zones of foundation pit excavation and unloading are proposed,which are divided into general impact zone,secondary impact zone,significant impact zone and strong impact zone.When the excavation width L of the foundation pit is not greater than D and the excavation depth h of the foundation pit is less than 0.15 H,it is regarded as the general influence area;When the excavation width L is not greater than D and the excavation depth h is between 0.15 H and 0.225 H,it is regarded as a significant influence area;When the excavation width L of the foundation pit is greater than D and its two-dimensional unloading ratio N2 is less than 0.33,it is regarded as a secondary affected area;when the two-dimensional unloading ratio N2 of foundation pit excavation is not less than 0.33,it is regarded as a strong influence area.

关 键 词：压力拱 卸荷比 基坑开挖 下卧隧道 

分 类 号：TU91[建筑科学—建筑理论]