饱和软黄土地层地铁隧道施工诱发的地表变形

摘要

开展西安饱和软黄土地层地铁隧道施工地表沉降特性研究具有重要理论意义与工程应用价值,以西安地铁三号线通化门-胡家庙区间隧道右线为工程背景,采用现场实测的手段研究了饱和软黄土地层矿山法地铁隧道施工诱发的的地表沉降规律,并与该地层下采用矿山法与盾构法施工和饱和软黄土地层与普通黄土地层下的地表沉降值进行了对比.实测数据表明饱和软黄土地层矿山法施工诱发的地表沉降最大值位于隧道中心处,其值为48.98 mm,影响范围约为2倍的隧道洞径,最终的沉降槽宽度为2D;纵向地表沉降变形历时曲线可分为3个阶段,其中第二阶段占总沉降量的3/4,为主要沉降阶段.饱和软黄土地层采用盾构法施工时地表沉降最大值为35.5 mm,而采用矿山法施工时地表中心沉降最小值为41.2 mm;与普通黄土地层相比,在普通黄土地层采用矿山法施工时地表中心最大沉降值为28.1 mm.结果表明:饱和软黄土地层地铁隧道施工诱发的地表沉降远大于普通黄土,当隧道存在饱和软黄土地层时必须引起重视应优先采用盾构法施工,如采用矿山法施工必须采取相应的控制措施.%It is of great theoretical significance and engineering value to carry out the research on sur-face subsidence characteristics of subway tunnel construction in saturated soft loess strata in Xi'an. Based on the engineering background of right tunnel of Tonghuamen-Hujiamiao on Xi'an Subway Line 3,the law of surface subsidence induced by construction of subway tunnel in saturated soft loess strata was studied by field monitoring.The ground subsidence induced by the construction of soft loess stra-tum subway tunnel is compared with the ground settlement value under the stratum by the mining meth-od and shield method and the saturated soft loess stratum and ordinary loess stratum.The measured da-ta show that the maximum value of surface subsidence induced by the construction of saturated soft lo-ess strata is located at the center of the tunnel with the value of 48.98 mm and the influential range is about 2 times the tunnel diameter.The final settlement slot width is 2D.The longitudinal curve of the vertical settlement of the tunnel can be divided into three stages,with the second stage accounting for about 3/4 of the total settlement,which is the main subsidence stage.The maximum surface settlement of the saturated soft loess strata when using the shield method is 35.5 mm,while the minimum ground surface settlement when using the mining method is 41.2 mm.Compared with the common loess strata, when using the mining method,the maximum settlement value is 28.1 mm.The results indicate that surface subsidence induced by tunnel construction in saturated soft loess strata is much larger than or-dinary loess.When the saturated soft loess strata exist in tunnel ground,it is necessary to pay more at-tention to the construction of shield tunneling.If the mining method is adopted,corresponding control measures must be taken.