地铁隧道双线暗挖斜穿地裂缝地表变形规律及控制技术研究

Study on Laws of Ground Surface Deformation Induced by Double Track Bored Metro Tunnel Obliquely Crossing Ground Fissure and the Control Technology

为分析暗挖黄土地铁隧道双线斜穿地裂缝时地表变形规律,以西安地铁3号线为依托工程,通过理论分析、FLAC3D模拟及实测,对地裂缝处地表纵向、横向变形规律进行系统研究。主要结论:地裂缝与掌子面关键体相交时,该阶段为控制掌子面稳定性及地层沉降的关键;穿越过程地裂缝处上、下盘将产生沉降错台及水平张拉,二者发展趋势较为接近,错台的发展及恢复分别集中在进度-1.25D^0和0~1.75D;受先行隧道扰动影响,后行隧道于地裂缝处将产生更大的沉降差和最终沉降;地表最终纵向沉降将在上盘距地裂缝约1D处出现最值点,沉降集中区范围可按已有规程进行投影确定;地裂缝处的地层沉降控制可采用减小导洞面积、留设核心土、增强超前支护、控制地表水下渗等综合措施进行。

In order to understand the laws of surface deformation of shallow-buried undercut metro tunnel crossing through ground fissure,this paper uses theoretical analysis,FLAC3 D numerical simulation and field observation based on the project of Xi＇an NO. 3 metro line to conduct a systematic research on the laws of the vertical and horizontal deformation of the surface near the ground fissure. Research concludes that where the ground fissure intersects with the key block of tunnel face,it is the key section to control tunnel face stability and ground settlement. During the process of crossing,the two sides will experience staggered settlement and horizontal tensioning and the two sides are subject to similar development trend.The development and recovery of the staggering are focused on the progress of-1. 25 D ~ 0D and 0D ~1. 75 D respectively. Influenced by the disturbance of the ahead tunneling,the follow-up tunneling may generate greater settlement difference and the final settlement at the ground fissure. The peak point of settlement is located about 1D from the ground fissure on hanging side,the scope of the settlement concentration can be determined according to the existing rules. Such comprehensive measures can be taken to control the stratum settlement at the ground fissure as reducing the size of the pilot tunnel,keeping core soil,enhancing advance support and controlling surface water infiltration.