砾砂地层中盾构隧道施工的地层损失率研究

Formation Loss Rate Study on Shield Tunnel Construction in Gravel and Sand Strata

以内蒙古自治区呼和浩特市轨道交通2号线帅家营站~内大南校区站盾构区间为工程背景,以经典的Peck公式为理论基础,通过软件FLAC3D建立数值模型并进行计算,推导呼和浩特地区砾砂地层中进行盾构施工的地层损失率.基于实际的施工过程,在软件中用内置的FISH语言模拟隧道开挖过程,并提取模型开挖过程中地表测点的竖向位移,与实际施工过程中该测点的实际位移做对比来验证模型建立的正确性.从模型中提取若干个地表沉降变形曲线,整理出各个断面的隧道中心处最大沉降值与沉降槽宽度的数据,分别代入到Peck公式中得到对应的地层损失率,通过最终的整理验证,得到呼和浩特地区地层损失率的范围为0.2%~1.66%,为今后呼和浩特地区开展盾构隧道施工提供了参考依据,为今后Peck公式在该地区的应用提供参考.

Taking the shield tunelling section from Shijiaying Station to Inner Mongolia University (South campus)Station o[Hohhot Rail Transit Line 2 in Inner Mongolia Autonomous Region as the engineering backgound,and based on the classic Peck formula,the numerical model was established and calculated by sofware FLAC3D.Besides,the formation loss rate in gravel and sand strata of Hohhot area was deduced.On the basis of actual conslruction process,the tunnel excavation process was simulated by the software with built-in FISH language,the vertical displacement of the suface measurement point in the model excavation process was extracted and compared with the actual displacement of the measurement point in the actual construction process so as to venify the correctness of the model establishment.Some curves of surface subsidence deformation were extracted from the model.The data of maximum stlement value and the trough widh at each section of the tunnel center were sorted out,and placed into the Peck formula to solve corresponding slrata loss rales.The final validation showed that the formation loss rate in Hohhot area was 0.2%~1.66%.It would provide a reference basis for the shield tunnel construction within the range of Hohhot area in the future,and also offer reference value for the future application of Peck formula in the region.