基于数值模拟及现场监测的新建隧道开挖对既有隧道影响分析

Analysis of the new tunnel excavation effects on an existing tunnel based on numerical simulation and field monitoring

既有隧道在临坡浅埋环境下对相交新建隧道修建的影响尤为显著.本文基于三维数值模拟以及工程现场监测,采用不同参数组合,研究了埋深与隧道高度比值(C/H)、临坡距与隧道跨度比值(D/W)、既有隧道是否回填以及不同的地表荷载对侧向边坡和地表道路变形产生的影响.研究结果表明,受既有隧道回填影响的敏感区域在平行于开挖方向既有隧道与新建隧道刚分离的区域;不同组合条件下的C/H与D/W决定了降槽曲线的形态与大小差异;结合工程安全控制标准确定可行的实际施工模型,将现场监测数据与模拟结果进行对比发现,尽管二者在分布形态上存在差异,但最终最大沉降量完全满足施工控制要求.

Existing tunnels have a particularly significant impact on the construction of intersecting new tunnels in the shallow buried environment near the slope.In this paper,based on three-dimensional numerical simulation and on-site monitoring,different parameter combinations are used to study the effects of the ratio of buried depth to tunnel height(C/H),the ratio of slope distance to tunnel span(D/W),whether the existing tunnel is backfilled or notand different surface loads on lateral slope and surface road deformation.The results show that the sensitive area affected by the backfilling of the existing tunnel is parallel to the direction of excavation where the existing tunnel is just separated from the newly-built tunnel;The C/H and D/W under different combination conditions determine the shape and size of the falling groove curve;Combined with the engineering safety control standard,the feasible actual construction model is determined,and the on-site monitoring data are compared with the simulation results.It is found that although there are differences in their distribution patterns,the final maximum settlement fully meets the requirements of construction control.