淤泥质粉质黏土中隧道暗挖变形控制分析

Analysis on Deformation Control of Tunnel Excavation in Muddy Silty Clay

管线密集、建筑林立、地层多变使得城市隧道与其周边环境的关系十分复杂。以软塑性淤泥质地层上的某地铁隧道工程为研究对象,利用有限元软件建立典型隧道断面计算模型;在隧道暗挖及实施超前支护措施的基础上,对洞内全断面注浆加固效果、竖向旋喷加固效果进行对比分析。结果表明地表垂直高压旋喷桩在最大桩间距时,加固后的拱顶沉降亦小于全断面注浆加固的拱顶沉降的一半。结合施工期间的监测数据,建议加固方案选择地表垂直高压旋喷桩,加固范围为隧道开挖轮廓线周边3 m,桩距为0.8 m×0.9 m。二次衬砌施工完成后拱顶沉降变得稳定,说明支护效果满足施工对隧道沉降量的控制要求。

The surrounding environment of urban tunnel is complex,with dense surface buildings (structures) and strict requirements for stratum deformation control.In this paper,taking the soft-plastic muddy stratum of a subway tunnel project as the research object,the calculation model of typical tunnel section is established by using the finite element software.Based on the implementation of tunnel hidden excavation and advanced support measures,the reinforcement effect of full section grouting and vertical rotary jet grouting in the tunnel are compared and analyzed.The results show that the vault settlement of surface vertical high-pressure jet grouting pile after reinforcement at the maximum pile spacing is also less than half of the vault settlement strengthened by full section grouting.Combined with the monitoring data during construction,it is recommended that the reinforcement scheme be selected as surface vertical high-pressure jet grouting pile,the reinforcement range be 3m around the tunnel excavation contour line,and the pile spacing be 0.8m × 0.9m.The vault settlement becomes stable after the secondary lining construction,which shows that the effect of system support meets the control requirements of settlement in construction.