上软下硬地层中盾构施工对地表沉降影响分析及施工控制技术

Analysis of Shield Construction Influencing Ground Settlement and Construction Control Technology in Upper-soft and Lower-hard Stratum

针对盾构穿越上软下硬复合地层(软土层与岩层复合地层)地表沉降难以控制的问题,以福州地铁4号线工程为依托,通过理论分析加实践验证的方法研究了盾构在上软下硬地层中掘进时,土仓压力、掘进速度、顶推力和扭矩等典型施工参数对地表沉降的影响。结果表明:盾构穿越上软下硬地层的地表沉降中,瞬时沉降占总沉降比重较高,沉降控制更应着重于瞬时沉降控制;土仓压力控制方面,应选取土仓内上部区域作为土压力控制值,并且提出了土仓压力、掘进速度等参数的建议值;利用合理的渣土筛分鉴定方法可以便捷、准确地判断开挖面的工程地质状况,可作为调整盾构施工相关参数的依据。

Targeting the issue that ground settlement of shield structure tunneling through the upper-soft and lower-hard stratum(compound stratum of soft soil and rock)is difficult to control,based on Fuzhou Metro Line 4 engineering,the influence of typical construction parameters including soil pressure,excavation speed,jacking force and torque on ground settlement when shield structure tunneling in the upper-soft and lower-hard ground is researched through theoretical analysis and practical verification.Results show that the instantaneous settlement accounts for a higher proportion of the total settlement when the shield passes through the upper-soft and lower-hard ground,and the settlement control should focus more on the instantaneous settlement control.In terms of soil pressure control,the upper area should be selected for soil pressure control value,and the suggested value of the soil pressure,tunneling speed and other parameters are put forward.Reasonable muck identification methods can quickly and accurately determine the engineering geological conditions of the excavation surface and provide a basis for the selection of relevant shield construction parameters.