Research On Long-term Settlement Laws Of Shield Tunnel And Stratum In Suzhou Soft Soil Area

With the vigorous development of urban subway construction and operation,there are more and more settlement problems in the operation of completed subway tunnels,which seriously affects operational safety,especially tunnels built in soft soil layers.During the shield construction period,the disturbance effect of the construction on the stratum will be consolidated and sub-consolidated settlement over a period of several years.However,in the soft soil layer,for the uplift and settlement of the stratum and the tunnel caused by the construction of a shield tunnel,most scholars usually consider the post-construction settlement and consolidation settlement separately,and few scholars regard it as a whole,considering the settlement state after a long period of operation.This paper defines long-term settlement as a combination of postconstruction settlement,consolidation settlement and operation settlement.Relying on the Suzhou Rail Transit S1 line project,through on-site monitoring and numerical simulation methods,this paper studies the long-term laws of the stratum and the tunnel caused by the construction of tunnels in the soft soil layer by different factors.The main research work and results of this paper are as follows:(1)By monitoring the settlement laws of the stratum and the tunnel after the construction of the shield tunnel between the Suzhou Rail Transit S1 Line Exhibition Center and the Xihuan Road interval tunnel,we have obtained the settlement law of the post-construction of the ground and tunnel,caused by the construction of the tunnel in the soft soil layer.(2)We establish a finite element model of the shield tunnel excavation ring by ring considering various factors such as face supporting force,grouting pressure,grouting layer,stratigraphic convergence,fluid-solid coupling,etc.Then,we compare with the results of on-site monitoring and verify its effectiveness,and consider the effects of long-term consolidation settlement and operation settlement on the basis of settlement after construction.(3)We study the influence of various factors such as grouting pressure,grouting filling rate,soft underlying layer thickness,tunnel permeation,local tunnel leakage,and train load on long-term settlement,and on this basis,measures to control the long-term settlement of the ground and the tunnel,such as establishing a unified settlement monitoring network,controlling post-construction settlement,artificially replenishing groundwater,and strengthening the underlying layer of the tunnel,are proposed.The above research explored the law of long-term settlement of the ground and the tunnel caused by the construction of tunnels in soft soil,which can provide a certain reference basis for the settlement control of tunnel construction and operation in similar soft soils.