地面出入式盾构隧道施工对周边地层扰动研究

Study on the Influence of Surrounding Strata during GPST Tunnelling Process

传统盾构法隧道施工前需进行工作井的开挖,在人口密集的都市区开挖工作井对地面交通和周边建筑物有较大影响。地面出入式盾构法(GPST)避开了工作井大开挖施工,从理论上可以有效减小隧道施工的地层扰动,但由于该工法施工工艺特点,在盾构机穿越土层过程中需经过不同覆土厚度的地层,因此对控制施工参数有很大要求。本文以南京南站-禄口机场站GPST盾构隧道示范工程为背景,基于非线性有限元方法分析隧道穿越负覆土、零覆土、浅覆土段几种不同工况下地层位移以及孔隙水压力的变化,并与监测数据进行对比分析。基于Peck公式与双线叠加原理基础之上探究施工参数对双线隧道地表沉降的影响。研究成果对未来该工法的推广应用具有一定的借鉴意义。

Conventional shield tunnel construction requires the excavation of working shafts,resulting in significant influence on surrounding environment in congested urban area.Ground Penetrating Shield Tunneling(GPST)method is able to avoid the excavation of working shafts,theoretically,it can reduce the influence on surrounding strata on tunnel construction effectively.However,due to the technical characteristics of the method,the shield must be driven beneath different cover-depths during GPST tunneling process.Thus the tunneling variables should be carefully controlled during GPST construction.The shield tunnel section was employed as the GPST demonstration work between Nanjing south railway station and Lukou airport station in Nanjing,and the non-linear finite element analysis(FEA)was adopted to study the tunneling-induced influence under different conditions,such as tunneling under the negative cover-depth,the ultra-shallow cover-depth,and the shallow cover-depth,then the soil displacement and pore-water pressure caused by tunneling activity were investigated by the comparison between FEA and in-situ monitoring.Based on the Peck formula and the double-line superposition principle,the effects of construction parameters on ground settlement of double-line tunnel were investigated.The outcomes of the paper can provide the practical construction reference for the GPST tunnels.