Elastic analysis of ground displacement and liner stress induced by shallow shield excavation considering non-uniform convergence deformation with liner
ZHANG Zhiguo1，2，BAI Qiaomu1，ZHAO Qihua2
(1. School of Environment and Architecture，University of Shanghai for Science and Technology，Shanghai 200093，China；
2. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection，Chengdu University
of Technology，Chengdu，Sichuan 610059，China)
Abstract：The geo-environmental effects caused by shield tunneling have been a key issue in urban metro construction. However，few investigations have been carried on the impacts of interaction between tunnel liner and soils. Particularly，the stress analysis of the liner is not conducted. A calculation method for soil displacements affected by tunneling with liner was proposed considering the non-uniform convergence deformation. The Airy stress function analytical solution of tunnel liner was established considering the compatibility of non-uniform convergence deformation between liner and soils. The stratum subsidence and horizontal displacement curves of soils from calculation were compared with the monitoring data. The influence of the material properties of soil and liner，the geometry and depth of tunnel and other main parameters on ground deformation and liner stress induced by tunneling were obtained through the parameter analysis. The non-uniform deformation mode was found to significantly affect the ground displacements. The soil settlements and horizontal displacement curves were in good agreements with the measured values. The maximum value of the surface settlement is close to the actual one. The tunnel radius and soil hardness have greater effects on the maximum subsidence of soils. Soil subsidence was reduced significantly by decreasing the radius and hardening soil. Change of the geometric parameters of liner has little effects on the soil settlements. The axial force and bending moment of liner are strictly symmetrical to axis of 90°/270° or tunnel vertical axes. The distribution of axial force along the circumference has the shape of 8. The shape of bending moment distribution was changed from 8 to 0 along the circumference with the increase of parameter k. The maximum axial stress and maximum negative moment occur in the position of arch lumbar. The values of lateral earth pressure coefficient k affect significantly the axial forces and bending moments of liners.