标题：Numerical analysis on stability of modifying support of large cross-section tunnel in shallow expansive soil
作者：Zhang, Xiantang ;Chen, Xiujin ;Xu, Bangshu ;Zeng, Zhongyi ;Zhou, Hongmin
作者机构：[Zhang, Xiantang ;Chen, Xiujin ;Zhou, Hongmin ] Shandong Provincial Key Laboratory of Civil Engineering Disaster Prevention and Mitigation, Shandong U 更多
来源：Journal of Mines, Metals and Fuels
关键词：Expansive soil; Numerical simulation; Shallow depth; Stability; Tunnel
摘要：There is a shallow large cross-section swelling soil tunnel which is covered by the tertiary (N) swelling soil and the quaternary sand loess. The buried depth of tunnel is between 10m to 40m. It needs redesign because of the landslide in the portal during construction process. Authors built finite element models using ANSYS 12.1 and imported FLAC3D program to get finite difference grid models of tunnel excavation. Considering the influence of expansion force in swelling soil, various support structures are simulated by use of different support units in the models. After changing the preliminary bracing design, the support parameters and measures is also changed. The stress of surrounding rock, displacement deformation, stress deformation of support structure and surrounding rock slide region are comparatively analyzed with numerical calculation. The calculation results show that support design after the change is reasonable and safe. It is proved according to the calculation that taking support measures in time after excavation of the upper bench can effectively control the stability of upper surrounding rock and the deformation of lower surrounding rock in the geological conditions of swelling soil. If pipe-shed support adding slip casting is adopted to strengthen the surrounding rock, the cement mortar can fix the gap between steel pipes and surrounding rock, and improve the strength and self-stabilizing capacity of the surrounding rock.