A set of slurry shield test system capable of cutter cutting and slurry automatic circulation is used to investigate the deformation characteristics, the evolution characteristics of support resistance and the distribution and evolution process of earth pressure during excavating and collapsing of slurry shield tunneling in circular-gravel layer. The influence of cover-span ratio on surface subsidence, support resistance and failure mode of excavation face is also discussed. Three-dimensional numerical calculations are performed to verify the reliability of the test results. The results show that, with the decrease of the supporting force of the excavation face, the surface subsidence goes through four stages: insensitivity, slow growth, rapid growth and stability. The influence of shield excavation on the axial earth pressure of the front soil is greater than that of the vertical earth pressure. When the support resistance of the excavation face decreases to the critical value, the soil in front of the excavation face collapses. The shape of the collapse is similar to that of a bucket. The ultimate support resistance increase with the increase of the cover-span ratio, however, the angle between the bottom of the collapsed body and the direction of the tunnel excavation axis when the excavation face is damaged increase first and then becomes stable. The surface settlement value and the range of settlement trough decrease with the increase of cover-span ratio. The numerical results are basically consistent with the model test results.
Key Words
circular-gravel layer; excavation face stability; model test; numerical simulation; slurry shield
Address
Xinrong Liu and Zuliang Zhong — School of Civil Engineering, Chongqing University, Chongqing 400045, China; State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China; National Joint Engineering Research Center of Geohazards Prevention in the Reservoir Areas, Chongqing University, Chongqing 400045, China ongshuang Liu
, Fei Xiong, Yafeng Han, Ronghan Liu, Qiang Chen and Wenwu Liu — School of Civil Engineering, Chongqing University, Chongqing 400045, China
