Influence of double-line large-slope shield tunneling on settlement of ground surface and mechanical properties of surrounding rock and segment

Abstract

The surface settlement formula of large slope tunnel is derived firstly. Then, the finite element model of shield tunnel is established by using ABAQUS software. Finally, the influences of tunnel slope, grouting pressure and shield tail clearance on ground surface settlement, and mechanical properties of surrounding rock and segments are studied by the field measurement and numerical simulation method. The results show that (1) For the slope is less than 4°, the slope increases by 1°, the settlement of ground surface increases by about 2.85 %, the shear stress of surrounding rock increases by about 4.5 kPa, and the tensile and circumferential stresses of segment increase by about 5 % and 3.1 %, respectively. (2) The proper grouting pressure is beneficial to the settlement of ground surface, and the mechanical properties of surrounding rock and segment. (3) For the shield tail clearance is less than 15 cm, the clearance increases by 1 cm, the settlement of ground surface increases by about 0.65 mm, the shear stress of surrounding rock increases by about 4.77 kPa, and the circumferential stress of segment reduces by about 0.02 MPa. Therefore, the grouting pressure with 200 kPa and the shield tail clearance with 10 cm are recommended.