Abstract:

Grouting pressure is one of the main causes for the longitudinal dislocation of shieldbored tunnel segments. A threedimensional finite element model is established by the ABAQUS software to calculate the longitudinal dislocation of segments caused by grouting pressure. The interactions between soil mass, grout mass, segments and bolts are taken into account. Grouting pressure induced by the diffusion of the grout on the segments is also taken into consideration. In the case of grouting through four symmetrical grouting holes under 0~0.5 MPa grouting pressure, the longitudinal dislocation of segments under uniform grouting pressure and that under nonuniform grouting pressure are calculated respectively. Conclusions drawn are as follows: 1) Grouting with nonuniform pressure has great influence on the degree of the longitudinal dislocation between the key segment and the neighboring segments. The dislocation degree increases when the nonuniformity of the grouting pressure increases, and the maximum dislocation can reach 1.35 mm. 2) Nonuniform grouting pressure has less influence on the dislocation of segments at the arch lumbar, and the dislocation is about 0.1 mm. 3) The grouting through the lower grouting holes has great influence on the dislocation of the invert segments, and the maximum dislocation of the invert segments without grouting reaches 0.75 mm. 4) Compared to the value of 10mm ultimate dislocation caused by multiple factors, the dislocation caused by nonuniform grouting pressure cannot be neglected.

Key words: shieldbored tunnel, segment, longitudinal dislocation, uniform grouting, nonuniform grouting, 3D FEM