NUMERICAL INVESTIGATION OF THE THREE-DIMENSIONAL PERFORMANCES OF A SHIELD-MACHINE-BORED TUNNEL IN LOOSE SANDS

摘要

This study first explores the impact on adjacent structures caused by a shield-machinebored tunnel in loose sand; observed displacements of structures have been reported that have rarely been examined in the past. Further, considering the difficulty of the reasonable prediction in advance of the ground convergence during tunnelling, a new method for the numerical investigation of the three-dimensional deformations induced by a tunnel in said ground conditions is developed, which is associated with the properties of backfill grout and pressure in the grouting zone, and a hardening soil-small strain model is selected for the simulation of soil behaviors. The influences on the ground deformations caused by changes in the operation parameters, such as the face and backfill grouting pressure as well as the elastic modulus of the backfill grout, are also explored. Finally, the strain level of the soil caused by tunnelling is examined and compared with the results from previous works, and a detailed discussion is provided.