中文摘要：

盾构技术在地下空间开发中得到广泛应用,保持开挖面稳定性是盾构施工的关键,但这方面的大尺寸模型试验研究一直很少。利用直径1 m的盾构模型,研究了干砂地层中不同埋深比（C/D=0.5,1.0,2.0）下盾构开挖面稳定性问题。试验中分析了埋深比对开挖面极限支护力及地表沉降的影响,揭示了开挖面稳定性与极限支护力及地表沉降的关系,提出同时监测控制开挖面土舱压力及地表沉降的重要性,并给出关键控制键参数。对确定开挖面极限支护压力有重要的指导意义。

英文摘要：

The shield technology has been widely used in underground construction.The face stability is the key problem in the shield tunneling.Large-scale model tests on the face stability of tunnels with the ratios of tunnel depth to diameter C/D = 0.5,1.0 and 2.0 are conducted in the dry sand.The influence of C/D on the ultimate support pressure and the settlement of ground surface are obtained.The support pressure decreases sharply with the increase of the face displacement.However,the settlement of the ground surface is not sensitive to the support pressure before the residual support pressure.Both the support pressure and the ground settlement are essential to the monitoring of the face stability in the shield tunnelling.