关键词: 深埋盾构隧道, 开挖面稳定性, 极限上限法, 极限支护压力, 三维对数螺旋

Abstract: In contrast to the high demands and fast development of shield tunnels, significant deficiencies exist in the shield tunneling techniques and theoretical researches for large-scale deep tunnels, and especially under hydraulic conditions, the issues related to the stability of the deep shield tunnel face become even more prominent. Based on the upper bound limit analysis and the unified parameters of water and earth pressures, the face stability of tunnel in the homogeneous soil is studied with considering the effect of water pressure. A three-dimensional log-spiral failure model of the deep shield tunnel face is designed; and then an equation for calculating the limit support pressure is developed. Based on the soil thickness-weighted average method, the developed theoretical procedure is applied to evaluate the face stability of tunnel in multilayered soils. The limit support pressure of the face in the Shanghai Yangtze River tunnel is determined with the proposed upper bound limit method of three-dimensional log-spiral failure mode. The calculated results are compared with the previous studies and the simulated results. Through this research, the calculation methods of the limit support pressure of deep shield tunnel face under hydraulic condition can be improved, providing a theoretical basis for the determination of the reasonable support pressure during the construction of shield tunnel.

Key words: deep shield tunnel, face stability, upper bound limit method, limit support pressure, three-dimensional log-spiral