Upper-bound solutions for the face stability of a shield tunnel in multilayered cohesive-frictional soils

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• 作者：Kaihang Han ; Chengping Zhang ; ^{chpzhang@bjtu.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Dingli Zhang
• 关键词：Shield tunnel ; Face stability ; Limit analysis ; Multilayered cohesive&ndash ; frictional soils
• 刊名：Computers and Geotechnics
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：79
• 期：Complete
• 页码：1-9
• 全文大小：1210 K

文摘

Tunneling in urban shallow soft ground is more frequently being carried out using the shield method. An important problem in the stability analysis of a tunnel face is to provide enough support pressure to the excavation face. Among the analytical approaches used to investigate the stability of a tunnel face, limit equilibrium methods or limit analysis methods are widely used. For cohesive–frictional soils, the results obtained from experimental tests and numerical simulations indicate that the failure soil in front of the tunnel face demonstrates two main features, i.e., a shear failure band in the lower part and a pressure arch effect in the upper part. Compared to the limit equilibrium methods, the limit analysis methods have a strictly theoretical basis and provide better results. To better interpret failure features, a new three-dimensional failure mechanism is proposed to analyze the limit support pressure of the tunnel face in multilayered cohesive–frictional soils based on limit analysis methods. The new failure mechanism is composed of five truncated cones that represent the shear failure band and a distributed force acting on the truncated cones that represents the pressure arch effect. The distributed force is calculated using Terzaghi earth pressure theory. The limit support pressures obtained from the new failure mechanism and the existing approaches are compared, and the new mechanism of this paper provides relatively satisfactory results for limit support pressures.