Face stability of shield-driven tunnels using multi-tangent technique
To address the face stability problem of deep-buried tunnels under nonlinear conditions,using Power-Law(P-L)criterion the approximate piecewise and by multi-tangent technique,a novel multi-cone failure mechanism is developed for tunnel faces based on the kinematic limit analysis theorem.A theoretical framework considering the tension cut-off(T-C)is proposed to evaluate the stability of tunnel faces.The reliability of the proposed method is validated through comparison with that in the existing literatures.Based on the back-calculated stress distribution and geometric feature of the failure mechanism,the influences of T-C under different parameters on the stability of tunnel faces are investigated.The results indicate that:(1)under the linear condition,the effects of T-C on the critical support pressure are more significant with high cohesion and small internal friction angle.Under the nonlinear condition,an increase in the nonlinear coefficient will not exacerbate the impact of T-C on the face stability.(2)For higher tensile strength,the effects of T-C on the stability of tunnel faces are significant.As the tensile strength decreases,the failure mechanism governed by T-C gradually shrinks,and the top of the failure mechanism exhibits noticeable blunting and looks like a dome.
stability of tunnel facemulti-tangent techniquePower-Law criteriontension cut-offlimit analysis
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维普
