A stability analysis approach of tunnel face considering a longitudinally inclined tunnel angle and anisotropic purely cohesive soils based on a continuous velocity field (CVF) is investigated in this study. Based on ...A stability analysis approach of tunnel face considering a longitudinally inclined tunnel angle and anisotropic purely cohesive soils based on a continuous velocity field (CVF) is investigated in this study. Based on the kinematic approach of limit analysis and the discretization technique, an improved three-dimensional CVF model for longitudinally inclined tunnels driven by pressurized shields is proposed. With the proposed model, the critical support pressure acted on tunnel face is determined by the work-balance equation. A serial of finite element numerical models are conducted to validate the proposed model. Finally, the effects of tunnel inclination angles, several dimensionless parameters as well as soil anisotropy on the critical support pressure are investigated. The numerical results show that the effects of the soil anisotropy and the tunnel inclination angle on tunnel faces should be considered in the actual design of tunneling engineering.展开更多
To address the seismic face stability challenges encountered in urban and subsea tunnel construction,an efficient probabilistic analysis framework for shield tunnel faces under seismic conditions is proposed.Based on ...To address the seismic face stability challenges encountered in urban and subsea tunnel construction,an efficient probabilistic analysis framework for shield tunnel faces under seismic conditions is proposed.Based on the upper-bound theory of limit analysis,an improved three-dimensional discrete deterministic mechanism,accounting for the heterogeneous nature of soil media,is formulated to evaluate seismic face stability.The metamodel of failure probabilistic assessments for seismic tunnel faces is constructed by integrating the sparse polynomial chaos expansion method(SPCE)with the modified pseudo-dynamic approach(MPD).The improved deterministic model is validated by comparing with published literature and numerical simulations results,and the SPCE-MPD metamodel is examined with the traditional MCS method.Based on the SPCE-MPD metamodels,the seismic effects on face failure probability and reliability index are presented and the global sensitivity analysis(GSA)is involved to reflect the influence order of seismic action parameters.Finally,the proposed approach is tested to be effective by a engineering case of the Chengdu outer ring tunnel.The results show that higher uncertainty of seismic response on face stability should be noticed in areas with intense earthquakes and variation of seismic wave velocity has the most profound influence on tunnel face stability.展开更多
基金Project(2017YFB1201204)supported by the National Key Research and Development Program of China
文摘A stability analysis approach of tunnel face considering a longitudinally inclined tunnel angle and anisotropic purely cohesive soils based on a continuous velocity field (CVF) is investigated in this study. Based on the kinematic approach of limit analysis and the discretization technique, an improved three-dimensional CVF model for longitudinally inclined tunnels driven by pressurized shields is proposed. With the proposed model, the critical support pressure acted on tunnel face is determined by the work-balance equation. A serial of finite element numerical models are conducted to validate the proposed model. Finally, the effects of tunnel inclination angles, several dimensionless parameters as well as soil anisotropy on the critical support pressure are investigated. The numerical results show that the effects of the soil anisotropy and the tunnel inclination angle on tunnel faces should be considered in the actual design of tunneling engineering.
基金Project([2018]3010)supported by the Guizhou Provincial Science and Technology Major Project,China。
文摘To address the seismic face stability challenges encountered in urban and subsea tunnel construction,an efficient probabilistic analysis framework for shield tunnel faces under seismic conditions is proposed.Based on the upper-bound theory of limit analysis,an improved three-dimensional discrete deterministic mechanism,accounting for the heterogeneous nature of soil media,is formulated to evaluate seismic face stability.The metamodel of failure probabilistic assessments for seismic tunnel faces is constructed by integrating the sparse polynomial chaos expansion method(SPCE)with the modified pseudo-dynamic approach(MPD).The improved deterministic model is validated by comparing with published literature and numerical simulations results,and the SPCE-MPD metamodel is examined with the traditional MCS method.Based on the SPCE-MPD metamodels,the seismic effects on face failure probability and reliability index are presented and the global sensitivity analysis(GSA)is involved to reflect the influence order of seismic action parameters.Finally,the proposed approach is tested to be effective by a engineering case of the Chengdu outer ring tunnel.The results show that higher uncertainty of seismic response on face stability should be noticed in areas with intense earthquakes and variation of seismic wave velocity has the most profound influence on tunnel face stability.
