Stability Analyses of Shallow Buried Square Tunnels with Rich Water
The square tunnel is widely adopted in urban areas due to its advantage of large space utilization.However,limited to the complex boundary conditions and stress concentration easily occurred in corners,it is difficult to investigate the stability of shallow square tunnels.Therefore,determining an appropriate critical supporting pressure is of great interest for avoiding collapse and ensuring construction safety,in particular on shallow buried tunnels in rich water strata.Within the framework of the upper bound theorem,a translational failure mechanism considering the condition where the failure soils extend to the ground surface,is established.The comparison with the existing work illustrates that the presented approach has better performance with the greatest improvement of 10.5％,and is more applicable for the stability issue of tunnels.The coefficient method is utilized herein to take account into the undesirable effect of pore water pressure,and it is found that the limit support pressure increases linearly with the rise of the cohesion and friction angle,and would decrease when coefficients rise.In the end,an approach to select reasonable coefficients is offered for the practical engineering.
shallow square tunnelsupper bound theorypore water pressurelimit supporting pressure
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