Analysis of Limit Equilibrium of Excavation Face of Adjacent Existing Structures Sand Tunnel
With the advancement of urbanization,the development and utilization of underground space is an effec-tive way to alleviate traffic congestion and expand urban space.The construction of adjacent structures of under-ground space has high risks.And the stability of excavation surfaces caused by the construction process isn't ig-nored.Therefore,taking the underground excavation project of the Chao-Shi Connection Line Tunnel of Beijing Metro Line 3 as an example,numerical simulation and similar model experiments were adopted to explore the insta-bility and failure characteristics of the excavation face of the sand layer tunnel with the adjacent existing structural conditions.Considering the characteristics of tunnel excavation face failure with asymmetric rupture angle,based on the Terzaghi loose soil theory,the lateral soil pressure coefficient and upper shear band rupture angle of the tradi-tional model were improved to propose a limit equilibrium analysis model,and derive the calculation formulas for overlying loose soil pressure and hypothetical support force.The research results and methods can provide reference for the stability analysis and reinforcement design of soil in the same conditions.
subwayexisting structuresand layer tunnelinstability of excavation surfacelimit equilibrium anal-ysisnumerical simulation