Mechanical Behavior and Excavation Optimization of a Small Clear-Distance Tunnel in an Urban Super Large and Complex Underground Interchange Hub

Close excavation section spacing, the mutual influence and interpenetration of various processes, multiple disturbances middle rock pillar in a small clear-distance tunnel pose great difficulty to construction. This study adopted Xiamen Haicang Evacuate Channel as research object. The belonged an urban super large complex underground interchange hub where adjacent tunnels were adopted. ABAQUS was used analyze different schemes, lithological grades, footage lengths for stability. deformation stress characteristics tunnel’s surrounding lining structure schemes (full method, bench center diaphragm (CD) double wall heading method), grades (III, IV V), (3 m, 4 m 5 m) introduced. results showed that method could effectively control horizontal displacement hance, overall state CD methods reasonable. vertical surface vault positively correlated with elastic modulus mass. When no temporary support present grade V mass, area from hance arch foot prone deformation. Reducing beneficial controlling hance. can provide reference on-site construction tunnels.