DYNAMIC CONSTRUCTIONAL RESPONSE OF A SHALLOW-BURIED AND UNSYMMETRICAL-LOADED DOUBLE-ARCH TUNNEL ACROSS AN ANCIENT LANDSLIDE

Surrounding rock-mass stability of underground engineering under complex geological conditions has been one of the hot topics for engineering geologists.This paper presents a case study of a double-arch tunnel Manxie No.4,one of Simao-Xiaomengyang expressway tunnels,encountered an extremely complicated geological structure.The authors simulated the dynamic constructional response of a shallow-buried and unsymmetrical-loaded double-arch tunnel across ancient landslide,including press field,displacement field and plastic zones in surrounding rock-mass.In addition,locations of stress concentration and potential failure zones are clearly delineated in rock-mass,which will not only provide information needed for guiding the construction of the tunnel,but also establish valid theoretical evidence for optimal design of the tunnel.At the end,the authors emphasize that complete treatment of whole ancient landslide and sufficient reinforcement of partition wall should be taken to ensure stability of surrounding rock-mass and safety of the whole double-arch tunnel.