Causes analysis and treatment of damage in a shallow buried box metro tunnel

Research purposes: Some damages such as leakage in deformation joint, disengaging and transverse cracks in ballast, water and sand gushing of ballast, have been found in the shallow buried box metro tunnel, which caused by excavation of adjacent deep foundation pit. In this paper, overview of the metro tunnel disease accident is researched, and then the main disease and distribution are sorted, at last, causes of tunnel disease are deeply investigated which provide reference for damage treatment. Research conclusions: (1) The structural differential settlement of tunnel is the main reason of leakage in deformation joint. Meanwhile, it is the important reason of disengaging, transverse cracks, water and sand gushing in ballast. (2) The compression of layer leads to huge and uneven settlement of tunnel structure which caused by the decrease of groundwater level. (3) As the shallow buried tunnel is weak to resist the excavation disturbance of adjacent foundation pit, ground fissure occurred above the metro tunnel caused by uncoordinated horizontal deformation between ground and tunnel structure, which will aggravate the tunnel leakage. (4) The reasonable treatment scheme of grouting reinforcement has been proposed. (5) The conclusion could be used for reference of similar engineering of metro tunnel. © 2016, Editorial Department of Journal of Railway Engineering Society. All right reserved.