Soil arching due to leaking of tunnel buried in water-rich sand
For tunnel buried in water-rich sand stratum, water intrusion into tunnel lining would bring sand particles into the tunnel and then caused ground subsidence or even cave-in of roadway (sinkhole). Until now, limited studies have been contributed to this topic. To investigate the geo-hazards and explore the associated failure mechanism due to tunnel leaking, both experimental test and comprehensive numerical simulations using the validated finite-difference-method and discrete-element-method (FDM-DEM) coupling method were carried out in this study. It was disclosed that displacements of the sand stratum surrounding the leaking tunnel could be divided into three regions (erosion, displacement, and static zones) by two ellipsoids; the stress changes caused by seepage erosion around the leaking tunnel were similar to that observed by the active door test. Finally, a stress arching model accounting for seepage erosion around a leaking tunnel was proposed. This model can help professionals evaluate stability of overburdening strata by giving soil stress distributions in sand formation surrounding a leaking tunnel with seepage erosion.
Keywords: Tunnel leaking, FDM-DEM coupling analysis, Water-rich sand, Seepage erosion, Stress arching