Damage-erosion Coupling Model And Water Inrush Mechanism Of Weakly Cemented Surrounding Rocks

During the construction process of deep tunnels,it is inevitable to pass through fault zones,Karst collapse pillars and other weak geological structures.The broken rocks located in fault zones are usually weakly cemented with strong water conductivity.Therefore,damage,deformation and fine material loss can be easily caused,and then water inrush disasters may occur.In this paper,laboratory experiments,theoretical modeling and numerical simulation methods were combined.Damage-erosion coupling model of weakly cemented surrounding rocks was established;water inrush process in tunnels was reproduced;evolutions and main controlling factors of water inrush characteristics under the action of stress-seepage were studied.The main contributions of this paper are as follows:(1)Hollow cemented rock samples were prepared and fluid-solid coupling test system was built;test scheme and testing method of fluidsolid coupling tests on weakly cemented rocks were designed.The characterization method of damage and erosion characteristics of weakly cemented rock was proposed.(2)Fluid-solid coupling tests of weakly cemented rock under different conditions were carried out to analyze the influence of different factors,i.e.,loading rate,water pressure,cemented material ratio and inner diameter size,on the damage-erosion characteristics of weakly cemented rock.(3)A damage-erosion coupling model of weakly cemented rocks under stress-seepage action was established in this paper,considering the stress-damage relationship,deformation coordination relation,mass conversion,non-Darcy flow law and particle migration effect caused by erosion.(4)Based on COMSOL Multiphysics platform,the numerical algorithm is built to solve the control equations of the established model,then the temporal-spatial evolution laws of fluid-solid coupling characteristics of weakly cemented rocks are obtained.