Study On Seepage Erosion Characteristics Of Weakly Cemented Fractured Rock Mass

With the transfer of coal and carbon resources mining center to the west,the change of mining environment and mining mode has caused a series of geological disasters including water burst and sand burst in the weakly consolidated rock,which has brought huge resistance to the construction of western engineering.It is urgent to put forward appropriate disaster reduction measures and prevention schemes based on the proved disaster mechanism.In this thesis,the seepage erosion problem of weakly consolidated rock mass is taken as the starting point,and the weakly consolidated rock samples with different proportions of cements are constructed by remodeling method and their physical and mechanical properties are calibrated.The seepage erosion characteristics of weakly consolidated rock samples with single fissure are studied by using self-developed seepage erosion device,and the microseepage erosion morphology and characteristic parameters of weakly consolidated rock are numerically calculated by using LBM-DEM coupling method.The seepage erosion law of weakly consolidated fractured rock mass is analyzed comprehensively with the seepage loss stability characteristics of macroscopic test.The main research contents are as follows:(1)This thesis selects quartz,kaolin,and Portland cement as raw materials and uses compression molding to reshape weakly cemented rock samples,and the weakly consolidated standard rock samples with cement ratio of 20%,30%,40%,50% and 60%were prepared.Uniaxial compression test and pressure seepage test were carried out to analyze the influence of cement ratio on the physical and mechanical characteristics of weak cement.(2)The seepage erosion test of weakly cemented fractured rock mass was carried out with the help of the self-developed seepage erosion device,and the change law of fracture morphology and erosion rate under different cement proportion,seepage pressure and fracture opening was analyzed.The seepage loss stability point of weakly cemented rock sample was determined based on the inflection point of the seepage rate curve,and the overall erosion process was divided into stages.The influence of different conditions on seepage loss stability of weakly cemented fractured rock mass is discussed.(3)A calculation method of seepage erosion coupled with lattice Boltzmann method and particle discrete element method is proposed.IBM method is used to realize the interaction between fluid and solid.The stress erosion model in the fluid dynamics theory of porous media is introduced as the theoretical criterion of erosion occurrence.The particle microparameters of different cement proportions were calibrated by uniaxial stress-strain curve and fracture characteristics of rock samples,and the rationality of seepage erosion simulation of weakly consolidated fractured rock mass was verified by particle sedimentation model.(4)Based on the LBM-DEM coupling method,a meso-seepage erosion calculation model of weakly cemented fractured rock mass was constructed to carry out numerical simulation of seepage erosion of weakly cemented fractured rock mass under different cement proportions,osmotic pressure and crack opening,and to analyze the evolution law of erosion morphology,erosion quality and seepage velocity under different conditions.The evolution characteristics of seepage erosion to seepage loss stability of weakly cemented rock mass are analyzed by comparing with macroscopic test.There are 62 figures,11 tables and 88 references in this thesis.