Evolution Of Mudstone Fractures And Water Loss Of Grouting Fluid Study On Seepage Characteristics

Mudstone,as a common deep soft rock mass,is widely distributed all over China,and with the increase of mining depth,the underground mechanical environment and geological structure are complicated,the development of the cracks in the surrounding rock of the mudstone roadway is also gradually increasing,which seriously affects the normal operation of the mudstone underground engineering.Grouting reinforcement is one of the common supporting methods in underground engineering,which can effectively improve the stability of fractured rock mass,but because of the clay mineral content in mudstone and its own porosity,it has certain water absorption,it causes the grout to lose water in the process of grouting and affects the grout diffusion.Therefore,the development of fracture and the effect of water loss of grout are the key factors to influence the grouting effect.In this thesis,the evolution law of mudstone fracture and the characteristics of water loss and seepage of grouting fluid in mudstone fracture are studied by means of laboratory test,theoretical analysis and numerical simulation:(1)Based on the change of water-cement ratio and cement fineness of ultra-fine sulphoaluminate cement grout,a series of tests on bleeding rate,fluidity,pumpability,initial setting time and compressive strength of concretes were carried out,the influences of different water cement ratio and different cement fineness on the basic properties of grout are analyzed,and the optimum proportion of grout is optimized,which provides a basis for the selection of grout properties in fractured rock mass.(2)The macro-mechanical properties and failure characteristics of mudstone are obtained by means of MTS816 rock mechanics testing system,and the whole failure evolution process of mudstone is analyzed by means of acoustic emission monitoring system,c T scanning experiments were carried out on the samples after the experiment,and the fractal dimension of mudstone fractures was calculated by MATLAB processing,thus quantitatively describing the development characteristics of mudstone fractures at different loading stages,based on the CT scanning image,the fracture of mudstone is reconstructed by Avizo,the visualization of the fracture is realized,and the evolution law of the fracture under different stress conditions is analyzed.(3)The fracture geometry parameters of mudstone are obtained based on CT scanning and fractal theory,and the physical model of single fracture channel is obtained by combining Barton standard curve and 3D printing technology,based on the water absorption of natural mudstone,the similar material of mudstone was developed,and the single-fissure water-absorption grouting blocks with different roughness were prepared for the grouting simulation experiment,the seepage characteristics of grout in the rough fracture of water-absorbing mudstone are revealed.(4)Based on the measured roughness of mudstone fracture and the viscosity of grouting fluid,the influence of different roughness and viscosity of grouting fluid on the seepage of grouting fluid in fracture passage is studied by Fluent numerical analysis method,the correctness of the seepage mechanism of grouting fluid in the rough fracture of water-absorbing mudstone is verified,and the theoretical guidance is provided for the follow-up mudstone grouting project.The thesis has 59 pictures,9 tables and 103 references.