Mechanism And Experimental Study On Grouting Reinforcement Of Mud Fault Fracture Zone In Tunnel

The tunnel construction involves a wide range of areas,and the geological conditions are complex and diverse,including many fault fracture zones with poor geological conditions.Many fault-breaking belts with poor strength and stability are one of the main causes of landslide accidents in tunnel construction,and grouting is one of the important technical means to solve these problems.Therefore,the grouting reinforcement mechanism and experimental study of the muddy fault fracture zone in the tunnel are carried out,which provides some guidance and reference for the grouting project.In this paper,mainly through the study of laboratory tests,based on the fact that the fracture zone of the actual fault zone is mostly sedimentary rock,containing sand,filler and water absorption,the single fracture grouting model test which is closer to the actual grouting engineering is carried out.In order to verify whether the test results of the single-fracture grouting model are consistent with the actual grouting effect of the fault fracture zone,a network crack grouting model test is carried out.By controlling the single factor variable,the effects of mud content,fracture opening degree,water-cement ratio and cement particle thickness on grouting diffusion capacity were studied respectively,and the following main conclusions were obtained:(1)The test results of ordinary Portland cement and ultra-fine cement grouting show that the use of ultra-fine cement instead of ordinary Portland cement can increase the diffusion distance by 50% to 60%.The test results of ordinary Portland cement and ultra-fine cement grouting prove that when the water-cement ratio is between 1-2,the water-cement ratio can increase by 10% to 20% for every 0.5increase.Therefore,when the crack contains more mud and is not easy to grout,the grouting material can adopt ultra-fine cement or increase the water-cement ratio,which can obviously increase the diffusion distance.(2)When the initial grouting pressure in the indoor simulated mud-crack grouting test is within a certain range,the diffusion distance of the initial grouting pressure is increased.When the initial grouting pressure reaches 500 kPa,the effect of increasing the initial grouting pressure on increasing the diffusion distance is not obvious.Therefore,the maximum initial grouting pressure of the indoor mud-crack grouting simulation test can be 500 kPa.Therefore,we can infer that in the case of alarge amount of mud in the actual tunnel fracture zone,excessively increasing the initial grouting pressure does not effectively improve the diffusion capacity.(3)The theoretical analysis results of the diffusion distance are larger than those of the single-fracture grouting model test.The main reason for the analysis is that the factors considered in the theoretical analysis are idealized and simplified,and many factors are inevitable in the simplification process.The diffusion distance of the network crack grouting model test is also larger than that of the single crack grouting model test,mainly because the grouting channel is the only one in the single crack grouting model test.In the grouting process,once the channel is not smooth,it will affect Slurry diffusion distance.