Research And Engineering Application Of Fracturing Grouting Mechanism Of Fully Weathered Sand Shale Based On Grouting Compaction Effect

With the continuous construction of underground space in China,the control of adverse geological disasters in the process of underground space construction has become an important research topic.The fully strongly weathered sand shale,which is often crossed in the process of tunnel construction,is one of the main sources of geological disasters affecting the safety of tunnel construction.The basic mechanical properties of the stratum itself are poor,and the resistance to deformation and bearing capacity are insufficient.Under the construction disturbance and groundwater,it is very easy to induce tunnel collapse,water inrush and mud inrush and other engineering disasters.Grouting method is the most commonly used method to control the geological disasters of fully weathered sand shale.Based on the existing grouting diffusion reinforcement research,aiming at the splitting compaction grouting reinforcement mode of fully weathered sand shale,this paper aims to achieve the quantitative description of grouting diffusion process and reinforcement effect of fully weathered sand shale through theoretical analysis,laboratory test,numerical calculation and numerical simulation,The main work of this paper is as follows:(1)In the aspect of grouting diffusion mechanism,the compaction characteristics of fully weathered sand shale under different water content are studied through indoor confined compression test,and the mathematical model describing the nonlinear compaction process of fully weathered sand shale is established,On this basis,a theoretical model of fracturing grouting diffusion process considering the coupling effect of slurry flow field and fully weathered sand shale stress field is established.Considering the compaction characteristics of fully weathered sand shale,the dynamic expansion calculation algorithm of fracturing channel is improved,and the complete description of fracturing grouting diffusion process of fully weathered sand shale is realized,The temporal and spatial distribution of the split channel opening in the process of grouting diffusion is revealed,and the influence of grouting speed,soil compaction characteristics,water cement ratio of slurry,grouting pressure and other factors on the grouting diffusion process is analyzed.(2)In terms of grouting reinforcement effect,the quantitative relationship between grouting effect and pressure is obtained through a series of laboratory tests.Combined with the original research results and considering the grouting compaction effect,the grouting effect is calculated as a whole,and the spatial distribution characteristics of the grouting reinforcement effect of the fully weathered sand shale are obtained.The key engineering parameters affecting the grouting are selected,and the grouting pressure,single hole grouting amount,grouting depth and grouting depth are analyzed systematically The influence of soil compaction characteristics and other factors on the fracturing compaction grouting reinforcement effect of fully weathered sand shale.(3)According to the research results of this paper,relying on the fully weathered sand shale grouting reinforcement project of Lianhua tunnel of Pinglian Expressway in Jiangxi Province,the stability of surrounding rock before and after grouting is calculated by numerical simulation,and the accuracy of grouting mechanism research of fully weathered sand shale based on grouting compaction effect is verified.