Study On Performance Optimization Of Grouting Materials For Cracks In Earth Sites And Simulation Of Grouting Process

As one of the important immovable cultural heritages in China,the earthen sites have a large number,rich varieties and a long history.However,due to the limitation of its own materials and the influence of natural environment and human factors,many diseases develop.Based on the exploration of disease mechanism of soil sites and the research and development and integration of reinforcement technology,a large number of protection and reinforcement projects have been effectively supported and a large number of endangered soil sites have been rescued.However,there are still difficulties in standardizing and scientificizing the quality control of the reinforcement process in the protection of earthen sites.In the field construction of crack grouting reinforcement,the working performance defects such as poor fluidity and bleeding stability of slurry and low pumpability of slurry are increasingly prominent,and the control of grouting pressure and other parameters is still determined by engineering experience,which seriously restricts the transformation of earthen sites from rescue protection to both rescue and preventive protection.Therefore,this study is based on the scientific needs of soil site protection and the practical engineering problems of grouting reinforcement,and takes calcined ginger nuts-earthen sites’ soil material as the research object,and carries out the performance optimization test of calcined ginger nuts-earthen sites’ soil material and the numerical simulation research of grouting process.The main research contents and conclusions of this paper are as follows:(1)The working performance test of the grouting slurry of calcined ginger nuts-sites’ soil was carried out,and the influence laws of different water-solid ratio,slurry ratio and slurry composition on the rheological properties,fluidity and bleeding stability of the slurry were tested and analyzed.The test results show that the slurry of calcined ginger nuts-earthen sites’ soil shows the rheological characteristics of power fluid.The consistency coefficient of slurry increases with the decrease of water-solid ratio and slurry ratio,while the fluidity and bleeding rate are opposite.Compared with CGN-N slurry,the rheological index,fluidity and bleeding rate of CGN-G slurry decreased by 3.28%,7.5% and 83.62% on average,and the consistency coefficient increased by 3.28% on average.When the ratio of slurry is 1: 10,the working performance of slurry reaches equilibrium.(2)Secondly,the modification test of the grouting slurry of calcined ginger nuts-earthen sites’ soil was carried out to test the preliminary working performance of the slurry with different dosage of naphthalene series water reducer and polycarboxylic acid water reducer and the physical and mechanical properties of the solidified stone body.The experimental results show that polycarboxylate superplasticizer and naphthalene superplasticizer can effectively improve the fluidity and rheological properties of the slurry,and improve the mechanical properties of the cured stone body.The mechanical strength of the stone body with 0.5%PNS and1.1%PCE is the highest for 28 days.The volume change rate of stone body with2.9%PNS and PCE for 28 days increased by 6.27% and 6.86% respectively.Comprehensive color difference,pore structure,volume change rate,etc.,adding0.5%PNS and PCE has the best modification effect on the slurry of calcined ginger nuts-earthen sites’ soil.(3)Finally,the numerical simulation of grouting process is studied.Take small fissures as the research object,Based on COMSOL Multiphysics platform,the effects of different optimized grouting slurry and grouting pressure on slurry diffusion in cracks are studied respectively.The results show that the grouting pressure plays a leading and decisive role in the diffusion of slurry,and the optimal grouting pressure is 50 k Pa for the constructed fracture model.Grouting slurry is also an important index that affects the diffusion of slurry.Compared with the composite slurry without adding 0.5%PNS and 0.5%PCE,the composite slurry of calcined ginger nuts-earthen site’s soil is more groutable,and the amount of grouting is more in the same time.When the grouting pressure is 50 k Pa,there will be no external stress on the fracture model,which has good engineering applicability.