Laboratory study on optimization of grouting parameters for tunnels in urban sand layers

WEI Jin; WANG Jintao; BIAN Haiding; ZHANG Wei; WANG Penglu; FENG Chang

doi:10.11860/j.issn.1673-0291.20240126

Abstract：To optimize the grouting parameters for tunnels in urban sand layers and improve grouting performance,a laboratory test system is independently developed in response to practical engineering challenges.The experimental design considers grouting pressure,soil porosity,and slurry water-cement ratio as independent variables,while the strength of the solidified body,slurry diffusion ra-dius,and grouting volume are selected as dependent variables.Regression analysis is conducted on the test results to derive equations describing the relationships between these variables.Based on the re-sulting linear regression models,optimized on-site grouting parameters are determined.The effective-ness of these parameters is evaluated through observations of excavation and slurry distribution at the tunnel face,core sample strength of solidified body,and surface settlement behavior.The results indicate that the derived equations exhibit strong linear correlations and statistically significant regression coeffi-cients,as confirmed by analysis of variance and correlation tests.Among the influencing factors,grout-ing pressure has the most significant impact on grouting volume,followed by slurry diffusion radius and solidified body strength.Soil porosity most strongly affects grouting volume,followed by strength,with the least impact on diffusion radius.The slurry water-cement ratio has the greatest effect on the strength of the solidified body,followed by grouting volume,and the least on diffusion radius.Field application of the optimized parameters reveals abundant and evenly distributed slurry veins during excavation.The tunnel face remains stable and upright,with no groundwater seepage.Core sample strength of solidified body meet design requirements,and surface settlement remains within acceptable limits.These out-comes indicate that the optimized grouting parameters significantly enhance grouting performance and ef-fectively ensure the quality and safety of tunnel construction in sandy urban strata.