| There are many highway tunnels and long mileage.It is necessary to cross many mountainous areas.During the excavation process,problems such as large deformation and excavation seepage of surrounding rocks seriously affect the safety of construction personnel and hinder construction progress.In the project,corresponding pre-saving measures are taken according to the specific geological and hydrological conditions to ensure the safety of tunnel construction.In the pre-saving measures,in addition to the reinforcement effect of the tunnel,the advanced small duct injection can also prevent leakage of groundwater to a certain extent.Through research on the parameters of the advanced small catheter grouting,the optimal value of the advanced small catheter grouting parameters is selected.While effectively suppressing the deformation and infiltration of the tunnel,it also avoids the waste of construction materials;The sensitivity of deformation and infiltration provides a reference basis for the optimization of the advanced small catheter grouting scheme during construction.This article takes a tunnel in Yunnan as the project support.Through the Midas/GTS numerical simulation software,the tunnel is established whether the tunnel is applied to the mechanical model of the changes in different parameters of the small catheter grouting in advance.The introduction of sensitivity analysis method is introduced to the best parameters of the effect of advanced small catheter grouting and the best parameter of advanced small catheter injection.Compare the on-site monitoring data and simulation results to verify the rationality of analog analysis.conclusion as below:(1)Midas/GTS numerical simulation software simulates whether the tunnel is performed for advanced small catheter grouting,and compare the analysis of the simulation results.After the advanced small catheter injection is cast,the tunnel deformation is reduced in the tunnel deformation,and the bottom of the arched bottom increases;after the advancement of the small duct injection,the distribution of the water pressure distribution of the pores of the tunnel has changed significantly,and the seepage flow is reduced.(2)Simulate the changes of different parameters of small catheter grouting,analyze the deformation of the tunnel and the flow of infiltration,and compare the optimal parameters of the advanced small catheter grouting.Propagoscular pipe grouting can be divided into two parts: advanced small catheter and grouting circle,and single factors affect analysis.The optimal length of the advanced small catheter in the small duct injection is 5m,the optimal pipe diameter is 32 mm,the optimal external pin is 15 °,and the optimal ring spacing is 30cm;1.5m,the best grouting range is 120 ° ～ 150 °.(3)On the basis of studying the laws of tunnel deformation and exudation,the introduction of sensitivity analysis method,quantitative calculation of the sensitivity of different parameters of small catheter grouting to deformation and infiltration.The results proved that in the parameters of advanced small catheters,the increase in the length of the advanced small catheter is the best effect on reducing the descending of the vault.The reduction of the pipeline of the small duct can inhibit the displacement of the tunnel palm crowded to the greatest extent.In the parameter of the grouting circle,the grouting ring is compared with grouting thickness,which can better strengthen the waterproofing effect,especially the extrusion displacement of the palm surface can be effectively reduced.(4)During the construction of the tunnel,measure the amount of monitoring inside the tunnel,and obtain deformation data during the tunnel construction process.After measurement,the cumulative deformation and deformation rate of the tunnel is within the specified range,and the tunnel is in a stable state.Compare the monitoring results of the tunnel vault settlement and the simulation results. |
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