TREATMENT EFFECT ANALYSIS OF SHALLOW-BURIED CRUSHED SURROUNDING ROCKS UNDER UNSYMMETRICAL PRESSURE REINFORCED WITH SURFACE PREGROUTING TECHNOLOGY IN HIGHWAY TUNNEL

Considering the case of shallow-buried crushed surrounding rocks under unsymmetrical pressure in a section of Guangfu tunnel to improve the strength of surrounding rocks and arching effect of tunnel,high pressure pre-grouting technology with cement grouting and cement-silicate grouting from ground surface is proposed to reduce the groundwater permeability of the surrounding rocks,and to protect water resources and ensure the safety of construction.The treatment effect is analyzed by numerical simulation and field experiment.The comprehensive analysis shows that after grouting,integral degree and strength of surrounding rocks are improved;and the velocity of convergence and crown settlement are increased.The deformation of tunneling is reduced;and the initial support and secondary lining mechanical behaviors are improved.The treatment of grouting is shown with good effect.