Pre-reinforcement Technology for Shallow-buried Tunnel Passing through Filled Karst Cave
To realize safe and rapid treatment of large filled karst cave in Tongchuan Tunnel,this paper simulates and analyzes two reinforcement schemes of tunnel face curtain grouting and surface grouting,and compares the deformation,stress,structural safety factor and plastic zone deformation of surrounding rock in the support structure under the two reinforcement schemes.The results show that:a)the deformation law of surface grouting and curtain grouting is basically consistent,with a peak deformation difference of only 0.2 mm(0.46％)and an arch crown displacement deformation difference of only 2.4 mm(8.4％);b)Curtain grouting scheme coordinates the stress and deformation characteristics of surrounding rock around the tunnel,and the tunnel clearance convergence deformation and plastic deformation zone is smaller than that of surface grouting scheme,with a clearance deformation difference of 5.3 mm(59.6％);c)The safety factors of support structure for curtain grouting and surface grouting are 5.1 and 5.5 respectively,and both reinforcement schemes can ensure the safe construction of the tunnel.At the same time,this paper comprehensively compares the advantages and disadvantages of the two pre-reinforcement schemes from the aspects of construction period,costs and construction organization,and recommends the surface grouting reinforcement scheme.
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