Research on the Comparison and Selection of Construction Methods for Multiple Tunnel Additions Adjacent to Cracked Tunnels
Based on the small-clear distance additional tunnel project of an expressway,and on the basis of the investigation of the existing tunnel lining crack damage,this paper adopts numerical calculation to study the construction method of additional tunnel adjacent to the existing crack tunnel under the conditions of Class IV surrounding rock,and then evaluates the structural stress on cracked tunnel and deformation characteristics of the surrounding rock under different construction conditions.Finally,the reasonable construction method of the additional tunnel is determined by comparison.The results show that:(1)the deformation of surrounding rock and the load-bearing capacity of new and old tunnel structures meet the requirements of the deformation capacity of surrounding rock and the bearing capacity of lining materials when different combined construction methods are used to construct the additional tunnels,but the tunnel structure safety is the highest when constructed using the cross diaphragm(CRD)method.(2)Tensile stress concentration occurred at the crack damage of the old tunnel lining when different combined construction methods are used,and the tensile stress at the crack damage is the smallest when constructed using the cross diaphragm(CRD)method.(3)The cross diaphragm(CRD)method and three-bench seven-step combination construction method are used to construct the additional left and right line tunnel separately,a small plastic zone showed up in the surrounding rock at the arch foot of the tunnel,while there is no plastic zone around the surrounding rock when using the cross diaphragm(CRD)method to construct the tunnel.(4)The comprehensive analysis suggests that the cross diaphragm(CRD)method is recommended for the construction of additional left and right line tunnels in the surrounding rock section of ClassⅣ.
cracked tunneladditional tunnelsmall-clear distancenumerical calculationcomparison and selection of construction method
万方数据
维普
