Study On Construction Technology And Parameters For Deep Ventilation Shaft With Large Diameter Of Highway Tunnels

With the development of the national economy,infrastructure construction continues to develop.some long highway tunnels also emerged,while the highway tunnel ventilation shaft is growing.In this paper,the construction of the ventilation shaft of No.1 highway tunnel in Shifang highway is taken as the engineering support,and the problems in the construction process of large and deep shaft are carried out.First of all,according to the problems in the construction process of the vertical shaft drilling machine,such as the reason of the skew in the process of the hole drilling,a reasonable correction scheme is put forward.The blasting method is used to control the blasting parameters and the blasting method The size of the blasting block of the rock;and the plugging of the shotcrete pipe in the process of shaft spraying,a kind of shotcrete pipe connection device suitable for the shaft spraying process is proposed.Secondly,according to the characteristics of the shaft and the slip line calculation method,the lateral pressure of the shafts with different diameters in the ?,? and ? are calculated.The finite element software ANSYS is used to analyze the shafts with diameters of9 m,11m and 13 m In the stage of ?,? and ?,the shafts of the initial support structure are selected and the reasonable parameters of shotcrete support are selected.By calculating the lateral pressure of the surrounding rock,the shafts with diameters of 9m,11 m and 13 m are calculated in ?,?,And the reasonable support thickness is selected.Based on the study of the initial and secondary systems,a set of large diameter deep shaft support parameters suitable for horizontal stratigraphic strata are obtained.And the thickness of the secondary lining of the shaft is calculated by elastic resistance method considering the pressure nonuniformity coefficient,shaft diameter and shaft depth.Finally,with the deformation of the template and the inclination of the template in the construction of the shaft slab in the tunnel of the provincial tunnel,the straight chamfer is changed to the arc-shaped chamfer by the chamfering of the cross section of the middle partition,The stability of the template to enhance the compression performance of compression,while sliding construction of the cross section can reduce the resistance along the way to save costs.