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Original title: Understand the advanced support of tunnel pipe shed at one time. There are too many detailed words. You need to collect them first! Source: Zhulong Forum Copyright belongs to the original author. As aout off during excavation, resulting in increased spacing and easy collapse. Therefore, medium pressure feeding, medium rotating speed and medium circulating fluid volume can be adopted during drilling; the radial error of the borehole plane shall be controlled within 20cm, and the angle error shall be less than 1 °, so as to avoid deflection and downward bending of the steel pipe of the pipe shed due to too large aperture. In the actual construction, it is generally difficult to avoid horizontal borehole bending, mining dth bit , so in addition to improving the positioning accuracy of the pipe roof, appropriate uplift (determined according to the geological conditions of the site) can be given to compensate for part of the borehole sag. Pipeconstruction oed for cively broken surrounding rock in front of the tunnel face by small pipe grouting, so that the surrounding rock can form a whole before the next step. The pipe shed is used when the geological conditions at the entrance of the tunnel are very poor (such as sandy soil, seriously broken rocks, loess, etc.). Generally, the length is about 20-30 meters. The pipe shed is a steel pipe with a wall thickness of 3.5mm and a diameter of 108mm. Of course,mining drill bit, the pipe shed can also be used when the geological conditions in the tunnel are very poor (for example, the length along the axis of the tunnel caused by roof fall in the tunnel is large, and the volume is large). Return to Sohu to see more Responsible Editor:. wt-dthtools.com