A method of tunnel auxiliary guide pit entering the main hole

Abstract

The invention discloses a method for entering a tunnel auxiliary pilot pit into a main tunnel, which comprises the following steps: (1) excavating a first auxiliary pilot pit obliquely toward the main tunnel; (2) adjusting the slope without changing the structural size of the first auxiliary pilot pit , so that when it intersects with one side of the main hole, the excavation contour line at the top of the center of the first auxiliary pilot pit is flush with the top excavation contour line of the center of the main hole, and the excavation continues until reaching the turning point; (3) Take the turning point as Starting from the base point and taking the width of the first auxiliary pilot pit as the turning radius, the second auxiliary pilot pit excavation stage is entered, and the other side is excavated in an arc until the center line is parallel to the center line of the main hole; (4) Gradually expand the second auxiliary pilot pit. Two auxiliary pilot pits, promptly excavate the 3rd auxiliary pilot pit, until reaching the contour line of positive hole; (5) turn over to positive hole excavation stage, continue to excavate positive hole; According to the plan, the roof lifting is no longer carried out, which shortens the construction period of the roof lifting, and further avoids the risk of falling blocks and landslides caused by the roof lifting plan.

Description

technical field [0001] The invention relates to the technical field of tunnel construction, in particular to a method for entering an auxiliary guide pit of a tunnel into a positive hole. Background technique [0002] In order to shorten the construction period of the double-track long tunnel of the high-speed railway, auxiliary guide pits are often set up. There is a large difference in size. When the auxiliary pilot pit is turned into a positive hole, the small pilot hole roofing scheme is mostly used to facilitate ventilation and drainage, and at the same time, it is conducive to excavation at both ends of the forward direction. [0003] In soft rock tunnels, the mountain shape is steep and the rock is weak. If the construction scheme of the roof is adopted, there will be safety risks such as falling blocks and landslides in the soft rock tunnel. However, in the prior art, in order to ensure good ventilation and drainage, there is no other There is an alternative and bet...

AI Technical Summary

Problems solved by technology

[0003] In soft rock tunnels, the mountain shape is steep and the rock is weak. If the construction plan of the roof is adopted, there will be safety risks such as block falling and landslides in the soft rock tunnel. However, in the existing technology, in order to ensure good ventilation and drainage, there are no other Alternative and better technical solutions, therefore, the construction plan of the roof must be adopted during construction, and in order to avoid the existing safety risks, the process of the roof must be further optimized, such as increasing the number of small conduits in advance Carry out a wider range of grouting to increase the stability of the surrounding rock to avoid falling blocks and landslides, or improve the stability of the arch frame of the pilot tunnel to reduce settlement, etc., but in the final analysis it is still based on the technical solution of the roof itself Improve

[0004] No matter what kind of improvement method, on the basis of the original technical scheme of overhanging the roof, the construction difficulty and construction period will be further increased. It may take about 45 days for rocky or watery areas

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