Large-span small-clear-distance shallow-buried tunnel excavation construction method

Abstract

The invention belongs to the field of tunnel construction, and particularly discloses a large-span small-clear-distance shallow-buried tunnel excavation construction method which comprises the following steps: determining basic mechanical parameters of surrounding rocks: testing the basic mechanical parameters of the surrounding rocks of a current construction section by carrying out an indoor test on a rock sample taken on site; after testing, according to the determined basic mechanical parameters of the surrounding rock, carrying out surrounding rock partition evolution analysis and excavation method judgment on the currently constructed section; tunnel arch advanced grouting reinforcement is carried out on the currently constructed large-span small-clear-distance segment; excavating an upper step and primarily supporting; excavating a middle step and carrying out primary support; excavating a lower step and primarily supporting; an inverted arch is excavated, and an inverted arch steel frame is installed and backfilled; and laying a waterproof plate, and completing construction after quality inspection. According to the method, an IV-level surrounding rock three-step four-step excavation mode and a V-level surrounding rock lining mode are adopted, namely, rapid excavation, strong supporting and frequent measurement are achieved, and tunnel construction safety is ensured.

Description

technical field [0001] The invention relates to the field of tunnel construction, in particular to an excavation construction method for a shallow-buried tunnel with a large span and small clear distance. Background technique [0002] The construction of long-span highway tunnels is difficult and risky. A safe, reliable and rapid excavation construction method is required. As far as the current development of highway tunnels in my country is concerned, there are relatively few shallow-buried, large-span and small-space tunnels, and there is little previous experience. At present, the excavation method of large-span tunnels with V-level surrounding rocks adopts the double-side-wall pilot pit method. [0003] The double-side-wall pilot pit method adopts three pilot pits on the left, middle and right to be excavated step by step. The pilot pits on the left and right sides are divided into upper and lower pilot pits. Excavation, a total of 7 steps. The construction method ca...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that excavation is divided into 7 steps. The upper and lower pilot pits cannot be constructed at the same time, resulting in a narrow working surface. The left and right pilot pits need to be separated by a certain distance before they can be constructed at the same time. The pilot pits on both sides of the entrance section cannot be constructed at the same time, which wastes equipment and human resources. , which seriously affects the construction period; the surrounding rock of grade V is good, and the lithology is good, so manual excavation with excavators and woodpeckers cannot be used, and blasting excavation must be adopted. Monitor the measurement results to ensure that the temporary support can be removed only when the cave body converges and the settlement of the cave roof is stable.

Medium-conducting blasting excavation is powerful, and blasting excavation is adopted, and the temporary support small conduits, steel mesh and steel supports are severely damaged, the reuse rate is extremely low, and the cost is high

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