Radial pre-grouting method before excavation of the lower steps of tunnels in confined water strata

Abstract

The invention provides a radial pre-grouting method before excavation of a lower bench of a confined water stratum tunnel. The radial pre-grouting method before excavation of the lower bench of the confined water stratum tunnel comprises the following steps that S1, after the excavation of the upper bench and initial support are completed, upper bench grouting holes are formed, a leakage point ofthe initial support is drained by using a grouting pipe, then upper bench radial grouting is carried out on the upper bench, the thickness of an upper bench consolidation ring is 3-5m, and the arrangement of the upper bench radial grouting holes and grouting process are determined according to the position of the leakage point, characteristics, water percolating capacity and water pressure; S2, lower bench radial pre-grouting is carried out on the surrounding rock, beyond 2m from a tunnel face, of the lower bench, the thickness of the lower bench consolidation ring is 7-10m; and the fissure water percolating direction and a lower bench water outlet point are inferred according to the upper bench leakage point fissure and structural plane trend, and lower bench pre-grouting holes are formedaccordingly, and the number of the pre-grouting holes is determined according to the water percolating capacity of the leakage point associated with the upper bench. According to the radial pre-grouting method before excavation of the lower bench of the confined water stratum tunnel, the difficulty of performing radial grouting again after excavation of the lower bench is reduced, the secondary grouting speed is improved, and the grouting effect is improved.

Description

technical field [0001] The invention belongs to the technical field of tunnels and underground engineering, and in particular relates to a radial pre-grouting method before the excavation of lower steps of tunnels in pressurized water formations. Background technique [0002] Radial grouting for tunnels in confined water formations is carried out after excavation of the surrounding rock. When the step method is used for construction, the radial grouting construction of the upper step is completed after the excavation of the upper step, and the leakage point of the upper step surrounding rock is checked. Grouting plugging; after the excavation of the lower bench, radial grouting is performed on the seepage point of the lower bench to block water. Grouting is difficult, and it is difficult to guarantee the grouting effect. Contents of the invention [0003] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a radi...

AI Technical Summary

Problems solved by technology

[0002] Radial grouting for tunnels in confined water formations is carried out after excavation of the surrounding rock. When the step method is used for construction, the radial grouting construction of the upper step is completed after the excavation of the upper step, and the leakage point of the upper step surrounding rock is checked. Grouting plugging; after the excavation of the lower bench, the radial grouting water plugging is carried out on the seepage point of the lower bench. Grouting is difficult, and it is difficult to guarantee the grouting effect

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