Tunnel pre-reinforcing and excavation construction method for crossing soil-rock boundary stratum

Abstract

The invention discloses a tunnel pre-reinforcing and excavation construction method for crossing a soil-rock boundary stratum. The tunnel pre-reinforcing and excavation construction method comprises the following steps of 1, precipitation pre-reinforcing; 2, excavation construction of a rear side tunnel section; 3, excavation construction of a middle tunnel section; and 4, excavation constructionof a front side tunnel section, wherein the middle tunnel section and the front side tunnel section are both three-step synchronous excavation tunnel sections; and in the excavation process from backto front in the step 2, the step 3 and the step 4, primary supporting is synchronously conducted on an excavated and formed tunnel hole from back to front. According to the tunnel pre-reinforcing andexcavation construction method for crossing the soil-rock boundary stratum, design is reasonable, construction is easy and convenient, and the using effect is good; and the underground water level islowered through precipitation pre-reinforcing, surrounding rock is effectively reinforced, then a suitable drilling and blasting method is selected according to the position relation between the soil-rock boundary and the tunnel hole, blasting excavation is conducted in a three-step synchronous excavation mode, so that the excavation process of a tunnel crossing the soil-rock boundary stratum is safe and reliable, and the stability of the tunnel structure can be ensured.

Description

technical field [0001] The invention belongs to the technical field of tunnel construction, and in particular relates to a tunnel pre-reinforcement and excavation construction method for crossing soil-rock boundary strata. Background technique [0002] In the construction process of railway and highway tunnel projects, due to the limitation and influence of geological conditions, it will cause great influence and difficulties to the construction during the construction process. In the process of tunnel construction, various combinations of rock strata are often encountered, such as weak and uneven surrounding rock, shallow buried bias landform, soil-rock mixed geology and so on. For the excavation and support of tunnels that pass through soil-rock mixed strata (also known as soil-rock interface geology or soil-rock boundary strata), at present, the main methods in China are advanced pipe shed grouting support, advanced horizontal jet grouting pile reinforcement, and controll...

AI Technical Summary

Problems solved by technology

During the actual tunnel construction, the main problems of tunnel excavation in the soil-rock boundary stratum are as follows: first, the softness and hardness of the rock and soil are uneven, and the blasting of the lower weathered rock layer will easily cause the upper soil layer to collapse, which is harmful to the construction personnel; second, the groundwater The enrichment area further softens the soil-rock boundary strata, causing serious deformation of the surrounding rock; third, the swelling of the expansive soil with water causes the primary support to deform and crack, and in severe cases, the deformed structure of the primary support arch will be damaged and the support capacity will be lost

Once the corresponding reasonable support measures are not adopted in the actual construction or the excavation method is improper, it is very likely to cause deformation of the support in front of the face, or even serious consequences of collapse

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