A construction method for deep and large vertical shafts in water-rich magmatic rock areas

Abstract

The invention discloses a construction method for a pitshaft of a deep and large vertical shaft of a tunnel in a water-rich magmatic rock area. The construction method comprises the following specificsteps that 1, the thickness and form of a grouting stopping pad are determined; 2, hole opening pipes of in-advance prospect holes are mounted; 3, after anchoring of the hole opening pipes of the in-advance prospect holes reaches to the strength, in-advance prospect hole construction is conducted; 4, the water yield in the in-advance prospect holes in the step 3 is tested; 5, the water plugging grouting scheme for a driving face is determined; 6, downward-advancing-type water plugging drilling grouting is adopted; and 7, pitshaft driving building construction is conducted. By adopting the construction method, the water inflow in the pitshaft in the excavation process is decreased, and the water pumping and draining pressure in the excavation process is decreased; and after excavation is completed, radial grouting is adopted on the shaft wall to plug leaked water of the pitshaft again, the situation that the water leakage amount of the pitshaft is increased along with excavation of thepitshaft and consequently a shaft flooding accident occurs is reduced, secondly, gaps between the shaft wall and surrounding rock are filled through radial grouting, and thus the tunnel structure andconstruction safety are ensured.

Description

technical field [0001] The invention belongs to the technical field of shaft shaft construction of deep and large shafts, and in particular relates to a construction method of shaft shafts of deep shafts in water-rich magmatic rock areas. Background technique [0002] At present, for the construction of deep and large vertical shafts of tunnels in water-rich areas, the shaft freezing method or the ground pre-grouting reinforcement method is usually used to pre-reinforce the water-rich shafts in advance and then adopt the normal sinking excavation method; while for magma The main problems in the wellbore construction of rich water and deep shafts in rocky areas are as follows: 1. The shaft pre-freezing method is mainly used in alluvium, and there are very few cases of freezing directly in bedrock (magmatic rock), and the following problems exist: (1) The construction process of freezing pipe drilling is complicated, and the drilling accuracy is difficult to guarantee when the...

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Problems solved by technology

[0002] At present, for the construction of deep and large vertical shafts of tunnels in water-rich areas, the shaft freezing method or the ground pre-grouting reinforcement method is usually used to pre-reinforce the water-rich shafts in advance and then adopt the normal sinking excavation method; while for magma The main problems in the wellbore construction of rich water and deep shafts in rocky areas are as follows: 1. The shaft pre-freezing method is mainly used in alluvium, and there are very few cases of freezing directly in bedrock (magmatic rock), and the following problems exist: (1) The construction process of freezing pipe drilling is complicated, and the drilling accuracy is difficult to guarantee when the depth is greater than 500m; (2) Due to the large freezing depth, there are extrusion fracture zones in the freezing section, the wellbore stability is poor, and there is no extrusion fracture zone freezing project Case; (3) Because the freezing depth is too deep, the expansion speed of the frozen soil at different layers is different, which makes the thickness of the frozen wall at the junction of the rock formations discontinuous, and the frozen pipe generates local stress, thus causing the frozen pipe to rupture; 2. Pre-reinforcement by grouting on the ground The wellbore construction conditions can be improved to a certain extent, but there are still the following main problems: (1) The magmatic rock formation has well-developed fissures and is rich in water, and the connection is irregular and uncertain. It is difficult to expose and seal all the fissures by ground pre-grouting , there is a large blind area for water blocking; (2) When the drilling depth is greater than 500m, the drilling accuracy cannot be guaranteed; (3) There is no systematic evaluation standard for grouting effect, and the evaluation can only be revealed through excavation; 3. Wellbore freezing method Both the ground pre-grouting method and the ground pre-grouting method have the characteristics of large investment, long construction period, and complicated process, and it is difficult to meet the railway tunnel construction principle of "long tunnel, short and large, and auxiliary passages quickly enter the tunnel".

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