Method for constructing huge underground powerhouse machine pit in high ground stress and basalt geology conditions

Abstract

The invention discloses a method for constructing a huge underground powerhouse machine pit in high ground stress and basalt geology conditions. The method comprises pre-supporting of separating piersand excavating of the machine pit; the separating piers are subjected to pre-supporting through countersunk anchor rods before the machine pit excavation, and the pre-supporting is timely carried outthough a locking anchor rod, heavy covering concrete and pre-stressed anchor cable combination; and the machine pit excavation is carried out in a planar area division and vertical layering manner and includes attenuated layer excavation, well digging section excavation and excavation in the lower layer of a well digging section. According to the method, the separating piers are subjected to multiple pre-supporting through the locking anchor rod, heavy covering concrete and pre-stressed anchor cable combination before excavating the powerhouse machine pit under the high ground stress and adverse basalt geology conditions, thus the excavation formation and stability of the separating piers of the powerhouse machine pit can be ensured; the powerhouse machine pit is excavated in an attenuated excavating, planar area dividing and vertical layering manner; the excavation sequences are reasonably set, so that the exploding range is reduced, and the excavating structure surface is timely supported, and as a result, the excavating formation, the stability and the safety of the machine pit can be ensured.

Description

technical field [0001] The invention belongs to the technical field of water conservancy and hydropower engineering, in particular to the technical field of machine pit excavation for underground powerhouses, and specifically relates to a construction method for a huge underground powerhouse machine pit under high ground stress and basalt geological conditions. Background technique [0002] In hydropower projects, excavation of mechanical pits is often required during the excavation of underground powerhouses. The excavation of mechanical pits has the characteristics of large engineering volume, high technical difficulty, and many unforeseen factors. For the excavation of machine pits in traditional workshops, the construction process of first constructing the lock bolts around the excavation area, and then excavating the machine pits in sections, has a good forming effect on the underground plant machine pits with low ground stress. However, in view of the excavation constr...

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Problems solved by technology

For the excavation of machine pits in traditional workshops, the construction process of first constructing the lock bolts around the excavation area, and then excavating the machine pits in sections, has a good forming effect on the underground plant machine pits with low ground stress. However, in view of the excavation construction of the machine pit of the giant underground powerhouse under the combined action of high ground stress and unfavorable geological structures such as basalt, the surrounding rock deformation of the early excavation of the plant is relatively large, and the hollowing rate is large. The load relaxation is intensified, and the traditional construction technology is adopted, the effect of machine pit excavation is not ideal, and the safety risk is high

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