Construction method of high ground stress and basalt underground factory building cavern

Abstract

The invention discloses an excavation construction method of a high ground stress and basalt underground factory building cavern, which comprises the following steps of: carrying out layered horizontal pushing construction on a middle part, and carrying out reserved excavation construction on protective layers at two sides; wherein, the middle part has a layer height of 4.0+ / -0.5m, the width of each protective layer is 5+ / -0.5m, a pre-cracking hole is arranged between the upper protective layer and the lower protective layer and the middle layered horizontal pushing, the pre-cracking hole adopts two layers of middle layered pre-cracking blasting, when the excavation construction of the protective layers on the two sides are finished, the system support construction is completed in time. According to the invention, a middle layered excavation mode is adopted, so that the blasting scale can be reduced, and the disturbance to the surrounding rock can be reduced; the pre-cracking hole is arranged between the protective layer and the middle layered horizontal pushing, so that the damage of blasting vibration to a side wall can be reduced, and the stress release is facilitated; the protective layers are reserved on both sides, so that the stress adjustment and relaxation deformation of the excavation surface occur in the protective layers, a permanent side wall cannot be influenced,the excavation work amount of the protective layers is small, the completion time is short, the support can be followed in time, and the influence of bad geology on the stability of the surrounding rock of a high side wall can be effectively controlled.

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 underground powerhouse caverns under high ground stress and basalt geological conditions. Background technique [0002] The caverns of underground powerhouses generally have the characteristics of large spans, high side walls, complex structures, and prominent stability problems in surrounding rocks. Due to the influence of high ground stress during excavation, high side walls loosen and collapse seriously. Traditional excavation techniques often use side walls Excavation is carried out by means of deep hole pre-splitting on the structural surface + blasting in the middle section. The deep hole pre-splitting blasting on the structural surface of the side wall has a certain impact on the stability of the surrounding ro...

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Problems solved by technology

[0002] The caverns of underground powerhouses generally have the characteristics of large spans, high side walls, complex structures, and prominent stability problems in surrounding rocks. Due to the influence of high ground stress during excavation, high side walls loosen and collapse seriously. Traditional excavation techniques often use side walls Excavation is carried out by means of deep hole pre-splitting on the structural surface + blasting in the middle section. The deep hole pre-splitting blasting on the structural surface of the side wall has a certain impact on the stability of the surrounding rock with high ground stress, and it takes a long time before it can be exposed for system support. Construction will lead to a long period of stress adjustment and relaxation damage on the permanent structural surface of the side wall, causing the side wall to fall, loose and collapse, which is not conducive to the stability of the surrounding rock and the safety of the construction period

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