Advanced drainage and precipitation system and method for sandstone aquifer and construction method

Abstract

The invention discloses an advanced drainage and precipitation system and method for a sandstone aquifer and a construction method. The advanced drainage and precipitation system for the sandstone aquifer comprises the follow steps that a water pumping hole is formed in the position, intersecting with the inclined shaft position, of the sandstone aquifer in the vertical direction; a drainage hole set is arranged around the inclined shaft in the sandstone aquifer in the axial direction of the inclined shaft, the drainage hole set is composed of a plurality of drainage branch holes, and the drainage branch holes communicate with the water pumping hole correspondingly. According to the advanced drainage and precipitation method and system for the sandstone aquifer, a mode that the long-distance drainage holes communicate with the large-diameter water pumping hole is utilized, advanced drainage and precipitation, drainage and pumping drainage are conducted on water of the water-rich low-permeability ultra-thick sandstone aquifer before inclined shaft construction, the problem that the water of the water-rich low-permeability ultra-thick sandstone aquifer is difficult to pump and precipitate is solved, geological guarantee is provided for safe and rapid tunneling of the inclined shaft, and compared with traditional methods such as freezing and wall back grouting, the cost and construction difficulty are reduced, and the efficiency, reliability and safety of water drainage and precipitation are improved.

Description

technical field [0001] The invention belongs to the field of water prevention and control in coal mines, and in particular relates to an advanced drainage system, method and construction method for a sandstone aquifer, and is especially suitable for advanced drainage when an inclined shaft passes through a water-rich, low-permeability, and extremely thick sandstone aquifer. Background technique [0002] In the Northwest Jurassic coalfields of my country's top ten coal production bases, the Cretaceous strata generally develop a layer of thick medium-coarse-grained red sandstone, commonly known as the Luohe Formation sandstone, with a thickness of about 300-500m. It has large pores, obvious bedding, and strong Low and easy weathering and other engineering geological characteristics, high water pressure, medium-strong water richness, poor-medium and extremely heterogeneous permeability have obvious hydrogeological characteristics of "easy to release, difficult to pump down". [...

AI Technical Summary

Problems solved by technology

It is difficult to achieve rapid and safe excavation by the methods of dewatering at the well point of deep wells, grouting behind the wall and freezing in the past.

Although the deep well point precipitation method has strong applicability to water-rich and high-permeability aquifers, due to the poor permeability of the Luohe sandstone, the required precipitation depth can reach hundreds of meters, and the characteristics of "easy to release and difficult to pump down". Its precipitation effect is difficult to meet the construction needs of inclined shafts, which requires a large amount of engineering, which seriously affects the construction speed and construction safety; Precipitation at well points cannot achieve an overall drop in water level, and there are prone to stagnant water in low-permeability areas and high-water-level areas

For the post-wall grouting method, due to the unclear diffusion law and mechanism of grouting materials in sandstone, parameter selection and grouting control are difficult, and the grouting effect cannot be guaranteed. After grouting, residual stress will be formed in the formation instead of It is beneficial to the excavation of inclined shafts, and the investment in grouting construction is also very large for long-distance inclined shafts

For the freezing method, because the Luohe Formation sandstone is very sensitive to freeze-thaw action, the freezing and expansion of water inside the sandstone during the freezing process will cause the primary micropores and fissures in the rock to further develop and expand, and the strength of the Luohe Formation sandstone after thawing continues to increase. Deterioration, increased deformation, widening of the main fractures in the sandstone after freeze-thaw damage, accompanied by many secondary fractures, and the deformation cannot be fully recovered after thawing, and further deformation will occur under the action of external pressure, thereby causing deformation of the deviated well. As a result, the water-richness and permeability of the thawed sandstone aquifer will be enhanced, and the structure and strength will be deteriorated. The deformation stability of the deviated shaft wall will be poor, and it will be more threatened by water inrush.

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