Method for smooth blasting excavation of large-diameter surge shaft and long-footage pilot well in soft-rock and extremely-soft-rock area

Abstract

The invention provides a method for smooth blasting excavation of a large-diameter surge shaft and a long-footage pilot well in a soft-rock and extremely-soft-rock area. The method comprises the steps of (A) excavation of the long-footage pilot well and (B) excavation of the surge shaft. (A) comprises the steps that I, blast holes of the pilot well are distributed; II, detonation is conducted on the pilot well; III, deslagging is conducted on the pilot well; and IV, a small step that horizontal blast holes are distributed is conducted. (B) comprises the steps that V, blast holes of a surge shaft are distributed; VI, surge hole detonation is conducted; and VII, a small step of surge shaft deslagging is conducted. Through a mode that the pilot well and the blast hole positions of the surge shaft are arranged, the detonating order is set, the hole depth, the hole diameter and the blasting strength of each blast hole is designed, the problems of peeling off, cracking and chip off-falling of a surrounding rock and a concrete lining caused by previous repeated blasting and excavation are solved, the smooth blasting effect is achieved, one-time excavation forming is achieved, and deslagging from top to bottom is achieved; and the construction mode is improved, the working efficiency is improved, the tunneling schedule is effectively guaranteed, the construction period is shortened, and further the safety of the personnel and equipment are guaranteed.

Description

technical field [0001] The invention relates to the technical field of water conservancy and hydropower engineering, in particular to a smooth-surface blasting excavation method for a large-diameter surge well with a length and footage of a pilot well in soft rock and extremely soft rock areas. Background technique [0002] In the field of water conservancy and hydropower, the surge well is a common hydraulic structure. The vertical depth of the built project can range from a dozen meters to more than 400 meters, and the diameter ranges from a few meters to tens of meters. The surge well can directly provide hydraulic power for the turbine, and its excavation quality and smooth surface effect have a great influence on the output effect of the turbine in the later stage, which is directly related to the power generation, and even related to the operating efficiency of the entire power station. [0003] The research object of the present invention is a method for excavating a ...

AI Technical Summary

Problems solved by technology

After each blasting, the surrounding rock at the excavation boundary is easily affected by the blasting, and cracks, spalling, falling blocks, over-excavation, and even large-scale landslides occur, which will cause great difficulties in the later lining work. In addition, repeated blasting vibrations It is easy to cause deformation, cracking and collapse of the surrounding rock and lining concrete that have been lined in the upper layer

This has seriously affected the progress, cost, quality and safety of surge well excavation construction

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