Blasting method for constant-volume air cushion layer on basic plane of dam foundation pit

Abstract

The invention discloses a blasting method for a constant-volume air cushion layer on a basic plane of a dam foundation pit. During blasting construction of the basic plane of a dam, a protection layer is canceled, but a large-step middle-deep hole is adopted for blasting; a blasted hole can directly reach the basic plane; and a constant-volume plastic air barrel is arranged at the bottom of the blasted hole and serves as the air cushion layer, so that defects of water seepage, rock slag and the like in the blasted hole can be effectively overcome, and the volumes of the air cushion layers in all the blasted holes are constant. During blasting, the air cushion layer achieves effects of buffering blasting impact waves and protecting rock on the basic plane, and the blasting method has the characteristics of high blasting effect consistency and high excavation efficiency.

Description

technical field [0001] The invention relates to the field of engineering blasting, in particular to a constant-volume air cushion blasting method on the foundation surface of a dam foundation pit. Background technique [0002] At present, high-efficiency blasting construction methods such as vertical medium and deep hole blasting are generally used in the blasting construction of dam foundation pits in water conservancy and hydropower projects. However, when it is close to the foundation surface of the dam foundation, in order to protect the bedrock and reduce the leakage phenomenon after the dam is completed, a protective layer must be reserved on the foundation surface, and then manual drilling, small-scale and small-dose blasting methods are adopted. Rock drilling is carried out layer by layer to the foundation surface of the dam. Since the area of ​​the dam foundation pit usually reaches tens of thousands of square meters, the blasting volume of the reserved protective ...

AI Technical Summary

Problems solved by technology

However, these methods also have limitations. The buffering effect on dry blast holes is better, and the buffer effect on water blast holes is poor.

In the practice of blasting the foundation surface of the dam foundation pit, the elevation of the foundation pit is lower than the surrounding level, and there is a large pressure difference, and water seepage is common in the rocks of the foundation pit. Water accumulation and slag accumulation generally exist at the bottom of the hole; using the above three flexible cushion methods, due to the different amounts of water accumulation and slag accumulation at the bottom of the blast hole, the air volume of the buffer layer in the hole is also uneven. The cushioning effect of the blasting is inconsistent, and the flatness of the bedrock protection surface decreases after the explosion, and local underbreak or overbreak is prone to occur.

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