Diversion tunnel blasting excavation back break and out break controlled construction method

Abstract

A diversion tunnel blasting excavation back break and out break controlled construction method comprises the steps of judging geological conditions, conducting surveying and setting out; determining the interval of blast holes on the tunnel outline line and conducting marking; drilling holes; feeding explosive into the blast holes; connecting a detonating network; conducting detonating; clearing dangerous rocks, discharging broken bits and the like. By the adoption of the diversion tunnel blasting excavation back break and out break controlled construction method, the smooth control blasting technology is adopted, during blasting excavation construction of a diversion tunnel with complicated geological conditions, rapid lithologic character change, joint fissure development and soft rock occupying the main part, the construction quality can be remarkably improved, the blast hole mark preservation rate of III-type relatively complete rock is 75.8%, the blast hole mark preservation rateof IV-type relatively broken rock is 48.3%, the flatness of the excavation face reaches 90%, the back break amount is effectively controlled, the average radial back break amount of III-type surrounding rock is controlled within 5cm, the average radial back break amount of the IV-type surrounding rock is controlled within 7 cm, the construction quality standard is met, good economic benefits can be achieved, and the diversion tunnel blasting excavation back break and out break controlled construction method provides the reference function for blasting excavation back break and out break controlled construction of similar surrounding rock diversion tunnels in the future.

Description

technical field [0001] The invention belongs to the technical field of tunnel construction, in particular to a construction method for controlling over- and under-excavation by blasting excavation of a water diversion tunnel. Background technique [0002] At present, the main constructions of tunnel excavation at home and abroad include: blasting excavation, non-blasting mechanical excavation, and the method of advancing and expanding pilot pits. Among them, blasting excavation is still widely used as a traditional tunnel excavation construction method. An important aspect of tunnel construction quality control is to minimize the damage of surrounding rock, so as to reduce the impact of blasting on reserved surrounding rock. The main reason for using smooth blasting and pre-splitting blasting in tunnel construction is to control the damage of blasting to the remaining surrounding rock, and its important sign is to control over- and under-break. The over-break and under-break...

AI Technical Summary

Problems solved by technology

Disadvantages: The blasting of the smooth surface after the main blasting hole makes the anti-vibration and anti-crack ability to penetrate into the reserved area worse than the pre-splitt

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