Blast hole construction method for reducing controlled blasting over-break and under-break through oblique flat curved tunnel

Abstract

The invention discloses a blast hole construction method for reducing controlled blasting over-break and under-break through an oblique flat curved tunnel. The method comprises the steps that a construction mode is designed, and a tunnel excavation contour line is optimized; cut holes, expanded holes, peripheral long holes and peripheral short holes are formed in a tunnel face, and the cut holes are formed in the both sides of a tunnel middle line at intervals symmetrically; the expanded holes are formed in the outer sides of the cut holes, and the cut holes and the expanded holes are arrangedsegmentally; the peripheral long holes and the peripheral short holes are uniformly arranged along the tunnel excavation contour line at intervals, and located on the inner side of the tunnel excavation contour line; and the peripheral short holes are arranged in the position, between the peripheral long holes and the cut holes, of the tunnel face. The method has the beneficial effects that the effects of tunnel inclination, flat curved tunnel side walls and other factors are considered in the blast hole construction method comprehensively, and a peripheral hole arrangement method is providedspecifically; and compared with an existing universal tunnel blasting hole arrangement method, the peripheral hole arrangement method has the advantage that the over-break and under-break degree is reduced.

Description

technical field [0001] The invention belongs to the field of tunnel engineering, and in particular relates to a construction method for reducing controlled blast over-under-excavation blastholes in inclined flat-curve tunnels. Background technique [0002] In recent years, with the continuous increase in the volume of tunnel construction in my country, the effective control of tunnel over-excavation and vibration velocity has become the focus of attention of all parties involved in the construction, especially during the construction of urban shallow-buried mine tunnels. There are many kinds of influencing factors on (structure) structures, and the tunnel overbreak and vibration velocity control have brought severe challenges. The existing tunnel overbreak control technology research results are mainly aimed at small slope tunnels or near-horizontal tunnels. The arch adopts long and short blastholes or dense holes and interval holes. Technical measures such as Φ108mm pipe sh...

AI Technical Summary

Problems solved by technology

If the influence of the steel frame on the drilling of the arch is only considered, and the factors affecting the tunnel slope and flat curve are ignored, then under the same hole layout conditions that still consider the extrapolation angle, the degree of overbreak and underbreak of the tunnel arch and side walls will be extremely large. There may be a risk of further increase, and the actual amount of concrete spraying will further increase

At present, how to reasonably and effectively reduce the degree of over- and under-excavation of curved side walls is still somewhat rare.

[0004] (2) Vibration reduction control measures such as pipe shed and small pipe grouting in a certain area of ​​the arch will reduce the construction progress and increase the cost of construction measures to a certain extent; on the other hand, increasing construction investment will often be accepted by the construction party Low, more difficult to implement

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