立井冻土爆破延迟时间计算结构模型研究

立井冻土掘进爆破合理的段间延迟时间应是在保证冻结壁和冻结管安全的前提下,能够获得良好的爆破效果。本文以此为出发点,重点从新自由面完全形成和降低爆破震动效应两个方面,对延迟起爆时间进行了初步探讨,建立了间隔延迟时间的计算结构模型;并就目前立井冻土爆破的施工条件,提出获得良好爆破效果的起爆延迟时间是100~200ms;而为降低爆破震动确保安全,延迟间隔时间则宜取200~250ms;综合考虑取值250ms,即选用1/4秒系列雷管较为适宜。现场井筒冻结段掘进爆破实践也验证了1/4秒延期起爆的合理性。

STUDY ON DELAY TIME CALCULATION STRUCTURE MODEL OF FROZEN-SOIL BLASTING IN SHAFT

The reasonable delay time Δt for frozen-soil tunnel blasting in shaft should be determined in terms of assuring the safety of frozen wall and frozen pipes and obtaining good blasting effects.Accordingly,emphasizing on the two facts of new free face forming completely and decreasing blasting vibrating effects,the authors analyzed delay detonation time and built calculation structure model of interval of delay time.Meanwhile,according to the construction condition of present frozen-soil blasting in shaft,the authors suggested that the delay detonation time should be 100～200ms for getting good blasting effects,but for decreasing blasting vibration and assuring the safety the proper delay time fell into 200～250ms.The authors determined Δt=250ms as the delay time through comprehensive consideration of the blasting situation,that is,the(1/4)s series detonators were adopted.The experiences of site wall casing frozen section tunnel blasting verified the reasonability of(1/4)s-delay time.