自由面变化条件下隧道电子雷管爆破参数确定方法

电子雷管的技术潜力目前仍未在隧道工程中得以充分发挥，一个重要原因是没有严密理论支撑的爆破参数计算方法，药量、孔间延时等核心参数多沿用普通矿山法设计；其次是不能解决第二自由面形成后爆破参数计算准确性问题。以重庆观音桥隧道为研究背景，基于Anderson理论和电子雷管延时特性，提出隧道爆破在单自由面形成双自由面过程中，不同自由面条件下电子雷管爆破参数设计的新方法。现场获取不同药量单自由面单孔爆破振动曲线，逐一计算各孔间延时下的多孔合成振动，对比不同药量、不同延时合成振动曲线后确定单自由面爆破参数；根据电子雷管特点设计短延时掏槽爆破现场试验，获得起爆48 ms后已形成第二自由面；据此设计第二自由面形成后单孔爆破试验并计算双自由面下的合成振速、爆破参数，最终形成爆破全过程爆破参数计算方法。对计算结果进行综合分析后，现场设计主掏槽单孔药量1.2 kg，辅助掏槽单孔药量1.4 kg，孔间延时为5 ms；主掏槽与辅助掏槽间最小时差为35 ms；采用上述优化参数进行现场试验，在低振速控制的同时实现高效进尺。

Determination method of tunnel blasting parameters using electronic detonator under changing condition of free surface

The technical potential of an electronic detonator has not yet been fully utilized in tunnel engineering. An important reason is that there is no calculation method of blasting parameters supported by rigorous theory. The pivotal blasting parameters such as charge and delay time, etc. are mostly designed following ordinary mining methods. And it can not solve the problem of calculation accuracy of blasting parameters after the formation of the second free surface. Taking Guanyinqiao Tunnel in Chongqing as the research background, based on the Anderson principle and the delay characteristics of the electronic detonator, a new method for designing the blasting parameters of electronic detonators was proposed under the different free surface conditions changing in the process of tunnel blasting, from single free surface to dual free surface. Firstly, based on the single-hole and single free surface blasting vibration curves of different charges acquired on site, the superimposed vibration of multiple blast-holes under each delay time was calculated one by one. After comparing the superimposed vibration curves of different charges and delays, it was determined the blasting parameters of single free surface, including the maximum single-hole charge and the optimal inter-hole delay. Secondly, according to the characteristics of the electronic detonator, the short-delay cut blasting field test was designed. By comparing the calculated waveform without considering the influence of the second free surface with the measured waveform affected by the vibration reduction effect of the second free surface, it was found that the second free surface had formed at 48 ms after initiation. Based on this, a single-hole blasting test was designed after the formation of the second free surface. By calculating the superimposed vibration velocity based on the single-hole waveforms before and after the formation of the second free surface, it was determined the blasting parameters under the dual free surfaces condition, including single-hole charge, inter-hole delay time, and delay between different types of holes. Finally, the calculation method of blasting parameters in the whole blasting process was formed. After the comprehensive analysis of the calculated results, the single-hole charge of the main cutting holes is 1.2 kg, and it is 1.4 kg of the auxiliary cutting holes, then the delay time between holes is 5 ms on site; the minimum delay time between the main cut holes and the auxiliary cut holes is 35 ms. The field test was carried out with the optimized parameters mentioned above, and it got high-efficiency footage as well as a low vibration velocity.