掏槽是岩石井巷爆破的关键，含空孔直眼掏槽技术在岩石爆破中应用广泛，针对含空孔直眼掏槽参数确定没有可靠依据的问题，以大空孔直眼掏槽为对象，在分析掏槽空孔效应的基础上进行了掏槽参数确定的理论分析，并结合算例验证掏槽爆破参数设计的有效性。研究结果表明：含空孔直眼掏槽，掏槽区岩石的破坏是炮孔产生的裂隙区以及由空孔的应力集中效应、自由面效应和碎胀空间效应共同作用的结果，3种效应对破岩的作用机理不同，应力集中效应对岩石的破坏是因为空孔附近的切向应力起主要作用，切向应力导致径向裂纹的产生，且径向裂纹的产生与炮孔和空孔距离有关，该距离存在临界值;自由面效应与空孔直径相关，大直径空孔加剧了应力波的反射，反射的应力波产生的拉伸破坏范围在空孔与炮孔连心线处存在最大值，连心线两侧拉伸破坏范围逐渐减小，即形成“凹”状片裂破坏;碎胀空间效应为破岩提供了充足的空间，有利于提高爆破效率，提出了动态碎胀系数的概念。从爆生气体对爆生裂纹扩展影响角度，分析了炮泥运动距离对爆生气体压力和裂纹扩展长度的影响，推导了爆生裂纹长度计算公式，空孔处片裂区范围公式、空孔处径向裂纹产生判据公式。含空孔直眼掏槽参数中炮孔与空孔距离L由爆生裂纹区、片裂区、空孔径向裂纹区共同决定，炮孔间距a由爆生裂纹区、空孔的碎胀空间(空孔半径r2)确定。

The cutting is the key to the blasting of rock roadway.The straight-hole cutting with empty-hole is widely used.Aiming at the problem that there is no reliable basis for determining the parameters of straight-hole cutting with empty-hole,taking straight-hole cutting with large empty-hole as object,based on the analysis of the effect of empty-hole,the theoretical analysis of the cut blasting parameters was performed,combined with a numerical example to verify the effectiveness of the design of the blasting parameters.Research shows that the cut-breaking rock is the result of the combination of fissures caused by explosive explosion in the blasthole,stress concentration effect,free surface effect and fragmentation space effect.The effect of three effects on rock breaking is different.The stress concentration effect causes rock failure to be the main role of tangential stress.The generation of cracks is related to the distance between the blastholes and the empty-holes,there is a critical value for their distance.The free surface effect is related to the diameter of the empty-hole.The large diameter hole exacerbates the reflection of stress waves,the tensile failure range produced by the reflected stress wave has a maximum value at the center line of the empty-hole and blast-holes,and the range of the tensile failure on both sides of the center line gradually decreases,concave chip crack failure is formed.The broken expand space effect provides sufficient space for rock breaking,improves blasting efficiency,and proposes the concept of dynamic broken-expansion coefficient.The influence of the moving distance of the stemming on the crack propagation length was analyzed.The formulas for calculating the length of blast cracks,formula of the range of the chipping area at empty-hole,and the formula for the criterion of radial cracks at empty-hole were derived.In the parameters of straight-hole cutting with holes,the distance L between the blast-hole and empty-hole was determined by the blast crack zone,the chip crack zone,and the radial crack zone of empty-hole.

1 大直径空孔掏槽破岩机理

   1.1 空孔的应力集中效应

   1.2 空孔的自由面效应

   1.3 空孔的碎胀空间效应

2 大直径空孔掏槽技术参数分析及确定

   2.1 掏槽布置

   2.2 掏槽参数设计

3 算例分析

   3.1 工程概况

   3.2 爆破方案优化

4 结论