单、双临空面岩塞爆破的贯穿机制与试验研究

Through mechanism and experimental study of rock-plug blasting with single and double free faces

深入研究岩塞爆破技术在工程改扩建或事故抢险中意义重大。首先从爆炸应力场角度分析单、双临空面条件下岩塞爆破的贯穿机制,揭示了2种条件的差异主要由岩塞体底部岩体的夹制作用以及临空面处反射拉应力波的联合作用引起。基于LS-DYNA的二次开发技术,分别进行单、双临空面条件下的单孔及全断面爆破开挖的爆破损伤数值仿真,结果表明,单、双临空面实际爆除深度的差异随着钻孔深度的增加而明显增大,当孔深大于5 m后,单临空面岩塞爆破的贯穿深度小于双临空面工况,在后者可贯通条件下,随着孔深增加,前者逐渐趋近后者的1/2。开展单双临空面的贯穿试验并针对已有工程结果进行统计,结果表明,钻孔深度较小时,单临空面条件下能贯穿,但随着孔深的增加,贯穿比例逐渐减小并趋近至0.5,而在同等条件下,双临空面岩塞爆破仍然成功贯穿。试验结果与数值计算结果相互印证且均表明,由于孔底的夹制作用以及临空面导致的拉应力波,当孔深较大时,单临空面岩塞爆破的贯穿深度趋近双临空面条件下的1/2。研究成果期望为类似工程提供参考。

Investigating the rock plug blasting technology is of great significance in engineering reconstruction or accident emergency rescue. At first,the through mechanism is analyzed by describing the stress field of the rock plug blasting with single and double free surfaces. Based on the secondary development of LS-DYNA,numerical simulation of the rock plug blasting with single and double free surfaces was implemented. Result reveals that the through depth of rock plug blasting with single free surface is little than that with double free surfaces,and the former is close to the half of latter. Experiment of rock plug blasting with single and double free surfaces was carried out three times. Results demonstrate that when the depth of rock plug blasting with single are 6.5 m and 8 m,the through depth are about 4.5 m and 6 m,But when the depth of the rock plug blasting with double free surfaces is 11 m,the rock plug could be through completely. Results of experiment and numerical simulation support each other,which reveals that the because of the suppress system and the tensile stress wave from the free surface,the through depth of rock plug blasting with single free surface is close to the half of that of the rock plug blasting with double free surfaces. Results expect to provide the reference of the similar engineering.