液态CO_( 2)相变开挖岩体孔间距参数研究

Study on borehole spacing parameters of rock excavation by liquid CO_(2) phase change

为保证液态CO_( 2)相变致裂技术在随州绕城南路综合管廊基坑石方开挖中的爆破效果,在进行实际施工生产之前,对73型液态CO_( 2)致裂管单管单孔致裂岩体性能进行了现场试验,在对液态CO_( 2)进行TNT当量计算之后,基于LS-DYNA有限元软件进行了单孔爆破数值模拟和不同孔间距的两孔爆破数值模拟。结果表明:73型液态CO_( 2)致裂管现场试验和数值模拟单孔最大岩体破坏范围分别为1.84 m和1.766 m,试验和模拟结果具有较高的一致性,数值模拟方法预测73型液态CO_( 2)致裂管致裂岩体范围上可靠性良好。73型液态CO_( 2)致裂管台阶爆破最优孔间距为2.0 m,双孔爆破相邻炮孔之间岩体最大损伤范围比单孔爆破岩体损伤范围增加13.25%。73型液态CO_( 2)致裂管的台阶爆破最优孔间距的确定有效保证了基坑台阶开挖的爆破效果,同时具有良好的经济和社会环境效益。

In order to ensure the blasting effect of pipe gallery by liquid CO_( 2) phase change blasting in the foundation pit in the South Ring Road of Suizhou,field experiments were carried out for the rock fracturing performance of a single type 73 liquid CO_( 2) tube in a single hole before the device is used in practice.The liquid CO_( 2) is converted to the equivalent TNT charge weight,and numerical calculations of single-hole and two-hole blasting with different holes spacing were carried out based on the LS-DYNA finite element software.The results show that the experimental and simulated maximum fractured areas of rock mass with single hole by type 73 liquid CO_( 2) phase change blasting are 1.84 m and 1.766 m respectively,which presents a good consistency with each other.The numerical simulation method can be used to predict the rock cracking with type 73 liquid CO_( 2) tube.The optimal hole spacing of the step blasting with type 73 liquid CO_( 2) tube is 2.0 m.The maximum damage area of the rock mass between adjacent blastholes of the double-hole blasting is 13.25%larger than that of the single-hole blasting.The determination of the optimal hole spacing for the step blasting with the type 73 liquid CO_( 2) effectively ensures the blasting effect of the step excavation of the foundation pit,and it has good economic and social environmental benefits.