液态CO_2致裂技术在管廊基坑台阶开挖中的应用

为了研究液态CO_2相变致裂下的岩体损伤并获得合理的台阶爆破参数,以随州市绕城南路地下综合管廊为工程背景,在DM95-2.5型致裂器的破岩性能现场试验的基础上,对致裂器破岩能力进行炸药的当量转化。并基于LS-DYNA有限元法对致裂性能进行2D数值模拟验证,最后对液态CO_2相变致裂技术在基坑台阶开挖中的运用进行3D数值模拟研究。结果表明:试验和数值模拟得到的DM95-2.5型致裂器破岩有效半径分别为1.15 m和1.05 m,二者之间具有良好的一致性;单管DM95-2.5型致裂器可等效转化为0.63 kg 2号岩石乳化炸药;当采用孔间距2.0 m,最小抵抗线1.5 m的单排炮孔起爆台阶时,炮孔之间裂纹全部贯通,开挖部分岩体破碎充分且无明显大块产生,爆破效果十分理想。本研究成果可为液态CO_2相变技术在同类台阶开挖工程中的运用提供理论指导和重要的参考价值。

Application of liquid CO_2 fracturing technology in bench excavation of utility tunnel foundation pit

In order to study the damage of rock mass caused by phase change of liquid CO_2 and obtain reasonable bench blasting parameters, taking the underground utility tunnel of South Ring Road, Suizhou City as the engineering background, based on the field test of the rock breaking performance of the DM95-2.5 fracturing device, the explosive equivalent conversion of the rock breaking ability of the fracturing device is carried out.And based on the LS-DYNA finite element method, the fracturing performance was verified by 2D numerical simulation. Finally, the application of liquid CO_2 phase change fracturing technology in the excavation of foundation pits was studied by 3D numerical simulation.The results show that the effective radii of DM95-2.5 fracturing device obtained by experiment and numerical simulation are 1.15 m and 1.05 m respectively, and there is good agreement between the experiment result and the numerical simulation data. The effect of the single-tube DM95-2.5 fracturing device can be considered equivalent to that of 0.63 kg No.2 rock emulsion explosive. When using a single row of blasting steps with 2.0 m hole spacing and 1.5 m minimum resistance line, the cracks between the blast holes are all penetrated, and the excavated part of the rock mass is sufficiently broken and no obvious large blocks are generated. The blasting effect is ideal, and the research results can provide theoretical guidance and important reference value for the application of liquid CO_2 phase change technology in similar bench excavation projects.