液态CO_(2)相变破岩时相邻天然气管道防护研究

Study on adjacent natural gas pipeline protection during rock fracturing using liquid CO_(2) phase-change method

在随州城市综合管廊基坑开挖工程中,保护相邻天然气管道不受到破坏十分关键。为此,首先开展乳化炸药和液态CO_(2)相变破岩的爆破漏斗试验。一方面基于FARO Focus~S 150型三维激光扫描仪和Split-Desktop 4.0软件对开挖后的漏斗形状和块度进行分析,另一方面基于NUBOX-8016型测振仪分析振动频率和峰值质点振动速度(PPV)的衰减规律,通过线性拟合方法获得适用于该工况的萨道夫斯基公式。其次使用拟合得到的萨道夫斯基公式理论计算相邻天然气管道的最小安全距离。最后基于LS-DYNA建立三维数值模型对理论结果进行验证。试验结果表明,单根DM95-2.5液态CO_(2)致裂管相变破岩产生的爆破漏斗直径和深度分别为1.14 m和0.59 m,爆堆块度主要分布在4~15 cm之间。液态CO_(2)致裂技术相比乳化炸药具有更强的破岩和改善块度均匀性的能力,此外在减灾方面具有更大的优势。数值模拟结果表明,根据拟合的萨道夫斯基公式确定液态CO_(2)相变爆破参数是可靠的。研究结果对于同类工程具有重要的参考价值。

During the pit excavation of a utility tunnel in Suizhou City,it is critical to protect the adjacent natural gas pipelines from damage.Firstly,crater blasting experiments are carried out using emulsion explosives and the liquid CO_(2) phase change rock-breaking method.On the one hand,the FARO Focus S 150 three-dimensional(3D)laser scanner and Split-Desktop 4.0 software are used to analyze the shape of the post-blasting craters and the fragmentation size of muck piles.On the other hand,the vibration frequency and decay law of peak particle velocity(PPV)are analyzed based on the NUBOX-8016 vibration monitor,and a modified Sadovsky formula for this excavation engineering is obtained by linear fitting method.Secondly,the minimum safe distance of adjacent natural gas pipelines is calculated using the modified Sadovsky formula.Finally,by using the LS-DYNA software,a 3D numerical model is developed to verify the theoretical result.The experimental results indicated that the diameter and depth of the blast crater induced by a single DM95-2.5 liquid CO_(2) fracturing tube are 1.14 m and 0.59 m,respectively,and the fragmentation size of the muck pile is mainly distributed between 4 to 15 cm.The liquid CO_(2) fracturing technology has a greater ability to break rock and improve fragmentation uniformity than emulsion explosives and has more advantage in disaster mitigation.The numerical simulation results showe that the determination of liquid CO_(2) phase change blast parameters based on the fitted Sadovsky formula is reliable.The findings of the present study are of great reference value for similar projects.