超临界CO2相变膨胀诱发冲击波的水下礁石致裂试验与模型研究

Underwater anti-reef rock breaking is the first problem faced by the Yangtze River to lift the waterway grade and build the gold waterway, and the use of super-critical CO2 phase transition expansion technology in the rock breaking process of the reef, there is a lack of understanding and control methods for the depth of fracture damage caused by phase transition expansion of CO2. In this paper, the attenuation Law of rock and water medium shock wave under phase transition expansion is discussed by underwater super-critical CO2 phase transition fracturing test, and the penetrating reflection equation of rock-water interface is deduced by combining the law of Snell with the conservation of momentum on the wave surface, and the wave equation of shockwave propagation in solid phase and liquid phase is established. In this paper, the formation mechanism and dynamic evolution law of rock damage are explored by means of rock acoustic wave test and numerical simulation before and after super-critical CO2 phase transformation, and the energy dissipation relationship of rock damage under super-critical CO2 phase transition shock wave is calculated by calculating the dissipation energy and release energy of rock fracture in rock damage area after fracturing. , this paper discusses the relationship between the vibration peak pressure and the damage depth of the coastal rock at a certain distance from the source, and puts forward a control method for the depth of the crack damage caused by underwater reef. The understanding of the mechanism of rock fracturing by super-critical CO2 phase transition expansion has important practical value for the regulation of the Yangtze River and even the offshore waterway.

水下除礁破岩是长江提升航道等级、建设黄金水道面临的首要问题，而利用超临界CO2相变膨胀技术在清礁破岩过程中，缺乏对CO2相变膨胀致裂损伤深度的认识与控制方法。项目通过水下超临界CO2相变致裂试验，探讨相变膨胀作用下岩石和水介质冲击波的衰减规律，结合Snell 定律和波振面上动量守恒推导应力波通过岩石-水界面的透反射方程，建立冲击波在固相和液相传播的波动方程；结合超临界CO2相变致裂前后岩石声波测试、数值模拟等，探索岩石损伤形成机制和动态演化规律；通过致裂后岩石损伤区计算岩石致裂的耗散能与释放能，给出超临界CO2相变冲击波下岩石损伤能量耗散关系；探讨距致裂源一定距离处岸边岩石的振动峰值压力与损伤深度的关系，提出水下清礁致裂损伤深度的控制方法。超临界CO2相变膨胀对岩石致裂机理的认识，对长江甚至近海航道整治均有重要的实用价值。

界CO2相变膨胀技术在清礁破岩过程中，缺乏对CO2相变膨胀致裂损伤深度的认识与控制方法。结合超临界CO2相变致裂的基本原理，自主研发了超临界CO2致裂试验装置，实现CO2充装压力、充装质量和温度的精确控制，通过CO2致裂管膛压试验，获得不同活化剂质量、不同充装压力、不同泄能片厚度下CO2致裂管起爆过程中超临界CO2相变膨胀压力特征（大小、时程、频率）。建立了相变膨胀整个过程的冲击波状态方程，获得不同致裂管类型、不同剪切片厚度下的相变冲击特性参数（破裂压力、冲击波波速、透射冲击波速、入射岩体应力）。基于冲击波的几何扩散性、Snell定律，建立了相变冲击作用下岩石介质冲击应力波衰减方程，表明冲击应力波在岩石中呈指数衰减关系。基于时域递归法，建立了超临界CO2相变诱发的地表振动速度计算模型，结合ls-dyna数值模拟验证了计算模型的可靠性。对比分析了CO2相变致裂与炸药爆破诱发的地表振动速度及衰减规律，表明超临界CO2相变的峰值压力仅为炸药爆破的1/3.36，但作用时间是炸药爆破的100倍，导致相变诱发的峰值振动速度仅为等当量炸药爆破的1/74~1/78，具有明显的减振效应。基于超临界CO2相变致裂试验，研究了CO2相变致裂损伤范围及其特征，结合岩石冲击损伤离散元仿真分析，分析不同致裂管腔体特征（大小、时程、频率）下，岩石损伤形成机制和动态演化规律。表明：CO2相变致裂损伤半径与泄能片厚度、充装质量呈对数增长关系，与岩石强度、钻孔孔径呈指数衰减关系，且增大泄能片厚度是增大损伤半径最有效手段；给出了CO2相变冲击波作用下岩石压碎区和裂隙区半径计算公式。超临界CO2相变膨胀对岩石致裂机理的认识，对长江甚至近海航道整治均有重要的实用价值。