深井高应力环境下岩石冲击力学响应与破碎机理研究

Percussive drilling can effectively improve the rock fragmentation efficiency, but this method is extremely limited by the high stress environment of deep wells. The reason is that the effect of high stress environment on the rock dynamic mechanical response and fragmentation energy dissipation is not clear. The theory is are almost absent about how to improve the performance of percussive drilling in deep wells. The rock SHPB test under high confining pressure will be conducted. According to the experimental results, the dynamical damage constitutive model of rock under high-stress environment will be established based on statistical and damage mechanics theory. It will be discussed whether the new constitutive model is suitable to describe the dynamic mechanical characteristics of rock under high stress environment, and how to determine the model parameters. The rock fragmentation process induced by the single tooth and air hammer impact will be simulated by using the model established. The relation among high-stress, rock fragmentation characteristic and energy dissipation will be studied according to the experimental and numerical simulation results. The effect of high stress environment on the rock fragmentation characteristic and energy dissipation will be revealed. The results from the research project will further enrich the dynamics theory of rock mechanics, and provide a theoretical basis for the improvement of impact drilling method in deep well.

冲击钻井能够有效提高破岩效率，但深井高应力环境制约了冲击钻井提速能力的发挥，其关键问题在于，深井高应力环境对岩石动态力学响应和破碎规律的影响机制尚缺乏深入研究，改善深井冲击钻井破岩方法缺乏理论支撑。本项目拟通过高应力环境下的冲击力学实验，基于统计学和损伤力学方法，建立高应力条件下岩石动态损伤本构模型，研究其描述高应力条件下岩石动态力学特征的适用性和参数确定方法，利用所建立的本构模型，开展深井高应力环境下单齿冲击和空气锤冲击破岩的数值模拟，基于实验和数值模拟结果，建立高应力与岩石破碎特征参数及破碎能耗的相关关系，揭示高应力环境对冲击岩石破碎特征和能量耗散影响规律。研究成果不仅丰富了岩石冲击动力学理论，也能为改善深井冲击钻井破岩方法提供指导。

冲击钻井能够有效提高破岩效率，但深井高应力环境制约了冲击钻井提速能力的发挥，其关键问题在于，深井高应力环境对岩石动态力学响应和破碎规律的影响机制尚缺乏深入研究，改善深井冲击钻井破岩方法缺乏理论支撑。本项目执行了一系列高围压条件下不同岩性（致密砂岩、玄武岩、安山岩等）的冲击破岩实验，开展了高应力环境下岩石动态本构模型研究，确定了模型参数；开展了高应力环境下岩石冲击数值模拟研究，研究了单齿冲击条件下井底应力环境对岩石破碎机制的影响，发现了围压对不同岩性的动态本构模型和破碎特征影响差异显著，形成了数值模拟研究岩石破碎机制和破岩工具的优化方法；分析了不同围压和冲击条件下破碎岩屑的块度特征，研究发现围压对岩石冲击破碎岩屑块度分布影响显著，围压极大地抑制了裂纹的扩展，减少了岩石破碎的平均块度。课题研究结果对钻井工艺设计具有重要意义，为开发新型高效的冲击破岩工具提供了重要的理论依据。