深部高应力软岩动静荷载组合作用力学机制与爆炸破岩机理

As the natural resources at the uppermost part of the Earth’s crust getting depleted, the ever-growing urbanization and industrialization have been providing unceasing thrusts for the exploitation of minerals, energy, and space at hostile depths in the Earth’s lithosphere. Among various means for exploiting the subsurface resources, the drill-and-blast technique represents the most commonly used approach to tunneling and shaft excavations in hydroelectric engineering and underground mining. Therefore, in order to exploit the natural resources at deeper formations, it is of practical and strategic significance to understand the mechanism of dynamic rock behavior under the effect of in-situ stresses of the Earth’s lithosphere. The present study focuses on the weakly-cemented porous sandstone which represents a typical class of high-stress soft rock. The characteristics of brittle-ductile transition are determined at first by quasi-static triaxial tests on the sandstone. Subsequently, a series of impact and blast loading experiments are performed on the sandstone under superimposed static stresses. The mechanisms of dynamic behavior and breakage of the typical high-stress soft rock exhibiting different brittleness and ductility under superimposed static loadings are then critically examined and demonstrated. On the basis of the experimental study, a numerical procedure is developed for modeling the mechanical response of the high-stress soft rock under the superimposed in-situ stresses and explosive disturbance. The modeling approach is subsequently employed to simulate and evaluate the fragmentation of the high-stress soft rock under varied in-situ stress conditions and blasting schemes. Consequently, the mechanism of blast fragmentation for high-stress soft rocks at deeper formations of the Earth’s crust is analyzed and demonstrated. The findings of the study could contribute to a better understanding of rock mechanics in deeper formations. The findings would also be of theoretical and strategic importance for the exploitation of natural resources at greater depths of the Earth’s lithosphere.

随着地球浅部资源日趋枯竭，人类对资源的开发利用逐渐转向地球深部。作为获取深地资源的重要手段，岩石爆破技术广泛应用于水电和采矿等领域的地下空间和矿体开挖，因此研究深部应力作用下的岩石动态行为机理对开发利用深地资源具有十分重要的意义。本研究以弱胶结多孔砂岩为研究对象，利用静态三轴试验确定其脆性-韧性转换特征，进而开展一系列静态荷载叠加条件下的冲击、爆炸试验，揭示该典型高应力软岩在不同围压作用下具有不同脆性、韧性特征的动静耦合行为规律和冲击爆炸破碎力学机制；在此基础上提出具有脆性-韧性转换特征的高应力软岩在深部应力场和爆破扰动共同作用下力学响应的数值模拟方法，进而模拟分析并定量评价工程尺度的高应力软岩在不同原岩应力和爆破工况条件下的爆炸破碎特征，最终揭示高应力软岩在深部工程中的爆炸破岩机理。研究成果对完善深地岩石力学理论体系，促进地球深部资源的开发利用具有重要的理论和战略意义。

随着地球浅部矿产日趋枯竭，人类对资源的开发利用逐渐转向地球深部。项目围绕深部岩体开挖响应开展了岩石动静荷载组合作用理论、原岩应力作用下的岩体爆炸动力响应、以及深部岩体开挖损伤机理等方面的研究工作，取得的具体成果如下：（1）推导了真三轴应力场中的球面波传播闭合解，通过利用应力投影技术分析不同地应力与爆破荷载组合工况下的加载路径，论证了原岩应力对爆破应力轨迹的平移和偏转作用，最终揭示了真三轴应力条件下的岩石爆炸动力响应机制；（2）利用岩石三轴压缩和冲击试验标定连续屈服面帽盖模型参数，进而开展了不同地应力与爆破荷载组合工况下的岩体动静耦合响应模拟计算，最终阐释了小主应力方向的岩体压缩效应对爆破粉碎区形成和径向裂隙发育的抑制作用机理；（3）建立了动态卸荷效应与人工降温过程协同作用下的深部岩体开挖响应理论模型，通过分析爆破冲击、瞬态卸荷、通风降温全过程中的完整应力路径，揭示了不同地质环境与开挖方案条件下的围岩开挖损伤机理，研究成果完善了深地岩石力学理论体系，同时为优化深部岩体开挖技术并提高深地资源开发利用效率提供了重要的科学指导和技术支撑。