深部岩石爆破的气–固耦合断裂建模与机制研究

The exploitation of deep mineral resources has become the inevitable trend of the development of mining industry both at home and abroad. At present, there are some serious problems in the deep mining, such as poor maneuverability and high risk of disaster. In the environment of rock mass with deep high stress and multiple cracks ,it has been a crucial factor that can not be ignored and avoided which the high pressure detonation gas (detonation product) drives the original fracture surface of rock to expand and leads to the unexpected blasting effect. The modeling and mechanism study of gas-solid coupling fracture in the process of deep rock blasting will be an significant foundation for revealing the disaster-causing mechanism of deep mining and establishing the theory of precision blasting. This project intends to adopt lattice -spring model which has prominent advantages in the treatment of brittle fracture problems combined with the particle method based on molecular dynamics which can effectively describe the expansion behavior of gas to establish a large-scale parallel computational model to describe the propagation, bifurcation and coalescence of the original crack and the new crack of rock under the action of explosion shock wave and explosive gas. Through numerical simulation, the characteristics and patterns of blasting failure in rock mass with deep high stress and multiple cracks will be obtained and the gas-solid coupling fracture mechanism of the evolution of cracks driven by detonation gas can be revealed, which will provide a fundamental understanding for improving the maneuverability and safety of deep blasting.

深部矿产资源的开发已成为我国及世界未来采矿发展的必然趋势。当前深部采矿中存在着爆破可控性差、灾害风险高的严峻问题。在深部高应力、多裂纹的岩体环境中，高压的爆生气体（爆轰产物）驱动岩石的原始断裂面扩展并导致非预期的爆破效果，这已成为不可再被忽略与回避的关键因素。针对深部岩石爆破过程开展气–固耦合断裂建模与机制研究，将是揭示深部采矿致灾机理与建立精准爆破理论的重要基石。本项目拟将在处理脆性断裂问题时具有突出优点的格点–弹簧模型，与可有效描述气体膨胀行为的基于分子运动论的微粒方法相结合，建立描述岩石原始裂纹与新生裂纹在爆炸冲击波和爆生气体共同作用下扩展、分叉、贯通的三维大规模并行计算模型。通过数值模拟研究获得高应力、多裂纹岩石中爆破破裂过程的特征与规律，揭示爆生气体驱动裂纹演化的气–固耦合断裂机制，为改善深部爆破的可控性与安全性提供基础认识。

本项目针对深部岩石爆破过程中的气–固耦合问题，深入开展了含裂纹岩石的微结构建模、爆炸冲击波导致的岩石断裂以及裂纹扩展等问题的数值模拟研究。建立了含转动自由度的三维格点-弹簧模型，揭示了冲击加载条件下裂纹起裂所需的“孕育时间”与拉伸应力的关系，以及“孕育时间”对动态演化的影响。研究发现冲击波在多孔样品内传播时会逐渐演化为弹性波-变形波的双波结构，气孔率和冲击应力共同决定着变形波的传播速度，多孔样品的Hugoniot曲线都包含线弹性阶段、塌缩变形阶段和滑移与转动变形等三个阶段。裂纹的分叉并不是裂纹起裂后马上发生分叉，而是随着裂纹扩展速度逐渐升高，当达到临界值后，扩展路径出现不稳定并伴随着较多的次级裂纹产生，经过一段时间的演化后，裂纹才发生分叉，并且随着加载率的增加，达到裂纹分叉所需时间会变短，同时单裂纹、微分叉裂纹两阶段对应的裂纹扩展长度也越短。项目的研究成果能够为深部矿产资源的安全开采提供有力的理论依据。