动力扰动下岩石节理面剪切-渗流机理研究

Predicting the groundwater seepage in rock fractures and understanding the frictional effect of rock joints under dynamic load conditions are the hot research topics in rock mechanics, which have great significance during bedrock deposit mining under sea water. In this project, the shear-flow behavior of rock joints is studied systematically under dynamic normal load conditions. Based on the self-design shear-flow laboratory experiments, fluid-solid coupling theory, rock mechanics, fluid mechanics and tribology, the formula for calculating the shear strength of rock joints under dynamic normal load conditions is proposed, which could reflect the relationships between joint roughness, water pressure, shear velocity, disturbance frequency, disturbance amplitude and shear strength. In parallel, the FLAC3D-OpenFOAM coupling simulation technology is proposed to reproduce the laboratory experiments and simulate the realistic project, which can reveal the mechanical response of the contact surface, the characteristic of shear dilatancy, the evolution of fluid flow pattern and the solute transport behavior of the fluid during shear. Finally, the methods of restraining fault slip and promoting fault permeability are proposed. This project promotes the development of dynamic fluid-solid coupling theory and provides the theoretical references for the safety assessment of deep rock engineering.

本项目聚焦国际岩石力学领域研究前沿，针对海底基岩矿山开采中迫切需要解决的含水岩石节理面在动力扰动下剪切滑移问题开展系统深入研究。基于流固耦合作用机理分析，通过自行设计的动力扰动下岩石节理面剪切-渗流试验，在岩石力学、流体力学和摩擦学相结合的理论框架下，建立含水岩石节理面在动力扰动下剪切强度计算公式，阐明岩石节理面粗糙度、水压力、剪切速度、扰动频率和扰动振幅对剪切强度的影响规律。开发FLAC3D-OpenFOAM耦合模拟技术，实现固体力学和流体动力学的耦合模拟，重现室内动力扰动下岩石节理面剪切-渗流试验全过程，揭示剪切运动过程中岩石节理面的力学响应、剪胀特征、节理内流态演化和溶质运移规律，并采用此技术模拟工程实际，提出抑制岩石节理面发生剪切滑移和促进岩石节理渗透性的方法。本研究不仅对动力扰动下岩石流固耦合理论的发展具有重要的理论意义，而且对深部岩体工程安全评估和设计具有重要的应用价值。

深刻认识动力扰动下岩石断裂面剪切渗流机制，对于海底基岩矿山开采、地热、石油和页岩气开发和二氧化碳地质封存具有重要意义。在此项目资助下，申请人团队成功开发了大型动态剪切渗流仪器，并对此设备进行了商业化推广应用，此仪器为开展动态剪切渗流室内试验提供了研究平台。利用此平台，开展了动力扰动下（含地震荷载）岩土材料的剪切滑移测试，剪切渗流测试。发现并阐述了岩土材料在动态法向力作用下剪切强度随法向力减小而增大的特殊现象，动态法向力既可以增强也可以削弱岩土体剪切强度，主要取决于动态法向力的振幅、频率和剪切滑移速度，并从微观上揭示了动态摩擦系数增强削弱机理，此结果对于工程防灾减灾具有重要的理论意义和价值。与此同时，建立了有限差分法和流体动力学软件耦合计算的新方法，此方法既可以计算岩石节理面剪切过程中的力学特性如剪切力、剪切面变形和剪胀等，又可以模拟在剪切运动过程中流体的流态演化和溶质运移规律，很好的将流体力学和固体力学结合在了一起，实现了真正的岩石节理面剪切-渗流模拟。截至当前，依托此项目已发表高水平论文10余篇，申请发明专利5项，参加国内外学术会议5次，并多次做学术报告。