深部开采围岩-充填体界面损伤及能量演化机制研究

Backfilling in goaf has been proved to be an effective way to prevent the subsidence of earth surface and achieve the objective of green mining, while interface fracture impacts the backfill effective control of surrounding rock failure directly and becomes one of the main study stream in deep mining. This project is based on the multi-scale feature for interface crack propagation of surrounding rock-backfill in the loading process with multiple methods of tests, numerical simulation and theoretical analysis. The evolvement features and damage distribution of surrounding rock-backfill interface will be studied under coupled effects of multi-factor, such as roughness, cement-tailings ratio and curing age. An associated model between interfacial fractures evolution characteristics and multiple factors will be built. Furthermore, the energy evolution law of surrounding rock and backfill will be explored from the perspective of energy dissipation, and the energy equation of surrounding rock-backfill collaborative support system will be established to reveal the energy damage evolution mechanism. Finally, a new interface constitutive model of surrounding rock-backfill will be developed based on statistical damage theory, which can be used to realize the quantitative analysis of collaborative support mechanical behavior, and the theory system of surrounding rock-backfill collaborative support will be preliminarily formed. This project can enrich and advance the theoretical study on the interaction mechanism between the backfill and surrounding rock, which has scientific significance and engineering application value to guarantee the safety and stability of the deep goaf.

为了防止地表塌陷，实现绿色清洁开采战略目标，空区充填是行之有效的方法，而界面裂隙直接影响着充填体对围岩破坏的有效控制，已成为深部开采研究领域的热点之一。本项目采用室内试验、数值模拟和理论分析相结合的研究方法，从围岩-充填体加载过程中界面裂隙扩展的多尺度特征出发，通过研究多因素（界面粗糙度、灰砂配比和养护龄期）耦合作用下界面裂隙粘合扩展规律、损伤分布情况，构建围岩-充填体界面裂隙演化特征与多因素的关联模型；并从能量耗散角度，探究围岩、充填体能量演化规律，进而建立围岩-充填体协同支护系统能量方程，揭示围岩-充填体损伤破坏能量演化机制；最后基于统计损伤理论，提出围岩-充填体界面本构模型，定量分析多因素/多界面耦合作用下围岩-充填体协同支护力学行为，初步形成围岩-充填体协同支护理论体系。研究成果对于完善充填体与围岩相互作用理论、保障深部空区安全稳定具有重大的科学意义与工程应用价值。

充填采矿法在控制采区地压、防止地表塌陷、保护环境等方面具有不可比拟的优势，成为金属矿山深部开采的最佳选择和必然发展方向。充填体与围岩的相互作用是充填开采的关键所在，且界面裂隙直接影响着充填体对围岩破坏的有效控制。本项目采用室内试验、数值模拟和理论分析相结合的方法对深部开采围岩-充填体耦合界面裂隙扩展、损伤破坏机理及能量演化规律展开研究。. （1）针对红砂岩进行了常规三轴压缩试验，结合PFC3D数值模拟及CT扫描三维重构，获得了不同围压下红砂岩内外部宏、细、微观裂纹扩展规律，揭示了不同围压下红砂岩力学特性、破坏形式以及损伤机理。研究成果加深了对岩石破坏机理的认识，PFC3D模拟程序为岩石内外部裂纹扩展宏-细-微观破坏模式研究提供了一种可行的新方法。. （2）开展了多项红砂岩-充填体共同承载试验，获得了红砂岩-充填体界面裂隙扩展过程，探明了不同因素与红砂岩-充填体破坏特征间的关联机制；充分考虑界面效应，建立红砂岩-充填体协同支护数值仿真模型模拟分析了不同条件下红砂岩-充填体力学特性，以验证和补充室内力学试验，从宏、细、微观多角度揭示了多因素影响下红砂岩-充填体力学特性、破坏特征、界面裂隙扩展过程及能量演化规律；根据红砂岩-充填体应力-应变曲线及变形破坏特征，基于损伤力学等理论构建了红砂岩-充填体损伤本构模型，揭示了红砂岩-充填体协同支护损伤破坏规律。. （3）进一步开展了红砂岩-分层充填体共同承载试验与数值模拟，分析了不同分层灰砂配比下红砂岩-分层充填体界面裂隙宏细观破坏特征及其相互关联机制，探究了灰砂配比和分层结构面对红砂岩-分层充填体损伤破坏、能量演化及协同支护作用效果的影响规律。. 研究成果有助于完善充填体与围岩相互作用理论，为金属矿山深部大规模安全开采与空区处理灾害防治提供理论支持。