基于“孔洞型”两体断裂力学模型的灌浆体与裂隙岩体相互作用机制研究

Because of the tectonic evolution, rock mass usually contains various flaws and cavities. The cement grouting technique is usually adopted to fill and reinforce the cavities. When the cement grouting materials are filled into the cavity, there exists the interaction between grouting body and fractured surrounding rock. However, the mechanical behavior is seldom considered in the current research. The cavity-type two-body fracture mechanical model, generalized from the structure characteristic of rock mass, will be presented including the surrounding rock, grouting body, cavity and flaw. The experimental and computational fracture mechanics will be used in this study. Biaxial compression experiments on specimens, which contain a cavity filled with the grouting body, will be conducted to investigate the deformation and fracture characteristics of cavity-type two-body experimental fracture mechanical model under the interaction between grouting body and fractured rock mass. Meanwhile, the digital speckle correlation method will be used to evaluate the deformation field, energy and stress intensity factor. Biaxial compression experiments on specimens without filled with the grouting body will also be conducted to compare with the former ones. A displacement discontinuity method (DDM)-based computer program, which incorporated friction interface elements and inhomogeneous bodies, will be developed. The cavity-type two-body numerical fracture mechanical model will be presented considering the interaction between grouting body and fractured rock mass. The experiment and numerical model studies will elucidate the influencing mechanism of the flaw geometry, cavity shape, cavity size, grouting body strength and confining pressure on the deformation and fracture indexes of the two-body model under the interaction between grouting body opening and fractured rock mass. The research finding of this project will provide a theoretical guidance for design optimization of cement grouting for cavities.

由于地质构造作用，岩石内部孕育了大量的裂隙和孔洞缺陷。工程中常用水泥灌浆技术处治孔洞病害，灌浆材料充填孔洞后，与裂隙岩体存在相互作用，而目前研究较少考虑这种力学作用。基于岩体结构特征，提出涵盖围岩、灌浆体、孔洞和裂隙等要素的“孔洞型”两体断裂力学模型，结合实验和计算断裂力学开展研究。双轴试验研究灌浆体和裂隙岩体相互作用下“孔洞型”两体断裂力学实验模型的变形破裂特征，引入数字散斑相关方法计算变形场、能量和应力强度因子，与含孔洞裂隙模型的力学响应相比较。将摩擦界面单元和多介质域引入位移不连续法，建立考虑灌浆体和裂隙岩体相互作用的“孔洞型”两体断裂力学数值模型。综合模型实验和数值研究结果，定量揭示灌浆体和裂隙岩体相互作用下裂隙几何特征、孔洞形状、孔洞尺寸、灌浆体强度、围压等因素对两体模型变形破裂指标的影响机制。研究成果可为工程岩体中孔洞病害的灌浆优化设计提供理论依据。

岩石是一种复杂的天然介质，在漫长的地质构造作用下，其内部孕育了大量的裂隙和孔洞缺陷，严重威胁着岩石工程的安全稳定。工程中普遍采用水泥灌浆充填孔洞缺陷，加固岩体。本项目采用室内试验、理论分析和数值模拟相结合的研究方法，引入岩石力学、断裂力学、分形理论、光测力学、数理统计、图像处理和3D打印等理论与技术，构建了“孔洞型”两体断裂力学模型，系统研究了灌浆体与裂隙岩体相互作用机制，全面完成了预期目标。主要研究内容和取得的研究成果包含以下几个方面：（1）结合水泥砂浆浇筑和3D打印技术，制备了含孔洞裂隙类岩石模型试件、裂隙网络岩体模型试件以及“孔洞型”两体模型试件。（2）基于室内压缩试验，结合分形几何理论量化表征破裂特征，定量揭示了灌浆体与裂隙岩体相互作用对模型试件裂纹起裂、扩展和贯通过程、破坏模式以及宏观力学参数的影响规律；构建了悬臂梁模型，解释了孔洞周边张拉裂纹的形成机制、以及灌浆体与裂隙岩体相互作用对裂纹演化的影响机制。（3）通过数字散斑相关方法计算了模型试件加载过程中全场变形量，通过热力学理论和红外热成像技术分析了模型试件加载过程中应变能积聚和耗散规律，定量揭示了灌浆体与裂隙岩体相互作用对模型试件应变场以及应变局部化带的影响规律。（4）提出了基于变形场数据的数理统计指标、灰度和纹理特征指标以及多元统计指标，有效地提取了模型试件破裂过程中变形场的动态演化规律以及前兆异常特征。（5）构建了考虑灌浆体与裂隙岩体相互作用的“孔洞型”两体断裂力学数值模型，从数值模拟的角度揭示了灌浆体与裂隙岩体相互作用对模型试件应力环境、裂纹演化及分形特征、宏观力学参数的影响规律。出版学术专著1部，发表学术论文20篇，其中SCI收录论文4篇，EI收录论文8篇；授权国家发明专利1项；培养硕士生3人。