土木工程与力学学院知识库

岩石是一种宏观连续但微观不连续的特殊介质材料，内部充满了大量孔隙、节理等缺陷，且呈随机状态分布，这些特殊结构导致岩石具有明显的尺寸效应。研究表明，不同尺寸的岩样，其变形过程及破坏模式明显不同，并且尺寸对岩石的抗压强度、弹性模量、耗散能等性质有显著影响。因而，尺寸效应一直都是岩石力学领域中被重点关注的研究课题之一。本文以花岗岩为研究对象，将岩石加工成不同长径比的圆柱体试件进行单轴压缩实验，得到了全过程应力-应变关系曲线。根据试验结果，分析了岩样长径比对岩石强度、变形特性以及破裂形式的影响规律。通过理论研究，分别推导并提出了岩样尺寸对岩石抗压强度影响的理论模型，岩样尺寸与岩石变形破坏过程中耗散能的理论计算表达式。将理论结果与试验结果进行对比发现，二者吻合良好。在此基础上研究了单轴压缩条件下岩石材料强度和变形尺寸效应的物理机制，分析讨论了岩样尺寸对于岩石变形破坏过程中能量耗散过程的影响机理。采用FLAC3D软件模拟研究了不同尺寸岩样在单轴压缩过程中裂纹产生、发展及贯通的过程，分析了应力、应变、耗散能的变化状况，并将数值模拟结果与试验结果、理论计算结果进行对比验证，对比结果比较吻合，从而证明了本文所建理论模型及数值计算结果的正确性。基于此，分析了不同尺寸岩样单轴压缩过程中能量演化规律，研究认为，岩样吸收的总能量与耗散能均与轴向应变呈正相关，弹性应变能随着轴向应变的发展呈现先增加后减小的趋势。

Rock is a special dielectric material which macro continuous but microscopic discontinuous, which is filled with a large number of pores, joints and other defects, and is distributed in a random state. These special structures lead to obvious size effect of rocks. The results show that the deformation process and failure mode of rock samples of different sizes are obviously different,and the size has a significant effect on the compressive strength, elastic modulus and dissipation energy of rock.Therefore, size effect has always been one of the most important research topics in rock mechanics.In this paper, The granite was processed into cylindrical specimens with different aspect ratios for uniaxial compression experiments. The stress-strain curves were obtained in the whole process. Based on the test results, the effects of aspect ratio on rock strength, deformation characteristics and fracture form are analyzed. It is found that the theoretical results are in good agreement with the experimental results. On this basis, the strength and deformation of rock materials under uniaxial compression are studied. The physical mechanism of size effect is discussed and the influence mechanism of rock sample size on energy dissipation process during rock deformation and failure is discussed.

The process of crack generation, development and penetration of rock samples of different sizes during uniaxial compression is simulated by FLAC3D software. The variation of stress, strain and dissipation energy is analyzed, and the numerical simulation results and experimental results are presented. The results of theoretical calculation are in good agreement with each other, which proves the correctness of the theoretical model and the numerical results. Based on this, the law of energy evolution during uniaxial compression of rock samples with different sizes is analyzed. The results show that the total energy and dissipation energy absorbed by rock samples are positively correlated with axial strain, and The elastic strain energy increases first and then decreases with the development of axial strain.