松软煤层煤岩体受到开采及地应力作用后，煤壁面的原生裂隙开始发育、扩展贯通， 削弱了煤体的强度和稳定性，而从能量角度分析松软煤体变形破坏的裂隙扩展过程，探 究不同裂隙倾角煤岩体能量演化对裂隙扩展模式的影响，可以更为深入地研究松软煤层 裂隙煤岩体的变形破坏规律。本文通过数值模拟和实验室试验相结合的方法，采用 DNS200 电子万能试验机及数字图像相关技术，得到松软煤层裂隙煤岩体变形破坏规律 和变形破坏过程中的能量演化规律，取得了如下研究成果： (1) 为研究松软煤层裂隙煤岩体变形破坏裂隙演化过程，针对不同预制裂隙倾角煤 岩体裂隙起裂、扩展模式的不同，开展不同裂隙倾角煤岩体物理和数值相似模拟试验。 通过数值计算获得煤岩体变形破坏过程中裂隙的起裂应力特征；采用数字散斑相关测量 技术获取煤岩体变形破坏表面应变场、位移场数据，分析煤岩体表面裂隙扩展规律以及 破坏模式。 (2) 选取了压缩条件下预制裂隙的滑动裂纹模型，分析了地应力作用下裂隙尖端的 应力分布，进行数值试验计算验证了模型的可适用性。试验得到裂隙起裂特征为：当 0 ≤φ≤45°时，预制裂隙两端受拉应力起裂；45°≤φ≤60°时，一端受拉应力另一端受剪切 应力起裂；φ≥75°时两端受剪切应力起裂。此外，在压应力作用下，裂隙周边存在压应 力和拉应力集中，产生垂直受力方向的剪切裂隙。 (3) 为识别和定位裂隙扩展路径，采用数字图像相关方法开展含裂隙松软煤体的变 形场演化试验。结果表明：接近应力峰值阶段，不同裂隙倾角试样的应变场分异速率-轴 向应变曲线先后出现明显增长点 P1和“尖点” P2，分别对应张拉裂隙和剪切裂隙起裂点； 倾角增大使得在变形过程中 P1 点发生提前；而 P2 点出现一定延缓现象，同时 P2 点所对 应的应力值更为接近峰值应力。 (4) 为研究不同倾角影响下松软煤层裂隙煤岩体的能量转化规律，建立了含不同裂隙倾角煤岩体峰前积聚能和轴向应变之间的自我抑制演化模型，模型可反映倾角大小对 能量转化的抑制效果。 将模型的本构方程与室内试验结果拟合，验证了模型的可适用性； 得到抑制能量转化作用的机制对峰前能量积聚的最终结果起决定性作用，裂隙煤岩体峰 前能量自我抑制作用随预制裂隙倾角增大而先增强后减弱，能量积聚速率先减小后增大， 相应的峰值点处的储能极限先减小后增大。 (5) 为探究与松软煤层裂隙煤岩体能量耗散与破坏模式之间关系，对比分析了不同 破坏阶段煤岩体的能量耗散量。结果表明：煤岩体在峰前未发生明显破坏阶段，系统输 入能量主要以积聚形式储存在试样内部，峰后发生明显破坏阶段，积聚的能量沿着裂隙 张裂的方向释放。小倾角裂隙煤岩体在变形破坏中易产生张拉裂隙，在煤矿工程中更易 引起煤体发生变形破坏。 
 

After the coal and rock mass in the soft coal seam are mined and subjected to in-situ stress, the primary cracks on the coal wall begin to develop and expand, which weakens the strength and stability of the coal body. Therefore, it is of great engineering significance to carry out the scientific research on the mechanical properties and deformation and failure process of the rock mass in the soft coal seam. By analyzing the fracture expansion process of soft coal mass from the Angle of energy and exploring the influence of energy evolution of coal-rock mass with different fracture inclination angles on the fracture expansion mode, the deformation and failure law of coal-rock mass with fracture in soft coal seam can be studied more deeply. In this paper, by combining numerical simulation and laboratory tests, the DNS200 electronic universal testing machine and digital image correlation technology are used to obtain the deformation and failure law of coal and rock mass in soft coal seam fissure and the energy evolution law in the process of deformation and failure, and the following research results are obtained: (1) In order to study the evolution process of deformation and failure cracks of coal and rock mass in soft coal seam, physical and numerical simulation tests of coal and rock mass with different inclination angles were carried out according to the different initiation and propagation modes of coal and rock mass fractures in different prefabricated fractures. Through numerical calculation, the characteristics of crack initiation stress in the process of deformation and failure of coal and rock mass are obtained. The digital speckle correlation measurement technology was used to obtain the data of strain field and displacement field on the surface of coal and rock mass deformation and failure, and the crack propagation law and failure mode on the surface of coal and rock mass were analyzed. (2) The sliding crack model of the prefabricated crack under compression was selected to analyze the stress distribution at the crack tip under the action of in-situ stress, and the applicability of the model was verified by numerical calculation. The experimental results show that the fracture initiation characteristics are as follows: when 0≤φ≤45°, both ends of the prefabricated crack are subjected to tensile stress; When 45°≤φ≤60°, one end is subjected to tensile stress and the other end is subjected to shear stress. When φ≥75°, both ends are subjected to shear stress and crack initiation. In addition, under the action of compressive stress, there are compressive stress and tensile stress concentration around the crack, resulting in shear crack in the direction of vertical stress. (3) In order to identify and locate the crack propagation path, the digital image correlation method was used to carry out the deformation field evolution test of the soft coal body with crack. The results show that: near the stress peak stage, the strain field differentiation rate-axial strain curves of samples with different crack inclination angles show obvious growth point P1 and "sharp point" P2 successively, which correspond to the starting point of tensile crack and shear crack, respectively. The increase of inclination makes the P1 point occur earlier in the deformation process. At the same time, the stress value corresponding to the point P2 is closer to the peak stress. (4) In order to study the law of energy conversion of coal-rock mass with different dip angles in soft coal seam, a self-inhibition evolution model between pre-peak accumulated energy and axial strain of coal-rock mass with different dip angles was established. The model can reflect the inhibition effect of dip angles on energy conversion. By fitting the constitutive equation of the model with the laboratory test results, the applicability of the model is verified. The mechanism that inhibits energy conversion plays a decisive role in the final result of prepeak energy accumulation. The self-inhibition of pre-peak energy in fractured coal-rock mass increases first and then decreases with the increase of prefracture inclination Angle, the energy accumulation rate decreases first and then increases, and the energy storage limit at the corresponding peak point decreases first and then increases. (5) In order to explore the relationship between the energy dissipation and the failure mode of coal-rock mass in the fissure of soft coal seam, the energy dissipation of coal-rock mass in different failure stages was compared and analyzed. The results show that the coal and rock mass have no obvious failure stage before the peak, and the system input energy is mainly stored in the sample in the form of accumulation, and the accumulated energy is released along the direction of crack and crack after the peak. In the process of deformation and failure of coal and rock mass with small dip Angle fissures, tensile fissures are easy to occur, which can easily lead to deformation and failure of coal mass in coal mine engineering. 

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