为研究超声波致裂对煤体力学损伤特性及能量演化规律的影响，利用电子万能压力试验机、声发射系统、对不同功率超声波致裂煤体进行单轴压缩试验，获得了不同功率超声波致裂煤体力学损伤参数，探究了声发射信号与不同功率致裂煤体损伤参量相互关系，采用盒子分形维数分析了煤体表面裂隙分形特征，阐明了超声波不同功率致裂煤体损伤劣化机制。试验结果表明，随着超声波致裂功率增大，煤体单轴抗压强度、弹性模量逐渐降低，煤体单轴抗压强度损伤参量、弹性模量损伤参量与致裂功率呈线性相关；单轴压缩过程中声发射振铃计数可分为平静期、上升期、波动期3个阶段，随着超声波功率增大，裂纹扩展孕育期时间越短，相对时长占比越小，裂纹扩展增长速率越大，对煤体强度的弱化效果逐渐增强，声发射信号突增现象明显，煤样终态破坏更加破碎，破坏特征随着致裂功率的增大煤体从弹脆性向延–塑性转化；煤体孔裂隙扩展贯通，煤体表面裂隙分形维数损伤参量与致裂功率呈线性正相关，分形维数损伤参量越大，表明煤体裂隙形态越复杂；基于声震参数分析了煤体损伤参量与声发射归一化参数的关系，具有较好拟合关系。以上结果表明，超声波致裂作用对煤体结构造成损伤，使煤层破坏变形，形成复杂的渗流网络，提高了煤层渗透率。

In order to study the mechanical damage characteristics and energy evolution law of coal after ultrasonic fracturing, uniaxial compression experiments were carried out on fractured coal with different power by using electronic universal pressure testing machine, acoustic emission system. The mechanical damage parameters of different power ultrasonic fracturing coal were obtained, and the relationship between acoustic emission signal and damage parameters of coal mass with different power fracturing was explored. The fractal characteristics of coal surface cracks were analyzed by box fractal dimension, and the damage degradation mechanism of ultrasonic fracturing coal caused by different ultrasonic power was clarified. The experimental results show that the characteristic strength and elastic modulus of coal gradually decrease with the increase of ultrasonic fracturing power, and the damage parameters of uniaxial compressive strength and elastic modulus of coal are linearly correlated with the fracturing power. During the uniaxial compression process, the acoustic emission ringing count can be divided into three stages, which are quiet period, rising period and fluctuating period. With the increase of ultrasonic power, the incubation period of crack is shorter and the proportion of relative time is smaller. With the increase of crack growth rate, the weakening effect on the strength of coal is gradually enhanced, the sudden increase of acoustic emission signal is obvious., the final failure of coal sample is more broken, and the failure characteristics change from elastic brittleness to ductility-plasticity with the increase of fracturing power. Coal pore fissure extension, and three is a linear positive correlation between the fractal dimension damage parameters of coal surface cracks and the fracturing power. The greater the fractal dimension damage parameter is, the more complex the coal fracture morphology is. Based on the acoustic parameters, the relationship between the damage parameters and the normalized parameters of acoustic emission is analyzed, and it has a good fitting relationship. The above results show that ultrasonic fracturing causes damage to the coal structure, makes the coal seam damage and deformation, and forms a complex coal seam seepage network, thus improving the permeability of coal seam.

0 引言
1 试验方案及结果
1.1 试验方案
1.1.1 煤样制备与仪器
1.1.2 试验系统
1.1.3 试验条件及步骤
1.2 试验结果
1.2.1 不同功率超声波致裂煤体的力学特性
1.2.2 不同功率超声波致裂后煤体单轴压缩破坏终态特征响应
1.2.3 不同功率超声波致裂煤体的声发射演化规律
2 试验结果分析
2.1 不同功率超声波致裂煤体裂隙扩展及分形特征
2.1.1 不同功率超声波致裂煤体裂纹扩展特征
2.1.2 不同功率超声波致裂煤体表面分形特征
2.2 基于声发射参数的损伤变量分析
2.3 超声波功率对煤体力学损伤及能量演化影响机制
3 结论