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不同加载速率条件下岩石的力学特性,对于其动载下破裂内在机制的研究具有积极的意义。基于颗粒流理论,通过黏结颗粒模型(bonded particle model,简称BPM)虚拟实现不同加载速率0.001~0.500 m/s下花岗岩单轴压缩和巴西劈裂试验,定量分析加载速率对应力-应变、破裂形态、应变能率及声发射的影响。结果表明:单轴抗压强度和抗拉强度及其对应峰值应变随加载速率增加而非线性增长;单轴压缩作用下,随加载速率增加,试样由单一斜截面破坏向多斜截面破坏转变,且主控裂隙带宽度急剧增大,由裂纹数量及水平向高应变率区域变化规律可明显看出,试样破坏程度随着加载速率增加而逐渐加剧;巴西劈裂作用下试样从一条主控裂隙向多条主控裂隙转变,且裂纹向圆盘试样两侧边缘部分延伸,破坏程度加剧;单轴压缩和巴西劈裂作用下,声发射事件及应变能率均随加载速率增加而呈现出非线性增长趋势。
The mechanical properties of rocks under different loading rates have a positive meaning for the study of the internal mechanism of failure under dynamic loading. Based on the theory of particle flow, granite uniaxial compression and Brazilian cleavage were virtually simulated with bonded particle model (BPM) at different loading rates from 0.001 to 0.500 m / s, and the effects of loading rate on the stress-strain and fracture morphology , Strain rate and acoustic emission. The results show that the uniaxial compressive strength, tensile strength and corresponding peak strain increase non-linearly with the increase of loading rate. Under uniaxial compression, with the increase of loading rate, the specimen changes from single oblique section to multi-oblique section , And the width of the main control fracture zone increases sharply. It can be clearly seen from the variation of the number of cracks and the horizontal-to-high strain rate region that the damage degree of the sample gradually aggravates with the increase of the loading rate. The dominant fissures change to a number of main fissures, and the cracks extend to the edge of both sides of the disk specimen, which aggravates the degree of damage. Under both uniaxial compression and Brazilian cleavage, the acoustic emission events and strain rates increase with loading rate Showing a non-linear trend of growth.