摘要
深部岩石常处于非静水压初始应力场,岩石所处应力状态的不同导致其对动态荷载的响应有所差异,为研究非静水压及动载耦合作用下岩石的动力学行为,利用分离式霍普金森杆试验系统,开展多种初始应力组合下的岩石动态压缩试验,分析不同非静水压条件对岩石能量耗散及破坏规律的影响规律。通过试验结果发现,轴压和围压均对岩石动态强度产生显著影响,以8 MPa时为临界点,岩石动态强度随着轴压提升呈先增加后减小的趋势,但岩石动态强度随着围压的增加持续增大;岩石耗散能随着轴压的增加逐渐减小,但随围压变化趋势较为复杂,在轴压较低时,耗散能随着围压的增加而减小,在轴压较高时,耗散能随围压提升表现出先增加后减小的特征。根据试样的表观及内部破坏形态,结合分形理论及CT扫描技术,分析不同非静水压力条件下岩石的破坏模式发现,岩石表观裂纹与轴围压比存在显著关联,当轴围压比较低时,岩石侧面及端面裂纹较少,随着轴围压比的提高,岩石表观裂纹明显增加。通过对岩石扫描后横向及纵向切片分析发现,岩石内部同时存在环向和径向裂纹,且岩石破坏由贯穿型剪切裂纹控制。同时可以发现,非静水压条件下岩石的破坏可分为中心圆台形岩块和周边破碎岩块2部分,当轴压增加时岩石的破坏程度加剧,而围压的提升则使得岩石破坏程度降低。
Deep buried rock is often in a non-hydrostatic initial ground stress field,and the different stress states lead to different rock response under dynamic loading.To study the dynamic behavior of rocks under coupled non-hydrostatic pressure and dynamic loading,the dynamic compression tests under different initial stress are carried out by using the split Hopkinson pressure bar(SHPB)experimental system,and the influence of different non-hydrostatic pressure on energy dissipation and failure characteristics of rock is analyzed.Based on the test results,it is found that both axial and lateral confining pressure have a significant impact on the rock dynamic strength.Taking 8 MPa as the critical point,the rock dynamic strength first increases and then decreases with the increase of axial confining pressure,but the rock dynamic strength will continue to increase with the increase of lateral confining pressure.The rock dissipative energy gradually decreases with the increase of axial confining pressure,but the trend of dissipative energy changes with confining pressure is complicated.When the axial confining pressure is low,the dissipative energy decreases with the increase of the confining pressure,and when the axial confining pressure is high,the dissipative energy shows a characteristic of increasing first and then decreasing with the increase of lateral confining pressure.According to the apparent and internal damage patterns of the specimens,combined with fractal theory and CT scanning technology,the influence of the damage pattern of rocks under different non-hydrostatic pressure conditions is analyzed.It is found that there is a significant correlation between the apparent cracks of rock and the ratio of axial-confining pressure.When the axial confining pressure ratio is low,there are fewer cracks on the side and end faces of rock.With the increase of the axial confining pressure ratio,the number of apparent cracks of rock increases.Through the analysis of the cross-sectional and vertical slices of the rock,it is f
作者
方士正
杨仁树
李炜煜
李永亮
陈骏
FANG Shizheng;YANG Renshu;LI Weiyu;LI Yongliang;CHEN Jun(School of Civil and Resource Engineering,University of Science and Technology Beijing,Beijing 100083,China;School of Safety Science and Engineering,Anhui University of Science and Technology,Huainan 232000,China;School of Energy and Mining Engineering,China University of Mining&Technology-Beijing,Beijing 100083,China;School of Mechanics and Civil Engineering,China University of Mining&Technology-Beijing,Beijing 100083,China)
出处
《煤炭科学技术》
EI
CAS
CSCD
北大核心
2023年第10期83-96,共14页
Coal Science and Technology
基金
国家自然科学基金资助项目(52227805,51934001)。
关键词
深部开采
非静水压
岩石破坏
SHPB
能量耗散
破坏特征
deep mining
non-hydrostatic pressure
rock failure
SHPB
energy dissipation
failure characteristic
