加卸荷条件下非贯通节理岩体破坏特性研究  

Study on failure characteristics of intermittent jointed rock mass under loading and unloading condition

作　　者：赵怡晴 刘佳伟[1,2] 金爱兵 孙浩[1,2] 王本鑫 魏余栋[1,2,3] ZHAO Yiqing;LIU Jiawei;JIN Aibing;SUN Hao;WANG Benxin;WEI Yudong(School of Civil and Resources Engineering,University of Science and Technology Beijing,Beijing 100083,China;Key Laboratory of Ministry of Education for Efficient Mining and Safety of Metal Mine,University of Science and Technology Beijing,Beijing 100083,China;State Key Laboratory ofWater Resources Protection and Utilization in Coal Mining,Beijing 100011,China)

机构地区：[1]北京科技大学土木与资源工程学院,北京100083 [2]北京科技大学金属矿山高效开采与安全教育部重点实验室,北京100083 [3]煤炭开采水资源保护与利用国家重点实验室,北京100011

出　　处：《中南大学学报（自然科学版）》2020年第7期1893-1901,共9页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51674015);煤炭开采水资源保护与利用国家重点实验室开放基金资助项目(SHJT-16-30.5,SHJT-17-42.1)。

摘　　要：采用颗粒流软件PFC(particle flow code)对非贯通节理岩体加卸荷条件下破坏特性进行研究。对砂岩材料进行室内单轴压缩试验,获取该岩样的抗压强度、弹性模量等宏观特征。采用PFC颗粒流软件中的平行黏结模型,构建完整试样,利用DFN(discrete fracture network)创建非贯通节理,并采用更符合实际工程的应力/时步加卸压方式对非贯通节理模型开展三轴压缩与非线性加轴压卸围压数值模拟。研究结果表明:在三轴压缩模拟中,峰值应力下降主要是因为岩桥内剪切裂纹增多,岩桥上方先出现裂纹的延伸,随后引发岩桥的贯通;在非线性加轴压卸围压模拟中,当轴向应力达到峰值后,岩桥破坏缓慢,且拉伸裂纹与剪切裂纹分布较均匀,岩桥贯通后,裂纹向模型上部进行扩展,最终破坏形式为非贯通节理上下两部分的滑移变形,且节理的破坏程度远大于三轴压缩的破坏程度。在卸荷过程中,节理两侧剪应力最大,岩桥中心次之,节理面的剪应力最小。The particle flow software PFC(particle flow code) was used to study the failure characteristics of intermittent jointed rock mass under loading and unloading conditions. The indoor uniaxial compression test of sandstone was carried out. The macroscopic characteristics such as compressive strength and elastic modulus of the rock sample were obtained. Using the parallel bonded model in PFC, a complete rock model was constructed and the DFN(discrete fracture network) was adopted to create intermittent joints. The model was used to carry out triaxial compression and nonlinear loading axial pressure-unloading confining pressure simulation using the stress/time step loading-unloading method which was more in line with the actual project. The results show that in the triaxial compression simulation, the peak stress decreases mainly due to the increase of shear cracks in the rock bridge, and the crack extension occurs first in the upper part of the rock bridge, which then leads to the penetration of the rock bridge. In the simulation of nonlinear loading axial pressure-unloading confining pressure, when the axial stress reaches the peak value, the rock bridge breaks slowly. The distribution of tensile crack and shear crack is uniform. After the rock bridge is connected, the crack expands to the upper part. The final failure form is the slip deformation of the upper and lower parts of the non-penetrating joint and the degree of damage of the joint is much larger than theat of the triaxial compression. During the unloading process, the shear stress on both sides of the joint is the largest, the center of the rock bridge is the second, and the shear stress of the joint surface is the smallest.

关 键 词：非贯通节理岩体 卸荷岩体 力学特性 数值模拟 

分 类 号：TU452[建筑科学—岩土工程]