摘要
为研究水和不同应力路径下泥岩崩解演化特征,采用扫描电镜、高能CT、三轴伺服压力机,探究微观颗粒结构、细观孔隙数量、宏观崩解及破坏块度的分形维数变化规律,揭示泥岩的跨尺度破坏机制。结果表明:(1)泥岩中黄铁矿与高岭石颗粒粒径和形态差异,产生的原生孔隙会成为水渗通道;随着含水率增加,高岭石结构劣化导致水渗通道变宽,细观孔隙分形维数逐渐增大。(2)大孔隙数量增多、贯通,泥岩发生自然崩解,崩解块度分形维数为1.26~1.77,大于孔隙分形维数。加卸载作用下破坏块度分形大于自然崩解状态块度分形,体现出力的损伤叠加作用。(3)加卸载作用下破坏块度分形维数具有分区性,在特征含水率之前,块度分形维数与强度成负相关关系,超过特征含水率后与强度成正相关关系,分形维数拐点可以作为含水率和应力影响的分界点,该点处水对主破裂面影响程度达到峰值。(4)卸载应力路径影响含水泥岩破坏特征和形态,低含水率泥岩呈脆性破坏,高含水率泥岩呈塑性破坏,张拉破坏增多,碎块多为“片状”。
In order to study the disintegration evolution characteristics of mudstone under water and different stress paths,scanning electron microscopy,high-energy CT and triaxial servo press were used to explore the fractal dimension variation law of microscopic particle structure,microscopic pore number,macroscopic disintegration and failure fragmentation,and reveal the cross-scale failure mechanism of mudstone.The results show that:(1)The particle size and morphology of pyrite and kaolinite in mudstone are different,and the primary pores will become water seepage channels.With the increase of water content,the deterioration of kaolinite structure leads to the widening of water seepage channel and the increase of microscopic pore fractal dimension.(2)The number of large pores increases and penetrates,and natural disintegration of mudstone occurs.The fractal dimension of disintegration block is between 1.26 and 1.77,which is larger than that of pore fractal dimension.The damage fragmentation fractal under loading and unloading is greater than that under natural disintegration,reflecting the damage superposition effect of external force.(3)The fractal dimension of fragmentation under loading and unloading is all partitioned.Before the characteristic water content,the fractal dimension of the block is negatively correlated with the strength,but it is positively correlated with the strength after exceeding the characteristic water content.The inflection point of the fractal dimension can be used as the demarcation point of the influence of water content and stress.At this point,the influence of water on the main fracture surface reaches the peak.(4)The unloading stress path affects the failure characteristics and morphology of water-bearing mudstone.The low-water-content mudstone exhibits brittle failure,and the high-water-content mudstone exhibits plastic failure.The tensile failure increases,and the fragments are mostly“flaky”.
作者
刘跃东
康红普
LIU Yuedong;KANG Hongpu(CCTEG Coal Mining Research Institute,Beijing 100013,China;Coal Mining and Design Department,Tiandi Science and Technology Company Limited,Beijing 100013,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2023年第S02期4162-4173,共12页
Chinese Journal of Rock Mechanics and Engineering
基金
中煤科工开采研究院有限公司“科技创新基金”项目(KCYJY-2021-QN-01)
国家重点研发计划(2017YFC0804205)
关键词
岩石力学
应力路径
含水泥岩
崩解破坏
分形维数
跨尺度
rock mechanics
stress path
water-bearing mudstone
disintegration failure
fractal dimension
cross-scale
