摘要
受开采卸荷扰动影响,深部岩体互层及其组合结构系统的破裂失稳是诱发采场突水等灾害的主要原因之一。为研究深部开采围压卸荷对岩体组合结构破裂的影响,室内开展了原生煤岩组合体三轴加卸荷-渗流试验,获得了不同初始围压下原生煤岩组合体围压卸荷致裂的竖向、倾斜及环向裂隙分类特征,研究了其轴压卸荷起点、围压卸荷终点的强度特征及主导破裂模式的力学机制;结合CT扫描与三维重构技术,获取了原生煤岩组合体卸荷破裂的几何特征;建立了围压卸荷量与岩体卸荷致拉破裂、致剪破裂的关系,揭示了围压卸荷致裂模式与渗透率突变关系,验证并判定了不同初始围压下原生煤岩组合体的主导卸荷致裂模式。结果表明:在围压卸荷和轴压加载共同作用下,原生煤岩组合体卸荷破裂模式主要分为围压卸荷致拉破裂、致剪破裂及轴压协同卸荷致裂模式3类;随初始围压增加,原生煤岩组合体围压卸荷致拉破裂的围压卸荷终点临界值及致剪破裂的轴压卸荷起点临界值均线性增加;围压卸荷可致轴压协同卸荷突降并驱动煤岩分界面及层理等原生裂隙结构环向张拉破裂,且以沟通倾斜及竖向裂隙为主导;而围压卸荷致拉破裂与致剪破裂模式均可致原生煤岩组合体渗透率突变增高,突变点致裂模式与其围压卸荷终点的卸荷量临界值密切相关。
Under the influence of stresses unloading after mining,the fracture and instability of the interbedding and combined structure system of deep rock mass is one of the main causes of water inrush in the longwall face.In order to study the influence of confining pressure unloading(CPU)on the fracture of rock mass combined structure in deep coal mining,the triaxial loading,unloading-seepage tests of primary coal-rock mass(PCRM)were carried out in the laboratory.The classification characteristics of PCRM under different initial confining pressures were obtained.And the strength characteristics of the starting point of axial compressive stress unloading and the terminal point of confining pressure unloading and the mechanical mechanism of the dominant fracture modes were studied.Combined with CT scanning and three dimensions reconstruction techniques,the unloading fracture geometric characteristics of PCRM were obtained.The relationships between the unloading level of confining pressure and the tensile fracture and shear fracture of rock mass were established.And the relationships between the fracture modes of CPU and the sharply increase of the permeability were revealed.Meanwhile,the dominant unloading fracturing modes of PCRM under different initial confining pressures were verified and determined.The results show that under the joint action of CPU and axial pressure loading,the dominant fracture modes of PCRM mainly include three types,and they are tensile fracture,shear fracture induced by CPU,and the fracture induced by the axial compressive stress unloading coordinated with CPU,respectively.With the increase of initial confining pressure,the critical value of unloading terminal point of confining pressure for the tensile fracture and the unloading starting point of the axial compressive stress for the shear fracture increase linearly.The CPU can cause the synergetic unloading of the axial compressive stress drop suddenly,that could drive primary crack structure in the coal-rock interface and bedding plane to ann
作者
李春元
雷国荣
何团
左建平
于祥
郑建伟
齐庆新
LI Chunyuan;LEI Guorong;HE Tuan;ZUO Jianping;YU Xiang;ZHENG Jianwei;QI Qingxin(Deep Mining and Rock Burst Research Institute,Chinese Institute of Coal Science,Beijing 100013,China;Beijing Technology Research Branch,Tiandi Science&Technology Co.,Ltd.,Beijing 100013,China;School of Mechanics and Civil Engineering,China University of Mining and Technology-Beijing,Beijing 100083,China)
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2023年第2期678-692,共15页
Journal of China Coal Society
基金
国家自然科学基金资助项目(51904303)
中国煤炭科工集团有限公司科技创新创业资金专项重点资助项目(2022-3-ZD001)
煤炭科学研究总院创新创业科技专项资助项目(2021-KXYJ-004)。
关键词
深部开采
煤岩组合体
围压
应力卸荷
拉破裂
剪破裂
deep coal mining
coal-rock mass
confining pressure
stress unloading
tensile fracture
shear fracture
