Advances in research on the evolution of trans-scale discontinuous structures during the creeps of strongly disturbed coals
ZHANG Liang;WANG Laigui;REN Ting;LI Xiangchun;GAO Ke;LI Haitao;ZHAO Shankun
煤炭科学研究总院有限公司 深部开采与冲击地压防治研究院河南省瓦斯地质与治理重点实验室—省部共建国家重点实验室培育基地煤炭智能开采与岩层控制全国重点实验室辽宁工程技术大学 力学与工程学院School of Civil中国矿业大学(北京) 应急管理与安全工程学院辽宁工程技术大学 安全科学与工程学院煤炭科学技术研究院有限公司煤矿灾害防控全国重点实验室
巷道围岩时效变形破坏、蠕变型冲击地压等灾害是深井面临的重大威胁,加之深部采动与结构变化的影响,亟需研究强扰煤岩体蠕变过程中跨尺度非连续结构演化规律,系统回顾煤岩体力学性质的尺度效应、非连续结构与多物理场效应,以及煤岩体长时稳定性、蠕变演化规律与力学模型。
强调不同尺度(细观−宏观−工程尺度)、不同尺寸(REV范围内)煤岩变形破裂过程中非连续结构(包括裂隙和矿物)与物理力学性质存在密切的关联特征。指出煤岩体跨尺度非连续结构导致应力场非均匀分布,造成力学各向异性、尺度效应及尺寸效应,进而出现非协调宏观破裂现象。透明解析与推演煤岩变形破裂过程中跨尺度非连续结构与多物理场演化规律,是认识煤岩灾变内禀机制的关键。明确指出现有蠕变实验与蠕变模型在煤岩表面变形及破裂方面具有优势,但无法预测煤岩内部变形与非连续结构;为此提出了全尺寸CT扫描重构、数字体图像相关(DVC)、跨尺度等效岩体−等效晶质建模(SRM-GBM)相结合的破解方法。对扰动煤岩体蠕变前沿问题进行了讨论,阐明了非连续结构与应力引起内部变形损伤诱发蠕变这一新观点,指出非连续结构和应力是煤岩非协调蠕变的主控因素,最后建立了强扰煤岩体蠕变过程中跨尺度非连续结构与多物理场演化的精细化建模及透明解析新方法。研究成果为相关矿山灾害的发生机理、预警与防控提供理论基础。
Disasters associated with surrounding rocks in roadways, such as time-dependent deformation failure and creep-induced rock bursts, severely threaten deep mines in China. These disasters, coupled with the impacts of deep mining and structural changes, render it urgent to explore the evolutionary patterns of trans-scale discontinuous structures during the creeps of strongly disturbed coals. This study systematically reviews the scale effects of coals' mechanical properties, the discontinuous structures and multi-physics field effects of coals, and the long-term stability, creep evolutionary patterns, and mechanical models of coals. It highlights the close correlation between discontinuous structures (including their fractures and minerals) and physical and mechanical properties during the deformation and failure of different scales (mesoscopic, macroscopic, and engineering scales) and sizes (within the range of representative elementary volume (REV)) of coals.
The results indicate that the trans-scale discontinuous structures of coals cause the nonuniformly distributed stress field, which results in mechanical anisotropy, scale effects, and size effects. Consequently, disharmonic macroscopic rupture will occur. The key to understanding the intrinsic disaster mechanisms of coals is the transparentized analysis and deduction of the evolutionary patterns of both trans-scale discontinuous structures and the multi-physics field during the deformation and rupture of coals. It is clear that existing creep experiments and models enjoy advantages in revealing the surface deformations and failure of coals. However, they fail to predict the deformations and discontinuous structures within coals. Hence, the authors of this study developed an approach that combines full-size computed tomography (CT) scanning and digital reconstruction, digital volume correlation (DVC), and trans-scale synthetic rock mass and grain-based modeling (SRM-GBM). This study explores the leading-edge issues related to the creeps of disturbed coals, introducing the new point of view that the creeps of coals are induced by internal deformation and damage caused by their discontinuous structures and stress. Accordingly, it proposes that discontinuous structures and stress serve as the dominant factors governing the disharmonic creeps of coals. Finally, this study developed new methods for fine-scale modeling and transparentized analysis for exploring the evolution of both trans-scale discontinuous structures and the multi-physics field during the creeps of strongly disturbed coals. The results of this study will lay the theoretical foundation for the occurrence mechanisms, early warning, and prevention and control of relevant mine disasters.
strongly disturbed coal;creep essence;trans-scale discontinuous structure;internal strain field;damage evolution;transparentized analysis;computed tomography (CT) scanning and digital reconstruction;fine-scale modeling
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会