摘要
受载煤岩动裂隙参数定量反演有助于从源头解译煤岩破裂“黑箱”过程及演化机制.为了解决实际工程中普遍存在的煤岩张拉、张剪破裂机制及动裂隙参数定量反演难题,本文从2类基本破裂的动力学特征出发,提出了针对煤岩动裂隙事件的广义张剪破裂震源表征模型,通过依次对动裂隙源产生、波传播到接收的全过程建模,提出了基于P波初始振幅的动裂隙参数定量反演新方法,并开展实验室和现场不同尺度煤岩破裂监测的实践应用.研究结果表明:在广义张剪破裂震源模型中,须满足动裂隙源表征张量中间特征值为零的约束条件,提出了采用Lagrangian乘子结合L-M算法的迭代求解方法,继而获取动裂隙源的张剪属性、破裂尺度、空间取向等破裂核心参数,新方法可适用于张拉、张剪和剪切破裂源反演,且反演结果物理意义明确、参数精度高;在煤岩断裂扩展过程中,利用新反演的破裂模式角及张剪体积分解表明微裂纹以张剪复合-张拉位移占优为主,动裂隙面取向与断裂扩展路径方向近乎平行,破裂运动方位主要沿最大主应力方向,故可以通过反演破裂源参数来获取应力场分布特征并预判主破断延伸方位;新方法也成功应用于煤矿现场矿震监测,反演获得矿震破裂源的破断面积、结构面取向及张剪属性等源头参数符合上覆岩层顶板张性断裂实际情况,且综合破裂源参数演化特征能更好地对大矿震超前预报,可以把破裂模式角降低、大震级张拉破裂事件频现、b值下降等作为大尺度顶板断裂的前兆规律.研究成果为工程岩体破裂演化定量反演分析提供了一种科学方法,对诱发地震机理、煤岩动力灾害监测等岩石破裂共性问题研究具有重要的理论意义和实践价值.
Quantitative inversion for cracking source parameters is helpful to interpret the fracturing evolution process and failure mechanism of loaded coal/rock masses.Deal with the lack of effective inversion methods for the cracking source with tensile mechanism or mixed-mode mechanism,which are common in practical engineering,this paper establishes a generalized tensile-shear fracturing(i.e.,GTSF)representation model based on the kinetics characteristics of tensile and shear fractures.Through forward modeling the whole dynamic process of cracking generation,wave propagation and sensor response,a new quantitative inversion method for cracking parameters based on P-wave onset amplitude is proposed.Then this proposed method is applied to analyze the coal/rock fracturing process both in laboratory and coal mine site.The results show that,in the GTSF representation model,the intermediate eigenvalue of the cracking source characterization tensor must be zero,which provides a necessary constraint.Such a constrained optimization problem is solved,by combining the Lagrangian multiplier and L-M iterative approach,to obtain the cracking parameters such as tensile-shear properties,volume,orientation,motion direction and so on.This proposed inversion method is universal for tensile,mixed-mode and shear fracturing source,and the calculating parameters have clear physical meaning and high precision.During the loading process of rock,based on the inversion results by the proposed method,the time-varying of the crack mode angles and crack decomposed volumes suggest that the fracturing modes of microcracks are mainly mixed-mode with tensile motion dominant.The orientations of microcrack planes are nearly parallel to the direction of fracturing propagation path,and the motion directions are mainly along the maximum principal stress direction.These results provide an experimental basis for obtaining the stress field distribution characteristics and predicting the principal fracture extension azimuth by inverting the source parameters.Thi
作者
王恩元
王笑然
刘晓斐
单天成
李楠
WANG Enyuan;WANG Xiaoran;LIU Xiaofei;SHAN Tiancheng;LI Nan(Key Laboratory of Gas and Fire Control for Coal Mines,Ministry of Education,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China;State Key Laboratory of Coal Mine Disaster Prevention and Control,Xuzhou,Jiangsu 221116,China;State Key Laboratory for Fine Exploration and Intelligent Development of Coal Resources,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China)
出处
《中国矿业大学学报》
EI
CAS
CSCD
北大核心
2023年第6期1058-1074,共17页
Journal of China University of Mining & Technology
基金
国家自然科学基金项目(52227901,51934007,52204249)。
关键词
张剪破裂
震源模型
动裂隙参数
定量反演
时空演化
破裂机制
tensile-shear fracture
source representation model
cracking parameters
quantita-tive inversion
spatio-temporal evolution
failure mechanism
