摘要
掌握煤矿采场坚硬顶板破断规律对揭示煤矿开采过程中的来压规律等方面具有重要作用。坚硬顶板破坏实质上是结构变形不协调的体现,有必要对结构可能存在的变形不协调区域开展数值方法研究。提出一种有限元数值模拟思路,计算常规弹塑性有限元方法无解时屈服面外应力场的等效节点力并称为不平衡力,阐明不平衡力的物理意义及以不平衡力分布指示变形不协调区域的理论依据,并以重设网格体现层间变形不协调对结构的影响,形成一套以不平衡力指示变形不协调区域的煤炭开采过程弹塑性有限元数值方法。以同忻煤矿8102工作面为研究对象,采用以上方法对该工作面随开采过程的顶板破断情况进行模拟,并得到了模型试验、现场实测资料的对比验证。研究表明:(1)连续介质边值问题解不存在意味着平衡条件、变形协调条件及本构关系无法同时满足,将出现变形不协调情况,并出现不平衡力。(2)不平衡力是结构应力状态偏离平衡位置的度量,其分布可用于指示煤炭开采过程中的变形不协调区域,进而判断顶板破断过程。(3)不平衡力分布主要受开采距离及厚硬层位的影响,8102工作面存在2个厚硬层位对不平衡力发展起阶段性控制作用。(4)在开采至110 m及270 m时,不平衡力分布区突破厚硬层位并向上发展,意味着厚硬顶板断裂、地应力得到释放,可能是导致剧烈来压的重要原因。
Revealing the fracture mechanism of hard roof makes a significant contribution to the analysis of hard roof weighing during a mining process.The fracture of hard roof is the manifestation of uncoordinated deformation,so it is necessary to carry out numerical modelling on the possible uncoordinated deformation area of the structure.An idea of finite element numerical simulation was proposed.The equivalent nodal force of the stress outside the yield surface was calculated when the conventional elasto-plastic finite element method was unsolvable,and called it unbalanced force.The significance of unbalanced force and the theoretical basis for indicating the uncoordinated deformation area through the distribution of the unbalanced force were elucidated.An elasto-plastic finite element method,which indicated the uncoordinated deformation area by unbalanced force,was formed considering the influence of uncoordinated deformation in interlamination by resetting meshes.No.8102 working face of the Tongxin Mine was taken as research object,and the numerical simulation of the fracture of hard roof during the mining process was carried out.The comparison with the model test and field measured data verified the effectiveness of the numerical method.The results were as follows:(1)The case where boundary value problems of continuum mechanics have no solution indicates that the structure cannot maintain continuity,meaning the equilibrium condition,deformation compatibility condition and constitutive relation cannot be satisfied at the same time and leading to the appearance of uncoordinated deformation and unbalanced force.(2)The unbalanced force is the measure of the deviation of stress state from the equilibrium position,the distribution of the unbalanced force can be used to indicate the development of uncoordinated deformation area during mining process,then offer the guidance to the judgement of the fracture of hard roof.(3)The distribution of unbalanced force is mainly affected by the mining distance and specific layers which may be thick and hard.In No.8102 working face,there are two specific layers play periodic controlling roles in the development of unbalanced force.(4)When the mining progress reaches 110 m and 270 m,the distribution of unbalanced force breaks through the thick and hard layers and develops upward,which means the corresponding layers are fractured and the stress is released,which may be a significant factor for weighting.
作者
杨强
王昀
段宏飞
朱卫兵
YANG Qiang;WANG Yun;DUAN Hongfei;ZHU Weibing(State Key Laboratory of Hydroscience and Engineering,Tsinghua University,Beying 100084,China;School of Safety Engineering,China University of Mining and Technology,Xuzhou 221116,China;Shanxi Institute of Science and Technology Co.,Lid.,Jinnsng Holding Group Co.,Ltd.,Datong 037003,China;School of Mines,China University of Mining and Technology,Xuzhou 221116,China)
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2023年第1期139-149,共11页
Journal of China Coal Society
基金
国家自然科学基金重点资助项目(51739006)
国家自然科学基金国际(地区)合作与交流资助项目(41961134032)。
关键词
不平衡力
坚硬顶板
变形不协调
弹塑性
unbalanced force
hard roof
uncoordinated deformation
elasto-plastic
