Evolution characteristics of overburden structure in inclined fully mechanized caving under residual coal pillars of the upper layer
刘用王红伟吴学松田程鹏关荣福聂云枭范志伟曹沛沛
LIU Yong;WANG Hongwei;WU Xuesong;TIAN Chengpeng;GUAN Rongfu;NIE Yunxiao;FAN Zhiwei;CAO Peipei
甘肃华亭煤电股份有限公司砚北煤矿西安科技大学能源学院西部矿井开采及灾害防治教育部重点实验室华亭煤业集团有限责任公司技术中心
特厚煤层分层综放开采上下分层工作面斜交布置时,下分层综放工作面间歇性过上分层遗留区段煤柱导致覆岩破断运动及矿压显现规律复杂,围岩控制困难,制约了煤矿安全生产。以甘肃华亭煤电股份有限公司砚北煤矿250203下综放工作面为工程背景,采用物理相似模拟实验、数值计算、现场实测相结合的方法,研究了上分层遗留区段煤柱下斜交工作面综放开采覆岩运移规律及应力分布演化特征,阐明了下分层综放工作面开采扰动下上分层遗留区段煤柱失稳特征及围岩支承压力变化规律,定义了斜交工作面覆岩内场和外场,揭示了下分层综放工作面过遗留区段煤柱覆岩结构演化特征。研究结果表明:① 下分层综放工作面开采诱发上分层遗留区段煤柱失稳导致覆岩大尺度空间垮落,扰动区内顶板结构渐次演化,形成“低位倒台阶组合悬臂梁+高位大结构砌体梁”组合结构。② 在工作面距区段煤柱15 m时,区段煤柱最大垂直应力达到46.7 MPa,较下分层未开采时增大了9.9%,煤柱形变现象较为明显;工作面位于区段煤柱正下方时,区段煤柱应力集中区域呈近似“月牙状”分布。③ 随着下分层综放工作面与上覆遗留区段煤柱斜交位置变化,外场覆岩破断形态呈近似对称梯形,结构动态失稳导致内场垮落形态呈“非对称双拱”、“对称双拱”、“单拱”演化过程。研究结果对特厚煤层分层综放工作面安全开采具有指导意义。
In the stratified fully mechanized caving of ultra-thick coal seams, the inclined layout of upper and lower caving faces leads to lower fully mechanized caving face intermittently crossing residual coal pillars of the upper layer. This results in complex overburden breakage and mine pressure behavior, posing challenges to surrounding rock control and hindering safe coal production. Based on the 250203 lower fully mechanized caving face at Yanbei Coal Mine of Gansu Huating Coal Power Co., Ltd., methods of physical similarity simulation experiments, numerical modeling, and field measurements were applied to study the overburden movement and stress distribution evolution characteristics under residual coal pillars of the upper layer during inclined fully mechanized caving. The instability characteristics of residual coal pillars of the upper layer and the variation patterns of surrounding rock support pressure under the disturbance of lower fully mechanized caving were clarified. The overburden of the inclined working face was categorized into internal and external fields, and the evolution characteristics of the overburden structure when the lower fully mechanized caving face crossed the residual coal pillars were revealed. The results showed that the mining of the lower fully mechanized caving face induced instability in residual coal pillars of the upper layer, resulting in large-scale overburden collapse. The roof structure within the disturbed zone evolved progressively into a composite structure of "low-level inverted step cantilever beams and high-level large masonry beams". When the working face was 15 m from the residual coal pillar, the maximum vertical stress of the pillar reached 46.7 MPa, an increase of 9.9% compared to the pre-mining state, with significant pillar deformation observed. When the working face was directly beneath the residual coal pillar, the stress concentration zones of the pillar displayed an approximately crescent-shaped distribution. As the inclined position of the lower fully mechanized caving face relative to the residual coal pillars changed, the overburden breakage in the external field exhibited an approximately symmetrical trapezoidal shape. The dynamic instability of the structure caused the overburden collapse in the internal field to evolve through stages of "asymmetric double arches", "symmetric double arches", and "single arch". These findings provide significant guidance for the safe mining of stratified fully mechanized caving faces in ultra-thick coal seams.
特厚煤层分层综放开采遗留区段煤柱斜交工作面覆岩结构
ultra-thick coal seams;stratified fully mechanized caving;residual coal pillars;inclined working face;overburden structure
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