近浅埋煤层大采高工作面双关键层结构分析

摘要

Through field measurement and statistical analysis show that the support load of large mining height working face is generally larger and this is an increasing tendency with the increase of mining height,there is large and small periodic weighting in longwall face,and the static load of thick equivalent immediate roof is the basic load of support of longwall face.Through physical simulation experiments,the mechanism of immediate roof thickness increase and the move upward of hinge point of roof structure at large mining height longwall face are explored,the definition of "equivalent immediate roof" is proposed,and the" double key strata" theory of large mining height longwall face in nearly shallow seam is established.Roof is mainly the "double key strata" structure of large mining height longwall face in nearly shallow seam.According to the gob filling degree by equivalent immediate roof,the double key strata roof structure can be divided into two types including" double voussoir beam" and "blique step voussior beam-voussoir beam",and the common situation is" blique step voussior beam-voussoir beam" double key strata structure.The model of double key strata roof structure is established,and the mechanism of large and small periodic weighting in longwall face is explored,and the calculation formula of the setting load of support and the support resistance is put forward,which provide the theory basis for the roof control of large mining height longwall face in nearly shallow coal seam.%根据实测统计分析,近浅埋煤层大采高工作面支架载荷普遍较大,且随采高增大有增加的趋势,工作面来压存在大小周期,厚度较大的等效直接顶静载是工作面支架的基本载荷.通过物理模拟实验,揭示了大采高工作面直接顶变厚和顶板结构铰接点上移的机理,提出了“等效直接顶”的定义,建立了近浅埋煤层大采高工作面顶板“双关键层”理论.近浅埋煤层大采高工作面顶板主要表现为“双关键层”结构,根据等效直接顶对采空区的充填程度,双关键层顶板结构分为“双砌体梁”和“斜台阶岩梁-砌体梁”两类,常见的是“斜台阶岩梁-砌体梁”双关键层结构.建立了双关键层顶板结构模型,揭示了工作面出现大小周期来压的机理,给出了支架初撑力和工作阻力的计算公式,可为近浅埋煤层大采高工作面顶板控制提供理论依据.