煤矿采空区充实率控制导向的胶结充填体强度需求
Strength demand of cemented backfill guided by backfilling ratio control in coal mines
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摘要: 胶结充填是一种在煤矿获得广泛应用的绿色开采技术,然而煤矿胶结充填体的强度需求却缺乏成套的科学设计方法。论文围绕煤矿采空区充实率控制导向的胶结充填体强度需求这一主题,通过实验室试验和理论分析等方法,实测得出胶结充填体单轴抗压强度(UCS)与侧限条件下压缩率之间的关系,阐明了煤矿充填开采采空区充实率的科学内涵,分析了采空区充填体的承载机制,建立了胶结充填采空区充实率表征模型,揭示了胶结充填体强度对充实率的影响作用机制,研究了多场景胶结充填目标充实率计算原理,形成了煤矿采空区充实率控制导向的胶结充填体强度需求动态设计方法。研究表明:(1)侧限压缩试验中,特定垂直应力对应的胶结充填体压缩率与充填体UCS呈现单调负相关,二者关系可利用上下边界Allometrical函数表征,且压缩率对UCS的敏感性随充填体强度增加而减小,即充填体强度达到一定程度后再提升强度对其压缩率的影响很小;(2)得出了充填体所受垂直应力、压缩率和充填体UCS三者的耦合关系,形成不同开采深度条件下胶结充填体UCS和压缩率的数学表征方法,建立了胶结充填充实率数学表征模型;(3)将充实率表征模型应用于控制顶板下沉、导水裂隙和地表沉陷多种应用场景,形成了目标充实率控制导向的胶结充填体强度需求设计方法。将研究成果应用于开滦集团某矿胶结充填体强度需求设计,得出充填体平均强度需求为3.00 MPa,并基于充填开采区域内煤厚、埋深等采矿地质条件的变化和工作面巷道布置方案,给出了CT1201、CT1202和CT1203工作面充填体强度需求的动态分布。研究成果丰富了胶结充填体强度设计理论,可为煤矿胶结充填工作面的充填体强度需求设计提供理论依据。Abstract: The cemented backfill is an environment⁃friendly mining technology widely used in coal mines. However,there is no systematically scientific method to design the strength demand of cemented backfill. In this paper,the strength demand of cemented backfill in coal mines guided by ground control is studied by using the labora⁃ tory test and theoretical analysis methods. The relationship between the uniaxial compressive strength (UCS) and the compressibility under the confined condition of cemented backfill is obtained. The scientific connotation of backfilling ratio in coal mines is clarified,and the bearing mechanism of cemented backfill in the goaf is revealed. The backfilling ratio characterization model of the cemented backfill is established,and the effect of the cemented backfill strength on the backfilling ratio is presented. The calculation principle of the target backfilling ratio is established, which can be used for multiple application scenarios. The dynamic design method of the strength demand of cemented backfill guided by backfilling ratio control is proposed. The results show that 1 In the confined compressive test,the UCS of cemented backfill is monotonically negatively correlated with the compressibility,which can be characterized by the Allometric function of the upper and lower boundaries. The sensitivity of compressibility to UCS decreases with the increase of UCS,which means increasing the strength of cemented backfill after reaching a certain level has little effect on its compressibility. 2 The coupling relationships among vertical stress,compressibility,and UCS of ce⁃ mented backfill are obtained. Theoretical characterization methods for UCS and compressibility of cemented backfill under different mining depth conditions are developed. The mathematical characterization theoretical model of backfill⁃ ing ratio for the cemented backfill in coal mines is established. 3 The backfilling ratio characterization model is used for various application scenarios including roof deformation control,water flowing fractured zone control,and surface subsidence control. The design method of strength demand of cemented backfill guided by target backfilling ratio con⁃ trol is obtained. The research findings are applied to a mine of Kailuan Group,the average strength demand of cemen⁃ ted backfill is 3.00 MPa. In addition,based on the roadway layout and the variation of mining geological conditions such as coal thickness and burial depth in the backfill mining area,the dynamic distribution of cemented backfill strength demand in each mining area is obtained.