考虑有效应力影响的煤矿地下水库储水系数计算模型

Storage coefficient calculation model of coal mine underground reservoir considering effect of effective stress

综合考虑煤矿地下水库储水系数的潜在影响因素,对弹性模量、上覆岩层体应力、泊松比、上覆岩层密度等进行理论分析,结合弹性力学、渗流力学的相关原理与知识,以及矿井水流动涉及的流固耦合渗流机理,建立了考虑有效应力影响的煤矿地下水库储水系数数学模型,并确定了模型解析解。以宽沟煤矿地下水库为例,计算该地下水库的储水系数并进行影响因素分析。结果表明:采高对储水系数的影响最大,上覆岩层体应力次之,弹性模量最小;储水系数随上覆岩层体应力、垮落带高度的增大而减小,随弹性模量、泊松比、采高的增大而增大。弹性模量每增加1.1 GPa,储水系数增大0.4%~3.0%;上覆岩层体应力每增加20 MPa,储水系数减小19%~39%;泊松比每增加0.1,储水系数增大10%~14%;垮落带高度每增加2 m,储水系数减小8%~11%;采高每增加1 m,储水系数增大20%~60%。根据该模型计算所得储水系数的分布范围为10%~35%,这与矿区抽排水工程试验值范围一致,验证了模型的准确性。

The potential influencing factors of storage coefficient are considered,and the elastic modulus,overlying strata stress,Poisson’s ratio and density of overlying strata are analyzed theoretically.Combined with the related principles and knowledge of elastic mechanics and seepage mechanics,as well as the fluid-solid coupling seepage mechanism involved in the flow of mine water,the mathematical model of storage coefficient considering the effect of effective stress is established,and the analytical solution of the model is determined.Taking Kuangou coal mine underground reservoir as an example,the storage coefficient of the reservoir is calculated and the influencing factors are analyzed.The results show that the influence of mining height on storage coefficient is the biggest,overlying strata stress is the second,and elastic modulus is the smallest.The storage coefficient decreases with the increase of overlying strata stress and height of caving zone,while it increases with the increase of Poisson’s ratio,elastic modulus and mining height.When the elastic modulus increases by 1.1 GPa,the increase range of storage coefficient is 0.4%-3.0%;when overlying strata stress increases by 20 MPa,the decrease range of storage coefficient is 19%-39%;when the Poisson’s ratio increases by 0.1,the increase range of storage coefficient is 10%-14%;when the height of caving zone increases by 2 m,the decrease range of storage coefficient is 8%-11%;and when the mining height increases by 1 m,the increase range of storage coefficient is 20%-60%.According to the model,the distribution range of storage coefficient is 10%-35%,which is consistent with the range of test value of drainage engineering in mining area,and the accuracy of the model is verified.