倾斜煤层底板突水流固耦合作用过程及数值仿真技术

发布时间：2018-08-24 10:20

【摘要】：承压水上开采,底板采动岩体裂隙在流固耦合作用下发育、扩展贯通,最终诱发底板突水,严重威胁着矿井的安全生产。长期以来,国内学者对水平及近水平煤层底板采动破坏特征及突水机理开展了大量的研究工作,取得了丰硕的理论成果,虽然对矿井水害的预测及防治发挥了重要作用,但对倾斜煤层底板的变形破坏特征及渗流特性的研究还不够完善。因此,本文采用理论分析、数值模拟以及现场实测相结合的方法,对倾斜煤层底板采动破坏特征以及矿井底板突水的危险性进行了系统性研究,并取得如下创新性成果:(1)基于半无限体理论及莫尔-库伦破坏准则,考虑了底板承压水压以及煤层倾角对采动底板的影响效应,结合倾斜煤层走向长壁开采时煤层采动底板支承压力分布规律,分别建立了倾斜煤层底板采动应力和破坏深度求解力学模型,推导计算了倾斜煤层采动底板内任一点处的水平应力、剪应力大小以及采动底板最大破坏深度。(2)按照正交试验设计方案,对倾斜煤层工作面底板破坏深度进行FLAC~3D数值模拟,对模拟结果分别进行矩阵分析和方差分析,确定了各主控因素对底板破坏深度的敏感性大小,给出了正交模拟试验的最优方案,即按照此方案实施后底板破坏深度最小,有效降低了矿井底板突水的危险性。(3)根据薄板理论,建立了倾斜煤层底板隔水关键层挠度求解力学模型,计算了倾斜煤层底板隔水关键层的挠度值,结合弹性力学中的莫尔-库伦破坏准则,求得了倾斜煤层底板隔水关键层任一点处的突水力学判据表达式。(4)对底板突水主控因素分别进行了主成分logistic回归分析和logistic回归分析。回归分析结果表明,主成分logistic回归分析的平均正确率较logistic回归分析的平均正确率高10%左右。基于主成分logistic回归分析,建立的底板突水回归模型的平均正确率较高,结合矿井实际开采地质参数,在一定程度上可以对倾斜煤层底板突水情况进行定性预测。(5)基于FLAC~3D数值仿真软件,建立了承压水上倾斜煤层底板流固耦合数值计算模型,模拟分析了工作面回采过程中,倾斜煤层底板孔隙水压力及渗流矢量的动态演化过程,确定了工作面底板的突水高危区,为倾斜煤层底板突水预测及防治提供了理论依据。(6)绘制了 3303工作面底板隔水关键层挠度函数的三维挠曲面以及底板挠度函数f(x,y)的等值线云图,求得了 3303工作面底板隔水关键层第一突水点处的突水力学判据表达式f(x0,y0),并给出了该工作面底板隔水关键层所承受的最大极限水压值。
[Abstract]:Under the action of fluid-solid coupling, the rock fissures in the floor mining are developed under the action of fluid-solid coupling, which eventually induces the water inrush of the bottom plate, which seriously threatens the safety of mine production. For a long time, domestic scholars have carried out a great deal of research work on the mining failure characteristics and water inrush mechanism of horizontal and near-horizontal coal seam floor, and obtained abundant theoretical results, although they have played an important role in the prediction and prevention of mine water damage. However, the study of deformation, failure and seepage characteristics of inclined seam floor is not perfect. Therefore, by using the methods of theoretical analysis, numerical simulation and field measurement, the characteristics of mining failure of inclined coal seam floor and the danger of water inrush from mine floor are systematically studied in this paper. The results are as follows: (1) based on the semi-infinite body theory and Mohr-Coulomb failure criterion, the effect of floor pressure water pressure and seam inclination on mining floor is considered. Combined with the supporting pressure distribution law of seam mining floor during longwall mining of inclined coal seam, a mechanical model for solving mining stress and failure depth of inclined coal seam floor is established, respectively. The horizontal stress, shear stress and maximum failure depth of mining floor at any point in inclined coal seam mining floor are deduced and calculated. (2) according to the orthogonal experimental design scheme, the FLAC~3D numerical simulation is carried out on the floor failure depth of inclined coal seam working face. The matrix analysis and variance analysis of simulation results are carried out, and the sensitivity of each main control factor to the depth of floor failure is determined. The optimal scheme of orthogonal simulation test is given, that is, the minimum damage depth of bottom plate is obtained after the implementation of this scheme. (3) based on the thin plate theory, a mechanical model for solving the deflection of the key layer of the inclined coal seam floor is established, and the deflection value of the key layer of the inclined coal seam floor is calculated. Combined with the Mohr Coulomb failure criterion in elastic mechanics, the criterion expression of hydraulic inrush at any point in the key layer of water barrier in inclined coal seam floor is obtained. (4) the principal component logistic regression analysis and logistic regression analysis are carried out for the main controlling factors of water inrush in the floor respectively. The results of regression analysis show that the average correct rate of principal component logistic regression is about 10% higher than that of logistic regression. Based on the principal component logistic regression analysis, the average correct rate of the regression model of floor water inrush is higher, which combines with the actual mining geological parameters. To some extent, it can be used to predict the water inrush from the inclined coal seam floor. (5) based on the FLAC~3D numerical simulation software, the fluid-solid coupling numerical calculation model of the inclined coal seam floor on the confined water is established, and the mining process of the working face is simulated and analyzed. The dynamic evolution process of pore water pressure and percolation vector of inclined coal seam floor has determined the high risk area of water inrush in the floor of working face. It provides a theoretical basis for water inrush prediction and prevention of inclined seam floor. (6) drawing the three-dimensional flexural surface of the deflection function of the key layer of the bottom plate of 3303 working face and the isoline cloud map of the deflection function f (XY) of the floor plate. The expression of hydraulic inrush criterion f (x0 / y 0) at the first water inrush point of the key layer of the bottom plate of 3303 working face is obtained, and the maximum limit water pressure of the key layer of the bottom plate of the working face is given.
【学位授予单位】：山东科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD745.2

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