黄土沟壑径流下浅埋煤层采动突水机理研究

With the focus of China's coal exploitation shifted to the northwest, serious coal mining induced water (and sand) inrush hazards under loess gully runoff appeared due to the interaction of overland runoff, loess gully landform, and shallow buried and thin bedrock geological and coal mining conditions. But the mechanism of water (and sand) inrush under loess gully runoff has not been fully mastered at present, and there is still no effective method for prediction of water (and sand) inrush under loess gully runoff. This project takes the Yulin-Shenmu mine area in Northern Shaanxi Province as the study area and centers on the issue of “mechanism of mining water inrush under loess gully runoff”. The rock-soil composite caving zone and water flowing fractured zone height predicting method and macroscopic modes of water inrush are studied by the field investigation, laboratory test, physical simulation and numerical simulation methods. The mechanism of water and sand inrush and the predicting method of crushing sand amount are studied using multiple particles flow mechanics analysis, indoor physical simulation experiment, and the numerical simulation of particle flow method under the loess gully runoff. The evolution mechanism of water inrush patterns is studied by soil-water interaction experiment and the fissure soil creep-penetration test. The study is not only of great significance for the development of the theories and methods of the mechanism and prediction of water inrush, but also has practical significance for the prediction and controlling of water hazard from shallow buried coal seam mining in western arid and semi-arid regions.

随着我国煤炭开发的重点向西北地区转移，地表径流、黄土沟壑地貌与埋深浅、基岩薄的地质采矿条件相互影响，形成了严重的黄土沟壑径流下浅埋煤层采动突水（溃砂）灾害。但目前对黄土沟壑径流下浅埋煤层采动突水（溃砂）机理尚未完全掌握，对黄土沟壑径流下突水（溃砂）预测还缺乏有效方法。本项目以陕北榆神矿区为例，围绕“黄土沟壑径流下浅埋煤层采动突水机理”这一科学问题，采用现场调研、室内试验、物理模拟、数值模拟等方法研究基岩-土层复合垮落带、导水裂缝带高度预计方法及沟谷采动宏观突水模式；采用力学分析、物理模拟、数值模拟等方法研究黄土沟壑径流下采动溃水溃砂机理及溃砂量时序预测方法；通过土-水相互作用试验和采动应力恢复裂隙土层蠕变渗透试验等方法研究采动突水模式演化内在机理。本项研究不但对于丰富煤层开采突水机理和预测方法具有重要意义，而且对于西部干旱、半干旱地区愈为普遍的浅埋煤层过沟开采水害预测防治具有实际指导意义。

本项目以地处陕北黄土沟壑区的红柳林井田为例，在综合水文地质与工程地质调查的基础上，采用理论分析、现场试验、室内试验、数值模拟分析、物理模拟分析和工程实践应用等研究方法，对陕北黄土沟壑径流下采动水害机理及其防控技术进行了系统的分析。主要研究成果如下：.（1）分别采用“三下规范”公式、“矿区规范”公式、多因素拟合公式和SVR对导水裂隙带高度进行了预测，结果表明，GA预测（X1X2）所预测的导水裂隙带高度最准确，稳定性更高。.（2）通过粉晶X衍射（XRD）物相定量分析测试分别测试了离石黄土和保德组红土的矿物成分。从保德组红土粘土矿物的绝对含量和构成来看，其粘土矿物以伊蒙混层和伊利石为主，尤其是伊蒙混层含量较高，因而其遇水具有明显的软化变形特性，决定了保德组红土的水稳定性和隔水性能较好。.（3）以离石黄土和保德红土为对象，应用同步辐射扫描CT与Avizo软件，实现土体三维重构，并对三维构建模型进行定量研究。选取等效直径，长径比和配位数三个参数用来定量描述黄土和红土在压缩过程中的变化情况，黄土在压缩过程中微小孔隙被压实，大孔隙增加，孔隙形状由球形向细长型发育，最后向球形恢复。红土在压缩过程中大型孔隙和中型孔隙向小孔隙转化，最后在破坏阶段产生新的孔隙，孔隙形状由细长型向球形转化。.（4）将黄土沟壑径流下采动水害划分为四种类型，即突水溃砂型、突水型、渗漏型和安全型。.（5）基于砂层单颗粒力学分析，提出了黄土沟壑径流下砂层采动突水溃砂机制。采用自制的试验设备，模拟研究了不同结构面宽度下松散层经过采煤上覆裂缝发生渗透变形破坏的类型和机制。.（6）针对黄土沟壑径流下采动水害类型，提出了差异化的系统水害治理模式。即综合控制水动力条件与控制砂源流动技术2种治理措施。