超大采高煤壁三维空间破坏规律及片帮机理研究

Fully mechanized mining of large mining height has become the main technical choice of thick coal seam because of its high efficiency, low coal loss and low cure rate. Comprehensive research of this project through laboratory experiments and field data analysis, numerical simulation and theoretical research combined according to the working face with large mining height whose high coal wall stability problem and high impact by the smaller mining height which easy to be stable. Study on the different structure and different loading methods of coal crack propagation rule. The quantitative analysis of influence of different structural parameters on the stability of coal wall will be studied. Study on the characteristics of the mining stress and the 3D surface shape of the coal face in the super large mining face. The stability coal wall coupling is established based on the steady model, the tendency of discrimination of coal wall potential failure surface by mechanical or energy method. The stability of coal wall coupling is established based on the steady model, the tendency of discrimination of coal wall potential failure surface by mechanical or energy method, clarify the coal mechanical structure and mining stress coupling under large mining height coal wall spalling mechanism, lay the foundation for the large mining height technology popularization and application.

大采高综采由于效率高、煤损少、含矸率低等优点已成为厚煤层主要技术选择。针对超大采高使工作面由较小采高易稳定发展为超大采高易冲击、超高煤壁易失稳等难题，本项目通过实验室实验、现场实测分析、数值模拟和理论研究相结合的综合研究法，研究不同结构特征和不同加载方式煤体裂隙扩展演化规律，定量分类分级不同结构属性对煤壁稳定性影响，表征超大采高工作面采动应力和煤壁片帮空间三维曲面形态，基于稳定性耦合建立采场煤壁稳态模型，利用力学或能量法对煤壁潜在破裂面进行倾向性判别，阐明煤体力学结构特征与采动应力耦合作用下超大采高煤壁片帮机理，为超大采高技术推广和应用奠定基础。

大采高一次采全厚开采方法由于煤损少、含矸率低、工艺流程简单等优点已成为我国8~9m以下厚煤层实现高效开采的主要技术选择。国外先进采煤国家曾将采高5.5m视为开采高度的上限，根本原因在于随着采高加大煤壁稳定性降低造成片帮频发影响工作面安全高效回采。.针对超大采高综采工作面煤壁稳定性差、易片帮的问题，本课题通过实验室实验、现场实测分析和理论研究等相结合的综合研究法，以榆林地区超大采高综采实践为基础对超大采高煤壁三维空间破坏规律及片帮机理进行了研究，结合金鸡滩煤矿8m超大采高综采提出了煤壁稳定性多维防控措施。取得如下研究成果：.（1）实地调研、统计分析了榆神矿区超大采高综采工作面采高与液压支架载荷的关系，发现了支架载荷与采高呈正相关，超大采高综采来压来压强度高、持续时间长并呈现大小周期来压现象；超大采高综采煤壁稳定性降低，基于“5点法”得出煤壁片帮体在空间上类似一不规则“锥形体”，在垂直煤壁剖面上类似“残月形”，片帮位置多发生于工作面中部及煤壁中上部。.（2）基于扫描电镜揭示了显微煤体结构特征，与现场宏观煤壁片帮形式的形成具有较好的呼应性，揭示了煤壁板裂化片帮渐进式破坏机理为煤体内生裂隙（割理）在采动应力影响下沿纵向扩展、贯通成板结构，继而在不同应力环境下发生不同形式的板状屈曲破坏。煤壁板裂化片帮与煤体强度、煤体结构特征和应力环境等因素相关，垂直应力的泊松效应、煤壁截割后的卸荷回弹以及采动动载应力波在煤壁自由面的反射等因素促使煤壁发生纵向张拉破坏。.（3）提高煤壁稳定性可通过改变煤体性质的内控法和优化支护能力、形式等外控法。内控法效果直接明显但操作复杂、影响生产连续性；基于煤壁稳定性力学模型提出了垂向、走向和倾向多个维度提高煤壁稳定性的针对性防护措施。即通过增强支架工作能力、增大护帮防护面积和护帮力、提升供液速度的多维防护措施。课题成果应用在世界首个8m超大采高工作面，实现了煤壁稳定可控，安全性大幅提高，工作面达到了日产6.16万吨。本课题研究成果为超大采高开采煤壁稳定性控制技术和装备提供理论支撑，为更厚煤层超大采高一次采全厚开采提供了理论基础。