基于薄煤层开采及煤岩体巷道变形特点，着重探究煤岩体变形规律，根据不同岩层组合的力学性质，系统地分析了岩和煤组合体的不均匀变形特征。首先，通过不同高度比“岩-煤-岩”组合体的单轴加载试验，分析不同高度比煤岩组合体加载破坏规律，结果表明：组合体强度受中间煤体高度影响，试件单轴抗压强度随煤体高度的增加而减小，而且，试件的破坏形态随着煤体高度的增加由拉伸破坏转变成斜面剪切破坏最终表现为煤体挤出破坏。组合体试件破坏受煤体部分主导，两端砂岩对中间煤体起约束作用从而提高煤体强度，煤体中部受到其约束最小且随着煤体高度的增加中间部分所受到的影响迅速衰减。然后，通过室内单轴加载与颗粒流等方式分析组合体裂隙发育全过程，结果表明，组合体裂隙发育的过程可分为四个阶段：1.裂隙孔隙压密阶段、2.裂隙产生并稳定发育阶段、3.裂隙加速发育并贯通阶段和4.破坏后的阶段。煤体内部缺陷的存在与其自身较低的强度导致了组合体微裂隙最初于煤体内部生成（在煤体高度非常小的条件下才会有裂隙自砂岩内部产生）；随着试件荷载的增大，随机分布在煤体的裂隙相互贯通并向砂岩部分延伸最终造成破坏；且最初的裂隙主要是轴压与端面效应产生的剪切裂纹，在加载至试件单轴抗压强度的0.8左右时，试件内部张拉裂隙开始快速发育，并且组合体开始丧失强度。

According to the characteristics of thin coal seam mining and surrounding rock deformation of coal and rock roadway,this paper explores the deformation law of coal and rock mass,and reveals the uneven deformation characteristics of rock and coal combinations based on the mechanical properties of different rock formations. Through the uniaxial loading test of “rock-coal-rock” combination with different height ratios,the loading failure law of coal rock combination is analyzed. The results show that the combination uniaxial compressive strength is mainly affected by the height of coal body,and increases with the increase of coal body height. With the increase of coal height,the failure mode of the specimen changes from tensile failure to inclined plane shear failure,finally displays as coal extrusion failure. Moreover,the sandstones at both specimen ends improve the strength of the coal body by constraining the coal in the middle section. This constraint in the middle section of the coal body is the smallest,and the influence on the middle section decreases rapidly with the increase of the height of the coal body. Finally,the method of uniaxial loading test and particle flow analysis are used to determinate whole process of fracture development. The results show that the fracture development process of the combination can be divided into four stages:fracture pore compaction stage,fracture generation and stable development stage,accelerated fracture development and penetration stage,and post failure stage. The micro cracks are formed in the area of coal defects at first (only when the height of the coal body is very small can the cracks come from the sandstone). With the increase of the load,the cracks randomly distributed in the coal body connect with each other and extend to the sandstone part,resulting in the ultimate failure. The initial cracks are mainly shear cracks caused by axial compression and end effect. When loading to about 0.8 of the uniaxial compressive strength of the specimen,the internal tensile cracks begin to develop rapidly,indicating that the strength of the composite begins to lose.

1 “岩-煤-岩”组合体力学试验特性

   1.1 试件的加工制备

   1.2 单轴压缩试验方法

   1.3 SEM电镜扫描与煤体裂隙发育

2 煤岩组合体力学特性与破坏特征

   2.1 不均匀变形机理

   2.2 裂隙演化规律

   2.3 组合体破坏特征

3 单轴压缩颗粒流分析

   3.1 计算模型

   3.2 裂隙分布规律

   3.3 裂隙演化规律

4 结论