基于声发射、数码摄像机录像及SEM系统,进行了不同加载速率下顶板砂岩-煤柱结构体试样单轴压缩试验,研究了加载速率对顶板-煤柱结构体力学行为的影响。结果表明:顶板-煤柱结构体宏观破坏起裂应力、单轴抗压强度和弹性模量均随加载速率递减而递减,但当加载速率递减至1×10-5mm/s,单轴抗压强度和弹性模量均出现了一个递增趋势;顶板-煤柱结构宏观破坏起裂是由于煤样原生缺陷产生的水平附加应力大于煤样抗拉强度而引起的,不同加载速率下宏观破坏起裂均发生在煤样部分,形成拉裂纹与不同程度局部弹射或片帮组合的宏观破坏起裂形式;不同加载速率下顶板-煤柱结构体的破坏均发生在煤样内,砂岩未发生明显破坏,煤样主要发生劈裂弹射破坏,高加载速率下储存在实体承载结构体内的弹性能将以试样宏观拉裂纹等薄弱面为释放通道而迅速释放,试样破坏呈“突发”性且砂岩回弹变形剧烈,弹射破坏加剧,煤样更加破碎;高加载速率下破裂断口凹凸不平,呈“撕裂”状,随加载速率降低,断口趋向平整、光滑且出现“锯齿区”,锯齿区台阶咬合摩擦在一定程度上抵抗了试样破坏,试样呈相对延性破坏。

In order to study the mechanical behavior of roof-coal pillar structure body under different loading rates,the uniaxial compression tests with different loading rates were carried out on the sandstone roof -coal pillar structure bodies. Also the acoustic emission (AE) monitoring technique,digital video camera system and scanning electron mi- croscope were used to investigate the effects of loading rate on the mechanical behavior of roof-coal pillar structure body. The results show that with the decrease of the loading rate,the macro-failure initiation strength,uniaxial com- pressive strength and elastic modulus of the structure body integrally decrease. However,both the uniaxial compressive strength and elastic modulus show an increasing trend at the loading rate of 1×10-5 mm / s. Moreover,when the horizon- tal additional stress produced by native defects in coal body is larger than the tensile strength of coal body,the macro- failure initiation of the structure body will occur. And the macro-failure initiations under different loading rates all oc- cur in the coal body as the forms of tension crack combined with partial ejection or spalling of varying degrees. Additionally,the failures of structure bodies mainly occur in the coal body and no obvious damage is observed for roof sand- stone. And the splitting ejection failure mainly occurs in the coal body. At a high loading rate,the elastic energy stored in the entity bearing structure of the coal body will be rapidly released through the macro-tensile crack as a releasing channel. Thus,the failure under a high loading rate is sudden and violent. The rebound deformation of roof sandstone is also severe. The coal becomes more broken than that at a low loading rate. Finally,the fracture surface of the structure body under a high loading rate is irregularity with a lacerated shape. The fracture surface becomes smooth with the de- crease of loading rate. An obvious saw tooth region is found in the fracture surface under a low loading rate. The occlu- sal frictions of steps in the saw tooth region resist the failure of the structure body in a certain extent and the structure body shows a relative ductile failure.