采动巷道侧向高低位厚硬顶板破断模式试验研究

Experimental study on fracture mode of lateral high and low thick and hard roof in mining roadway

陕蒙地区冲击地压显现大多发生在二次采掘扰动影响下,煤层上方厚硬岩层结构破断诱发工作面采场附近动压显现已成为煤矿生产中重大安全隐患。为阐明采动巷道上覆高低位厚硬岩层破断对区段煤柱受力以及巷道围岩稳定性的影响,建立高低位厚硬岩层破断结构的力学模型,得到破断扰动影响下区段煤柱结构变形特征及应力分布特征,以巴彦高勒煤矿11盘区煤样试样为研究对象,利用自行设计的高位岩层模拟加载装置,借助非接触式全场应变测量系统的数字散斑相关分析方法,对高低位厚硬岩层在区段煤柱上方不同破断位置组合下区段煤柱及低位岩层的应力变形特征进行了试验研究。分析了上覆高低位厚硬岩层侧向不同断裂位置组合下区段煤柱受力特征及应力传递机制,建立了巷道上部厚硬顶板不同断裂位置与结构整体失稳荷载的力学模型。结果表明:高低位厚硬顶板岩层破断将会引起煤柱采空区应力集中,高低位厚硬岩层不同的破断位置组合,对下部岩层的运动变形和区段煤柱应力分布和巷道围岩稳定影响显著。区段煤柱整体结构稳定性与破断点位置密切相关,煤体在回转作用下破坏所需的应力大小与高位岩层顶板破断点对采空区顶煤的力矩负相关。随着破断点远离区段煤柱,区段煤柱受力由压剪逐渐转化为采空区煤顶传递的压弯作用。高低位厚硬岩层顶板破断的相对位置影响低位顶板的破断情况,当低位破断点处于高位破断点以内,低位顶板随高位顶板破断1次,反之则低位岩层顶板将会随着高位岩层破断回转发生2次破断。随着高位顶板的破断,采动巷道及煤柱上覆岩层应力减小,区段煤柱稳定性下降,冲击地压风险增大。试验研究为陕蒙地区深部厚硬顶板条件下采动巷道动力灾害防治和区段煤柱设计优化提供了参考。

The appearance of rock bursts in Shaanxi and Inner Mongolia area mostly occurs under the influence of secondary excavation dis⁃turbance.The breaking of the thick and hard rock structure above the coal seam induces the appearance of dynamic pressure near the working face and has become a major safety hazard in coal mine production.In order to clarify the impact of the breaking of the high and low thick hard rock layers overlying the mining roadway on the strength of the section coal pillars and the stability of the roadway surround⁃ing rock and establish the mechanical model of the breaking structure of the high and low thick hard rock layers,and obtain the section coal pillars under the influence of the breaking disturbance structural deformation characteristics and stress distribution characteristics.The authors take the coal sample from the 11th panel of Bayangole Coal Mine as the research object,use a self-designed and processed highlevel rock layer simulation loading device,and use the digital speckle correlation analysis method of the non-contact full-field strain measurement system,carry out the stress and deformation characteristics of the section coal pillars and low-level rock formations under the combination of different breaking positions of the high and low thick hard rock layers above the section coal pillars.The force characteris⁃tics and stress transfer mechanism of the coal pillars under the combination of different fracture positions of the overlying high and low thick hard rock layers are analyzed,and the mechanical models of the different fracture positions of the thick and hard roof on the upper part of the roadway and the overall instability load of the structure are established.The test results showed that the breaking of high and low thick and hard roof rock layers will cause stress concentration in the coal pillar goaf.The combination of different breaking positions of high and low thick and hard rock layers has a significant impact on the movement and deformation of the lower rock layers,the stress distribu⁃tion of the section coal pillars,and the stability of the surrounding rock of the roadway.The overall structural stability of the coal pillar in the section is related to the location of the breaking point.The stress required for the failure of the coal body under the action of rotation is negatively related to the moment of the breaking point of the high-level rock roof on the top coal in the goaf.As the breaking point is far⁃ther away,the section coal pillar's force is gradually transformed from compression and shear to the compression and bending effect trans⁃mitted by the coal roof of the goaf.The relative position of the top slab breaking of the high and low thick hard rock layers affects the breaking of the low roof.When the low breaking point is within the high breaking point,the low roof will break once with the high roof.Otherwise,the low rock roof will rotate twice as the high rock breaks.Times broken.With the breaking of the high roof,the stress of the mining roadway and the overlying strata of the coal pillar is reduced,the stability of the coal pillar in the section decreases,and the risk of rock burst increases.The experimental research provides a reference for the prevention and control of dynamic disasters in mining roadways and the optimization of section coal pillar design under the conditions of deep thick and hard roof in Shaanxi and Inner Mongolia.