侧向渗透-轴向承载下煤样破坏及水-力耦合作用机制

Mechanism of coal sample failure and water-force coupling under lateral permeation-axial load

煤矿邻空煤柱在采空区水渗透及上覆岩层载荷作用下变形破坏特征复杂。为研究这种侧向渗透-轴向承载作用下煤柱的变形特征,通过用于圆柱形试件渗透实验的单侧水压加载装置,进行不同侧向渗透压力下的煤样压缩试验,研究煤样的破坏特征与渗透特性。结果表明:煤样破坏总体上呈非对称形态,煤样在侧向渗透-轴向承载下的变形破坏可分为压密、弹性、裂隙稳定扩展、非稳定扩展、峰后破坏5个阶段;随着侧水压力不断增大,煤样峰值强度逐渐下降,裂隙稳定扩展阶段对应的轴向应变减小,使得水能在较小轴向应变下进入煤样内部空隙中,导致煤样脆性增加,加速煤样的破坏。

The characteristics of deformation and failure of coal pillar under goaf water infiltration and overburden load is complex.In order to study the deformation characteristics of coal pillar under the action of lateral permeation-axial load,a unilateral hydraulic loading device for the permeability test of cylindrical specimens was used to carry out compression tests of coal samples under different lateral permeation pressures and to study the failure characteristics and permeability characteristics of coal samples.The results show that:the deformation and failure of coal samples under lateral permeation-axial load can be divided into five stages:compaction,elasticity,stable fracture expansion,unstable fracture expansion and post-peak failure.With the increasing of lateral water pressure,the peak strength of coal samples gradually decreases,and the axial strain corresponding to the stable fracture expansion stage decreases.The water energy enters the inner void of coal sample under small axial strain,resulting in increased brittleness of coal sample and accelerated failure of coal sample.