围压加载条件下岩体损伤特征实验及数值模拟分析

Experimental and Numerical Analysis of Damage Characteristic of Rock Mass under the Condition of Confining Pressure Loading

为了研究煤岩动力灾害的发生机制,分别对 3 种不同强度的混凝土试样进行了单轴压缩实验和围压加载实验,并利用声波发射仪器对围压加载条件下试样破坏过程进行监测;采用数值模拟方法,从微观层面观察试样的损伤特征。实验结果表明:围压加载条件下试样破坏类型单一,在试样中部附近发生拉伸断裂。模拟结果表明:试样初始破坏是在纵向拉应力的作用下从岩体内部开始,逐步沿横向向两边扩展;当围压使纵向拉力达到了岩体的抗拉强度时,继续增大围压,初始破坏区域扩大直至发生瞬间断裂。

In order to study the occurrence mechanism of coal and rock dynamic disasters, uniaxial compression experimental and confining pressure loading experimental were carried out on 3 kinds of concrete samples with different strength, and the failure process of specimens under confining pressure was monitored by acoustic emission instrument;the damage characteristics of specimens were observed at the microscopic level by numerical simulation. The experimental results show that the failure type of the specimen under confining pressure is single and tensile fracture occurs near the middle of the specimen. The simulation results show that under the action of longitudinal tensile stress, the initial failure of the sample starts from the interior of the rock and gradually expands along the transverse direction to both sides;when the confining pressure makes the longitudinal tension reach the tensile strength of the rock mass, the initial failure zone is enlarged with the increase of confining pressure, until the instantaneous fracture occurs.