动载作用下端锚锚固体力学响应特征研究

为研究动载作用下巷道围岩失稳破坏机制，基于SHPB试验系统，研究了不同冲击气压（0.2、0.3、0.4、0.5、0.6 MPa）下预应力端锚锚固体的应力波传播规律及层裂破坏特征，采用图解法计算了锚固体试件的层裂强度及应变率，建立了锚固体层裂损伤模型并采用高速摄像机进行了验证。结果表明：不同冲击气压下试件应力波峰值应变均呈指数形式衰减，且空间衰减幅值及衰减指数与冲击气压呈正相关关系；锚固体试件层裂首先发生在自由端附近，沿反射波传播方向层裂厚度逐渐增加，0.3 MPa冲击气压以上，试件每两处层裂面中间产生一道新层裂；在18～33 s^?1应变率范围内，应变率率效应占主导地位，层裂强度最高达69 MPa，而应变率为41 s^?1时，层裂强度降低至17 MPa；锚固体自由端在动载冲击后出现层裂闭合现象，但在锚固端由于锚固界面残余黏聚力作用，层裂位置未发生闭合现象。

Study on mechanical response characteristics of end anchorage body under dynamic load

In order to study the instability and failure mechanism of roadway surrounding rock under dynamic load, the stress wave propagation law and spallation failure characteristics of pre-stressed end anchorage body under different impact pressures (0.2, 0.3, 0.4, 0.5, 0.6 MPa) are studied using SHPB test system. The spallation strength and strain rate of anchorage body specimen are calculated by graphical method, and a spallation damage model of anchorage body is established and verified by high-speed camera. The results show that the peak strain of stress wave decays exponentially under different impact pressures, and the spatial attenuation amplitude and attenuation index are positively correlated with the impact pressure. The spallation of the anchorage body specimen first occurs near the free end, and the spallation thickness increases gradually along the reflected wave propagation direction. When the impact pressure is above 0.3 MPa, a new spallation occurs in the middle of every two spallation surfaces of the test piece. In the range of 18?33 s^?1 strain rate, the effect of strain rate is dominant, and the spallation strength is up to 69 MPa. While the strain rate is 41 s^?1, the spallation strength decreases to 17 MPa. The free end of the anchorage body shows spallation closure after impacted by dynamic load, but spallation closure is not observed at the spallation position at the anchor end due to the residual cohesion at the anchorage interface.