中文摘要：

由于爆破开挖,巷道内常含有径向裂隙,并影响巷道的稳定性,为了详细地研究含径向裂纹巷道在冲击载荷作用下的动态断裂行为,采用砂岩材料制作巷道模型试样进行中低速冲击动态断裂试验,并采用AUTODYN有限差分软件进行数值模拟分析。分析巷道对称轴线上的径向裂纹在冲击荷载作用下的扩展特性及止裂现象,并采用试验–数值–解析法计算出裂纹的起裂韧度及扩展速度等参数。研究结果表明：（1）巷道围岩在静力载荷作用和动力载荷作用下的破坏行为有较大差异,动力载荷下破坏仅是裂纹尖端处的起裂、扩展;而静力载荷下破坏除了发生在裂纹尖端处,也会在巷道拱肩、拱脚及两侧帮处发生破坏。（2）巷道对称轴线上的裂纹在冲击载荷下的扩展路径大致沿着裂纹的原方向扩展,扩展路径中存在明显的止裂现象。（3）采用试验–数值–解析法能够较好地计算出裂纹的起裂速度及扩展速度,进一步采用位移外推法能够求解出巷道内裂纹的动态应力强度因子时程曲线,利用测试的裂纹起裂时间确定起裂韧度。

英文摘要：

Tunnels contain radial cracks due to the blasting excavation,and these cracks affect the tunnel stability significantly. In order to study the dynamic fracture behavior of tunnels containing radial cracks under the impact loading,the medium and low speed impact experiment was carried out by using the sandstone tunnel models,and the finite difference code AUTODYN was used for the numerical simulation. The propagation path and the arrest of the crack under the impact loading were studied,and the crack initiation toughness and propagation speed were calculated with the experimental-numerical-analytical methods. The fracturing behaviors of surrounding rock under the static and dynamic loadings are quite different. The damage under the dynamic loading is only the crack initiation and propagation at the crack tips,whereas the damage under the static loading occurrs at the crack tip,arch shoulder,arch foot and sidewalls. The propagation path of the radial crack is along the original direction of the crack under the impact loading,and the crack arrest phenomena was observed clearly in the propagation path. The experimental-numerical-analytical method can be used to determinate the initiation and propagation speed quite well. The curves of the dynamic stress intensity factors of cracks versus the time were obtained by using the displacement extrapolation method. The dynamic initiation toughness was determined using the initiation time measured with the strain gauges.