关键词: 锚杆无损检测, 剪切力, 轴向载荷, 盒维数, 应力波特性

Abstract: In order to study the effect of shear force and axial load on reflected signal characteristics in complex rock strata, the box dimension and stress wave property parameters of fractal dimension are applied to nondestructive testing. The effect of different dynamic load on the same specimen and different shear force on the stress wave behavior was studied by loading different concentrated loads in the middle of the free end of the bolt. MATLAB software was used to calculate the box dimension of the detection signal, and the changing law of the box dimension under different circumstances was summarized. The amplitude, effective value, standard deviation and amplitude frequency of the detected signal are analyzed to judge the signal strength and its rule. The results show that the signal strength decreases gradually with the increase of the axial load of the anchorage structure and the free end shear of the anchor bolt. The shear force affects the ultimate bearing capacity of the bolt. With the gradual increase of shear force, the box dimension will increase, and so will the ultimate bearing capacity of the anchoring structure. With the increasing of axial load, the box dimension first increases and then decreases, and the anchorage structure fails at the maximum box dimension.