In the process of dynamic unloading, the radial stress unloaded first and then rebounded, the circum stress concentrated. 初始应力动态卸荷时，动应力在隧洞径向表现为卸荷回弹，而在切向出现动应力集中，表现为加载。
Under the action of the horse head movement, the vibration of the sucker-rod and, furthermore, thedynamic stress will be induced. 在这种悬点位移作用下，将引起抽油杆柱的振动，导致杆柱中的动应力。
