Abstract
Abstract
To realize coupling between the yielding and partition failure processes, a new hierarchical control device was designed. The new stage control device comprised an internal and external two-stage structure similar to “piston + sleeve.” Under the action of the surrounding rock pressure, primary yielding occurred first, and the cone slid along the inner wall of the yielding sleeve. With an increase in the surrounding rock pressure, secondary yielding occurred, and the tray slid along the outer wall of the yielding sleeve. The device had a simple mechanical structure and exhibited reliable mechanical properties. It had a convenient and rapid installation process, and the load-displacement curve was obtained by laboratory tensile tests. Mechanical test results showed that the device exhibited a clear function of graded pressure yielding, which was consistent with the designed sectional control curve. The results show that the new hierarchical control device exhibited a good control effect on the surrounding rock and is helpful for TBM in realizing fast driving.