Safety cage derrick structure for expanding excavation of diversion surge shaft

The safety cage derrick structure comprises a cage body, an anti-falling safety mechanism for improving the safety of the cage body is arranged at the upper end of the cage body, and the anti-falling safety mechanism comprises a mounting frame, a capturing device, a movable frame, a lifting lug and a connecting rod. Mounting frames are fixedly arranged on the two sides of the upper end of the cage body, capturing devices are movably arranged at the lower ends of the mounting frames through rotating shafts, movable frames are arranged at the positions, at the upper ends of the capturing devices, in the cage body, lifting lugs are fixedly arranged at the upper ends of the movable frames, and connecting rods are fixedly arranged on the two sides of the lower end of each movable frame. The anti-falling safety mechanism is good in using effect, once the lifting rope is broken and the cage body is in a weightless state, the anti-falling safety mechanism can be quickly popped out towards the two sides, so that the a