Theoretically, the blockage is most likely to occur when three large stones meet in the same section, and the section is mostly occupied by stones, and the flowable area is small. Generally, the maximum particle size of the stone and the inner diameter of the pipe d: D1:3 (Note: This item is specified in the Regulations, according to the conveying height and the type of stone, 1:2.5 to 1:5), and is in the pump A square grid is arranged on the machine hopper to prevent the super-path stone from being mixed in. In the concrete mixture with poor ratio of concrete and poor concrete, the water will penetrate through the aggregate gap, causing the aggregate to coalesce and cause the pipe to block. It often occurs in the pipeline bending, reducing diameter and the middle of the pipeline. In addition, when the concrete water-cement ratio is too large, it is easy to isolate, causing the mortar to separate from the aggregate and blocking the pipe. It is more common in the segregation blockage of