According to the structural features of pre-cast pile and combined with practice of concrete project,it introduces hydraulic pressure inner mode and designing calculation,manufacture,checking and repairing,equiping and unloading skill of the whole outer mode system,offers ensurance for the quality of pile products.

Deep-hole reduction flush light demolish driving in main and auxiliary shaft freeze bedrock of Chaoyang Coal Mine and the steel form cast-in-place wall of a well design and construction;

This paper gives an analysis about the mechanics state of the whole form forthe middle-low pillar pier.

When enlarge the shaft diameter,metal mold plates were used to fill concret.

As the construction schedule was very tight and high quality exterior appearance was requested,large integral steel formwork was adopted for the works and satisfactory results have been achieved.