In the design of the impermeable curtain grouting engineering,high-pressure cement grouting with orifice-closed method was adopted.

The application of orifice-closed grouting method construction technique in low-pressure non-cover-weight grouting under complex geological conditions was discussed,and the reasonable parameters were proposed.

In this paper,the necessity for steam condese -water full closed redeem technique is analyzed, the steam condense-wa-ter full closed redeem system based on PLC is developed,and the structure diagram,signal detect method,control logic relation,the keypoint of PLC program project as well as boiler priority supply electrical circuit chart are given.