In the construction of high-pressure grouting, the flow resistance of cement slurry is very large (generally 5MPa) at the end of grouting, the working pressure of hydraulic system is very high, a large amount of hydraulic oil flows back to the oil tank through bypass, and the directional valve is in position 0. At this time, restart, the motor and oil motor will rotate, while the hydraulic cylinder will not move, resulting in "crash". This is the result of the action of the equipment safety protection device. The plug wire located in the center of the end cover of the reversing valve must be removed, the valve core must be moved with a steel bar, and then the plug wire must be screwed well before normal operation. In the actual construction, whether the grouting is terminated or the pipe is blocked, the "crash" will occur.
The above operation is not only a waste of time and oil, but also inconvenient. Therefore, we try to replace the plug wire with the stop valve (valve switch) in the liquefied gas pipeline. In case of "crash", turn the valve core of the stop valve 90 °, the small hole is connected, insert the reversing valve with No. 8 iron wire (or brazing strip), reset the valve core, pull out the iron wire, and close the stop valve to resume work. This greatly simplifies the operation and facilitates the specific use.
In case of grouting interruption caused by grouting termination or pipe blockage accident, in order to prevent deposition in the pump or high-pressure rubber hose, the slurry in the high-pressure rubber hose must be drained, and the grouting pump and high-pressure rubber hose must be washed with clean water.
The traditional method is to remove the high-pressure hose joint and drain it directly. Due to the high pressure of cement slurry in the high-pressure rubber hose, it is easy to hurt people by spraying and rubber hose shaking, which also causes site pollution and affects civilized construction.
According to the analysis, we believe that the emptying valve can better solve this problem, so a tee with stop valve is added at the cement slurry outlet of the high-pressure grouting pump. When the holding pipe needs to be emptied, open the stop valve (on-off valve) on the tee for pressure relief, and then remove the rubber pipe, so as to avoid various dangers of directly unloading the joint and simplify the operation.
The above transformation was carried out at the construction site of Cangzhou post and Telecommunications Bureau. After comparison, the workers reflected well. For the pile foundation task of the building of Hebei Julu Electric Power Bureau, the high-pressure grouting technology is adopted in the foundation pit slope protection, and the two valves have played their due role in the grouting construction. When dealing with accidents, the operation is simple, time-saving and labor-saving, the oil and slurry discharge position is clear, the control is flexible, and the site sanitation is ensured. This is in sharp contrast to the first-class scene of other construction teams when grouting. The equipment has not been changed much, but the effect is obvious, which has been highly praised by the owner and the supervisor.