Matters needing attention for stretching and grouting operation

 Problems    |      2018-10-19
1. In order to ensure that the theoretical elongation value and the actual elongation value are within the specified range, additional friction must be reduced to ensure that the corrugated pipe positioning is accurate and there is no debris in the hole.
2. Calculate the theoretical elongation value and tensile control stress of the steel strand carefully according to the cable test report and tensile jack calibration test report before tension, and make detailed disclosure to the operators.
3. Carefully check all preparations before tensioning, mainly including: whether the concrete strength reaches tensile strength, whether the jacks, oil gauge and tensile control numerical table required for tensioning are corresponding, whether the installation of tubing is accurate, whether the anchor pad and steel strand are cleaned, and whether the tensioning record and the prefabricated beam are corresponding.
4. Tensioning shall be carried out strictly in accordance with the operation specifications, oil intake shall be carried out slowly, and lifting pressure, line drawing, quantity elongation and other work of jacks shall be basically consistent when the two ends are tensioned symmetrically.
5. The stretching shall be carried out in the prescribed order, and the stretching shall not be optional. The stretching shall be recorded carefully.
6. The grout ratio of cement slurry should be strictly controlled, including the consistency, mixing time and bleeding rate, as well as the static time and the slurry pressure.
7. Strictly observe the safety operation standards, and do not violate the rules. Do safety protection work.
8. Carefully check whether the oil pipe is aging, and do not stand near the oil pipe when stretching, in case the high-pressure oil pipe breaks or hurts people.
9. Workers shall wear protective glasses for grouting in the hole, so as not to injure eyes by spraying cement.