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Prestressed anchor cable construction quality control points.
(1) The steel strand, tensioning equipment and anchor gear shall be qualified as the factory certificate;
(2) The hole position, hole depth, pore diameter and hole inclination should meet the requirements of design and specification;
(3) The anchoring of consolidation grouting should be strictly in accordance with the technical specification for construction of hydraulic structure concrete grouting (SL62-94) requirements into the line, after filling the anchoring sound wave test, the average wave velocity should not be less than 3000 m/s;
(4) Remove the plastic casing in the anchorage section of the prestressed anchor cable, and the surface grease of the steel bar shall be clean and clean, and shall not distort in parallel with each other;
(5) the grouting of anchor hole shall start from the PVC grouting pipe through the bottom of the hole to ensure that the grouting is compacted, and the grouting record shall be accurate, complete and clear;
(6) The center line of the anchor pier shall coincide with the anchor axis, and the concrete construction of the anchor pier shall meet the standard requirements;
(7) Uniformly apply the tension load and control the loading rate, and the tensioning equipment must be calibrated and plotted;
(8) According to 5% of the total number of prestressed anchor cables, the sampling acceptance test shall be conducted according to the stress control: the measured value shall not be more than 5% of the design value, or not less than 3% of the design value;
When the grouting strength reaches 80% of the design strength, the tensioning prestressed anchor cable is started.
The tensioning equipment is required to be used, and the pressure gauge reading - tension relation curve is drawn and submitted to the supervision engineer with the official document.
Pressure gauges that have been removed, overhauled, or subjected to a strong impact must be re-calibrated.
The construction method of prestressed anchor cable tensioning is applied to the whole tensioning after pre-tightening.
In order to ensure that the steel strand is smooth and uniform, the steel strand should be pre-tightened by 10% of the design load.
The formal tensioning adopts the overall tensioning, which is increased by 25%, 50%, 80%, 100% and 110% of the design value.
The load applied uniformly, and the loading rate should not exceed 0.1 of the design stress per minute. After each stage of tension, the load was stabilized for 5min, and the elongation value of the measuring line was measured and recorded.
If the actual elongation value is greater than 10% or less than 5% of the theoretical elongation value, it is necessary to stop the tension and take remedial measures.
The tension load is locked for 10 ~ 20min after 110% of the design load according to the design requirements.
