1, ready for the tension before the work:
(1) T beam strength of concrete reaches 90% of the design strength before tensioning.
(2) good tension with working platform shall be built.
(3) the oil pump, jack, tools, anchor ring, clip, wrench, pliers, screwdriver, paraffin wax, copper gaskets, cotton and other ready.
(4) the removal of prestressed steel strand and the rust on the plate and concrete, prestressed steel strand to beam inside and no rust and flat plate surface has no rust, concrete and other debris.
(5) work was laid anchor ring and clip, put work before the anchor ring, prestressed steel strand bundle straighten out first, so that each bundle of prestressed steel strand five monofilament, in turn, work through the shackle of five hole;When the anchor ring beam doesn't work well, do not use a hammer or other hard surface of the iron work directly on the anchor ring.Hard thick mat board or other objects, work force make the anchor force uniform, prevent them from damage or deformation, anchor ring and plate should be consistent with strict work.Put clip, clip embedded steel, pipe, prestressed steel wire clamp, should make the living of each clip width consistent and all live clip sew into the center of the beam of prestressed steel strand, jaw exposed the length of the part should be consistent and tidy.
(6) put limit board and jack, jack can use chain or steel hook hanging in the erection of transverse pole, or use the lever hoist lift.Pay attention to the front and rear don't reverse position jack, jack should be put smooth, and jack, limit board and anchor ring to match between closely.
(7) after fit between pump and jack, oil pipeline and oil pressure gauge.Attention should be paid to jack and supporting the use of oil pressure gauge, jack the front end of the feed line.
(8) exhaust air, connected to the power supply, to the pressure oil pump slowly come on, make jack piston elongation reached 17 cm, so repeated three times, check whether there is any abnormal situation on pressure oil pump and jack.
(9) put the anchor ring and clamping piece, should give every time tool anchor ring wall and clamping piece daub wax.
2, tensioned prestressed steel strand: loosen the oil return line pressure valve and the corresponding decompression valve, tighten the oil inlet line of decompression valve, pressure oil pump operator on both ends with radio contact, ensure tension at the same time.In the process of tensioning, the operator must be gripped filling valve, see oil pressure gauge pointer at the same time, the oil will be subject to pointer can rise at a constant speed slow.On both ends of tension in the process, the operator often keep in touch, it is advisable to keep both ends the oil pressure gauge reading broadly, 10% at the beginning of the corresponding stress reading sigma k readings, researchers measured in straight board feet measured, recorder for recording, reading is accurate to mm.Continue to tension, to 90% sigma k readings, measuring elongation, arrived at the sigma 100 k reading, corresponding elongation measurement, record, operator take time at the same time, the pressure to 105 sigma k, keep the oil pressure gauge reading for 5 minutes.
3, pressure oil pump oil return: loosen the feed line of decompression valve and the corresponding pressure valve, tighten the oil return line of decompression valve, open the power supply, to pump oil, the operator when jack piston had just finished the fallback, loosening the oil return line of decompression valve, don't let the gas gauge pointer readings back up too high.
4. Remove the jack, on to the next bunch of tension.
5, and plugging of prestressed steel strand gap: after all the tension, prestressed steel strand water mud or plaster block seam, ensure that can achieve certain pressure grouting.
Safety matters
1, the operator had better wear goggles, prevent the pipeline rupture or joint is lax, injection hurt eyes.
All join points between 2, pressure pump and the jack, copper tube speaker interface should be in good condition, should tighten nut, such as oil, both ends of downtime at the same time, add copper gaskets or asbestos line.
3, pressure oil pump components on both sides of the end, the operator cannot is opposite is tensioned or tensioned prestressed steel strand.Tension in the process, must not touch the oil pipeline and jack.When there is pressure, can not remove the oil and the nozzle head.Tension has been completed, should wait for a few minutes, then remove the tensioning device.
4, rainy days when tensioning, should build fortification canopy, prevent the tensioning device in the rain.Tensioning area should be clearly marked, the tensioning personnel access to the tensioning area is prohibited.
5, oil pressure gauge must be chosen to safekeeping, verification on a regular basis.
The duct grouting
1, before grouting, grouting machine in the clear water is rinsed clean, prevent debris into the slurry pipeline.
2, grouting, pressure water flushing hole, or use the high pressure air blow hole.
3, the slurry shoulds not be too thin, water cement ratio control within 0.4, agglomerate cement may be used.
4, grouting and preparations were made, on the other end of the open mortar pump, pressure grouting.
5, when the grouting end discharge water, slurry, thick paste, screw die valve, continue to pressure grouting, grouting machine at this time of the pressure gauge reading rise, when its rise to cannot continue to rise, or 1.5 ~ 2 mpa, close the mortar pump, wait a few minutes, the pressure gauge reading is likely to decline, reopened mortar pump, the pressure gauge reading will rise again, when rose to 1.5 ~ 2 mpa, close the mortar pump.So many times, to both ends of prestressed steel strand gap is no longer a significant water out.Open the mortar pump, grouting of the closing valve.And then open the discharge valve, the pressure gauge reading to zero.
6, on to the next hole grouting work.
Matters needing attention
1, the hole grouting, mastering the spray pump personnel must wear goggles, wearing shoes, gloves, plugging grouting hole, should stand in the side of the hole, in case of mortar jet cuts.
2, if some passes from one end of the completion of grouting or grouting not full, must be from the other end of the grouting.
3, after the grouting, flush timely grouting pump, nozzle, valve, etc., to prevent on cement solidification, the use of unfavorable to the next.