Prestressed Cable For Long-term Durability

In recent years, along with prestressed anchorage technology extensively applied, the efficiency research of long-term running of the prestressed anchorage system has been a hot topic in the field of geotechnical engineer. Based upon plenty of documents research and practice, with the help of the digging tests,analyzing and monitoring the prestress's changing of the being on service of anchor ropes, combining the analysis of numerical calculation, the long-term running of the prestressed anchor ropes is studied in the paper, and a series of research results are obtained which will be useful to therory and practice.(1) By one engineering and undergoing service for over 20 years of long prepare the site of the ropes of stress anchor to open to dig test, and get the allover length glue the preparing of connecting stress anchor noting of ropes to strach mass and drill a hole thickness etc. of accuracy and mortar safeguard body to contain very great impact towards preparing the run - time limit of the ropes of stress anchor.(2) Based on the analysis of the field excavation material, it is concluded that the operation of prestressed anchor after years in steel corrosion rule is "segmented" distribution, according to the different external environment in different corrosion features, "serious corrosion area, mild corrosion area and non-corrosive area.(3)Found the prestressing force of anchor ropes'long-term change law by site monitoring the stresses weaken law of the prestressing of anchor ropes that had used, which contains mutative characters and laws under different impact factor. The prestressing of anchor ropes' stresses weaken obviously in forty days after it had completed tensioning locking, especially in the first ten days. The stress attenuates to 20% of tension locked value, then it doesn't weaken obviously, though its general tendency is attenuation.(4)The drilling flexure results in prepare stress loss to have a certain impact on reinforcing of anchor ropes. The bigger the punching tortuosity is, the bigger the prepare stress loss is, the more weak the anchor ropes reinforce the rock at the same time, what is known from the numerical simulation test that raising the angle of punching is inversely proportional to the dimension to which the prestressed anchor cables generates stress on the rock. The prepare stress loss impact on stress and displacement value behind over a long period of time, however, it does not impact on the reinforcing scope obviously. The stress and displacement value's loss severity of prestressed anchor cables impacting on rock is directly proportional to the loss severity of prestressing force.(5)Analyzing different Anchor communities'separation distance in the numerical simulation test, get conclusions that after anchor communities'separation , distance reduces. After the cluster anchor spacing lets up, the anchor ropes of 7 m spacing prepares stress after losing 10% of reinforce effect anchor Ropes from the same 8 m spacing don't prepare the reinforcing of stress loss effect likeness;The anchor Ropes of 6 m spacing prepares stress after losing 10% of reinforce effect anchor Ropes from the same 7 m spacing don't prepare the reinforcing of stress loss effect likeness;The anchor ropes of 6 m spacing prepares stress after losing 20% of reinforce effect anchor Ropes from the same 8 m spacing don't prepare the reinforcing of stress loss effect likeness. The proper distance of the group anchors is obtained, which will have some reference value of the long-term running of the prestressing anchor ropes.