Control Technology Research On Low Shrinkage Of Short Prestressed Anchor Cable

The traditional tension technology of pre-stressed anchor cable constructionusually use through center jacks and use the anchorage of follow-up clip. Because theelastic deformation of steel strand after the stress, the clips were driven and put theanchorage to the position of limit plate, and the limit plate stopped clips to moveoutward and only allowed continuous elongation of the steel strand until a maximumtension. When locking, Jack return, the more Jack shrink, the bigger the clampingforce, until the final locked. But when the clip retracted, steel strand also subsequentlyretracted, this caused the original tensile force have a certain loss, this loss accountedfor a smaller proportion of design tension and elongation value for the longer tensionanchor cable and could be generally solved by the means of over tensioning. But forthe short anchor cable, or when the tension was smaller, the retraction value of steelstrand accounted for a relatively larger proportion and made bigger pre-stress loss.Retracted follow-up force was also smaller for the anchor cable having less tensionwhen it was locked, this made the clips not tight and also prone to thread failure.Therefore, it is difficult to ensure the construction quality of pre-stressed anchor cable.In order to solve the practical problem that tension loss of short pre-stressedanchor cable is larger problems and retraction of tension of short pre-stressed anchorcable is relatively larger, this thesis reports on the tension control technology of theanchor cable, the investigation results revealed the low retracted control technology ofshort pre-stressed anchor cable, and the research results were applied in thepre-stressed pier of Pushihe Pumped Storage Power Station. It achieved the objectiveof reducing pre-stressed loss that used the technology of low retracted anchorage inthe construction of pre-stressed pier. At the same time, retraction and pre-stressedloss of low retracting anchorage is studied, the difficult problems that existed in theconstruction of short of pre-stressed anchor cable were solved, these provides basisfor design, and guide the construction, ensure the construction quality.Previously, there was not better solution for the loss of short pre-stressed anchorcable. The new construction technology of low retracting anchorage in this thesis isapplied for the first time in the field of domestic hydropower. This research will play aguiding role in the construction of similar projects in the future, and can be widely usedin vertical pre-stressed structure, such as large span pre-stressed concretecontinuous beam, continuous steel structure and etc. And can also be used intransverse pre-stressed structure of railway concrete beam, circumferentialpre-stressed structure of cable-stayed bridge tower, slope anchorage and othershorter pre-stressed cable structure with remarkable economic benefits and socialbenefits.