Working Mechanism Analysis Of Pre-stressed Anchors

As an effective support means, the pre-stress reinforcement technique is being used in the slope engineering, foundation pit excavation, and so on. Especially, with the development of highway construction and hydraulic power station engineering, a number of huge slopes need to be strengthened in order to keep them from failure by using the reinforcement technique that is combined by pre-stressed anchor rope and retaining structure, such as piles, walls, lattice beams. In recently, a new type pre-stressed anchor rope, the single bore multiple anticorrosion-anchors system (SBMAAS), which can undertake more working load and be extended into the deeper of slope soil or rock mass where the medium has better quality and is stronger, has been invented and used in some large hydraulic power station slope engineering in China. When the new type anchor rope and lattice beam are tied in together as a permanent integrated retaining structure, it becomes the most important, feasible and reliable reinforcement technique in hydraulic power high slope engineering which need to be in good condition during its lifecycle.Around the reinforcement technique combined by pre-stressed single bore multiple anticorrosion-anchors system and lattice beam, a series of research works, which include the mechanism and the analysis technique of the new type anchor, has been executed. In this dissertation, the main investigation works and some conclusions are summed up as follows:(1) An analytical approach has been set up for the tension or the compression anchorage which is embedded into the non-homogeneous stratum in order to study on the interaction mechanism between the pre-stressed anchor rope and the soil or rock mass. And then, it is proved out that the proposed technique is more practicable and reasonable for the calculation about the anchorage by contrasting the theoretical solution with the tests.(2) On the base of analyzing about the experimental results of tests in field, an analysis model for pre-stressed single bore multiple anticorrosion-anchors system has been developed from the forenamed technique about compression anchorage. A conclusion has been drawn out that the conventional analysis procedure to be used in design with interface shear stress uniform pattern may underestimate the new type anchorage's ultimate capacity by studying on the bond stress distribution characteristic and its effect factors, such as the synthesis spring stiffness, the interval of the element anchors and the diameter of borehole. Subsequently, some basic principles and methods have been proposed for the inner anchorage structure design.(3) In order to comprehend the interaction mechanism of pre-stressed single bore multiple anticorrosion-anchors system with rock mass, a numerical model is submitted and analyzed thoroughly by using the simulation procedure FLAC^3D. The numerical results not only verify the previous theoretical solution about the anchorage axial stress and bond shear stress but also discover a fact that the anchorage load is diffused as a "inclined compression bar" pattern alone the radial in rock mass near borehole.