Numerical Simulation On Anchoring Mechanism Of Pressure-dispersion Anchor Cable And Dynamic Response Of Ground Motion

The pressure-dispersion anchor has been widely used in geotechnical anchoring engineering as a new type of prestressed anchor cable. The theory about anchoring mechanism of the pressure-dispersion anchor lag behind engineering applications, the pressure-dispersion anchor features were infulenced by many factors. It still needs to study the anchoring mechanism of the pressure-dispersion anchor deeper, in order to gudie the design and construction effectively. At the same time, little papers about the anchoring mechanism of the pressure-dispersion anchor under the ground motion have been reported, but mainly concentrated in the study under the static state.On the basis of previous studies, this paper mainly research on the anchoring mechanism and characteristics infulenced by the parameters about the interface of grout-rock, the cell anchorage length and the anchor body diameter by using of numerical analysis. The dynamic responses of the displacement and stress about the pressure-dispersion anchor been studied under the factors of the different earthquake intensity by numerical analysis, the failure model of the pressure-dispersion anchor have also been discussed in this paper. The full text of research results are as follows:(1) The paper got some conclusions by setting four groups of grout-rock interface mechanics parameters to research the stress distribution of the anchorage by using of numerical analysis method. The peak of interface shear stress increases with the interface mechanics parameters within a certain range, while the effective distribution length of the interface shear stress decreases. The peak of grout axial compressive stress decreases with the increases of the interface mechanics parameters. The interface shear stress and the grout axial compressive stress decay rate increasing with the increasing of interface mechanics parameters. Under the condutions of the four groups grout-rock interface mechanical parameters and two groups of different prestension, the interface shear stress curves mainly presented in two forms with "rise+drop+plummeting+exponential decay" and "rise+steep drop" distribution.(2) The stress distribution law with different cell anchorage length in the soft rock were studied in this paper. Units of different length anchorage at the same loads, the peak shear stress declined with the increase of the anchorage length slightly, while the effective length of shear stress showed a slight increase with the increase of the anchorage length. The peak axial stress of the mortar body by anchoring segment length changes less affected, the peak axial stress and the distribution of length of mortar body with the external load increases. While the study also found that the plastic zone expansion speed and range about the shorter length of anchoring element much higher than the longer length of anchoring element. The results show that, in order to ensure a certain safety margin for strong weathered earthly soft rock slope reinforcement in the design, the cell anchorage length should not be less than3m.(3) On the condition of different anchor body diameter, the shear stress area and the grout axial compression cross area increases with the diameter of the anchor body. The anchoring section of receipt of the rock mass to the restraints are weakened, this will lead directly to the peak of the interface shear stress and the grout axial compressive stress significantly reduced, but the effective distribution length of shear stress would not increase with the anchor body diameter in the same proportion.(4) Under the load of horizontal seismic, the anchor cable force, the grout axial stress and the interface of shear stress will appera greater rate of increase in the earthquake process. When the initial pretension is200kN, the anchor cable axial force in the level of7^8^9earthquake process were increased by22.%,335%,48.9%, the peak of grout axial stress were increased by50%,64.5%,82.5%respectively.(5) There are three failure modes about the pressure-dispersion anchor, which mainly contain the anchor cable strength failure, the local compression damage in the grout, the outer anchor head failure under the earthquake.This paper was granted the National Science Foundation of China (50874085) titled "anchor reinforcement mechanism and design method of pressure diffusion cable in slope reinforcement" and the Guangdong Provincial Science and Technology Plan Project (63123) with title of "Key technologies research on instability prediction and disposal of expressway steep slope".