Research On Anchored Effect Of Distributed Pressure-type Unbonded Pretressed Anchorage Cable On Slope

Depended on the National Science Foundation of China (50874085) with title of "anchor reinforcement mechanism and design method of pressure diffusion cable in slope reinforcement" and the Guangdong Provincial Science and technology plan project (63123), the stress features and anchoring role of the pressure diffusion cable is studied by means of indoor model experiment and numerical simulation as engineering background of Guanghe highway construction projects in this paper. The main contents of the research are as follows:①The general concept of similarity principle, finite-element strength reduction, limit equilibrium slice and centrifuge modeling test methods are briefly introduced.②By the principle of centrifuge model tests and finite element strength reduction, as well as pre-trial experience, the test program was proposed in this paper. Multi-function testing equipment for the geotechnical engineering is used to evaluate slope stability model for complex slope. The test program which the buried pipe and added loading in the slope was creatively put forward. In response to the program, FLAC was used to analyze the variation of slope stability of 3 cases as the non-steel pipe, within steel pipe, smaller or greater cohesion force between the rock slope and the media. Through the comparative analysis of slope's stress, displacement and safety factor, shear strain increment and the velocity vector, the results showed that the intensity variation of slope would be changed when the slope was placed by steel pipes. However, this influence was negligible when the shear strength indicators c,φbetween the steel and the media material is enough to small. The model test was recommended to reduce the shear strength indicators c.φ, which could verify feasibility and rationality of the test program.③Indoor model test was used to research the reinforcement effect of slope enforced by the distributed pressure-type unbonded pretressed anchorage cable. As Guanghe Highway of the No.6 Section from K24+583 to K24+810 of the right slope is the experimental prototype. The test model was designed based on the similar principles; In this experiment component ofⅠ~#model (non-reinforced slope),Ⅱ~# model (after anchoring slope), the slopes are increased weight to slide. The slope's deformation, the pre-stressed anchor's change and prestressed anchor the distribution of axial force were analyzed. And the destructive state of the slope and the pressure of the anchoring effect of dispersed, as well as pressure dispersed anchor force transfer mechanism were learned. Besides, a new method for calculating the safety factors was used based on similar principles, strength reduction, and limit equilibrium method of sub-solving the slope of the safety factor. The calculation results showed that the safety factor of the prototype non-anchor slope was 1.073 and the safety factor of the prototype anchor slop was 1.444, which meet the slope stability design requirements.④Using FLAC3D, numerical simulation was acceptd to analyzed the research content of the model test. The slope's stability with no reinforcement and the reinforced slope's stability, and the anchoring effect of the pressure diffusion cable are learned. The results showed that:increasing the slope weight can make the slope sliding occurred and the slope whose safety factor would be greatly improved from 1.07 to 1.47. The numerical calculation results are similar with the model test results to master the reinforcing effect of the anchor, which could forward to verify rationality of the test program.⑤The slope's stability was reduced by rotating the slope model in the model experiment, while, slope could be slided by increase loading. The slope's rotation and the loading process were studied for the slip surface and safety coefficien by numerical simulation.⑥According to the design data of right side high slope-site at No.6 tenders(K24+583-K24+810) in Guanghe highway, as a complement of indoor model experiment, numerical simulation is used to study he impact of failure on the slope stability during excavation while anchoring. And the stress feature, slope stability, and dispersed anchor reinforcement effect of working conditions are analyzed in this paper. The results showed that:the slope's safety factor with no anchor is 1.06, which can not meet the requirement of engineering design. So the reinforced slope stability increased significantly and the safety factor was 1.49, which all meet the slope stability design requirements.