Study On The Anchoring Mechanism Of Umbrella-shaped Anchor And Its Reinforced Soil Slopes Technology

The soil layer anchor, which can make full use of the soil strength, improve the slope stability, have strong adaptability and low costs, has become the one of the most economic and effective technical method for slope reinforcement, Many experts has done a great deal of researches about it. In recent years, the umbrella soil anchor has become a hot research topic. It's a new kind of bit expanded structure which is developed based on the principle that the cross section area of umbrella in a closed state is small while the open area becomes bigger after stressed. Compared with the traditional technique of soil anchorage, umbrella-shaped anchor has the characteristics of efficiency construction, full pullout load capacity after first tensioned and no age limit. However, this technology doesn't come out for a long time, there are still some problems need to be solved,. So it is necessary to carry out further exploration.In this thesis, combined with the characteristics of the existing umbrella anchor, in view of the new type umbrella-shaped anchor without grouting anchor, designed and produced by Yangtze River Scientific Research Institute, carried out the research about the anchoring mechanism and application in soil slope engineering research. The specific research and the main achievements are as follows:(1) Based on the force transfer of the anchoring section, learned about the anchoring mechanism and bearing characteristics of the umbrella-shaped anchor. Based on the research of bit-expanded anchor, summarized estimation formula of the ultimate pullout load capacity and the failure mode while the soil slopes reinforced. Then according to estimation formula, verified the effect factors about the pullout load capacity.(2) with the method of theory combining with field test, carried out field tests of different sites, anchor depth and condition of hole, a total of 7 groups. The results further cleared the umbrella-shaped load-bearing characteristics, influencing factors of uplift bearing capacity and the destruction form, and the umbrella anchor uplift bearing capacity estimation formula of accuracy is verified.(3)The design method of umbrella-shaped anchor technology used in soil slopes have been summarized, then with a practical engineering, using the Morgenstern-Price method, through GEO-SLOPE /W software, analyzed the stability of the soil slopes which was reinforced by umbrella-shaped anchor, achieved the conclusions that the umbrella-shaped anchor can effectively improve the stability of soil slopes.