Research Of Bearing Capacity For Fully Grouted Anchor In Highly-Moderately Weathered Sandstone

The bearing capacity of anti-float anchor have a great influence on the stabilityof underground engineering with reference to the high groundwater level. Underengineering background of some super-high business-living building foundationanti-floating in PanYu,GuangZhou. Experimental investigation on anti-float anchorwere conducted to researching the bearing capacity of anchor in highly-moderatelyWeathered sandstone. Some conclusions come as follows.Based on analysis of displacements in loading process of pullout test.We candraw conclusion that in this test the bearing capacity of anti-float anchors are no lessthan840kN, Trough the destructive test the bearing capacity of two anchor are840kN,945kN;Base on the results of test,taking allowable displacement intoconsideration.When displacement reach5~10mm，taking corresponding load asultimately bearing capacity.The geological distribution have a significant influence on performance ofanchor.When some rock layer’slocation is near from the top of bolt that giving a fullyplay to bond strength of layer. Geological distribution should be considerate whencalculated bearing capacity.The results of test show that the bond strength characteristic value of siltyclay,strong-weathered and moderately-weathered sandstone weare respectively68.02kPa,117.12kPa,261.25kPa. These valus would be a reference for similarproject.According to the limitation of loading conditions in field test. Analysisingultimate bearing capacity of anti-float anchor in different layers by mathematicalmodels.The result shows that it is feasible to use mathematical models predicts theultimate capacity. The load-displacement relations and ultimate loads calculated from numericalanalyses produced good agreement with those measured by field tests.Under the sameloading level, the normal forces and displacements is nonuniform distributed alongdepth,and nolinear decreased as the depth increased. The main stress period of anchorin the range of30D (D is the diameter of anchor).Whether the grouted length（in acertain ranges）or diameter of an anchor increased, the bearing capacity of anchor alsoincreased. The geological distribution have a significant influence on performance ofanchor,which embodied in whether the rocklayer can supply a highly performance.Construction technology have a obviously influence on anchorage effect ofanti-float anchor.Improving construction process is a good way to increasing bearingcapacity of anti-anchor,while improving geometric characteristics have no obviouslyeffect.The conclusions of this paper were gained from anti-floating project offoundation in PanYu,GuangZhou and would be a important guidance for similarproject, and have realistic meaning in anti-float rockanchor study.