Field pull-out tests and failure model of GFRP screw anchors used to stabilize canal slopes of expansive soils

In order to repair the slide of the canal slope of expansive soil in Dengzhou County,Henan Province,China,the screw anchor made of glass fibers reinforced plastic(GFRP) is used to anchor the concrete frame girder above the berm of the canal slope of expansive soils and the concrete slab below the berm of the canal slope of expansive soils.The geogrid paved in fill soil of the canal slope improves the factor of safety against complete sliding surface,and the geofoam slab under the concrete slab is used to reduce the expansive force,and GCL under the concrete slab is used as seepage prevention liner.The field pull-out tests of GFRP screw anchor are introduced,and the test results of un-grouted and grouted anchors are presented.The average pullout force of the grouted anchors is 45 kN,and that of un-grouted anchors is 36 kN.The influences of anchoring parameters(such as superimposed soil thickness,anchor hole length,interval time between anchoring and pullout test) and soil type on the pull-out force and pull-out displacement of GFRP screw anchor are analyzed.Finally,the failure models of GFRP screw anchor observed in the tests are summarized.