Experimental Study On Bearing Performance And Deformation Behavior For GFRP Anti-floating Anchor

Glass fiber reinforced polymer(GFRP)anchor has characteristics of high tensile strength,good corrosion resistance,low relaxation and strong anti-electromagnetic interference ability and so on.Using the GFRP in anti-floating engineering field is favorable,which also brings about a sense of progress meaningness.In this paper,two kinds of self-designed anti-floating anchors with different materials are used in outdoor pull test.Based on the new stress-testing method and the improved device of displacement test,bearing capability and deformation characteristics of different types of GFRP anti-floating anchor are studied in moderate weathered granite with the concrete floor.And the variation rules of the stress of the GFRP anchors,anchorage body,second interface between anchors and rock are revealed.The anchoring characteristics of anchors in foundation slab of different anchorage length,different bending radius and different bending length are obtained.At the same time,the rationality of this test method is also analyzed.Test results provide reference for the application of the GFRP anti-floating anchor.The main work and research results are as follows:1.Based on the destructive pull-out tests of steel and GFRP anti-floating anchor in different diameter and anchorage length,it successfully implanted the triple fiber bragg grating sensor series in the GFRP,anchorage body and the second interface.The bearing capacity of the test anchor and the variation of axial force and shear force in the anchorage body are researched.At the same time,the relative slip between the rod and the anchorage body is tested and calculated by the improved displacement testing device.(1)The maximum transmission depth of GFRP anti-floating anchor with diameter of 28 mm is 3~3.5 m and the maximum shear stress of the anchor reaches 4.2 MPa at 1.1 m.The distribution of axial and shear stress in the anchorage body and the second interface are similar to that of the rod,the effective length is 1.5~1.8 m,The maximum transmission and the maximum shear stress are at the depth of 0.45 m.(2)According to the destructive load,the bearing capacity of GFRP anti-floating anchor and steel anti-floating anchors with the diameter of 28 mm is respectively 360 k N and 320 k N,their optimal anchorage length is 4~5 m;the bearing capacity of GFRP anti-floating anchor with the diameter of 32 mm is 440 k N,the optimal anchorage length should be greater than 4.5 m.(3)According to the pull-out amount of GFRP anchor,the paper suggests to use the minimum load which is corresponding to the displacement of rod and anchorage body within 10~20mm to determine the ultimate bearing capacity of the bolt.(4)The test measures the pull-out amount of the rod and the anchorage body.It is advised that this test mode can be applied in the destructive and acceptance tests.2.The anchoring performance and the bonding characteristic of anchor with different anchorage length,different bending radius and different bending length are measured by the large-scale pull-out field test of anti-floating anchor in the inverted floor.The different influence factors on the anchor’s bearing capacity and pull-out amount are be comparative analysis.The bearing capacity and quantity’s change rule of different types of anti-floating anchor in concrete could be got.(1)The longer the bending length of GFRP anti-floating anchor is in foundation slab,the smaller the ultimate bearing capacity.But the longer the bending length of steel anti-floating anchor is,the greater the ultimate bearing capacity,which reflects the fact that the bending treatment of GFRP rebar weaken the bearing capacity.(2)Bending treatment of GFRP anchor can reduce the pull-out amount and play a role in limiting the sliding deformation.In addition,the appropriate increase of the bending radius of the bolt also helps to reduce the pull-out amount.(3)It is proved that the GFRP anti-floating anchor was fracture damage in the concrete after analyzing the stress change of the rod and the test phenomenon caused by continuing to pull the bolt after it broke.3.The causes of the abnormal failure of the test anchor are analyzed.The influence of the placement of the external anchorage test equipments on test results is studied.