Study On Anchorage And Lap Properties Of Glass-fiber Mesh In Earthen Matrix

Our country’s earthen buildings have a long history and are widely distributed.However,the low strength and poor toughness of earth materials are always the most unsafe factors for earth construction.At present,fiber mesh has gradually become the most popular material in building reinforcement due to its light weight and strong toughness.Using fiber mesh to strengthen earthen matrix not only improves its strength,but also makes it have excellent crack resistance and higher bearing capacity.Whether the fiber mesh can give full play to its excellent performance in the earthen matrix depends on the bonding ability between them,which is the basis of their joint action.Therefore,this paper is supported by the National Natural Science Foundation of China: Study on the bonding mechanism and seismic performance of adobe masonry,through the pull-out test of glass-fiber mesh in earthen matrix,this paper studies the anchorage and lap performance of glass-fiber mesh in earthen matrix,and explores the bonding mechanism of glass-fiber mesh in earthen matrix,The bond constitutive model between fiber mesh and earthen matrix is established to verify the value range of effective anchorage length of glass-fiber mesh in earthen matrix,so as to provide theoretical reference for the application and popularization of glass-fiber mesh in practical engineering such as strengthening and repairing earthen buildings.The main research work of this paper is as follows:(1)The mechanical properties of the earth used in the test are tested.Through the geotechnical test,it is obtained that the optimal earth sand ratio suitable for making the earthen matrix is 1:1,and the mixing moisture content is 20%.Through the uniaxial compression test of raw clod,two kinds of chemical reinforcing agents,silicone acrylic lotion and polyurethane,were selected to strengthen the earth.Through the test,it can be found that the average compressive strength of earthen block strengthened with polyurethane is significantly improved,and the increase range can reach 102.96%.Therefore,polyurethane reinforcement agent is selected for chemical reinforcement of earthen materials in this test.The mechanical properties of the glass-fiber mesh materials used in the test are tested.Through the static tensile test,it is found that the single ultimate tensile strength of the glass-fiber mesh used can reach 501.43 MPa,which fully meets the test requirements of anchorage performance test and lap performance test in earthen surface layer.(2)Through the pull-out test,the mechanical characteristics of the anchorage bonding of glass-fiber mesh in the earthen matrix are studied,considering the anchorage length of glassfiber mesh in the earthen matrix,the thickness of relative protective layer of matrix and the spacing of fiber mesh,the pull-out test was carried out on 36 specimens designed and made,this paper analyzes and puts forward the method to improve the bonding performance between glass-fiber mesh and earthen matrix under the anchorage state.The test results show that the embedded length of glass-fiber mesh in the earthen matrix is the main factor affecting the bonding performance between them.In a certain embedded length range,appropriately increasing the buried length of the fiber mesh,the thickness of the protective layer of the matrix or reducing the spacing of the fiber mesh can improve the bonding ability between the two,so that they can work together better and give full play to the advantages of the two materials.(3)Through the pull-out test,the mechanical characteristics of the lap bonding of glassfiber mesh in the earthen matrix surface layer are studied,considering the influencing factors such as the lap length,lap mode and fiber mesh spacing of glass-fiber mesh in the earthen matrix,the pull-out test was carried out on 24 designed and manufactured specimens,this paper analyzes and puts forward the method to improve the bonding performance between glass-fiber mesh and earthen matrix under the overlapping state.The test results show that the lap length of glass-fiber mesh in earthen matrix is the main factor affecting the bonding performance between them.In a certain range of lap length,appropriately increasing the lap length of glassfiber mesh in the earthen matrix,adopting the bonding lap method or reducing the fiber mesh spacing can improve the bonding ability between them,so that they can work together better and give full play to the advantages of the two materials.(4)According to the test data,the mechanical behavior of glass-fiber mesh in the process of pulling out the earthen matrix is theoretically analyzed,to explore the bonding mechanism of glass-fiber mesh in each stage of the pull-out process of earthen matrix,the corresponding bond constitutive model is proposed,the rationality of the model is verified by combining the experimental data and relevant theories,the model is used to verify the value range of effective anchorage length of glass-fiber mesh in earthen matrix.It is found that when the anchorage length of glass-fiber mesh in earthen matrix is between 250mm～300mm,it can reach its ultimate tensile strength,and the bonding stress between them reaches the strongest state,which is in good agreement with the test data.