Research On Numeric Simulation Of Bond Behaviors Between Anchors And Concrete

In order to maintain the structure and the rock mass stabilized, anchorage technology chains structure and stratum tightly by mean of inbuilting bolt in soil or rock stratum, which transmits structure’s tension or strengthen the stratum itself based on the shear stress between bolt and stratum around. The anchorage technology adopted in the Geotechnical Engineering improves the strength and reliability of rock mass, saves materials in engineering, reduces the dimension of structure and lightens the weight of member. It also has already became the one of the most effective methods to enhance the Geotechnical engineering stability and solve complex Geotechnical engineering stable question.With the promotion and application in the Geotechnical Engineering domain, anchorage technology is employed to the concrete stuctures by the majority of technicians,who consider the similarity of problems.Thereby, the concrete post-anchorage technique is used widely.In this paper, Numerical simualtion analytical methods is adopted to investigate the issues of interfacial bonding between anchor bar, mortar and concrete.ANSYS, a FEM software, is used to analyse appropriate mechanical model,which represents the composite consisted of anchor bar, adhesion agent and concrete, and the their interfaces between different materials.The paper selects a series of models of different constitutive relations of bonding interfaces, layer thicknesses of the adhesion agent and the outside dimension of concrete members, then calculates and studys these factors impact the cracking load, ultimate load and the distribution rules of shear stress in the two interface of anchoring system. Also, compared and analysed with the existing theoretical results. The main study findings are as follows:(1) Based on ANSYS, it is established that a universal model which calculate bonding-slip issues between the three-phase medium of bolt, adhesion agent and concrete and interfacial bonding-slip failure occurs among members.The analysis results indicates that the model established can reflect the mechanical properties of the anchoring system accurately.(2) In the case of the same geometric dimension of model, Some significant conclusions are obtained in the simulation by modifying the constitutive relations of bonding-interface in the anchoring system with reference to the first examples. Cracking load of the anchoring system is associated with the shear stiffness of bonding-interface and ultimate load and critical crack length increase with the increase of interface rupture energy.(3) Under the condition that the constitutive relations of bonding-interface is identical, the analysis is carried out regarding to the second examples, which means maintaining the bolt diameters and the outside dimension of concrete members unchanged, modifying the nozzle diameters (or layer thicknesses of the adhesion agent). The results demonstrate that cracking load of the anchoring system decreases a little with the increase of the layer thicknesses of the adhesion agent and the ultimate load is almost unchanged.(4) Based on the third examples, the calculations preserve bolt diameters and layer thicknesses of the adhesion agent unchanged, modifying the outside dimension of concrete members with the premise of the same constitutive relations of bonding-interface, showing that the cracking load and ultimate load remain unchanged.(5)Compared with the results obtained by theoretical calculations on a hypothesis that the cross-section of mortar layer can only transmit shear stress while neglect its normal stress, the numerical modeling analytical calculations indicate that the middle layers of adhesion agent exist axial stress. Therefore, if the shear stiffness is not small enough or the rupture energy is not big enough the theoretical results don’t quite match the numerical modeling calculations and these differences are caused by the axial stress. Thus, there are applicable conditions by using the previous theoretical calculation methods.