A Study On Longitudinal Dynamical Regulation Of Anchor System With Small Strain

Anchoring system on rock and soil is widely used in geotechnical engineering. ordinarily anchor system has lots of defects because of affected by different facters .It has a long time to study on how to find the defects and timely check the system,it is also a long time to search the ways in improving the bad anchor system.actually there are more orless shortages in different tests. The technology that is used in longitudinal dynamical test on bolt with small strain is a simple, economical rapid and tried one. There are three kinds of methods of anchor dynamical response: numerical method,analytical method and experimental method in this paper. Firstly, the theory of pile longitudinal dynamical response is utilized to determine the longitudinal dynamical response of an integrate anchor with small strain. And a mathematical-mechanical model is set up .An analytical solution is obtained in the time domain for the vibration of an anchor under a steady impulse load of sine applied at the anchor head. Based on the solution, the transient response of the anchor loaded by semi-sine force is acquired with superposition principle.at the same time, the problem described above solved in the frequency domain and the analytical solution for steady response of single anchor is developed under different boundary conditions by Fourier transform,inverse Fourier transform and Laplace transform. In the same way, an analytical solution is obtained in the time domain and in the frequency domain for the vibration of a defect anchor under a steady impulse load of sine or semi-sine applied at the anchor head. Secondly using the software of ANSYS, numerical calculates have been done to an integrate anchor and a defect anchor by 1-D and axis symmetry numerical calculate.to the method of 1-D, element of BEAM3 and element of COMBIN14 are used together. The problem has been solved by reduced option of transient analysis.and compared the result by numerical method with what by analytical method. Element of PLANE42 is used in axis symmetry numerical calculate. An analytical solution is obtained in the time domain to an integrate anchor or a defect anchor because of flaws in steel bar. To a defect anchor with bad mortar around it, the numerical method of modal analysis type is used to go ahead to research the corresponding frequency and the real part of eigenvalue. Lastly comparing with the result of numerical method and experimental method to the same model in lab, it shows that the result of numerical method is in accord with that of experimental method.