Research On Effects Of The Dynamic Test Signal By Subsoil Of Pile

The low Strain method has been widely used in pile integrity testing. In practical engineering test, reflected wave carry some important engineering information, such as pile length, bearing stratum characteristics, different subsoil of pile have different effects on signal. However, it is difficult for researchers to study caerfully, because stress wave attenuation occurs in propagation process. Torsional-shear wave and P-wave has a similar propagation theory, however, for the same defects, its reflected wave are inconsistent. It can not be used for engineering testing because the method of the excitation way still in the research stage.In this article, ANSYS / LS-DYNA is used to perform numerical simulation, torsionalshear wave’s excitation and extraction, subsoil of pile and sediment’s effetcion to stress wave are discussed, without considering material damping and soil damping.Firstly, simulating the propagation of stress wave in pile by LS-DYNA, determining the appropriate unit size and calculation parameter. Lateral inertial effect is also briefly discussed.Secondly, Based on the numerical simulation results of torsional-shear wave, experiments is tested in round pile and square pile. Using the auxiliary block can get a good signal for round pile is first proposed.Next, choosing different subsoil of pile, studying their differences from eflected wave shape, wave distortion, wave velocity, frequency. and then, verifing the result of numerical simulation by the model pile p-wave test.Lastly, when sediment esists at the bottom of end bearing pile, the influences of the thickness of sediment and the quality of sediment to stress wave are discussed. Further discussion to calculate pile length are performed, so that it can be applied to guide engineering practice.