Model test and numerical simulation of the pile tip resistance under different penetration depth

Abstract:

Macro and micro researches on pile tip penetration burried in different depth of bearing layer in pure sand is carried out under self-designed visual model test by the means of high-resolution digital imaging devices, the digital microscope visualization and image analysis procedures. The 3D non-circle particle PFC3D numerical simulation method is developed to mainly research the process of pile tip penetration in laboratary model tests in pure sand.The macro and micro variation of soil parameters is connected with the macro mechanical response in order to reveal the mechanism of soil variation aroud pile tip in the course of penetration. It mainly represents that pile tip resistance is closely related to the particle contact force around pile tip in micro side: the compacted area of particles at the bottom of the pile tip,the changing tendency of porosity and coordination number nearby the pile foot mainly decide the possibility of pile tip resistance’s change in correspond to the buried depths;when the ultimate pile tip resistance is reached, the slightly increase of capacity is caused by reinforcing effect induced by pile tip resistance to frictional resistance of pile surface side,which presented as the decreasing of porosity and increasing of contact force of particles around pile surface side in bearing layer in micro level.