Dynamic Characteristics Research on Undisturbed Saturated Soft Clay

Abstract Due to the extremely strong rheological properties of soft clay, the dynamic characteristics of undisturbed saturated soft clay with sand layers in Ningbo area were studied. Experimental results demonstrate that the dynamic pore pressure, cumulative axial strain and double amplitude dynamic strain of unidirectional vibration cycle increase with the axial cyclic stress ratio increasing, and because the excess hydrostatic pore water pressure will gradually dissipate with vibration cycle increasing, the strain increases and the dynamic pore pressure decreases with the progress of vibration cycle. Besides, it can be noticed that the dynamic pore pressure and double amplitude dynamic strain of bidirectional vibration cycle are generally larger than that of unidirectional vibration cycle. Because bidirectional vibration cycle needs controlling the change of axial stress in the horizontal and vertical direction, larger instantaneous strain will be generated by external load, and excess hydrostatic pore water pressure is larger. In addition, due to the negative correlation between dynamic elastic modulus and strain, the dynamic elastic modulus of bidirectional vibration cycle is generally smaller than that of unidirectional vibration cycle. Finally, with the cyclic vibration continuing, energy is continuously lost and damping ratio decreases.