Waveform effect of cyclic loading of dynamic character and stiffness degradation characteristics of marine deposited natural soft clay

Dynamic characteristics of natural soft clay under long-term cyclic loading have been widely studied. However, the previous researches focued on the dynamic characteristics under only one kind of cyclic loading waveform. Different kinds of exterior cyclic loading affect the natural soft clay subgrade, such as earthquakes, high buildings, high speed rails, wave loads, oil tanks, reservoirs and so on, and they demonstrate different wave patterns. Stress-controlled dynamic triaxial tests are performed under the square, triangle, sine cyclic loading, and considering the effects of cyclic numbers, dynamic amplitudes, and frequencies, the dynamic characteristics of natural soft clay are studied and analyzed, and the dynamic characteristics under different cyclic loading waveforms are compared. For comparing the stiffness degradation of soft clay under different cyclic loading waveforms, degradation index defined by cyclic shear modulus is used to analyze the stiffness degradation process.