Behaviour of sensitive Leda clay under simple shear loading

An experimental investigation was conducted on sensitive Leda clay from Ottawa area using simple shear device. Both small strain and large strain tests were conducted. Carleton University simple shear device was improved to measure shear properties at small strain amplitudes. Strength tests at large strain levels indicate that Leda clay might reach a steady state during monotonic loading. Under cyclic loading, the clay deformed with progressively increasing cyclic strain. Liquefaction becomes a concern when cyclic stress exceeds at least 60% of their monotonic undrained strength. Few small amplitude cycles do not produce significant strength loss. Successful application of small strain quasi cyclic tests proved to be an optimum means of obtaining modulus and damping data in laboratory. Material specific modulus reduction and damping ratio curves are presented for Ottawa area Leda clay. Results show that behaviour of sensitive clays is not similar to that of typical non sensitive clays.