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Abstract Effects of number of cycles，preloading frequency，dynamic prestress ratio，density，sampling technique，preshearing mode and duration of confinement on the maximum shear modulus(Gmax) of sand were systematically investigated by applying the preloading to the tested dry sand samples using the non-resonant vibration supplied by resonant column apparatus. Testing results indicated that：(1) The Gmax of dry sand decreased with increase of number of cycles when it was lower than a threshold number. At this threshold number，the maximum reduction of Gmax might be over 20% for some cases. (2) However，beyond this threshold number，Gmax started to recover with increasing number of cycles. The reduction of Gmax with number of cycles decreased with the increases of preloading frequency，dynamic prestress ratio and sample density；but their qualitative relationship was not affected by the sampling method and preshearing mode. The increase of Gmax with confinement duration was minor and the increase rate was slightly greater for the sample with preloading than that without preloading. The variation of Gmax with number of cycles may be accounted for the jointed effects of sample densification，interparticles wear process and particles reorientation or coordination number reorientation.
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Received: 30 March 2011
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2011, Vol. 30 
