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Abstract Aimed at the seismic response and damage of fill subgrade，a large-scale shaking table model test of subgrade with the scale of 1：20 is introduced. The model subgrade is built by soil with a height of 1.93 m，length of 3.0 m and thickness of 1.4 m. A series of tests were performed with different kinds input seismic waves，amplitudes and frequencies. The dynamic responses of subgrade under earthquake，weak of portions，failure modes，as well as the influence of ground motion parameters are discussed. Results show that the subgrade has amplification effect to input seismic waves，and the effect become extremely prominent around the crest of the subgrade and the top of the retaining wall. The study also show that the top of the retaining wall and the crest of the subgrade are the vulnerable parts of subgrade and cracks normally appear near these parts under seismic motion. The amplification coefficients of the peak acceleration along subgrade slope surface decrease with the increasing earthquake amplitudes. The soil in subgrade has amplification effect to input seismic waves at high frequency and filtering effect at low frequency；and the filtering effect becomes more prominent with the increase of earthquake amplitudes. Lots of cracked locations are identified under gradually increased seismic. Vulnerable parts of the subgrade to earthquake loading and various factors that affect the earthquake-resistant behavior of the subgrade，such as the frequencies of waves，are discussed under seismic motions of different levels. The results are helpful to reveal the mechanism of subgrade damage under earthquake，and provide references for aseismic design of subgrade engineering.
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Received: 03 December 2010
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2011, Vol. 30 
