Effect of strain rate on consolidation behavior of Ariake clay and selection of the suitable strain rate

The effect of strain rate on the consolidation behavior of Ariake clay is investigated by the constant rate of strain (CRS) consolidation tests under different strain rates, and the suitable stain rate in CRS consolidation tests is discussed based on the comparison results of CRS consolidation tests and routine incremental loading (IL) consolidation tests. The test results show that the stress-strain curves of Ariake clay shift in a parallel manner to the right with the increase of the strain rate. The preconsolidation pressure (p_c) increases by about 17% and the coefficient of consolidation (c_v) in the virgin consolidation range increases by about 34% respectively with a tenfold increase in the strain rate. The values of p_c and c_v from CRS tests with a strain rate of 0.02%/min are comparable to those from IL tests. The average strain rate up to 90% of strain of 24 h in the virgin consolidation range of IL tests is close to 0.02%/min based on the calculation of average strain rates up to different strains in IL consolidation tests. It is suggested that the strain rate in CRS consolidation tests corresponding with the mean value of average strain rate up to 90% of strain of 24 h under different consolidation pressures in IL tests should be adopted.