EXPERIMENTAL STUDY ON PERMANENT STRAIN BEHAVIOUR OF SILTY CLAY UNDER TRAFFIC LOADING

The permanent strain behavior of silty clay subjected to the high speed train induced vibrations is investigated. The over-consolidation ratio and various drainage conditions with different stress levels are considered in experimental study. As a result, the accumulation rate of permanent strain increases quickly in the initial number of cycles and then decreases constantly in the drained condition, then the accumulation of permanent strain achieve to a stable value. While the increase rate of permanent strain is very slowly in the undrained condition, but will act a sudden increase after a large number of load repetitions. The ultimate accumulated strain in drained condition is larger than in undrained one under the same cyclic stress level. It also can be deduced that the over consolidated samples exhibit more resistance against repeated loadings. For engineering application of ground settlement prediction during high speed train operation, a modified permanent strain formulation is presented, which has reasonably described the permanent strain of silty clay.