Influences of overconsolidation ratio on undrained creep behavior of overconsolidated saturated clay

The results from creep tests on reconstituted clay are presented and used to develop a preliminary framework of undrained creep behavior of overconsolidated clay. Based on the results of undrained creep tests on the samples with different OCRs under the same stress ratio close to the slope of CSL, as the creep time increases, the pore pressure decreases to the end of creep, from a positive value to a negative one. The stress paths of the specimens with different OCRs all reach the critical state line. However, the highly overconsolidated specimens do not fail. At the beginning of creep, there are parallel lines for the relationship between the axial strain rate and the creep time for different OCRs. The specimens with higher OCRs are all in the state of stress dilatancy during the undrained creep. The higher the value of OCR is, the much more creep time the specimen reaching the greatest dilatancy state needs. Under the same stress ratio, the OCR is the important factor influencing the specimens to fail or not.