THE SETTLEMENT RATE STANDARD FOR EQUAL PRELOADING BASED ON HYPERBOLIC FITTING METHOD

Based on hyperbolic fitting method,two equations describing the relationship between the settlement rate and the residual settlement,and that between the residual settlement and the post-construction settlement,were established.The settlement rate standard and the unloading time prediction method under the conditions of equal loading were proposed.These formulas reveal that settlement rate was directly proportional to square of residual settlement,the ratio of post-construction settlement to the residual settlement depended on not only the consolidation rate of soil,but also the preloading duration with equal loading and the design working life of pavement,but the preloading duration had little effect on the settlement rate standard.Allowed settlement rates were a power function of the controlled post-construction settlements.An analysis of a case history showed that the settlement rate standards provided by the technical specifications and some local engineering experiences were suitable only for the embankment behind abutment,it took too long reloading time for the standards to be applied to common embankment and the embankment adjacent to structures such as culvert.