The Study On The Settlement Of Road Soft Soil Foundation By Variable-weight Combianation Forecasting Model

The soft soil foundation has large settlement and the post-construction settlement will last for a long time under load. There will be potential post-settlement that maybe made largish harm to traffic and transportation for high-grade highways built on soft soil foundation, so it is necessary to calculate and forecast soft soil foundation settlement before. There are many factors that influenced the soft soil foundation settlement, and every factor varies with time, on the other hand the characters of soft soil are complex, so it is hard to ensure parameters of soft soil. Because of these, calculation and forecast post-settlement of soft soil foundation exactly become hot spot and difficulty. Therefore, to study and find out new methods of soft clay roadbed settlement calculation and forecast have important leading significance for our country's developing highway construction.Firstly, through the deeply study of developing law and characteristics of soft soil foundation settlement, the engineering properties of soft clay have been recommended and the conclusion has been obtained that the settlement developing experiences three stages The three stages are instant settlement, concretive settlement, shortly concretive settlement, whose characteristics are discussed. Secondly, based on the stress strain relation and the common law of soft soil foundation settlement, an idea has been put forward that the characteristics of consolidation settlement-time curve are similar with the S-type growth curve. Then based on the S-type growth curve models, a variable-weight combination forecasting method has been presented with the idea of combination prediction, and a variable-weight combination S-type growing model has been established, which can forecast the settlement of soft soil foundation at any time using limited measured settlement data. Finally, the settlement calculation programs are developed in Matlab programming language, which is applied in the engineering practice of Harbin circles city highway. The final results indicate that the effect of the prediction by the two models are superior to other former models and the methods are so flexible that they offer effective and applied ways in forecasting the settlement of soft soil foundation.