Analysis of surcharge preloading reinforcement effect in a certain expressway´s soft foundation

The surcharge preloading can control the post construction settlement of expressway foundation in soft soil area effectively, and it has great influence on the well operation of expressway. This paper analyzes the mechanism of surcharge preloading, and comes up with a conception of OEF, which can describe the reinforcement effect of road foundation accurately. By analyzing the settlement data about thousands of sections of the expressway in soft soil area, combining with the formation condition, the settlement regulation of soft soil foundation affected by the filling depth and surcharge preloading duration is summarized. The result shows that: with the increase of filling depth, the overall settlement of road foundation makes a rise; in addition, there is an approximate linear relation between the filling depth and primary consolidation settlement. While the OEF is in a low level, the effect of surcharge preloading is distinct. When the OEF goes to a certain degree, the effect of surcharge preloading will get down. There is an optimal duration of surcharge preloading, which can reduce the post-construction settlement and has excellent economic benefits. This conclusion has the reference significance to the design and applications of surcharge preloading of expressway soft foundation.