Abstract:With the continuous construction of transportation projects and the steady advancement of reconstruction and expansion projects, the analysis of differential settlement between new and old subgrades in soft soil sections has become increasingly important. For the reconstruction and expansion project of a coastal expressway, and combined with the design data of the old roads and the on-site engineering investigation data, the residual settlement of the old roads is analyzed and calculated. And the settlement of the newly-built subgrade is calculated by using the Lizheng-Soft Soil Embankment Calculation Module. The calculation results show that both the “cement mixing pile + foam concrete replacement” method and the “pipe pile + surcharge preloading” method can effectively control the differential settlement between the new and old subgrades and prevent the occurrence of longitudinal cracks in the pavement at a later stage, in which the “cement mixing pile + foam concrete replacement” method can better deal with the situation where the triangular area of the widened gradient section is not easy to be compacted, which can provide a reference for the widening scheme of soft soil sections in the future.
