Research on settlement of soft ground under overloading-unloading and reloading

Base on the 4-year in-situ measured data,the change of settlement on soft foundation of express way under surcharge-unloading and reloading wass analyzed.The good effect was gained on the soft foundation treated with plastic drainage belt combined with surcharge preloading.The final settlement accomplished mostly during the period of filling and surcharge preloading.The rate of settlement decreased during the reloading after surcharge-unloading.Compared with the standard of post-construction settlement of express way,the settlement caused by reloading is evitable.The settlement didn’t accomplish quickly after reloading.It is unsuitable to calculate the primary consolidation settlement with the data of Cs as the settlement calculation in over-consolidated soil.Under the field experiment,a coefficient larger than 1 should be multiplied when modulus of compressibility and layer-wise summation method are chosed in primary consolidation settlement calculation under surcharge-unloading and reloading.