Secondary consolidation characteristics and settlement calculation of soft soil treated by overload preloading

In order to examine the secondary consolidation characteristics of the soft soil treated with overloading preloading and analyze the post-construction settlement of the soft soil foundation treated with overloading preloading, the soft soil of the Dongting Lake is remolded considering the influence of stress history on the structure of the soft soil. In the test, the field conditions are simulated, and the one-dimensional consolidation creep test of soft soil remolded samples is conducted after surcharge preloading and recompression. The results show that the main consolidation time of soft soil after unloading and loading after preloading is significantly shortened, which is about 1/3 that of soft soil without surcharge preloading, and the main consolidation time of soft soil is almost not affected by the construction of drainage shaft. Moreover, the higher the preloading, the smaller the secondary consolidation coefficient is, and the overloading preloading is helpful in eliminating the secondary consolidation settlement of soft soil. The secondary consolidation coefficient increases with the increasing building load. Furthermore, the secondary consolidation coefficient of soft soil without preloading increases slightly when the drainage shaft is set up, and that of soft soil after overload preloading decreases slightly, but the effect is not obvious. Considering the stress history and introducing the overload increment ratio, the relationship between the secondary consolidation coefficient and the overload increment ratio is found to be linearly decreasing. The corresponding calculation model is established, and the calculation formula of the secondary consolidation settlement is put forward. The results of the tests and analyses are of some guiding significance for the design and construction of precompression foundation.