A study of the effect of heating on vacuum preloading for soft ground

The conventional vacuum preloading method takes a long time to treat the super soft soil foundation, and its reinforcement effect is sometimes limited. The vacuum preloading combined with heating technology is a new soft ground treatment technology proposed in recent years. In this work, a model test device with a temperature controlling regulator is designed. One of the typical soft clay in the Ningbo area is applied in this model test. A comparative study is carried out to evaluate the effects of the vacuum preloading combined heating and conventional vacuum preloading treatment. The development trends of temperature, pore pressure and settlement of the soft soil foundation under different heating temperatures (from normal temperature to 80 ℃) are analyzed in detail, and the physical and mechanical characteristics of the soil before and after different technology reinforcement are compared. The results show that compared with the conventional vacuum preloading, the vacuum preloading combined heating technology can accelerate the consolidation rate, reduce the post-construction settlement and improve the bearing capacity of the soft soil foundation. When the heating temperature is not high, the effect of vacuum preloading increases with the temperature, and this trend increases nonlinearly. When the temperature reaches a certain value, the strengthening effect of the combined thermal treatment technology will be attenuated or even counter-acting. According to the inversion analysis of consolidation settlement, the consolidation coefficient of the soft soil treated at 40 ℃, 50 ℃ and 60 ℃ increases by 30%, 35% and 5%, respectively, compared with the normal temperature. Considering the treatment effect and economy, heating to 40~50 ℃ is the suitable temperature range of the thermal foundation treatment technology.