ISSN 1000-3665 CN 11-2202/P

    加热对软土地基真空预压排水固结的影响研究

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

    • 摘要: 常规真空预压法在处理超软土地基时耗时较长,且加固效果有限。真空预压联合加热技术是近年来提出的一种新型软基处理技术,但国内相关研究刚刚兴起。针对宁波典型软黏土地基,利用自制的温控模型试验装置,设计并开展了真空预压联合加热与常规真空预压处理效果的对比研究,细致分析了不同加热温度情况下(常温~80 ℃)软土地基的温度、孔压和沉降的发展趋势,对比了不同技术加固前后土体的物理力学特性变化情况。研究结果表明:相比于常规真空预压法,真空预压联合加热技术能加快固结速率,减小工后沉降,提高软土地基承载力;当加热温度不高时,真空预压法处理效果随温度升高而增强,但这种趋势并非线性增长;当温度达到一定值后,热法联合处置技术的加固效果会衰减,甚至起反作用;通过对固结沉降的反演分析得出,相比于常温情况,40 ℃、50 ℃和60 ℃处理后软土固结系数分别提高30%、35%和5%;从处置效果和经济性出发,加热到40~50 ℃是热法地基处理技术的较适宜温度范围。

       

      Abstract: 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.

       

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