真空预压联合加热技术模型试验及作用机理研究

Model Test and Mechanism Study on the Ground Improvement Method of Vacuum Preloading with Heating

真空预压法处理吹填土和淤泥质土等超软土时,会出现固结速率慢甚至失效的情况.真空预压与加热相结合是近年来国内外学者对真空预压改进的有益尝试,但相关研究尚处于探索阶段.对此,设计了软基模型试验装置,开展了联合加热的真空预压与常规真空预压对比试验,结果表明加热能明显加快软基真空预压固结过程,且能增大软基预压期固结沉降.理论分析表明,相比于常温(22℃)情况,加热到40℃后地基最终沉降增加了23.8%,软土径向固结系数提高了80%.在此基础上,从土的温度效应、井周淤积和真空汽化等方面分析了加热对真空预压软土地基固结过程的影响,探讨了真空预压联合加热的作用机理和实际应用注意事项,研究结果可为真空预压联合加热的技术研发和推广应用提供参考.

The consolidation rate will be slow when the vacuum preloading applied to the treatment of super-soft soil,such as dredged soil and muddy soil. There will be some failure situation also in engineering practice for the use of vacuum preloading. The combination of vacuum preloading and heating is a useful attempt by worldwide scholars to improve the traditional vacuum preloading method in recent years. However,the related researches are still at an initial stage. A device for soft soil foundation model test was designed. Model tests for vacuum preloading with heating and conventional vacuum preloading was carried out and compared,respectively.According to the test results,the consolidation process was significantly improved by heating.Theoretical studies had shown that the final settlement increased by 23. 8% and the overall consolidation coefficient increased by 80% after heating to 40℃ when compared to the normal temperature condition( 22℃) . On the basis,the effects of heating on the consolidation process of vacuum preloaded soft soil foundation were analyzed. The mechanism of vacuum preloading combined with heating was revealed from soil temperature effect,siltation blockage effect and vacuum vaporization effect. Finally,the practical usage of vacuum preheating with heating was discussed in detail. The study results are expected to provide a theoretic support for the technology innovation and application promotion of vacuum preloading combined with heating.