The combined vacuum surcharge preloading method has the double reinforcement effects of vacuum preloading method and surcharge preloading method. The lateral extrusion deformation due to surcharge preloading was counteracted by the lateral shrinkage induced by vacuum preloading, which ensures the stability of the upper embankment,accelerates the subsoil consolidation and enhances the construction speed. Based on the practical engineering of expressway soft soil treatment,the full monitoring was conducted for the complete and effective observation sections,according to four field test sections. The analyzed results show that the main settlement reinforced by the combined vacuum surcharge preloading method occurs in the early and middle phrase; the settlement and rate is large in the early stage,reaches maximum in the middle stage and becomes little in the last stage; the maximum settlement rate is 0. 09cm/d and less than the allowable value of 1cm/d required by of surcharge preloading method, which indicates that the reinforcement effect of combined vacuum surcharge preloading method is significant.%真空堆载预压法具有真空预压和堆载预压双重加固效果,真空预压产生的侧向收缩变形与堆载产生的侧向挤出变形相抵消,保证了上部路堤的稳定性,加速地基土的固结,提高了施工速度.依托高速公路软基处理实体工程,设置四个现场监测试验段,对完整有效的观测断面的沉降进行了全程监测.分析结果表明,真空堆载预压法加固的路基沉降量主要发生在初期和中期,沉降速率在监测初期较大、中期时达到最大值,后期的沉降量和沉降速率减小,最后阶段最大沉降速率为0.09 cm/d,小于堆载预压规定的允许值1cm/d的要求,表明真空堆载预压法加固效果显著.
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