真空预压加固软土地基作用机理分析

真空预压技术已在港口、道路工程领域得到应用，但长期以来在作用机理的认识上还存在争论或不明确。结合工程试验资料，对真空预压加固区应力场、孔隙水压力变化以及有效加固范围进行了分析，结果表明，真空预压使加固区土体与膜上及周围土体间产生一个大气压差?P，在?P作用下地基土产生正的超静孔隙水压力?u，随着?u的逐渐消散而转化为有效应力，力学关系符合有效应力原理；真空预压作用下孔隙水压力测试应考虑?P的影响；真空预压与堆载预压在应力特点、附加应力传递、有效加固深度等方面有明显区别，工程应用中应充分考虑。

Analysis of action mechanism of treating soft foundation with vacuum preloading

Based on the engineering tests, the stress, pore water pressure and effective depth range of treating soft foundation with vacuum preloading are analyzed. The analytical results show that: the vacuum preloading brings atmosphere about pressure difference between treating groundsill and its entourage; and brings plus pore water pressure; the mechanical relation is accordant with effective stress principle. The test results of pore water pressure are influenced by atmosphere pressure. Vacuum preloading and surcharge have distinct difference in stress action characteristics, stress treating transfer and effective treating range etc.