Considering that current analytical solutions for straight-line vacuum preloading method do not take the nonlinear property of soil and the time-dependent loading into account simultaneously, a general analytical solution was proposed. The solution was based on the assumption that the vacuum pressure distributes linearly along the depth of vertical drains, and additional stress caused by a general time-dependent loading was also considered. Detailed solutions were studied for three special loading schemes, i.e. instantaneous loading, ramp loading and multi-stage loading. The results show that consolidation degree is significantly affected by the variational ratio of compressibility index to permeability index(cc/ck), the ratio of ultimate effective stress to initial effective stress, and the loading time. When the ratio ofcc/ck is less than 1.0, a high ratio of the ultimate effective stress to the initial effective stress leads to a rapid consolidation rate. However, when ratio of indices cc/ck is higher than 1.0, the case is reversed. In addition, the maximum induced excess pore water pressure can be reduced by applying the load in stages. At the end of consolidation, a negative excess pore water pressure occurs, the value of which equals to vacuum pressure in vertical drain.%针对现有直排式真空预压法固结解未同时考虑土体非线性和逐渐加载这2个因素的不足,基于竖井内的真空负压沿深度方向呈线性分布的假设,同时考虑堆载引起的附加应力随时间的变化,采用非线性渗透和压缩模型,推导直排式真空预压法下竖井地基固结的通用解.在通用解的基础上,针对瞬间加载、线性加载和多级线性加载这3种特殊加载模式给出详解.研究结果表明:土体的渗透指数与压缩指数之比(cc/ck)、最终有效应力与初始有效应力之比以及堆载随时间的变化会对直排式真空预压法下的竖井地基固结度产生较大影响;当cc/ck<1.0时,最终有效应力与初始有效应力之比越大,固结速率越快;当cc/ck>1.0时,最终有效应力与初始有效应力之比越大,固结速率越慢;线性加载和分级线性加载可有效降低土体中的最大超静孔压;土体中的最终超静孔压为负压,在数值上与竖井内的真空负压相等.
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