堆载吹填淤泥并同步真空预压地基固结解析分析

针对软土地基堆载吹填淤泥并同步真空预压加固技术,考虑吹填淤泥的堆载作用在吹填时线性增长、在同步抽真空预压时指数形非线性衰减的变化过程,考虑地基附加应力沿深度的抛物线形非线性衰减变化、以及竖向排水体施工引起的涂抹效应,基于等应变假设,推导了软土地基在径竖向同时固结时任意点的超孔隙水压力和地基整体平均固结度的显式解析解答。运用该解答对某工程现场试验中软土地基的固结过程进行了计算,通过计算结果与实测结果的对比分析发现,采用所提出的解答,可以得到与实测固结度随时间变化趋势相一致的计算结果,验证了所提出的解答的适用性·同时也发现水平向渗透系数是决定计算结果准确性的关键参数。

Analysis of Consolidation due to Preloading by Vacuum and Surcharge of Hydraulically-Filled Mud Subjected to Synchronous Vacuum-Preloading

The synchronous vacuum preloading technique for treating soft ground and its overlying hydraulic surcharge fills is analyzed. The surcharge effect of hydraulically-filled mud is considered, involving the variations from linear increasing in surcharge with the process of hydraulic filling to non-linear exponential decreasing in surcharge with the process of vacuum preloading. The decrease in surcharge-induced stress with depth, as well as the smear effect due to installation of vertical drains, is also considered. Based on the equal strain assumption, explicit analytical solutions are derived for the excess pore-water pressure at any arbitrary point in soil and the overall average degree of consolidation of soft ground under simultaneously radial and vertical consolidation. The consolidation process of soft ground for a field test is calculated by using the proposed solutions. From a comparison of the calculated with measured results, it is found that the calculated results are consistent with the measured ones in terms of the tendency of the variation of the degree of consolidation with time. Thus it verifies the applicability of the proposed solution. Meanwhile, it is found that the horizontal hydraulic conductivity is a key parameter governing the precision of the calculated results.