中文摘要：

为解释公路路基在超载预压加固后工后沉降仍大于预测结果的现象,通过Bjerrum蠕变图及切线次固结系数定义分析了超固结土次固结系数的时间效应,建立了相应的次固结系数随时间增长的双曲线理论模型。鉴于实际土体的次固结特性比Bjerrum蠕变图揭示的复杂,故结合土工试验对该理论模型进行修正,提出更具普适性的次固结系数随时间增长关系式,并建立了与其相一致的工后次固结沉降公式,供超载预压工程估算工后沉降使用。研究结果表明：超固结土次固结系数不仅与有效应力定义的超固结比有关,而且也与次固结发展时间有关;当有效应力超固结比较小时,土体的次固结系数初期随时间迅速增长,后期可近似地认为其为常数;当有效应力超固结比较大时,土体的次固结系数初期随时间变化缓慢,但后期将有明显的发展,故次固结系数的长期时间效应不容忽略,在评估超载预压地基的工后沉降时应引起足够重视。

英文摘要：

In order to explain the phenomenon that post-construction settlement of highway subgrade reinforced by surcharge preloading is still greater than prediction,the time effect of secondary consolidation coefficient of over-consolidated soil was analyzed based on Bjerrum＇s creep diagram and the tangent definition of secondary consolidation coefficient,and then a corresponding hyperbolic theoretical model of secondary consolidation coefficient which increased along with time was established.As the secondary consolidation characteristics of actual soil were more complex than those revealed by Bjerrum＇s creep diagram,this theoretical model was modified by soil tests and a more generalized time-growth model of secondary consolidation coefficient was proposed,and a formula of post-construction secondary settlement corresponding to it was also established to estimate the post construction settlement in surcharge preloading engineering.The results show that secondary consolidation coefficient of over-consolidated soil is not only related to the effective stress defined over consolidated ratio,but also related to thedevelopment time of secondary settlement.When the effective stress defined over consolidated ratio is relatively small,the secondary consolidation coefficient of the soil increases quickly along with time in early period,and it could be approximately regarded as a constant in late period.When the ratio is relatively large,the secondary consolidation coefficient of over-consolidated soil increases slowly along with time,but it will have a significant development in late period.So its long-term time effect cannot be ignored,which must be taken seriously into account in evaluating the post-construction settlement of surcharge preloading ground.