天然沉积结构性土的次固结变形预测方法  

A method for predicting deformation caused by secondary consolidation for naturally sedimentary structural clays

作　　者：曾玲玲[1,2] 洪振舜[2] 刘松玉[2] 章定文[2] 杜延军[2] 

机构地区：[1]福州大学土木工程学院,福州350108 [2]东南大学岩土工程研究所,南京210096

出　　处：《岩土力学》2011年第10期3136-3142,共7页Rock and Soil Mechanics

基　　金：国家自然科学基金资助项目(No.50878050)

摘　　要：结构性土存在着其特有的变形和强度特性,次固结特性也表现出明显区别于与重塑土。通过对连云港天然沉积原状土和重塑土进行一维压缩次固结试验,研究了典型结构性土的次固结特性。试验结果表明,土体由于受结构性影响,结构破坏前后其次固结特性发生明显变化;结构屈服前(固结压力小于固结屈服压力)不发生次固结变形或次固结变形甚微;当土体处于屈服状态时,土体次固结变形突然增大,次固结系数Cα出现峰值;结构屈服后(固结压力大于固结屈服压力),Cα随固结压力的增大而减小,表现为与当前的应力水平和时间密切相关的特性,应力水平对Cα的影响会随着次固结时间的增长而削弱。基于以上机制,建立了考虑结构性影响的次固结变形计算模型,该模型中Cα不仅与压缩指数Cc有关,且也与时间有关,基于该模型计算得到的Cα值和次固结变形均与试验值吻合较好。It has been well documented that the mechanical behavior of naturally structured clays is different from that of remolded clays due to aging during depositional and post-depositional processes.However,the effect of soil structure on secondary consolidation is still seldom investigated.A series of oedometer and secondary consolidation tests were performed on both undisturbed and remolded samples of Lianyungang marine clay to investigate the secondary consolidation behavior.The results show that the secondary consolidation behavior changes dramatically in the vicinity of the consolidation yield stress.When the consolidation pressure is less than the consolidation yield stress,the creep can be neglected.However,the coefficient of secondary consolidation Cα,increases dramatically in the vicinity of the consolidation yield stress.Then,Cα decreases with the increase in consolidation stress.It is also found that the coefficient of secondary consolidation is a function of the ratio of t over tp and compression index.A method for calculating the secondary consolidation deformation is also proposed based on the above relationships.The data compiled from available literature were used to verify the effectiveness of the proposed method.

关 键 词：次固结 天然沉积结构性土 固结屈服压力 沉降计算 

分 类 号：TU447[建筑科学—岩土工程]