中文摘要：

土体在天然沉积过程中由于时间效应会产生次固结变形和结构性,两者都使土体的固结屈服压力增大,传统Bjerrum次固结模型无法解释后者的机理,也无法描述结构性土的次固结变形特性。通过天然沉积结构性土的次固结试验,基于Burland提出的孔隙指数Iv和固有压缩曲线ICL,分析了结构性土的次固结变形机理。当固结压力小于固结屈服压力时,天然沉积结构性土的结构强度抵抗了孔隙的压缩势,压缩曲线与固有压缩曲线间的距离△Iv随压力增大而增大,该阶段存在稳定的土颗粒骨架结构,土颗粒的蠕动变形受抵抗,导致几乎不产生次固结变形;而当土体处于临界屈服状态时,土结构强度受破坏,孔隙压缩势的抵抗作用消失,大孔隙骨架坍塌,Iv发生骤减,土颗粒的蠕动变形剧烈,次固结系数骤增出现峰值;△Iv随固结压力的进一步增大而减小,次固结系数的变化表现出与△Iv密切的线性相关性;基于天然沉积土SCL压缩曲线说明了天然沉积土的次固结变形不可能无限发展。

英文摘要：

Secondary consolidation deformation and structure of soil are produced during naturally sedimentary process due to time effect,and then the consolidation yield stress increases.Bjerrum model is not proper for the deformation mechanism of secondary consolidation of structural clays.Based on oedometer tests on Lianyungang structural clays and the concept of void index proposed by Burland,the deformation mechanism of secondary consolidation of structural clays is studied.Change of void ratio index（△Iv） ranges between the intrinsic compression line（ICL） and the compression line of natural sedimentary structural clays.When the consolidation pressure is less than the yield stress（termed as preyield state）,the structural strength provides the resistance to the compression potential of void.As a result,△Iv increases with the consolidation pressure before yielding of soil structure and the secondary consolidation deformation can be ignored during this stage.When the consolidation pressure exceeds the yield stress,△Iv decreases with the increase of the consolidation pressure mainly due to the collapse of the large void structure.The coefficient of secondary consolidation,Cα,reaches a peak value at the critical yield state and then decreases with the consolidation pressure.It is concluded that the secondary consolidation deformation will not develop infinitely due to the existence of the compression line（SCL） of natural sedimentary clays.