长江漫滩相软土结构性特征及其工程效应分析

采用自由活塞薄壁取土器从地表至深度30 m取得不扰动原状土样，通过室内的固结压缩试验，并结合现场CPTU原位测试，利用重塑土的压缩与强度特性作为描述天然沉积土相应特性的基准框架，探讨了长江漫滩相天然沉积软土的物理力学性质。结果表明，长江漫滩相天然沉积软土具有高位结构性，固结系数Cv在土体屈服后急剧降低，屈服前后有明显的分段特征。同时指出，在静荷载水平相对较低的低路堤结构下，软弱土层沉积过程中形成的固结屈服压力和结构强度对其工程特性的影响相对更加显著。减小对天然沉积土的施工扰动作用、充分利用土结构力学效应、尽可能使地基工作于力学性质良好的屈服前阶段，在实际工程应用中具有重要的现实意义。

Structural characteristic and engineering effect analysis of Yangtze River backswamp soft soil

Free piston thin wall samplers were employed to obtain undisturbed specimens of natural sedimentary soils from ground surface to the depth of 30 m. One-dimensional consolidation compression tests performed on the undisturbed samples, and in-situ piezocone penetration test?CPTU, were adopted to investigate the physical and mechanical behavior of the Yangtze River backswamp soils. And then, intrinsic compression line (ICL) and intrinsic strength line (ISuL) of reconstituted clays were used as a basic frame of reference for describing the corresponding characteristics of natural sedimentary clays. The above results indicate that the Yangtze River backswamp soils have a high level of soil structure; consolidation coefficient Cv shows a rapid decrease after yielding and has obvious features of stages. Another conclusion could be drawn that the consolidation yield pressure and structural strength of natural sedimentary soils have more notable effects on engineering characteristics under lower static load level of the low embankment. Moreover, it's of practical value to decrease the construction disturbance of natural soil and make full use of the structural strength in engineering application.