低路堤下长江漫滩相沉积土的工程特性评价  

Assessment of engineering properties of Yangtze River backswamp sedimentary soil under low embankment

作　　者：刘维正[1] 石名磊[1] 

机构地区：[1]东南大学交通学院,南京210096

出　　处：《东南大学学报（自然科学版）》2008年第5期844-849,共6页Journal of Southeast University：Natural Science Edition

基　　金：江苏省交通科学研究计划资助项目(06y14;06y15)

摘　　要：针对长江漫滩典型沉积土的薄壁样,通过一系列室内物理力学试验,利用固有压缩曲线(ICL)作为描述原状土压缩特性的基准框架,探讨了该区域土层的基本特性.结果表明,长江漫滩相天然沉积软土具有强结构性.根据结构性土的孔隙比e由固有孔隙比eR与附加孔隙比es所组成,且在屈服后阶段,es与固结压力σv′成反比关系,及屈服前零压缩的理想状态,确定了原位屈服应力与原位压缩曲线.结合CPTU原位测试结果,从天然压缩特性和固结性状方面,分析得出了在低路堤结构下,附加应力未达到原位结构屈服应力,地基处于屈服前状态,长江漫滩相沉积土平均固结指标较大,地基沉降稳定快.为充分利用天然沉积土的结构强度,地基处理适宜浅层处置方案.Basic physical and mechanical characteristics of soil in Yangtze River backswamp were investigated based on laboratory and in-situ tests. First, one-dimensional consolidation compression tests were performed on the undisturbed samples of Yangtze River backswamp typical sedimentary soil, and intrinsic compression line （ICL） was used to describe the corresponding characteristics of natural sedimentary clays. Then, in-situ piezocone penetration test （CPTU） combined with laboratory permeability test were conducted to analyze the consolidation properties of undisturbed samples in Yangtze river backswamp. Results indicate that the Yangtze River backswamp soil has a strong resistance of soil structure. The void ratio e of structural soil is the summation of the void ratio sustained by the intrinsic fabric, ea, and the additional void ratio due to the structure, es. At the postyield state, es is inversely proportional to σ′v. From these findings and the idea condition of zero compression at the pre-yield state, the field yield stress and field compression curve can be determined. From the aspect of compressibility and consolidation characteristics, another conclusion can be drawn that the average coefficient of permeability and consolidation are large which manifests a faster stability of foundation settlement in this test road section at the pre-yield state, and shallow treatment method can be applied to the improvement of highway soft ground under low embankment in order to make use of the natural structural strength.

关 键 词：固结特性 压缩性 土结构性 长江漫滩 低路堤 

分 类 号：TU411[建筑科学—岩土工程] TU433[建筑科学—土工工程]