高原湖相泥炭土次固结特性及机理分析  

Secondary consolidation properties and mechanism of plateau lacustrine peaty soil

作　　者：桂跃[1] 余志华[1] 刘海明[1] 曹净[1] 王兆昌 

机构地区：[1]昆明理工大学建筑工程学院,云南昆明650051 [2]中国有色金属工业昆明勘察设计研究院,云南昆明650051

出　　处：《岩土工程学报》2015年第8期1390-1398,共9页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金青年基金项目(51108217);云南省科技厅应用基础研究计划项目(2011FZ047);岩土力学与堤坝工程教育部重点实验室开放基金项目(GH201401)

摘　　要：泥炭土地基在长期荷载作用下将产生显著的工后沉降,必须明确其次固结特性及机理。针对取自昆明、大理的高原湖相泥炭土开展了一系列次固结试验,探讨了取样深度、加荷比R、加荷方式、固结压力p对次固结系数Cα的影响。试验结果表明：分级加载下,泥炭土的e–lgt曲线以反＂S＂型为主,次固结变形占总变形量的比例较大;泥炭土在宏观上与普通原状土存在相似的Cα–p关系,即Cα随p的增大而增大到峰值,之后减小并趋于稳定;但泥炭土峰值Cα对应的p不等于前期固结压力cp,而为100~200 k Pa。通过建立微结构模型,对泥炭土次固结特性进行了机理分析,认为峰值Cα对应的固结压力p应为泥炭土从多孔隙状态压缩至相对密实状态的临界荷载。昆明泥炭土的次固结系数和压缩指数具有一定的相关性,二者比值Cα/Cc可视为常数,和已有研究结果基本一致。The peaty soil foundation has notable post-construction settlement due to long-term loading. Based on the test results, the secondary consolidation properties of peaty soil from Kunming and Dali cities are studied, and some influencing factors of the secondary consolidation coefficients （Ca）, such as the depth of sampling, consolidation pressure （p）, loading ratio （R） and loading method, are discussed. The results show that the curve of e - lgt is mainly reverse ＂S＂, and the secondary consolidation deformation has relatively high percentage in the total compressive deformation. The secondary consolidation coefficient （Ca） of peaty soil increases with the increasing consolidation pressure to the peak value, then decreases slowly and stably. But the consolidation pressure corresponding to the peak value of Ca, is about 100~200 kPa, does not agree with the preconsolidation pressure （Pc）. The mechanism of the secondary consolidation is analyzed by establishing the micro-structure models for peaty soil. A conclusion is drawn that the peak value of consolidation pressure is the critical load which generates peaty soil changing from porous to tight state. Moreover, there is a significant correlativity between the coefficient of secondary consolidation and the compression index, and the Ca/Cc ratio is almost a constant value, which is consistent with the values reported in the literatures for similar soils.

关 键 词：泥炭土 次固结 固结压力 加荷比 Cα/Cc 

分 类 号：TU47[建筑科学—结构工程]