昆明泥炭质土动剪切模量与阻尼比的试验研究  

Experimental study of dynamic shear modulus and damping ratio of peaty soil in Kunming

作　　者：丁祖德[1] 黄娟[2] 袁铁映[2] 彭立敏[2] 王志良[1] 

机构地区：[1]昆明理工大学建筑工程学院,云南昆明650500 [2]中南大学土木工程学院,湖南长沙410075

出　　处：《岩土力学》2017年第12期3627-3634,共8页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51768028;No.51308270;No.51408284);云南省应用基础研究计划项目(No.2013FB015);国家重点基础研究发展计划项目(973计划)(No.2011CB013802)~~

摘　　要：利用DDS-70型动三轴仪开展了昆明盆地泥炭质土的动力学参数试验研究,分析了不同围压、固结比、振动频率对泥炭质土的最大剪切模量G_(max)、动剪切模量G_d、剪切模量比G_d/G_(max)及阻尼比λ的影响规律。试验结果表明:泥炭质土的G_(max)随围压和固结比呈线性增大。随着剪应变dg的增大,泥炭质土的G_d减小,λ增大,当剪应变较小时,变化幅度较小,剪应变增大到一定程度后,变化速率加快。相同剪应变下,G_d随着围压和固结比的增大而提高。不同围压、固结比及振动频率下的G_d/G_(max)变化较小。围压、振动频率对λ的影响较为明显,而固结比对λ的影响没有明显的倾向性。根据试验结果,建立了考虑围压和固结比影响的G_(max)回归方程,采用Davidenkov模型及依据阻尼比与剪应变的经验关系,得到了泥炭质土的动剪切模量比及阻尼比模型,拟合结果显示,建立的模型能较好地描述泥炭质土的模量阻尼比随剪应变的变化规律。进一步对比分析了不同地区泥炭质土以及不同土类的模量阻尼比特性的差异性。Dynamic properties of peaty soils from Kunming basin are investigated through a series of undrained cyclic triaxial testing. The effects of confining pressure, consolidation ratio, and loading frequency on the maximal shear modulus G_（max）, dynamic shear modulus G_d, normalized shear modulus G_d/G_（max）, and damping ratio λ are analyzed. Test results indicate that G_（max） of Kunming peaty soil increases linearly with increasing confining pressure and consolidation ratio. G_d decreases as well as λ increases with increasing shear strain amplitudedg. When shear strain amplitude is small, G_d and λ change slightly. As shear strain increases to a certain degree, they change rapidly. G_d/G_（max） is weakly influenced by confining pressure, consolidation ratio and loading frequency, the damping behavior is significantly influenced by confining pressure and loading frequency and is weakly influenced by consolidation ratio. A regression model considering confining pressure and consolidation ratio is developed. Meanwhile, the relations are provided for G_d/G_（max） and λ versusdg by using the Davidenkov model. The results show that the fitting models can describe the variation for peaty soil well. The difference of dynamic shear modulus and damping ratio characteristics for peaty soils in other regions and different soils is analyzed as well.

关 键 词：泥炭质土 动剪切模量 阻尼比 动三轴试验 

分 类 号：TU431[建筑科学—岩土工程]