第一章土的物理性质(双语)(精品)

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,第一章 土的基本性质和工程分类,CHAPTER1 Basic Characteristics and Engineering Classification of Soils,第一节 土的形成,1.1 The Formation of soils,一、土的搬运和沉积,The Transportation and Sedimentation of soil,土是岩石风化的产物,.,To the Civil En,gineer soil is any,uncemented,or,weakly cemented accumulation of mineral particles formed by the weathering of rock,the void space between the particles containing water and/or air.,运积,土,:,Transported soil,残,积土,:Residual soil,一,、,In a brief,soil is the products of weathering rock,.,The weathering action and main nature of soils,土的特征：,The characteristics of soils:,（,1,）,碎散性,:,（,2,）三相体系,（,3,）自然变异性,性质复杂，不均匀，各向异性且随时间而在不断变化。,注：岩石三相体系：固体矿物、液体、气体,二、风化作用和土和主要特点,第二节 土的三相组成,1.2,The Three-Phase Composition of soils,一、固体颗粒(,Solid Particle),一粒径级配(,Particle size gradation/grading,),粒径级配：粒径大小及其在土中所占的百分比.,界限粒径土性质改变的粒径尺寸,粒组以界限粒径为依据，根据其大小分为若干组,200 20 2 0.05 0.005 分界粒径,漂石 卵石 园砾 砂粒 粉粒 粘粒,块石 碎石,粗粒土（无粘性土）,(,coarse-gained soils/none-cohesive soil,),细粒土（粘性土）,(,fine-gained soils/,cohesive soil,),1.粒径级配的分析方法,筛分试验,sieve analysis test,d0.1mm(d0.074mm),筛分法,d 0.1mm(d0.074mm),水分法（比重计法）,12.,粒径级配曲线(,Particle size distribution curve),小于某粒径含,量,式中:,G,总称量，,X,筛余量,粒径,小于某粒径,土的含量（%,）,d,30,d,60,d,10,图1-1 土的,粒径级配累计曲线,1,3.粒径级配累积曲线的应用,d,60,控制粒径,d,30,特征粒径,d,10,有效粒径,不均匀系数(,coefficient of uniformity),均匀土 不均匀土,曲率系数(,coefficient of,curature,)：,表示连续性好:,判断,好级配土(,well-graded),：,（二）土粒成分（,Particle ingredient）,固体成分,1.,粘土矿物的晶体结构和分类,The crystal,structure,and classification of,clay minerals,粘土矿物：片状铝硅酸晶体,The basic structural units of most clay minerals consist of a silica tetrahedron(,四面体),and an,alumina,octahedron(,正八面体).,分类：（依硅片和铅片的组叠形式的不同）,高岭石（）,(,kaolinite,),1:1,亲水能力差,蒙特石（）(,montmorillonite,),2:1,亲水能力强,伊利石（）(,illite,),介于二者之间,2.粘土矿物的带电性质,利用电渗现象排水,片状粘土颗粒带负电的原因,极性水分子,阴极,电渗,水泵,原生矿物颗粒粗，呈粒状,次生矿物颗粒细微，多呈片状（,plate-like）,或针状(,needle-shaped),1.,粘土比表面积代表粘土特性的重要指标,2.,颗粒形状重要意义，磨圆度粗糙度与抗剪强度指标有关。,二、土中水,Water in soils,（三）颗粒形状和比表面积,（,一）结合水(,held water),1,强,结合水特性接近固体，完全不能移动,2.,弱结合水粘滞水膜，能发生变形，但不因重力而流动（土产生塑性的原因）,（二）自由水(,free water),1.,毛细水(,capillary water),毛细管中的,负 静水压力,h,c,u,c,自由水面,毛细水中张力分布,+,-,（1-6）,2,.重力水(,gravity water),三、土中气体(,air in soils),吸附于土颗粒表面及溶于水的气体,与大气相通的气体可以排出,封闭性的气体不可以排出,存在有封闭气体的土，称为橡皮土，工程中决不允 许,第三节 土的物理状态,1.3 The Physical State of Soils,一、土的三相关系（,The three phase relationships of soils）,三相图(,Three phase diagram/skeletal diagram/block diagram),（二）确定三相量比例关系的基本试验指标,（,The basic test indexes for decide the scale relationship of three phases）,1、,土的密度（,bulk density）,实验室：环刀法,容,重（,unit,weigt,）,2、土粒比重（,specific gravity of the solid soil particles）,3、土的含水量（,water content,or moisture content）,实验室：烘干法,（三）确定三相量比例关系的其它指标,1、,孔隙比,(,The,void ratio,is the ratio of the volume of voids,to the volume of solids,i.e),2、,孔隙度,(,The,porosity,is the ratio of the volume of voids,to the total volume of the soil,i.e),3、,饱和度,(,The,degree of saturation,is the ratio of the volume of water to the total volume of void space,i.e),The void ratio and the porosity are inter-related as follows:,4、饱和密度,For a fully saturated soil(,S,r,=1),saturated density is:,5、干密度,For a completely dry soil(,S,r,=0),dry density is:,6、,浮容度,When a soil in-,situ,is fully saturated the solid soil particles(volume 1 unit,weight G,s,w,)are subjected to,upthrust,(,w,).Hence the,buoyant,unit weight,(,/,)is given by:,i,e,三相指标的换算（表,1-5,）,二、土的物理状态,(The physical state of soils),（一）粗粒土（无粘性土）的密实度,(The compactness of,none-cohesive soil,),1,、,分类,(Classification),无粘性土：,（,1,）砂土,相对密度(,relative density,),In the case of sands the,relative density,(D,r,)is used to express the relationship between the actual void ratio(e)and the limiting values,e,max,and,e,min,.The relative density is defined as:,(1-19),疏松,中密,密实,(多用于填土方的质量控制),天然砂土的密实状态，还可根据标贯试验(,standard penetration test,STP),的锤击数,N,来区别：,N10,松散,10,N15,稍密,1530,密实,（,2,）碎石密实状态野外鉴别方法：,（二）粘性土（细粒土）的稠度,The consistency of,cohesive soils(fine-gained soils,),1.,粘性土的稠度状态,The consistency state of,cohesive soils,稠度，土的软件硬程度或土对外力引起变形或破坏的能力。,图1-20 土中水与稠度状态,半固体 塑性状态 流动状态,2界限含水量(又称阿太堡界限),The,Atterberg,limits,W,p,(plastic limit),试验室用搓条法（经验法）,W,L,(elastic limit),在试验室用锥式园锥仪,3.液性指数,(,The liquidity index),工程上用以判别,重,塑土软硬程度,表1-7,坚硬 硬塑 可塑 软塑 流塑,4、塑性指数（,plasticity index）,I,p,是细粒土分类的依据。,粘土(,clay),粉质粘土（,silty,clay）,（不代百分号）,第四节 土的结构,1.4 The structure of soils,决定土的性质的因素：,一、,一、,粗粒土（无粘性土）的结构（,The structure of,coarse-gained soils/none-cohesive soil）,单,粒结构（,single-grained,structure,）：,颗粒之间点与点的接触,二,二、细粒土的结构：（,The structure of,fine-gained soils/cohesive soil）,受范德华力，胶结作用力，库仑力，毛细压力,The net inter-,particle forces govern the,structural form,assumed by clay mineral,particles in a soil,the two extreme,structures are dispersed structure(,分散结构),and flocculent structure（,凝聚结构),.,The dispersed structure results when there is net repulsion(,净反力),between,particles and the,flocculent structure when there is net attraction（,净吸力）.,图,三、反映细粒土结构特性的两种性质,Two characteristics of fine-,gained soils reflecting theirs,structural nature,（,一）,粘性土的灵敏度(,The sensitivity of,cohesive soil),原状土的无侧限抗压强度,具有与原状土相同密度和含水量并彻底破坏其结