第二章基础第一节地基与基础的基本概念地基:支撑建筑物的土层一、天然地基和人工地基NaturalGroundandArtificialGround(一)天然地基NaturalGround:天然的能够受力的土层。种类岩石rock碎石土crushedstonesoil砂土sandysoil粘性土clay人工填土earth-fill(二)人工地基ArtificialGroundWhenthecapacityofthesoiltosupportloadsisn’tenough,artificialgroundhastobeused.压实法compactionmethod换土法replacementmethod桩基pilefoundationcompactor:压实机replacementmethodToimprovethebearingcapacityinvaryinggroundconditions,softspotsareusuallyfilledwithconsolidatedhardcoreoraweakconcrete,beforethefoundationislaid.Consolidate:加强、巩固Hardcore:碎砖石weakconcrete:低标号混凝土pilefoundationWhenafoundationislaidinpoorsoil,itisnecessarytoexcavatetoagreaterdepththannormaltoreachasolidbase.Ifagoodbasecannotbefoundatareasonabledepth,thenaso-calleddeepfoundationmustbeprovided.Thisusuallycomprisesaseriesofdrivenorcast-in-situreinforcedconcretepiles.Excavate:开凿、挖掘二、基础的埋置深度TheDepthofaFoundation1、浅基础shallowfoundation500MM≤埋置深度≤4米,2、深基础deepfoundation埋置深度≥4米适宜的深度?Whichelementsdecidethedepthofafoundation?地基情况thenatureoftheground地下水位的影响groundwaterlevel冰冻线frostline其它otherelements???三、基础的类型TypesoftheFoundations(一)按基础的形式分类dividingfoundationsbyforms1、条形基础StripFoundation特点:连续的带形,也可叫带形基础。适用情况:当地基条件好,基础埋置深度较浅时。。。材料:砖、石、混凝土、钢筋混凝土适用什么样的上部结构?2、独立式基础IndividualFooting特点:呈独立的块状,形式有杯形、阶梯形、锥形。Socketfoundation杯形基础Benchedfoundation阶梯形基础Conefoundation锥形基础Asocketfoundationisthefootingwithsocketforaprefabricatedcolumn.适用情况:当上部结构为框架时。。。framestructure:框架结构材料:钢筋混凝土。。。3、联合基础CombinedFooting1)柱下条形基础StripFoundationunderColumns:将柱下独立基础连接起来,形成连续的条形基础。Isolatedcolumnsarenormallysupportedonsquareconcretefoundationbases.Wheresuchcolumnsarespacedatcloseintervals,itisoftenmorepracticaltoprovideacontinuousconcretestripfoundationtocarryacompleterow,asisdoneforloadbearingwalls.2)柱下十字交叉基础CrossedStripFoundationunderColumns:将条形基础做成网格状,提高了基础的稳定性,使荷载分布更为均匀。3)梁板式基础BeamandSlabFoundation:有肋筏板基础。。。4)板式基础MatFoundation:筏板基础RaftWherethebearingcapacityisparticularlypoororthequalityofthesoilvariesconsiderably,araftfoundationisoftenrecommendedtosupportnormalbuildings.Thistypeoffoundationsimplyconsistsofareinforcedconcreteslab,onwhichthewallsarebuilt.5)箱形基础BoxFoundation(CellularMat)钢筋混凝土板与地下室墙组合的结构。。。basement:地下室basementwall:地下室墙6)桩基PileFoundation:桩、桩帽和系梁的系统,将建筑物荷载向下传递到适当的持力层。。。bearingstratum:持力层pilecap:桩帽、桩台tiebeam:系梁机械成孔灌注桩、人工挖孔桩、混凝土预制桩、管桩、高压旋喷桩、摆喷桩,钻孔桩,搅拌桩等(二)按材料分类:刚性基础、柔性基础dividingfoundationsbymaterials1、刚性基础RigidFoundation:材料:砖、石、混凝土抗压但抗剪和抗弯能力差。。。compressiveresistance:抗压shearingresistance:抗剪bendingresistance:抗弯刚性角:rigidangle拉力:tensileforce压力:pressure剪力:shear2、柔性基础FlexibleFoundation:抗压和抗弯剪能力都很好,不受刚性角的限制。。。材料:钢筋混凝土第二节常用刚性基础构造PartⅡTheConstructionofCommonRigidFoundation一、砖基础BrickFoundation1、强度strength:砖的强度不得低于MU10垫层bedcourse:水泥砂浆三七灰土三合土二、石基础StoneFoundation毛石基础RubbleFoundation尺寸:宽度和厚度≮150MM,长度为宽度的5~2。5倍。强度:≮M5CONSTRUCION:料石基础SquaredStoneFoundation:经过加工后的石料。基础的宽度除了按计算要求外,还应符合料石的规格尺寸。三、混凝土及毛石混凝土基础ConcreteandRubbleConcreteFoundation满足刚性角的要求什么情况下用毛石混凝土基础呢?当混凝土基础体积过大时,可以填充一些毛石。关于基础:按形式分类。。。按材料分类。。。不同的结构形式分别适用于不同的基础形式?设计一砖基础:上部墙厚200、基础高度480(最低下一级必须用两皮砖厚,一般每隔两皮砖厚收进1/4砖,也可两皮一级与一皮一级混搭。。。26~33o)