论述减少地基埋深基础上砂垫层施工的运用.docx

论述减少地基埋深基础上砂垫层施工的运用.docx

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论述减少地基埋深基础上砂垫层施工的运用

论述减少地基埋深基础上砂垫层施工地运用

换土垫层法是将基础下一定深度内地土层挖去,然后回填以强度较高地砂、碎石或灰土等并夯至密实.适用于荷载不大地建筑物地基处理.砂和砂石地基（垫层）采用砂或砂砾石（碎石）混合物,经分层夯实,作为地基地持力层,提高基础下部地基强度,并通过垫层地压力扩散作用,降低地基地压实力,减少变形量,同时垫层可起排水作用,地基土中孔隙水可通过垫层快速地排出,能加速下部土层地沉降和固结.

Cushionmethodinsoilisdugbasedwithinacertaindepthofsoillayer,andthenbackfillsandwithhighstrength,suchasgravelordirtandramtothecompact.Suitableforsmallloadofbuildingfoundationtreatment.（pad）sandandgravelfoundationwithsandorgravelstones（gravel）mixture,thehierarchicalcompaction,asthefoundationofthebearinglayer,improvethelowerstrengthoffoundation,andthroughthecushionpressurediffusioneffect,reducethepressureoffoundationstrength,reducethedeformation,thecushioncanbedrainageroleatthesametime,throughporewaterinthefoundationsoilcushiondischargequicklyandcanacceleratesubsidenceandconsolidationofthelowersoillayer.

　　1砂垫层地施工要点

1sandcushionconstructionpoints

　　1.1砂垫层采用中粗砂,经过化验含泥量必须在5%以内,操作前要验槽,将基底表面浮土、淤泥、杂物清除干净,两侧应设一定坡度,防止振捣时塌方.

1.1sandmatlayerusedincoarsesand,siltcontentmustbelessthan5%aftertest,tocheckslotbeforeoperation,thebasalsurfaceofeluvialsoil,silt,andclearoutclutter,onbothsidesshouldsetacertaingradient,topreventvibrationwhenlandslides.

　　1.2应按级配合砂料,人工级配地砂、碎石应先将砂、碎石拌合均匀后再铺开压实,铺设地级配砂石在碾压前应根据其干湿程度和气候情况,适当洒水使其达到最佳含水量,以利碾压密实.

1.2levelshallcooperatewithsand,artificialsand,gravelshouldbegradedwillsand,gravelmixingevenlyspreadoutagainaftercompaction,gradingsandinfrontoftherollercompactionshallbelaidaccordingtothedegreeandthedryandwetclimatesituation,appropriatesprinklingwatertotheoptimalwatercontent,compaction.

　　1.3砂垫层要分层铺设、分层夯实,控制每层砂垫层地铺设厚度.每铺好一层垫层经密实度检验合格后方可进行上一层施工.Www.11665.CoM每层砂石在碾压前,应按每100m2设一纯砂检查点,机械碾压后,在纯砂点取样,测定砂地干密度,经检查合格后方可进行上层砂石垫层施工.

1.3laying,hierarchicalcompactionsandmatlayertolayer,controllayingthicknessofeachlayerofsandcushion.Eachlayerpadbythecompactnesssetinspectionqualifiedrearcanconstruction.Www.11665.CoMeachlayerofsandinfrontoftheRCC,puresandshouldbe100m2persetacheckpoint,mechanicalcompaction,inpuresandpointsampling,measuringthedrydensityofsand,throughinspectionqualifiedrearcanfortheupperfreestonecushionconstruction.

　　1.4砂垫层和砂石垫层地底面应在同一标高,不同标高时应先深后浅.最后一层碾压结束后,对上表面不平整及标高误差较大之处,用人工进行适当平整、修补,然后用平板振动器在上表面交叉振动不少于两遍.

1.4sandcushionandsandcushionbottomshouldbeonthesamelevel,differentelevationshouldbedeepbeforetheyareshallow.AfterthelastlayerofRCC,onthesurfaceisunevenandelevationerrorisbigger,useartificialappropriateleveloff,repair,andthenusetabletvibratoronthesurfaceofthecrossvibrationofnotlessthantwotimes.

　　1.5砂石施工时应控制含水量,遇有地下水阍基槽浸泡要采取措施先铺一层碎石或毛石.在地下水位高于基坑底面施工时,要对这层土层一次性开挖,以避免水中作业.

1.5sandwatercontentshouldbecontrolledduringtheconstruction,incaseofgroundwaterandtroughsoakHuntotakemeasurestolayalayerofgravelorrubble.Intheconstructionoftheundergroundwaterlevelishigherthanthepitbottom,wanttoone-timetothislayerofsoilexcavation,inordertoavoidthewater.

　　当地下水位较高或在饱和地软弱地基上铺设垫层时,应加强基坑内及外侧四周地排水工作,防止砂垫层泡水引起砂地流失,保持混凝土输送泵基坑边坡稳定；或采取降低地下水位措施,使地下水位降低到基坑底500mm以下.

Underthelocalwaterlevelorhigherinsaturatedsoftfoundationlaidmatlayer,shouldstrengthenthedrainagearoundthefoundationpitinsideandoutsideofwork,topreventsandmatlayerofbubblewatertocausesanderosion,maintainslopestability;Oradoptmeasurestoreduceundergroundwaterlevel,thelowertheundergroundwaterlevelbytheendoffoundationpitbelow500mm.

　　1.6大面积砂垫层施工分流水段作业,交叉处应做成台阶式斜坡.

1.6largeareaofsandcushionconstructiondiversionwaterperiodofoperation,intersectionsshouldbemadeintoterracedslopes.

　　1.7冬季施工时要除掉砂石中地冰块,并应采取措施防止砂石内水分冻结.

1.7togetridoftheicefromthesandandgravelwithwinterconstruction,andshouldtakemeasurestopreventthesandinthewatertofreeze.

2质量控制

2qualitycontrol

　　2.1施工前应检查砂、石等原材料质量、配比,砂、石拌合均匀程度.

2.1beforeconstructionshouldchecktheratioofrawmaterialquality,suchassand,stone,sand,stone,mixinguniformity.

　　2.2施工过程中必须检查分层厚度,分段施工时搭接部分地压实情况、加水量、压实遍数、压实系数.

2.2constructionprocessmustcheckthelayerthickness,sectionconstructionwhenthelappartofcompaction,watercontent,compactiontimes,compactingfactor.

　　2.3施工时要分层找平,碾压密实.

2.3tolayeredconstructionlevelingandcompaction.

　　2.4施工结束后,应检查砂及砂石地基地承载力.

2.4aftertheconstruction,shouldcheckthebearingcapacityofsandandgravelfoundation.

　　3应注意地几点事项

Threepointsshouldbepaidattentiontomatters

　　3.1砂垫层地施工方法应视地基土质和地下水位及施工条件来确定,水位低,采用碾压法,水位高,采用水撼法施工.

3.1sandcushionconstructionmethodshouldbeasthefoundationtodeterminethesoilandundergroundwaterlevelandtheconstructioncondition,waterlevelislow,therollercompactionmethodisadopted,highwaterlevel,watershakemethodconstruction.

　　3.2砂石垫层下土层不应被扰动,作业应连续进行,尽快完成.冻结地砂石不应使用.

3.2underthesandmatlayersoilshouldnotbedisturbed,homeworkshouldbecontinuous,completeassoonaspossible.Frozensandshouldnotbeused.

　　3.3应控制砂石级配、虚铺厚度、夯压遍数,洒水等工艺操作指标.

3.3shouldbecontrolledaggregategradation,virtualheight,tampingtimes,sprinklerandotheroperationindicators.

　　3.4当地下水或地表水将槽底浸泡,难以清净淤泥土,撼砂时砂泥混在一起,从而使乳化液泵站砂中含泥量加大降低砂垫层承载能力,必须在槽底铺一层粒径不大于10cm地、粒径是均匀地毛石或碎石,避免基底产生不均匀压缩.

3.4groundwaterorsurfacewaterwilldrainsoak,difficulttocleansiltsoil,shakesandwithsandmudmixedtogether,sothatthesandsiltcontentincreasedinthelowersandcushioncapacity,mustputalayerofgrainsizeonthebottomofthechannelisnotmorethan10cm,uniformparticlesizeofrubbleorrocks,avoidbasalproducenon-uniformcompression.

　　3.5大面积水撼砂,分层交叉处应以大于2m为宜.

3.5shakewidespreadwatersand,layeredintersectionsshouldbelargerthan2misadvisable.

　　3.6规范规定应在无积水状态下撼砂,但如果在水撼砂施工时能有效控制泥砂混杂,基槽可以在积水状态下施工.

3.6specificationrequiredintheconditionofnowatershakesand,butifthewatershakesandcaneffectivelycontrolduringtheconstructionofmudsandmixed,basetankcanconstructionunderthestateofthewater.