公路软土地基处理的方法.pptVIP

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软土地基处理新技术

------预应力混凝土管桩组员：王帅、吕东洋、李鹏飞、原锡栋、杨文瑞过去在一般公路通过软土地区，由于线路等级标准不高，路基宽度窄、立交少、纵坡要求不严，且多低路堤，故对路基大部分地段处理工程少，仅对桥头高路堤部位重视些。但从高速公路出现后，因要求全立交、桥涵通道多，路堤高度多超过软土填土极限高度。加之软土中含有大量亲水胶体微粒，土体多呈海棉状结构，因其孔隙比大、含水量多、透水性小、抗剪强度低、压缩性强在路堤高填土的自重作用下，要经过较长时间才能趋地压密稳定、因此其沉降稳定要花费长时间。此外软土结构在大交通量、重载车辆的作用下，路基容易产生侧向膨胀挤出滑动，基底沉降现象也严重，为了增强压密稳定力度和较短时间达到最终沉降，消除侧向滑动位移，以免路堤向两侧膨胀挤出，确保路基及其外侧建筑物或其他农田、虾池、鱼塘的安全，因此必须对软基进行处理。对软土地基处理方法的几点体会：表层处理法01置换法02加载法03竖向排水法04?Thick?layer?of?soft?soil?treatment?design?is?difficulty?in?the?designof?foundation?treatment?and?is?the?key?to?the?success?of?the?whole?foundation?treatment?project.?At?present?domestic（国内的）?mostly?in?coastal?areas?is?relatively?rare,?the?commonly?used?treatment?measures?are?sand?pile,?crushed?stone?pile?and?cement?mixing?pile?and?CFG?pile,?vacuum?preloading,?prestressed?concrete?pipe?pile?and?the?EPS?lightweight?embankment?and?so?on.Allkindsoftreatment’sselectionmainlydependsonitsarea,thegeologicalhydrologicalconditionsoftreatmentsegment,thesuccessfullocalexperience,aswellastheEconomyoftreatmentprogram,etc.Thecommontreatmentsprogramindeepsoftsoilareasfollows:1、Cementmixingpile2、CFGpile3、PHC(PrestressedConcretePiles)4、Vacuumpreloading5、EPSembankment6、CompactedgravelpilePrestressedConcretePile12Prestressedconcretepilesrequirehigh-strengthconcreteandcarefulcontrolduringmanufacture.Castingisusuallycarriedoutinafactory,wherethecuringconditionscanbestrictlyregulated.Specialmanufacturingprocessessuchascompactionbyspinningorautoclavecuringcanbeadoptedtoproducehighstrengthconcrete.Thistypeofpileisgenerallylesspermeablethanreinforcedconcretepilesandmaybeexpectedtoexhibitsuperiorperformanceinamarineenvironment.Hardsteelpoints(fixedorattachabledrivingshoes)canbeusedatthetoeofjointedpilesforprotectionwhenpenetratin