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1、摘要摘要隨著我國工程建設(shè)的發(fā)展,變徑灌注樁基礎(chǔ)越來越多的應(yīng)用于大(重)型建(構(gòu))筑物,雖然已有資料對變徑灌注樁的單粧承載機理有了介紹,但到目前為止,對變徑灌注樁這一新粧型的在豎向荷載作用下的沉降規(guī)律,以及其他因素對它豎向承載力大小的影響規(guī)律和粧及樁側(cè)、樁底土破壞規(guī)律的研究成果還是不夠,有待進一步研究。本文采用數(shù)值計算的方法對豎向荷載作用下單粧基礎(chǔ)承載性狀進行了研究。將研究主體樁身視為彈性體,而樁側(cè)和粧底的土體假定成理想彈塑性材料,根據(jù)以往前人對灌注樁的研究經(jīng)驗采用大型有限元軟件ANSYS作為計算工具對變徑灌注樁進行模擬
2、計算;針對變徑灌注粧的受力特點將計算模型簡化為平面軸對稱模型,并選用Goodman接觸面單元來模擬樁土之間的滑移問題。本文研究對象是變徑灌注粧,它的樁底和樁側(cè)是利用振動桿等向壓縮得到的夯實土,同時得到樁側(cè)土對樁的初始側(cè)向應(yīng)力,文中對樁側(cè)和粧底夯實土不同壓縮模量的土層厚度予以了假定。分析內(nèi)容如下:振動桿頭強行施加給土大小不同的側(cè)向壓力時,樁的沉降規(guī)律;側(cè)向力使樁的承載力提高的原因;側(cè)向力大小對樁的承載力提高多少;當(dāng)樁只加墊層時,樁底墊層厚度對樁的承載力提高多少和樁的沉降大小影響。關(guān)鍵詞有限元;接觸;樁基;變徑灌注樁;承載
3、性狀I(lǐng)燕山大學(xué)工學(xué)碩士學(xué)位論文Abstract燕山大學(xué)工學(xué)碩士學(xué)位論文Withthedevelopmentofmunicipalengineeringandlotsoflarge-scaleBuildingsandconstructionsbeingbuilt,Variantsectioncast-in-situpilesareusedmoreandmorewidelyinengineering,andthereissomedateonbearingbehaviorsofVerticalloadoftheVariant
4、sectioncast-in-situpilesforthepractice.butthestudyonthesettlementdisciplinarianofthenewpileoftheVariantsectioncast-in-situpiles,thecarryingcapacitychangerulesandthebreakruleswhenotherfactorsarevaried,isnotenough,thefiirtherstudiesareexpected.Themainpartstudiedin
5、thispaper,pilebody,wasconsideredaselasticbodyandthesoilbodyofthesideandbottomofthepilewasassumedastheidealelastic-plasticmaterialAccordingtotheformerstudiesondrivencast-in-placepile,thelarge-scalefiniteelementanalysissoftware,ANSYS,wasusedhereasthecalculationtoo
6、lforanalogycalculationofthevariantsectioncast-in-situpilescast-in-situpiles.Basedonthestresscharacteristicofthevariantsectioncast-in-situpilescast-in-situpiles,thecalculationmodelwassimplifiedtoplanerotationalsymmetrymodel,andGoodmancontactsurfaceunitwaschosetos
7、imulatetheslippingbetweenthesoilofthesideandbottomofthepile*TheobjectofnumericalsimulationisVariantsectioncast-in-situpilesandthesoilunderorbesidethepileistampedhomologyineachdirectionwithvibrationstaff.Thethicknessofthesoilunderorbesidethepilewithdifferentinten
8、sityispresumedinthispaper.Thecontentofthispaperwillbeintroducedasfollows.First,computethesedimentationandcarryingcapacityofthepilewithdifferentx—directionstresstotheb