冻土区桩基回冻过程对单桩承载力和桥梁施工的影响分析

232423(24)42294233200412ChineseJournalofRockMechanicsandEngineeringDec.200420043302004419*(50378043)[e-mail]121322(1730070)(2730000)(3210096)TU471.7A1000-6915(2004)24-4229-05INFLUENCESOFREFREEZINGPROCESSOFGROUNDONBEARINGCAPACITYOFSINGLEPILEANDBRIDGECONSTRUCTIONINPERMAFROSTWuYaping12GuoChunxiang1PanWeidong3ZhaoShiyun2ZhangLuxin2(1SchoolofCivilEngineeringLanzhouJiaotongUniversityLanzhou730070China)(2StateKeyLaboratoryofFrozenSoilEngineeringColdandAridRegionsEnvironmentalandEngineeringResearchInstituteCASLanzhou730000China)(3SchoolofCivilEngineeringSoutheastUniversityNanjing210096China)AbstractBasedonthetheoryofheatconductionthispaperpresentsgoverningdifferentialequationsofgroundtemperaturefieldboundaryconditionsinitialconditionsandfiniteelementmodelforsinglepileinpermafrostwiththeconsiderationofairtemperaturehydrogeologicalconditionsconcretetemperatureinitialgroundtemperaturefieldandphase-changeeffect.Foracast-in-placeboredpileinapracticalbridgestructurethatwasbuiltintherepresentativehumidpermafrostintheQinghaiTibetplateauthegroundtemperaturefieldofrefreezingprocesswascalculated.Thetemperaturesalongthepilebodyvariedwiththedepthandrefreezingtimewhichwereusedtoevaluatethevariationofbearingcapacityofthesinglepileandinfluenceoftemperaturesontheplanofbridgeconstructionaccordingtothebridgecode.Thepresentedprocedureandconclusionsachievedcanprovideatheoreticalbasisforshorteningconstructionperiodandlayingoutbridgeconstructionplaninpermafrostregions.Keywordssoilmechanicspermafrostcast-in-placeboredpilerefreezingbearingcapacityofsinglepilebridgeconstruction•4230•20041[12]2(1)[3]16m31m20mR10m30m(10m)11Fig.1Diagramofcalculationmodel(2)712d[45]712d(28d)31rTrrTryTytTC∂∂+⎟⎟⎠⎞⎜⎜⎝⎛∂∂∂∂+⎟⎟⎠⎞⎜⎜⎝⎛∂∂∂∂=∂∂lll(1)TClmT(TTΔ±m)Cl[36]⎪⎪⎩⎪⎪⎨⎧Δ+Δ+Δ-++ΔΔ-=)()(22)(mummufmfTTTCTTTTTCCTLTTTCC(2)[]⎪⎪⎩⎪⎪⎨⎧Δ+Δ+Δ-Δ--Δ-+Δ-=)()()(2)(mummmfufmfTTTTTTTTTTTTTTTllllll(3)fufCfl(kJ/m3)CulumTL10|)(TtryTt==(0r0.5m)(4)20|)(TtryTt==(r0.5m)(5)1T2T()2324.•4231•0=∂∂nT(r=R)(6)z=∂∂nT(=y30m)(7))(aTThnT-=∂∂l(=y0)(8)h15W/m2[7]z0.055/maT[8]⎟⎟⎠⎞⎜⎜⎝⎛+++=3ð46408ð2sin2.12satAtTT(9)61028.2-×=A/h=sT2.04.5t(h)(1)[9]tttpTtMTK}{}{dd][}]{[=+(10)][K][MtT}{ttp}{t][K][Mtp}{∑∫∫⎜⎜⎝⎛+∂∂∂∂=eT][][][NyNyrKl∑∫+⎟⎟⎠⎞∂∂∂∂eTd][dd][][ssNhrryNyNr(11)∑∫∫=eTdd][][][ryNNCrM(12)∑∫=eTad][}{stsNrhTp(13)(10)Crank-Nicolson+-=⎟⎠⎞⎜⎝⎛Δ+Δ-ttttppTtMK}{}{}{][2][ttTKtMΔ-⎟⎠⎞⎜⎝⎛-Δ}{][][2(14)(6)(9)CltΔ(14)41[3]fuC+DZ422.2kg/m2551.21/4228121/4Fig.2Meshingofquartercalculationmodel1Table1Hydrogeologicalandthermodynamicparameters/m/%/kgm3lu/kJm3lf/kJm3Cu/kJm3Cf/kJm3Cfu/kJm301.540.012004059569028302230622541.53.560.09002050305424801980781253.58.024.5150051055648248018713825884.0250097209720229022903986525006264626423002300•4232•20042Table2Groundtemperaturevaryingwithdepthandrefreezingtime30d45d60d/m10.0320.5330.2130.6590.4730.79020.0551.6250.3111.6110.4971.59730.1932.0530.5612.0450.7912.03740.7562.0801.0362.0721.2072.06550.6982.0420.9952.0361.1862.03160.5251.9570.9091.9531.0971.95170.4951.8450.7711.8460.9661.84780.5321.7590.8561.7551.0461.75190.7131.7041.0061.6951.161.686100.5881.6440.9451.6321.1181.620110.4171.5790.8281.5661.0291.552120.2711.5090.7091.4980.9311.483130.1601.4360.6071.4280.8391.415140.0741.3630.5241.3600.7631.349150.0131.2940.4661.2940.7061.286160.0191.2310.4331.2340.6691.228170.0091.1760.4301.1800.6531.176180.0591.1290.4591.1330.6591.129190.1871.0900.5171.0920.6821.088200.3641.0550.5971.0550.7191.0520.3051.4520.6591.5070.8601.507/%2143.7357.075()2257.07%(100%)5(3)[10]G.0.1G.0.1-13Table3DesignloadofsignalpileskN1#2#(+)2278.962599.652599.65()2037.141676.981676.98(++())1402.501062.501062.50()4[10]6.2.2-2][P=+=∑][21][0sAmlfUPii623.5kN(15)UU=3.141.03=3.2342mifil2324.•4233•4Table4Tangentialstrengthbetweenpileandsoil/kPa//kPa0.51.01.52.02.53.03070110150190230270(kPa)(m)4[10]G.0.1iilfΣ=3020=600kN0mm0=0.7AA=1.54m2][s=′+-+=222206)34(][ggsskdkd=××+××[phone]kPa(16)(15)3()[10]8.3.5][21][0stAmmFPii′+′′=∑(17)it(kPa)Fi(m2)m′′=′′m1.40m′[10]8.3.5=′0m0.7AA=3.140.72=1.54m2][s==0][ss350kPa40.5(17)[P]=3456kN30.5530d0.305()45d0.6596(1)()()(2)0.51.[M].19942.(JGJ118-98)[S].19983.[M].19994.[J].200227(5)5175205.[J].2003(3)27296CominiGGuidiceSLewisRWetal.Finiteelementsolutionofnonlinearheatconductionproblemswithspecialreferencetophasechang[J].Int.J.forNumericalMethodsinEng.197416(8)6136247.[M].19898.[J].198810(1)35399.[M].198810.(TB10002.5-99)[S].2000