基坑降水引起的相邻建筑物直接经济损失预测研究.ppt

directlosspredictiononbuildingsaroundconstructionpitcausedbygroundwaterpumping songjianxue zhengzhouuniversity 1 incollaborationwithsongdanju outline backgroundgroundwatertableafterpumpinggroundsettlementcausedbywaterpumpinggroundsettlementandsettlementgradientadjacentbuildingdirectlosspredictionpracticalapplication 2 1studybackground moreandmoreskyscrapers deepfoundationpits moreandmoreundergroundprojectsmetroundergroundshopmallresultin deepexcavation 3 zhengzhouinternationalconferenceandexhibitioncenter icec 4 zhengzhouicechotel 5 zijingshanmetrostation inthefuture thel 2metrolinewillrunbeneaththisstation herewillbeabusytransfercenterfortravelers 6 adjacentgroundsettlementandcrackcausedbygroundwaterpumpinginconstructionpit 7 pipelinecutbygroundsettlementthatresultedfromgroundwaterpumping 8 residentialbuildingsdamagedbygroundsettlementthatresultedfromgroundwaterpumping 9 howfar magnitude issettlementmagnitudetheonlyfactor 10 constructionpitgroundwaterpumping determiningofgroundwatertableandcontourafterpumping buildingdirectlossvs groundsettlementgradient groundsettlementgradient determiningofgroundsettlementandcontour adjacentbuildingdirectlossprediction 11 2groundwatertableandcontourafterpumping 2 1generalalgorithmforwatertabledetermining a solutionoffluidmechanism strictanalyticsolution b solutionofhydraulics approximatesolution 3 dstableflow 2 dstableflow 12 c numericalsimulation porewaterpressurenumericalsimulation 1 13 porewaterpressurenumericalsimulation 2 14 groundsettlementnumericalsimulation 1 15 groundsettlementnumericalsimulation 2 16 however thesealgorithmsaretoocomplicatedtobeappliedinpracticalproject ontheotherhand mostofthechinesecivilengineersareusedtofollowingthenationalcodessystem thismustbetakenintoconsideration 17 18 assumptions 2 dimensionstableflow withoutwatercuttingwallsurroundingthepit determiningofgroundwatertableafterpumping thegroundwatertablemaybeobtainedby 19 dupuit sequation 20 loessgeologicalarea alluviongeologicalarea 21 beforeapplying thevalidityoftheformulahastobechecked sixprojectsarechosenascasesstudy andonlyoneisdiscussedhere zhengzhoumetrostation athletecenterstation 22 23 24 calculatedwatertableandmonitoredwatertable 25 26 calculatedwatertableandmonitoredwatertable afterverificationinsixprojects itisfoundthatthedupuit sequationcanbeusedtodeterminethewatertableafterpumping 3 1algorithm soilcompressionaccumulation sca fortheconvenienceofengineers thealgorithmstipulatedinchinesenationalcode sca isemployed 3groundsettlementcausedbywaterpumping 27 s2 usuallyverysmall maybeneglectedaccordingtothenationalcode inordertoobtaineds1 themodificationfactor hastobedeterminedfirst 28 modificationfactor determinedbylocalengineeringgeologycondition 3 1 modificationfactor 29 modificationfactor 30 presume complywiththestandardnormaldistribution 31 take as0 29 thenthesettlementcalculationerror 32 4buildinglossresultsfromgroundsettlement 4 1mainassumptiononlydirectlossistakenintoconsideration 33 34 4 2algorithmthegroundneartheconstructionpitisdividedintoaseriesofdonuts 2 equation 3 1 isemployedtodeterminethesettlementofeachdonut themiddlelineofeachdonutistakenastarget 3 settlementgradientbetweenbordereddonutsisobtained 4 economiclossratevs groundsettlementgradientissetup 5 acertainscopearoundthepitischosen allbuildingslossinthescopeisaccumulated 35 4 3donuts4 3 1usually thegeometriccenterofpitissetasthecenterofalldonuts4 3 2theaffectingscope takenas5sw sw thedepthofwatertablefallingbeneaththepitground isdividedintoaseriesofdonutswiththeincrementas0 2sw 36 4 4groundsettlementgradient 37 groundsettlementgradientinthecaseproject 38 generally thefurtherthedistancefromthepitedgeis thesmallerthegroundsettlementgradientis 39 however ifadonutrunsacrossoverthesoilsurfacewhichisbelowandabovethewatertablebeforeandafterpumping thegradienthereislikelytoleapsignificantly 40 forthesakeofsecurity 1 istakenasthethresholdofgroundsettlementgradient 4 5thethresholdofdifferencesettlementbuilding 41 4 6therelationshipbetweengroundsettlementgradient g andeconomiclossrate ofbuilding 1whengissmallerthan1 0 2theoretically whengapproaches 1 3severalhistoricalcasesareemployedtosettherelationshipbetweengand suchas aboveparametersareallfromreference then theformoftheequationisdeterminedas 42 thepowelloptimizemethodisusedtoobtaintheparameters thena 0 9692b 30 4862c 0 03179 43 theformulaisderivedfrommasonrystructuresaroundconstructionpit 4 7buildingdirectlossprediction thedirectlossofdamagedbuildingcausedbygroundwaterpumpingmaybeobtainedas v currentvalueofbuilding and vn rebuildcostofbuildingv depreciationofbuilding 44 5practicalapplication acaseprojectischosentoverifythealgorithm 45 ifacertainbuildingislocatedinonedonut thengissetasthegradientofthedonut ifacertainbuildingiscross overseveraldonuts thengistakenasthemaximumgradientofthedonuts assumptions 46 47 48 49 50 51 52 discussiontakeitforgranted thebuildingslosswillincreasewiththeincreasingofwatertablefalling however theanalysisresultsshowthatalthoughthegeneraltendencyoflossincreasewithwatertablefalling atsomecertainspot thecurveturnstothereversedirection moredetailanalysisshowsthatthebuildinglossisinproportiontothegroundsettlementgradient ratherthansettlementitself andgisaffectedbythesoildistributionandwatertableofacertainarea 6conclusions 53 1thedupuit sequationisverifiedtobeadequatetodeterminethewatertableafterpumpinginconstructionpit 2fortheconvenienceofengineers thealgorithmstipulatedinchinesenationalcode soilcompressionaccumulation maybeusedtodeterminethegroundsettlement forthenorth eastpart