雪峰山地应力英文报告.docx
- 文档编号:27777511
- 上传时间:2023-07-04
- 格式:DOCX
- 页数:21
- 大小:123.01KB
雪峰山地应力英文报告.docx
《雪峰山地应力英文报告.docx》由会员分享,可在线阅读,更多相关《雪峰山地应力英文报告.docx(21页珍藏版)》请在冰豆网上搜索。
雪峰山地应力英文报告
3-DINITIALGEOSTRESSREGRESSIVE
ANALYSISOFXUEFENGSHANTUNNEL
ChinaCommunication2ndHighwaySurveying,DesignandResearchInstitute
April,2002
Writtenby:
QiuXiangboLiShuchen
Participants:
LiShucaiChenCongxinQiuXiangbo
LiShuchenXuBangshu
Checkedby:
Prof.LiShucaiProf.ChenCongxin
1.PREFACE
XueFengShantunnel,averylongtunnellocatedatShangruiHighwayfromShaoyangtoHuaihua,Hunan,whichlengthabout2*7500meters,isthemostlonghighwaytunnelwhichalreadyinconstructiondesigningstepinourcountry.Althoughthesurroundingrockmassismostly“integral”,buttherearealsolocatedseveralpenetrativefaults.Partsofrockmassisalittlefragmented,whosedepthreachabout850meters.Thegeostress’magnitudeanddistributionwillplayanveryimportantroleonstabilityoftunnelwhencarryingouttunnelexcavationundersuchasituation.Geostressinsitumeasurementusinghydraulicfracturingmethodhavebeencarriedoutinthreebore,altogether28measuringpoints,theresultshowsthat,comparedwithotherarea’sgeostressinChina,itbelongtomiddlegeostresshorizontal.
Althoughtheinsitumeasurementisthemostdirectlywaytogetthegeostressfieldinformation,butforthereasonoflocationandexpense,it’simpossibletocarryoutinsitumeasurementinlargescale.Ontheotherhand,sincethecomplexityofgeostress’causeofformationandtheexcessiveimpactworkingon,themeasuringpoint’sresultisinfactjustthereflectionofalocalstressfield.Furthermore,sinceitaffectedbytheerrors,themeasuringresultis,tosomeextent,discrete.So,tosatisfytheneedofengineeringdesignandconstructioninamorereasonableway,itquitenecessarytocarryoutthegeostressregressiveanalysiswhichjointingtheinsitugeologicalconditions,througheffectivecomputationanalysismethod,andonthebasisinsitumeasurements.Thenwecangetthemoreprecisegeostressfieldwhichcanbeusedinalargescalearea.
Asfortheknowledgeofgeostress,it’sHeimwhofirstlyproposeof‘hydraulicpress’in1978,theninaperiodoftime,peopletaketherockmassaselasticbodyinthehalfinfinitespace,andtodeterminethegeostressbytherockmass’selfweight.Butsincethefifty’sofpreviouscentury,becauseoftheboomingneedofgeotechnicalengineering’sdevelopment,thegeostressmeasurementhasgrowledrapidly,andagreatamountofvaluableinformationhasbeenaccumulated.Peoplegettoknowthat,therearemanycausesofgeostress’formation,whichincludingrockmass’weight,constructionprocessofrock,constructionmovement,topographycondition,temperature,theearthsurface’scorrasion,undergroundwater,andearthquake,amongwhichthemostimportantisrockmass’weightandgeologicalconstructionprocess.Peoplealsoconcludedsomegeostress’distributionrulesfromthelargeamountofinsitumeasurementinformation.Todayinmiddleandlargescaleundergroundengineering,especiallyinlargescaleundergroundengineering’sstabilityanalysis,peopleareabletoanalysestheexcavationarea’sgeostressfieldonthebasisofinsitumeasurementoftheexcavationarea.Twokindsofnumericalanalysismethodsforgeostressfield’sanalysisaremostlyused:
oneisdisplacement-basedbackanalysismethod,whichistobackanalysistheinitialgeostressfromtheinsitumeasurementofthedisplacementofexcavation;theothermethodisstressregressionmethod,whichistoconstructthearea’sFiniteElementMethodcomputationmodelonthebasisoftheknowledgeoftheformationofthearea’sgeostressfield,andtogetthebestfittingresultbetweenthemeasuredandthecomputedgeostress,thengettheinitialgeostressoftheexcavationarea.Thelattermethodisadoptedinthisanalysis.
2.PRINCIPLEANDMETHODOFREGRESSIVEANALYSIS
Onthebasisofthegeologicalmechanicsanalysis,thegeostressaremainlycomefromtheselfweightandthegeologicaltectonicstressfield.Theanalysisforthegeostressconstructthenumericalcomputationmodelonthebasisofsuchaviewpoint,andcarryoutfittinganalysisusingmultivariateregressionanalysismethod.
Fromtheprincipleofmultivariateregressionmethod,wetakethecomputationalvalueofgeostress
asthedependentvariable,andtaketheselfweightstressandthecomputationalstress
whichcorrespondingtheFEMcomputationandtheinsitumeasurementastheindependentvariable,thentheregressionequationtaketheformas:
(1)
wherethekisthenumberofthemeasurepoint;
istheregressionvalueofthek-thpoint,
isthemultivariateregression’scoefficientwhichcorrespondingtotheindependentvariable;
and
aretheone-rowmatrixofthecorrespondingcomputationalstress;nisthenumberofworkingcase.
Assumingtherearemmeasuringpointsaltogether,thenthesumofsquareoftheresidualerrorofminimumsquaredeviationmethod is:
(2)
where:
isthemeasurementofjstressatthek-thmeasuringpoint,
istheFEMcomputationalvalueofjstressatthek-thmeasuringpointundertheiworkingprocess.
Onthebasisofprincipleofminimumsquaredeviationmethod,thenormalequationwhichminimizethe
is
(3)
Solvethisequation,wegetnregressioncoefficientL=(L1,L2,……..Ln,)T,thentheinitialregressionstressatPpointcanbegetbyaddingthepoint’scomputationalvalueunderallworkingprocesses
(4)
wherej=1,2,……..6correspondingthesixpartsoftheinitialstress.
FortheregressiveanalysisofgeostressatXueFengShantunnel,basedonthemeasurement,wecantakethegeostressfieldasthesumoftheselfweightandtheboundarytectonicstressfield,throughdecomposing,simulatingtheselfweightandboundaryloadstressfield,andthengetthecompoundthecomputationalstressfieldatlast.
Selfweightstressfield:
adoptingthemeasureddensityofrockmass,computetheweightstressfieldcausedofselfweight,simulatingthemodel’ssideandthebottomdisplacementrestriction,butrestrictit’snormaldisplacement.
Tectonicstressfield:
byaddinghorizontalaveragingunitpressureontwosides,tosimulatehorizontaltectonicstress.Forthenoloadingsideandbottomboundary,therestrictionisassameasthecaseofselfweightstressfield.Andsimulatingthehorizontalshearstressbyaddingtheboundarydisplacementrestriction,adding0.002m’sdisplacementonthelongerboundary,andadding0.008m’sdisplacementontheshorterboundary(asforthemethodofgettingshearstressfieldbyaddingboundarydisplacement,pleaserefertothereference[1]).
3.REGRESSIVEANALYSISOFTHEGEOSTRESSFIELD
3.1ComputationareaandtheFEMmodel
IntheareaofXueFengShantunnel,thereareallthreebores.Tobettersimulatethegeostressfield,wetakethecomputationareaintunnel’saxesextendingabout8000m,andnormaltoaxisextendingto2000m,theheightequationisfromsurfaceto0heighthorizontal.Theoriginislocatedat(480000,1010000)inlandcoordinate.Thecalculatezoneanddrillpointspositionsketchmap,pleaseseefig.1.Tomodelingconvenience,wetakethenorthdirectioninlandcoordinateasYaxis,andtheeastdirectionasXaxis,uprightnessdirectionasZaxis.Thereareall20531equa-parameterelementsand15485nodesincomputationarea.TheFEMmeshisshowedinfig.2.
Fig.1CalculateZonePlaneandDrillPointsPosition
Fig.23-DFEMMesh
BasedonthegeologicalinformationofXUEFENGSHANtunnel,themainrocktypesconsideredincludemetsandstone,silicasandshaleandmylonite,andthemainlyconsideredfaultsincludeF2、F3、F4、F5、andF6,thegeologicaldistributionisshowedinfig.3,themechanicalparametersareshowedintable1.
Fig.3GeologicalsectionofTunnelAxis
Table1Mechanicalparametersofrockmass
Rocktype
Young’smodulus(GPa)
Possion’sratio
Density(T/m3)
35
0.26
2.71
59
0.16
2.74
35
0.26
2.71
30
0.24
2.7
33
0.23
2.70
F2
20
0.35
2.68
F3,F4,F5,F6
22
0.27
2.68
3.2Resultofregressionanalysisofgeostress
Usingtheinformationof28measurepointsinthreehole,aswellasfourthree-dimensionalFEMsimulationofgeostress,throughcarryingoutmultipleregressionanalysis,wegettheregressioncoefficientoffourindependentvariable(correspondingselfweightstress,tectonicstressontheaxisdirection,tectonicstressnormaltoaxisdirection,andshearstressinhorizontalplane)asL1=0.9737784,L2=28.33104,L3=4.792041,L4=15388.15.Themultiplecorelationcoefficientr=0.9542671,closingto1,whichmeanstheregressioneffectisgood.ThepartialcorrelationcoefficientV1=0.9407532,V2=0.9330360,V3=0.7743598,V4=0.3596208,theformerthreepartialcorrelationcoefficientareallpreferably,meansthattheselfweightstress,thetectonicstressoftunnelaxisdirection’,andtectonicstressnormaltotunnelaxisaddedonthemodelaremoreprominenceforthemeasurements,andcan’tbeeliminated.
Aftersolvingindependentvariables,takingthemintoequation
(1),andwegettheregressionvalueatthemeasuredpoints.Thecomparebetweenregressionresultsandthemeasuredvalueareshowedintable2.
Table2.Compareofthemeasurmentsandtheregressionresults(Mpa)
Numberofbore
Depth
(m)
Measurements(Mpa)
Fittedvalue(Mpa)
Max.horizontalprinciplestress
Min.horizontalprinciplestress
Bodystress
Max.horizontalprinciplestress
Min.horizontalprinciplestress
Gravitystress
ZK2
75.63
6.58
4.26
2.04
4.19
3.30
1.88
150.68
8.43
5.71
4.07
5.06
3.87
3.60
217.65
11.00
8.68
5.88
10.97
7.30
5.68
273.09
13.25
8.03
7.37
15.30
10.10
7.81
329.12
13.11
9.29
8.89
16.55
11.43
9.67
375.16
12.57
8.25
10.13
17.53
12.70
11.45
404.68
14.37
9.55
10.93
17.
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 雪峰 山地 应力 英文 报告