Desk Study and Field Assessment Report 02 Final with MS review.docx
- 文档编号:24444099
- 上传时间:2023-05-27
- 格式:DOCX
- 页数:81
- 大小:70.30KB
Desk Study and Field Assessment Report 02 Final with MS review.docx
《Desk Study and Field Assessment Report 02 Final with MS review.docx》由会员分享,可在线阅读,更多相关《Desk Study and Field Assessment Report 02 Final with MS review.docx(81页珍藏版)》请在冰豆网上搜索。
DeskStudyandFieldAssessmentReport02FinalwithMSreview
Client:
GuangdongLNGTerminalandTrunklineProject–JointExecutiveOffice
Project:
GuangdongLNGTerminalandTrunklineProject,China
Title:
PreliminaryLandslideRiskAssessmentofProposedPipelineRoutesBasedonDeskStudyandSelectedFieldVisits
DocumentReference:
5001585/GTG.2001334/DeskStudyandFieldAssessmentReport(02Final)
02
Final
JHC
EML
SPP
PGF
MS
13/02/2003
01
Draftforreviewby:
Client,
Prof.P.G.Fookes,
MrM.Sweeney
JHC
EML
SPP
DTS
DTS
20/12/2002
Revision/Status
Purpose/Description
Originated
Checked
Reviewed
Authorised
Date
CONTENTS
EXECUTIVESUMMARY1
1.INTRODUCTION3
1.1Background3
1.2SubsequentWorkonLandslideRisk4
1.3Scopeofwork5
1.4Programme6
2.REGIONALSETTING9
2.1GeologyandTerrain9
2.2ClimateandWeathering10
2.3KeyTerrainIssues10
2.3.1SlopeProcesses10
2.3.2Otherissues11
3.LANDSLIDEHAZARDANDRISK13
3.1Introduction13
3.2NaturalTerrainLandslidinginHongKong15
3.3ApplicabilityofHongKongLandslideStatisticstotheGuangdongArea17
3.4CutSlopeFailuresinHongKong18
4.LandslideRiskAssessmentfortheProposedPipelineRoute21
4.1Introduction21
4.2NaturalTerrainLandslides22
4.2.1OverallRisk22
4.2.2RelativeRiskwithinLandslideProneLengthsoftheRoute24
4.3Man-madeCutSlopes26
4.3.1Introduction26
4.3.2AssessmentoftheProposedPipelineRoute26
4.4CombinedNaturalTerrainandCutSlopes30
4.5Summary31
4.6ComparisonofRiskwithOtherPipelines33
5.OPTIONSFORTHEMITIGATIONOFLANDSLIDERISK34
5.1Introduction34
5.2‘RidgeandSpur’Alignments35
5.3Engineeringthepipelinetoisolateitfromexistingandpotentiallandslideanderosionprocesses36
5.4ManagementofSpoil36
5.5ManagementofSurfaceWater37
5.6Summary38
6.FIELDASSESSMENTOFVISITEDAREAS39
6.1StakeNos.B084toC007-2(seeTerrainMapNo.11)43
6.2StakeNos.B072-1toB083(seeTerrainMapNo.12)44
6.3StakeNos.B048toB055-1(seeTerrainMapNo.13)45
6.4StakeNos.B030-1toB039(seeTerrainMapNo.13)46
6.5StakeNos.B002toB012-1(seeterrainMapNo.14)47
6.6StakeNos.A001toA016(seeTerrainMapNo.14)48
6.7StakeNos.A034-1toA039-1(note:
noTerrainMapproducedforthisarea)49
6.8StakeNos.1001to1032(seeTerrainMapNo.15)50
6.9StakeNos.1123to1131(seeTerrainMapNo.16)51
6.10StakeNos.2015to3006(seeTerrainMapNo.17)52
6.11StakeNos.3031to3042(seeTerrainMapNo.18)53
6.12StakeNos.3060to3068(seeTerrainMapNo.18)54
7.CONCLUDINGREMARKS55
7.1LandslideRisk55
7.2OtherTerrainIssues58
7.3TheWayForward58
8.References60
TABLES(inthetext)
Table1FieldVisitProgramme.
Table2SummaryGeologyofGuangdongProvince.
Table3RiskAssessmentDefinitions(fromRoyalSociety,1992;CrudenandFell1997).
Table4RainfallThresholdsforLandslideActivityinHongKong(Evans,1997;Evansetal.,1997).
Table5WidthClassesofRelictandRecentLandslidesintheNaturalTerrainLandslideInventoryforHongKong(fromEvansetal.,1997).
Table6LandslidesinHongKongRecordedbytheGeotechnicalEngineeringOffice(fromFelletal.,1996).
Table7SlopeApproachClasses(OrientationofthePipelineRelativetotheSlope).
Table8NaturalTerrainRiskAssessment:
SummaryStatistics.
Table9SummaryofNaturalTerrainLandslideSusceptibilityClassesforSelectedHongKongBedrocks(adaptedfromEvansandKing,1997).
Table10NaturalTerrainLandslides:
RelativeRiskClasses.
Table11NaturalTerrainLandslides:
SummaryoftheLengthsAssociatedwitheachRelativeRiskClass.
Table12Example1,aFullyEngineeredandMaintainedCutSlopes:
AssessmentoftheProbabilityofCutSlopeFailure(basedonFindlayandFell,1995).
Table13Example2,MinimallyEngineeredCutSlopes:
AssessmentoftheProbabilityofCutSlopeFailure(basedonFindlayandFell,1995).
Table14LandslideRiskAssessmentfortheAugust2002PipelineRoute:
SummaryStatistics.
APPENDICES
AppendixAPreliminaryNaturalTerrainLandslideRiskAssessment
AppendixBPreliminaryCutSlopeLandslideRiskAssessment
AppendixCPreliminaryCombinedLandslideRiskAssessment
AppendixDTechnicalPaper:
FrameworkforAssessingtheProbabilityofSlidingofCutSlope(fromFelletal.,1996)
AppendixELocationofWaypointsandPhotographs
AppendixFSummaryofGeologyoftheGuangdongProvince
FIGURES
Figure1RegionalContextandKeyMapofGuangdongProvince
Figure2LandslidesRupturesFrequencies
Figure3aScaleofWeatheringGradesofRockMass
Figure3bModelsofWeatheringinGranite
Figure4TypicalShallowHillsideFailure
Figure5ProblemsAssociatedwithRoutingAcrossDeepGullysandSpurs
Figure6TypeofLandslidesonCutSlopes
Figure7EventTreeIllustratingPotentialPipeRuptureScenariosAssociatedwithCutSlopeFailures
Figure8FlowchartforCutSlopeInstabilityRiskAssessment
Figure9ASummaryoftheCombinedRiskAssessmentApproach
Figure10PipelineConstructiononSideSlopes
Figure11PipelineConstructionalongNarrowRidges
Figure12PipelineConstructiononSteepSlopes
Figure13SecuringthePipelineonNarrowRidgeLines
Figure14EarthworksonMountainpipelines:
SpoilManagementStrategies
Figure15DiversityofRestorationWorksonSteepSlopes
(Figure2andFigures10to15havebeenprovidedbyBP).
PLATES
Plate1NaturalTerrainLandslides:
RelativeLandslideRisk
PHOTOGRAPHS
ThephotographsareincludedindigitalformatonaCDattheendofthisreport.
DRAWINGS
5001585/GTG.2001334/100to119Rev.APreliminaryNaturalTerrainLandslideRiskAssessment–Sheets1to20
5001585/GTG.2001334/120Rev.AKeyMapforLandslideRiskAreas
5001585/GTG.2001334/010to018Rev.ATerrainMaps–Sheets1to9
5001585/GTG.2001334/021to028Rev.APreliminaryLandslideMapofAreasCoveredbytheTerrainMaps–Sheets1to8
PleasenotethatallthedrawingsarereproducedindigitalformatonaCDincludedattheendofthisreport.
EXECUTIVESUMMARY
TheproposedGuangdongLNGpipelinepassesthroughapproximately60kmofdissected,hillyterrain.Thesehillsareparticularlypronetolandslidingbecauseofthecombinationoflong-termdeeptropicalweatheringandthefrequenthighintensityrainstorms.Themajorityofthesenaturalterrainlandslidestendtooccurwithintheweatheredresidualsoilsthatmantlemuchoftheterraintodepthsofover25m.AspartoftheNovember2002fieldvisitweinspectedaround30kmofthemostseverehillyterrain.Ourobservationsduringthevisithaveindicatedthatexcavationofa12mwideplatformforthepipelineright-of-wayisunlikelytoexposeindurated‘rock-like’materials.Asaresult,thepipelinewillbeatriskfromlandslidesthatmayoccurwithintheweatheredsoilsandrocksandoverlyingcolluvium.
Constructionofthepipelinealongtheproposedalignment,whichcrossessignificantlengthsofsidelongground,wouldrequireextensivecuttingintothehillslopestocreatearight-of-wayplatform.Failureofcutslopesalsopresentsasignificanthazardtothepipeline.
TheobjectiveoftheNovember2002fieldvisitwastoprovideanindicationofthenatureandscaleofthelandsliderisktotheproposedroute(asofAugust2002)andtoadviseontheoptionsavailableforreducingtheserisks.TheworkpresentedinthisReportprovidesanindicationoftheleveloflandslideriskthatshouldbeexpectedalongtheproposedroute.Ascenariohasbeenassessedthatconsidersthecurrentroutealignmentwithnolandslidepreventativemeasuresorslopemaintenance.
Thelandslideriskreflectsacombinationofthethreatpresentedbybothnaturalterrainlandslidesandcutslopefailures.ThesetwoissueshavebeenconsideredseparatelyintheReport.Ofparticularnote,theestimatedriskassociatedwithman-madecuttingscanbehigherthanthatresultingfromnaturalterrainlandslides.ThisisconsistentwithexperienceinneighbouringHongKong.Pipelinedamagecausedbylandslidestendstoinvolvecatastrophicfull-borerupture.
Ourbestestimateofthelandslide-triggeredrupturerateisintherangefrom0.38to0.042peryearforthe300kmlengthofpipelineroute.Thisisequivalentto1.27to0.14ruptures/1000km/year.Consideringjustthe60kmtotallengthoflandslideprone(hilly)terrain,theequivalentfigurebecomesaround6.4to0.7ruptures/1000km/year.
Anumberofoptionsareavailableformanagingthepotentiallandslideproblems,including:
∙Adoptingalignmentsthatavoidsectionswherethepipewouldbeexposedtohighlevelsoflandslideriski.e.avoidsidelonggroundandsteep-sidedgulliesorravines;
∙Ensuringthatallcutslopesaredesigned,constructedandstabilisedtoahighstandard.Thisoptionneedstobeaccompaniedbyaprogrammeofon-goingmaintenance,repairandclean-upoperations.
Ahighstandardofdesignandconstruction,includingdetailedstabilisationworksforthecuttings,canprobablydeliversignificantriskreduction.However,itwillbeatamajorcostandwillrequirealong-termcommitmenttomaintenance,repairandclean-upoperationstoensurethatwhencutslopefailuresoccurtheyarenotallowedtodeterioratetoapointwheretheycanleadtopiperupture.Iftheseoperationsaresub-standardorreduced,thelandslideriskassociatedwithcutslopefailureswouldbeincreased.
Experiencehasshownthatthemostcost-effectiveapproachtoreducinglandslideriskistoadoptaroutingstrategythatminimisesthenecessityforconstructiononsidelongground(sideslopes)andcrossingsofsteepcatchments.Alternativeroutingcanbebasedonth
- 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:
- Desk Study and Field Assessment Report 02 Final with MS review
链接地址:https://www.bdocx.com/doc/24444099.html