Table Of ContentEnvironmental Science and Engineering
Subseries: Environmental Science
Series Editors: R. Allan (cid:129) U. Fo¨rstner (cid:129) W. Salomons
·
Fawu Wang Tonglu Li (Eds.)
Landslide Disaster
Mitigation in Three Gorges
Reservoir, China
123
Editors
Dr.FawuWang Prof.TongluLi
KyotoUniversity Chang’anUniversity
DisasterPreventionResearchInst. SchoolofGeological
ResearchCentreonLandslides EngineeringandGeomatics
Gokasho,Uji,Kyoto611-0011 No.126YantaRoad
Japan Xi’an710054
[email protected] People’sRepublicofChina
[email protected]
ISSN 1863-5520
ISBN 978-3-642-00131-4 e-ISBN 978-3-642-00132-1
DOI 10.1007/978-3-642-00132-1
SpringerDordrechtHeidelbergLondonNewYork
LibraryofCongressControlNumber:2009920521
(cid:2)c Springer-VerlagBerlinHeidelberg2009
Thisworkissubjecttocopyright. Allrightsarereserved,whetherthewholeorpartofthematerialis
concerned,specificallytherightsoftranslation,reprinting,reuseofillustrations,recitation,broadcasting,
reproductiononmicrofilmorinanyotherway,andstorageindatabanks.Duplicationofthispublication
orpartsthereofispermitted onlyundertheprovisions oftheGermanCopyright LawofSeptember9,
1965,initscurrentversion,andpermissionforusemustalwaysbeobtainedfromSpringer.Violationsare
liabletoprosecutionundertheGermanCopyrightLaw.
Theuseofgeneraldescriptivenames,registerednames,trademarks,etc.inthispublicationdoesnotimply,
evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfromtherelevantprotectivelaws
andregulationsandthereforefreeforgeneraluse.
Coverdesign:IntegraSoftwareServicesPvt.Ltd.
Printedonacid-freepaper
SpringerispartofSpringerScience+BusinessMedia(www.springer.com)
Foreword
The purpose of the Three Gorges project is to construct a large dam, forming a
large-scalewaterreservoirinthevalley.Whenthefinaldesignreservoirwaterlevel
is reached, the length of the reservoir will be longer than 660 km, which extends
fromthedamsiteatSandoupingtowntoMaoer-XiaGorgeinChongqingCity.The
reservoir crosses the low–medium mountainous area consisting of the fold zone
fromSiniansystem to MesozoicErathem,whichisdistributedin HubeiProvince,
HunanProvince,YunnanProvinceandChongqingCity,tothelowmountainousarea
formedbythefoldzonerangingfromtheTriassictotheJurassicPeriods,whichis
distributedintheeasternpartofChongqingCity.Generally,thereservoirareacan
bedividedintotwoparts.TheeasternpartisfromSandoupingtowntoBaidicheng
in Fengjie County,with a lengthof 160 km. In this part, threeportionsconsisting
oflimestoneformedthenarrowThreeGorges.BetweentheThreeGorgesaretwo
portions consisting of clastic rocks forming wide valleys. At the dam site are the
Pre-Sinian System crystal rocks. In the Three Gorges parts, thick bulk limestone
anddolomitearemainlydistributed,sandwichingthinlayersofsandstoneandshale.
The mountain height at the gorge areas is about 600–1,200 m, and the width at
thoseareasisonly200–300m.Thegeomorphologycharacterizedbyhighmountains
and deep valleys formed the famous three gorges, namely, Qutang Gorge in the
west, Wu Gorge in the middle, and Xiling Gorge in the east. The Xiling Gorge
is divided into eastern part and western part. The dam site is located between the
easternpartandwesternpartofXilingGorge.Theupstreamvalleyofthedamsite
consistsofgneissandmixturerockofthePre-Siniansystem,with16-kmlong,wide
valley.OneofthetwowidevalleyareassandwichedbythethreegorgesistheZigui
basin valley formed in the Jurassic Period; the other was formed by shale during
theSilurianPeriod.Thewidthofthe riverinbothareasis about300–400m, with
a mountain height of 500–800 m. The slopes in these areas are relatively gentle.
The western part extends from Baidicheng to Maoer-Xia Gorge, with a length of
490km.ItcrossestheeasternpartoftheSichuan–Chongqingbasin,whichfeatures
low mountains formed by fold zones during the Triassic to Jurassic Periods. The
height of the mountain ridges is about 300–600 m, and the valley width is about
500–1,000m. The bank slope height is about 100–300 m, with a gentle slope of
15–30◦. In the partfrom Baidichengto FengduCountytown, the lengthof which
is270km,theYangtzeRiverflowsalongtheaxisoftheYunyangSynclineandthe
v
vi Foreword
Fengdu Anticline which consists of thick red sandstone and shale of the Jurassic
Period. The bank slopes in this part are almost dip-structured slopes. In the part
fromFengdutotheendofthereservoir,Maoer-XiaGorge,theYangtzeRivermainly
crossesthenortheastwardcomb-stylefold.Whentherivercrossesthecorepartof
theanticlinewhichfeatureslimestoneoftheTriassicPeriod,smallandshortgorges
wereformed.Thesegorgesdistributedamongtherelativelywidevalley.Themain
tributaries,suchastheDaning-heRiver,Xiangxi-heRiverandMeixi-heRiver,are
alsoinhighmountainsandsteepgorgeslandscapes.
Meteorologically,thereservoirislocatedintheWesternHubeiProvince,andthe
Chongqingheavyrainfallarea.Theaverageannualprecipitationis1,100mm.The
rainfallgenerallyconcentratesin summer,andthe maximumdailyprecipitationis
between 150 and 240 mm. Also in summer, the rain likely continues for several
days.
Summarizingtheabovefeatures,theThreeGorgesareahasconduciveenviron-
mentsoftopography,geomorphology,rockmassstructure,valleystructure,andcli-
mateconditionsfortheformationoflandslides.Asaresult,landslideshaveoccurred
inthisareaextensively.Themajorworktostudythestabilityofbankslopesofthe
ThreeGorgesReservoiristoinvestigatethelandslidedistributioninthisarea,and
assessthestabilityofthebankslopes.Intheregionswithdensepopulationsuchas
townsandvillages,andthosepartswithmaintrafficlines,itisespeciallyimportant
toinvestigateandstudythelarge-scalelandslides.
Theinvestigationandresearchonlarge-scalelandslideswasemphasizedfromthe
firstperiodwhenthepre-investigationofgeologyintheThreeGorgesareafordam
constructionbeganinthe1950s.1956–1967wasthefirstworkingperiod.Underthe
leadershipoftheThreeGorgesGeologicalTeamoftheformerGeologyandMineral
ResourceMinistry,andGeneralSurveyTeamofYangtzeRiverWatershedManag-
ingOfficeofHydro-powerMinistry(laterthenamewaschangedtoYangtzeRiver
Water PowerCommittee),membersfromBeijingCollegeofGeology,Changchun
CollegeofGeologyandChengduCollegeofGeologyparticipatedina1:100,000-
scaleengineeringgeologysurveyinthereservoirarea,andpointedoutninelarge-
scalelandslidessuchastheXintanlandslide,andfivepotentialriskyrockmasssuch
as the Lianziya cliff. It is concluded that the part including the Xintan landslide
andLianziyacliffisa dangerouspartwithalowlevelofstabilityforbankslopes.
The second time period dates from 1968 to 1983. The main work in this period
wastoconductadetailedinvestigationintheabove-mentioneddangerouspart.The
topographicsurveyandexplorationwasconductedbytheGeneralSurveyTeamof
theYangtzeRiverWaterPowerCommitteeandtheHydrogeologyandEngineering
GeologyTeamofHubeiProvince.Thedeformationmonitoringwasconductedby
the Landslide and Rockfall Investigation Office of Xiling Gorge (established by
Scientific and Technological Committee of Hubei Province). Thereafter, a defor-
mationmonitoringsystem was also established atthe Huanglashilandslide,while
otherlarge-scalelandslideswithobviousdeformationwereundergoingmonitoring
for early warning. In 1985, the reactivation of the Xintan landslide was predicted
successfully,andthelosscausedbythelandslidewasmitigatedtoaverylowlevel
ofoccurrence.Therewasnobodykilledbythelandslide.
Foreword vii
In 1982, the western part of the Baota landslide reactivated and formed the
Jipazi landslide. In addition, Xintan landslide reactivated in 1985. Both of them
formedmajorgeo-hazards,andcounter-measurestopreventfurtherdisastershould
be implemented. There is especially the need for further discussion on the Three
Gorgesprojectitself.From1983to1988,aperiodjustbeforethedamconstruction,
anewperiodstartedfortheinvestigationofbankslopestabilityandlandslidesinthe
reservoirarea.CountermeasureworkswereconductedontheJipazilandslide,the
Xintanlandslide,andtheLianziyariskycliff.From1989whenthedamconstruction
started, the exploration, monitoring, and counter measure works were continued.
At the same time, landslide investigationworkswere also applied to a wider area
includingtributariesthathavevalleyscharacterizedbyrelativelylowerstability.
From1983,theresearchongeologyandearthquakesintheThreeGorgesarea,
includingbankslopestabilityassessmentandlandslideinvestigation,wasreinforced
by the Department of Environmental Geology, Ministry of Geology and Mineral
Resource. The Hydrogeologyand EngineeringGeology Team of Hubei Province,
Nanjiang Hydrogeology and Engineering Geology Team in Sichuan Province,
ChengduCenterofHydrogeologyandEngineeringGeology,GeneralSurveyTeam
of Yangtze River Water Power Committee, Landslide and Rockfall Investigation
Office of Xiling Gorge of Hubei Province conducted excellent work. China Uni-
versity of Earth Science (Wuhan), Changchun College of Geology and Chengdu
CollegeofGeologyactivelyparticipatedinthelandslideresearchinthearea.From
Changchun College of Geology, Guangjie Li, Mancao He, Jianping Chen, Lei
Nie, Jingshan Bo, ChuanzhengLiu, XinshengLi, HuimingBao, DianqiangChen,
FawuWang, TongluLi, YonggangJia, BingjianLing,MinghuiLiu,HongjunLiu,
YanLiang,TingkaiNian participatedthe field investigationanddata analysesand
obtained significant results. Notably, Mancao He completed the stability assess-
ment of the Jipazi landslide, and his work was included in the final report. For
the predictionof the Xintan landslide, ChuanzhengLiu estimated the sliding area
andslidingmassvolume,pointedouttheslidingrouteanddirection,andpredicted
thedangerousareacorrectly.Hisanalysiswasusedforthefinalprediction,andan
appreciationletter was sent to ChangchunCollege of Geologyfrom the Scientific
andTechnologicalCommitteeofHubeiProvince.
Through nearly 40 years of investigation in the Three Gorges area, a general
knowledge was established for the landslide distribution, and mechanism and the
stabilityofthemajorlandslidesinthisregion.Inthewholearea,thereare392land-
slideswithavolumelargerthan10,000m3.Amongthem,57%(222landslides)have
highstability,22%(88landslides)havemediumstability,and21%(82landslides)
have low stability. Along the main stream of the Yangtze River in the reservoir
area,thereare170landslidesand86rockfalls.Amongthe170landslides,thereare
3 super large-scale landslides with volumes larger than 1×108 m3, 29 large-scale
landslideswithvolumesbetween1×107and1×108m3,42medium-largelandslides
withvolumesbetween1×106m3and1×107m3,62mediumlandslidewithvolumes
between1×105and1×106m3,and34small-scalelandslideswithvolumessmaller
than1×105m3.
Thethreesuperlarge-scalelandslidesaretheFanjiapinglandslide,theGaojiazui
landslide, and the Taibaiyan landslide. The Fanjiaping landslide is located 8 km
viii Foreword
east of Badong County town, and has a volume of 1.1×108 m3. The Gaojiazui
landslide is located on the south bank near the Yunyang County town, and has
a volume of 1.3×108 m3. The Taibaiyan landslide is located near Wanzhou City,
andhas a volume of 1×108 m3. All of the three super large-scalelandslideswere
stablebeforewaterimpoundment,andnowtheyarealsoremainingstableafterthe
currentimpoundment.Amongthe 29 large-scalelandslides, there are 8 landslides
withlowstability.TheyaretheXintanlandslide,Jipazilandslide,Huanglashiland-
slide, Daping landslide, the Zuojituo landslide, the Cicaotuo landslide, Sandengzi
landslide, and Yunyang Chengxi landslide. The first three landslides, the Xintan
landslide,Jipazilandslide,andHuanglashilandslideespecially,alsohavehighrisk.
Dueto thecountermeasureworksfromthe 1980s,their stabilitieswere improved
greatly.Foralloftheeightlarge-scalelandslideswithlowstability(duetotheirvol-
umes)arebetween1×107and1×108m3,theworkloadswerequiteheavy.Besides,
theother21large-scalelandslidesalongthemainstreamoftheYangtzeRiverhave
relatively higher stability. They are remaining stable even after the current water
impoundment.Amongthemediumlarge-scalelandslides,medium-scalelandslides
andsmall-scalelandslides,about80%havehigherstability.Only20%ofthemhave
lowstability.However,itisveryimportanttopayattentiontothedip-structurered-
layer slopes distributed from Yunyang to Wanzhou, where large-scale landslides
occurredfrequently.
Amongthe86rockfallsalongthemainstreamoftheYangtzeRiver,thereare4
sites with large volumes. Three of them are located on the south bank of Wushan
County town, and one is located near Wanzhou City town. The three large-scale
rockfallsin Wushan are (1) the Baihepingrockfallwith a volumeof 4.6×107 m3,
which is the largest rockfall in the Three Gorges area, but was stable before the
impoundment. It is also remaining stable after the current impoundment, (2) the
Yaqianwanrockfallwith a relativelysmaller volumeof 1.4×107 m3. However,its
stabilityislow,androckfallsoccasionallyhaveoccurredinthissite.Closeattention
shouldbepaidtothissite;(3)theDawanrockfallwithavolumeof1,200m3.Itis
stableevenafterthecurrentwaterimpoundment.TherockfalllocatedinWanzhou
CitytownistheDiaoyapingrockfallwithavolumeof1.7×107m3.Itisstablenow
andhaslowrisk.
Themostdangerouspotentialrockfallistheabove-mentionedLianziyarockfall,
which is located on the south bank of the main stream of the Yangtze River. This
cliffconsistsoflimestoneoftheCarboniferousandPermianPeriods.Atthebottom
ofthelimestoneisacoalseam.Theclifffacingtheriveris700mlongand200–250
mhigh.Thelimestonewascutbyfissuresandjointsintomanyblocks.Amongthe
risky rock blocks, South-1 block and South-2 block have a volume of 9×105 and
2×104 m3,respectively.Thepossiblefalllocationsarethevalleysintheeastside.
Becausetheycannotfalldirectlyintotheriver,theriskisrelativelylow.However,
theirfallwillhavenegativeinfluenceontheNorth-3block,whichhasavolumeof
2.5×106 m3.IfSouth-1andSouth-2blocksfalldown,theNorth-3blockwillface
theYangtzeRiverdirectly.Theriskwillbeincreasedgreatly,becausethemountain
structure here is a dip structure with a low angle of the coal seam, which is the
potential sliding plane. Fortunately, the fissures in the rear part did not reach the
Foreword ix
coalseam,andtheNorth-3blockisalsoconnectedtothemainmountainbody.The
possibilityforthewholeblockslidingisrelativelylow.Themostdangerouspartof
thecliffistheblockcutbyFissureT9.Thisblockhasavolumeof1.2×106 m3.It
willslideintothemainstreamalongaweaklayerofcarbonatedshale.Accordingto
thedeformationmonitoringdata,themonitoringpointatthetopoftheLianziyacliff
movednorthtotheYangtzeRiveratanannualrateof1.6mm.Thecountermeasure
worksonthispotentialrockfallwereconductedbeforethewaterimpoundment.
Now,theThreeGorgesdamhasbeencompletedfor2years,andthewaterlevel
will reach the design water level, 175 m in 2009. The investigations of the land-
slideandriskyrockmasses,andthemonitoringandcountermeasureworksarealso
ongoing.Aftertheimpoundmentofthereservoir,somelandslideswerereactivated,
andsomeslopesbegantodeform.Itisalsoveryimportanttoconductresearchand
monitoringon the landsliding phenomenonfor the purposeof disaster mitigation,
andpayattentiontothetsunamicausedbythelandslides.
My students, Fawu Wang and Tonglu Li, are trying to compile the research on
landslides in this area in a book, written in English. It is a very significant work.
Thisbookremindedmeofthe activeinvestigationlifewhenI wasyoung,andthe
time when I worked as a member of the National Expert Team on Geology and
Earthquakefortheproject.Ihopewhatwehavedoneandwhattheyounggeneration
willdocancontributetothedisastermitigationinthisimportantproject.
IhopepeoplehaveinterestintheThreeGorgesprojectcouldbenefitfrominfor-
mation found in this book. Also I would like to express appreciation for the kind
supportoftheauthorsinthisbookandfortheirgreatcontributions.Forthosewho
want to know more about the landslides in this region, I will like to recommend
the Final Report on Geology and Earthquake submitted by National ExpertTeam
fortheThreeGorgesprojectpublishedinJune1988,theComprehensiveReporton
TypesofBankSlopeandtheirStabilityintheThreeGorgesdamreservoirfinished
byChengduCenteronHydrogeologyandEngineeringGeology,NanjiangHydro-
geologyandEngineeringGeologyTeamofSichuanProvince,andHubeiProvince
Hydrogeology and Engineering Geology Team under the technical advice of the
NationalExpertTeamonGeologyandEarthquakepublishedin1995.
ZhoudiTan
FormerProfessorofChangchunCollegeofGeology
October2008,Changchun,China
Preface
The Yangtze River is the largest river in China, and the Three Gorges section is
oneof the mostbeautifulpartsof the river.In orderto harnessthe hydropowerof
theYangtzeRiver,adreamwasenvisionedbyMr.SunYat-Sen,thefirstpresident
of China. In 1918, Sun Yat-Sen suggested in his book,Strategy for State, “a dam
shouldbesetheretoletshipsgodownstreamandusethewaterresourceaspower”.
Through the efforts of the Chinese people the dream came true after 100 years.
Begun in 2004, the Three Gorges dam construction was completed in 2006, and
the dam operationwill becomefully functionalin 2009,when the reservoir water
level will reach the maximum height of 175 m. Before the dam construction, the
waterlevelattheThreeGorgesdamsitewas90m.Anincreaseof85mofslowly
rising water in a reservoir with a length of about660 km from the dam to its ter-
minusatChongqingCityhasgreatlyimpactedtheenvironment.Theimpactonthe
geo-environment,especiallythe instabilityphenomenonandlandslides, wasgiven
great attention, because landslides not only affect the people living on the bank
slopesbutalso affectnavigationandshippingon the river.In addition,the sliding
masses moving into the reservoir will have negative effects on the lifetime of the
reservoiritself.Becauseoftheimportanceofthisconsideration,bankslopestability
and landslide problemshave been, and will continue to be studied systematically.
ThestudiescanbedividedintotwoperiodsseperatinginJune2003,whenthefirst
reservoirimpoundmentwasconductedforpartialoperation.Tosummarize,thestud-
iesbeforetheimpoundmentwereconcentratedonlandslidesiteidentification,and
instabilityevaluationofexistinglandslides;whileintheperiodaftertheimpound-
ment,thestudiesshiftedtolandslidemonitoringandpredictionoflandslidescaused
bywater-levelchangesduringthe reservoiroperation.Thepurposesofthe studies
forthetwoperiodsarethesame,whichistoacquiresufficientdataandinformation
forlandslidedisastermitigation.
Theideatoeditthisbookwasinitiatedbytheinterestofnon-Chinesecolleagues.
WheneverwepresentedourresearchintheThreeGorgesarea,othersalwayswanted
toknowmore.TheThreeGorgesareaisamysteriousandchallengingareaforthem.
Asaresult,thisbookaimstopresentthelandslidestudiesintheThreeGorgesdam
reservoirareaforthetwoperiodsbeforeandaftertheimpoundment.Chineseexperts
on landslides learned much about landslides in this area as a result of the great
project.Itisveryimportanttodocumenttheseimportantexperiences.Acomparison
xi
