本文研究的琼州海峡(广东省徐闻县的南岭村至海南省玉包角)的海底电缆路 由勘察项目是在收集勘察区域附近的自然环境条件和工程地质条件历史资料的基础 上,并且对路由区进行详细的环境地质调查通过使用单波束!旁扫声纳!浅地层 剖面等仪器设备进行勘察,并对勘察成果资料进行解析判读,初步查明路由区水深! 海底地形!地貌特征及浅地层岩性!地质构造!不良地质现象等问题;初步查明各 种地质现象的具体位置!规模!性质!产状,并评价它们对路由管道铺设稳定性的 影响程度,为工程建设以及日后的海底管道铺设!维护提供切实可靠的数据和资料 主要从以下几个方面对琼州海峡海底电缆铺设的可行性进行了全面的!多学科 的研究与评价,并得出以下结论: 1!3条路由的长度接近,通过的地质地貌单元相同路由O一12.3km段,地形平 缓,除近岸局部中度风化玄武岩的埋深小外,大部分区域的软塑一可塑状态沉积物厚 度超过3m,有利于海底电缆的埋设和安全运行路由12.3一20.7km段(长约8.4km), 水深截面呈锯齿状,表层松散沉积物薄,突起地形武岩埋深小,局部有零星的珊瑚 礁分布,南部隆起带北坡受滑坡威胁较大,工程地质条件较差路由20.7一30.Okm 段(长约9.3km),地形起伏不大,可塑一硬塑状态沉积物厚度超过3m,除海岸线附 近玄武岩埋深较小外,工程地质条件良好 2!不良的地质现象主要是活动沙波!陡坡地形!滑坡!浅埋玄武岩和珊瑚礁, 路由北段堆积区局部有流塑的软弱淤泥质粘土夹层 3!CPT静力测试分析结果表明,路由区内多处砂体在地震等外力作用下,有发 生液化的可能,但砂体液化对海底电缆的影响不大,而砂体发生液化后其状态变得 更稳定 4!两岸终端站区域的抗震设防烈度为7度,地震动峰值加速度为0.159,地震 动反应谱特征周期为0.355 5!腐蚀性测试结果表明,路由区内的沉积物和海水的腐蚀性不强,但路由北段3一7km!水深4一10m的海域,Zm以浅的硫酸盐还原细菌含量较大,要求3一7恤段电 缆的埋深在Zm以上 6!路由区海域内表层流的理论最大可能潮流流速的最大值为286c而S,底层海 流的理论最大值为198c而S,对海底电缆的施工和安全维护影响较大 关键词:琼州海峡;海底电缆;勘察;环境地质QiongzhouStraitSubmarineCableFeasibilityStudy Abstract ThestudyoftheQiongzhouStrait(fromtheNanlingVillageinXuwenCountyof GuangdongProvincetoYubaojiaoofHainanProvinee)SubmarineCableroutingsurvey Projeet15intheeolleetionofsurveyeonditionsandthenattlralenvironmentoftheregion surroundinggeologicaleonditionsonthebasisofhistoriealinformation,andtoeonduet detailedenvironmenialRoadfromDistrietgeologiealsurvey.Aeeordingtothe bathymetrieandtoPograPhiemethod:wewillusesinglebeam!sideseansonar! sub一bottomProfllerandotherequiPments,tocarryouttheSub一bottomProfilesurvey,then analyzingandinterpretationthedataresultsofthesurvey.Theaimofthesurvey15to PreliminarilyProsPectthewaterdePth,theseabedtoPograPhiefeaturesandthe PetrograPhyofthesub一bottomProfile,thegeologiealstrueture,theadversegeological Phenomena,etc:toPreliminarilyexPlorethesPeeifieloeation,seales,nature,oceurrenees ofthevariousgeologiealPhenomena,andtoevaluatetheirinflueneeonthestabilityofthe PIPelinelayingalongtheroute.WebelievethatalltheseworkeanProvideeffeetiveand reliabledataorinformationfortheengineeringeonstruetionandthesubmarinePIPeline layingandmainienaneeinthearea. OnfeasibilitystudyandevaluationoftheQiongzhouStraitSubmarineCablelaying, wewillmainlyfromthefollowingeomPrehensive,multidiseiPlinaryasPeetstoanalysis andexPound,andeonelusionsaredrawnasfollows: l!ThethreeroutesextendforapProximatelyequallengthandPassthroughbasieally identicalgeologiealandtoPograPhiealunits.Intheo一12.3knlseetionoftheroute,the toPography15slowlyinelined,andexeePtthemoderatelyweatheredbasalt15buriedat shallowdePthinsomeloealoff-shoreareas,thesoftPlastietoPlastiesedimentsexeeed 3minthic知essinmostofthearea,whieh15favorablefortheburialeonstruetionandsafe oPerationofsubmarineeable.Inthe12.3一20.7kmseetion(about8.4knllong)oftheroute, thewaterdePthseetiontakestheserrateform,thesurfaeeloosesedimentsaregenerally thin,basaltsareburiedshallowinProtrusiverelief,andloeallyeoralreefsoeeur sPoradieally.Generally,landsliPmayeasilyoeeurinthenorthsloPeofthesouthuPlifted 111zone,andtheengineeringgeologiealeonditionsherearePoor.Inthe20.7一3O.Okillsection (about9.3kmlong)oftheroute,thetoPograPhy15notrem眺ablyundulating,herethe Plastie一hardPlasticsedimenisaregenerallyover3minthiekness.ExeePtthebasalt15 generalburiedatshallowdePthnearbytheeoastlines,theengineeringgeologieal eonditie,n15favorableingeneral, 2!AdversegeologicalPhenomenamainlyineludeaetivesandwave,steePsloPe toPogra:Phy,shallow一buriedbasaltandcoralree几,aswellastheweaksiltelayinter一layers oeeurringloeallyintheaeeumulationareainthenorthseetionoftheroute. 3!CPTstaticforeetestingresultsindieatethatPossibilityofliquefactionexistswhen sandbodiesintherouteareaaresubjeettoexogenieforeessuchasearthquake,ete.,just thesand一liquefaetionhaslittleeffeetonthesubmarineeable,evenmore:theroutearea statewillbeeomemorestableafterthesand一liquefaetion15oeeurred. 4!Intheterminalstationareasaroundthetwoeoasts,theanti一seismiefortified intensity15setatgrade7onthe形ehter.5seale,ataPeakgroundaeeelerationof0.159for agroundmotion,andataneharaeteristiePeriodof0.355onagroundmotionresPonse SPectru一n. 5!Corrosivetestresultsindieatethatthesedimentsandseawaterandintheroute areaarenotstronglyeorrosive.However,intheseaareawithawaterdePthof4一1Omin the3一7knlseetionofthenorthPartoftheroutearea,agreatnumberofsulPhate deoxidizingbaeteriaoeeuratadePthofZm. 6!ThetheoretieallyPossiblemaximumtidaleurrentsPeedforthesurfaeelayer eurrentintherouteseaarea15286em/s,whilethetheoretieallymaximumvalueforthe bottomlayerseaeurrent15198em/s,Whiehwillhassignificantinflueneeonthe eonstruetionandsafetymainienaneeofsubmarineeable. Keywords:QiongZhouStrait:SubmarineCable:InsPections:Environmental geology IV目录 0引言.............................................1 1项目概况...........................2 2路由海区环境条件...................................3 2.1气候..................................................#3 2.1.1气温...............................................#.3 2.1.2降水...............................................#.3 2.1.3风.....................................................4 2.1.4雾.....................................................4 2.1.5热带气旋.................................4 2.1.6灾害性天气.............................................5 2.2水动力条件.................................,.......6 2.2.1潮汐...................................................6 2.2.2潮流...............................................#.7 2.2.3余流...............................................7 2.2.4风暴潮.......................................7 2.2.5波浪...........................................8 2.2.6海水温度............................#9 2.2.7海水盐度...............................#10 2.2.8海水悬沙..............................................10 2.3区域地质概况...........................................11 2.3.1地层..................................................11 2.3.2火山岩..................................13 2.3.3区域构造.................................#13 2.3.4新构造运动的表现......................................16 2.3.5地形地貌..............................................17 2.3.6表层沉积物类型及分布..................................18 2.4海上活动...................................#19 夕3勘察概况..........................................19 3.1勘察范围................................................19 3.2勘察内容.........................................23 3.2.1工程物探..............................................23 3.2.2岩土工程勘探..........................................23 3.2.3腐蚀性测试............................................23 3.2.4海流观测..............................................23 3.3勘察依据................................................23 3.3.1法规依据..............................................23 3.3.2技术依据..............................................24 3.4实施.....................................................24 3.4.1测量参数..............................................25 3.4.2导航定位..............................................25 3.4.3路由走廊工程物探普查..................................25 3.4.4设计路由详查..........................................39 4路由的地质地貌条件................................39 4.1浅地层分层概况...........................,........39 4.2路由的地质地貌状况....................................39 4.2.1北部堆积区(0一7.Ikm).................................39 4.2.2北部侵蚀一堆积区(7.1一10.4km)...........................39 4.2.3中央深槽(10.4一19.skm).................................39 4.2.4南部隆起带(19.8一20.7km)....................,..39 4.2.5南部近岸侵蚀一堆积区(20.7一29.gkm)....................39 4.3不良地质现象...........................................39 4.3.1沙波!沙堤沙丘........................................39 4.3.2冲刷槽!冲刷脊和丘状突起..............................39 4.3.3陡坡与滑坡............................................39 4.3.4珊瑚礁和浅埋岩石......................................39 4.3.5软弱地层.........,..............................39 5路由工程条件评价..................................39 5.1工程地质条件...........................................395.2海洋环境条件...........................................39 5.3海上活动................................................39 6结论和建议........................................39 6.1结论....................................................39 6.2建议....................................................39