库水上升条件下不同土体类型岸坡渗流场特征

第41卷第5期煤田地质与勘探Vol.41No.52013年10月COALGEOLOGY&EXPLORATIONOct.2013收稿日期:2012-08-29基金项目:(973)(2011CB710604)作者简介:(1986).文章编号:1001-1986(2013)05-0056-06库水上升条件下不同土体类型岸坡渗流场特征张国超，胡新丽，范付松，赵鑫(中国地质大学(武汉)工程学院，湖北武汉430074):库水位与岸坡体内地下水渗流场的动态变化密切相关。传统的饱和土渗流分析方法无法准确描述水位上升过程中岸坡内渗流场的规律。从饱和-非饱和非稳定渗流理论出发，在室内实验得到基质吸力和体积含水量关系的基础上，通过对实验数据拟合，得出VanGenuchten模型中土水特征参数。以三峡库区典型岸坡为例，模拟库水匀速上升时，坡体为粉质黏土、粉土、砂土和砾石土4种岩土介质类型下的渗流特征，并监测坡面高程为165m和155m竖直剖面上的孔隙水压力变化。结果表明：库水位匀速上升过程中岸坡体内浸润线呈“V”字型，并且各时步“V”字型浸润线的拐点连线随渗透性的增大有逐渐与坡面平行的趋势；揭示了4种土体类型孔隙水压力随时间的变化规律。研究成果可为水库岸坡的防治提供较重要的借鉴与参考。:岸坡；渗流场；库水位上升；不同岩土介质；VanGenuchten模型:P642.22：ADOI:10.3969/j.issn.1001-1986.2013.05.012SeepagefieldcharacteristicsofbankslopewithdifferentsoiltypesduringreservoirwaterlevelriseZHANGGuochao,HUXinli,FANFusong,ZHAOXin(FacultyofEngineering,ChinaUniversityofGeosciences,Wuhan430074,China)Abstract:Therearecloserelationshipbetweenthedynamicchangesofseepagefieldinreservoirslopeandreser-voirwaterlevel.Thetraditionalanalysismethodologybasedonsaturatedseepagelawcannotdescribethedynamicchangelawofseepageinslopewhilereservoirwaterlevelrises.Fromthetheoryofunsaturatedandtransientseepageandonthebasisofgettingtherelationshipbetweenmatricsuctionandvolumetricwatercontentinlabo-ratoryexperiments,throughexperimentaldatafitting,VanGenuchtenmodelparametersofthesoilhydraulicchar-acteristicshavebeengot.TakingatypicalslopeinThreeGorgesReservoirareaasanexampleandsimulatinguni-formwaterlevelriseinreservoir,theslopeshowedseepagecharacteristicsinfoursoilmedia,thatissiltyclay,siltysoil,sandorgravelsoil,andtheporewaterpressurechangeattheelevationof165metersand155metersoftheslopehasbeenmonitored.TheresultshowsthattheseepagelineshowedaVshapeintheslopewiththeuniformwaterlevelrise,andateachtimesteptheconnectionlineoftheturningpointhasgraduallythetrendtobeparallelwiththeslopewithincreasedpermeability.Thevariationregularitiesofporewaterpressurewithtimeinfourtypesofsoilhavebeenrevealed.Theresearchresultscanprovideimportantreferenceforthecontrolofreservoirbank.Keywords:reservoirslope;seepagefield;reservoirwaterlevelrise;differentgeotechnicalmedia;VanGenuchtenmodel[1-2]40%[3]Sevaldson[4]第5期张国超等:库水上升条件下不同土体类型岸坡渗流场特征·57·Henkel[5]LIUHongyan[6][7-10][11]WANGXinglin[12][13][14][15][16]4MATLABVanGenuchten(VG)SEEP/W165m155m1非饱和土VanGenuchten计算模型[17]aw=uuψ−(1)auwuVanGenuchten1980VG[18]srrws0[1()]0nmhhθθθθαψθ−⎧+⎪=+⎨⎪⎩＜≥(2)wθsθrθαnm=11/nMualem(1978)[19]ws2s0.50wrwswsr0d()dkkθθθθθψθθθθψ⎛⎞⎜⎟⎛⎞−⎜⎟=⎜⎟−⎜⎟⎝⎠⎜⎟⎝⎠∫∫(3)(2)(3)(1)2s/2s{[1][1()]}0[(1)]0nnmnmkhkkhαψαψαψ−−⎧−+⎪=+⎨⎪⎩＜≥(4)sk(2)VanGenuchten(2)(4)VanGenuchten-Mualem2数值计算与分析SEEP/W42.1(1)570m280m441Fig.1Themechanicalcalculationmodelofthereservoirslope·58·煤田地质与勘探第41卷2.24(12)MATLABlsqcurvefitVG33α10−4VGMATLAB2表1粉质黏土基质吸力和体积含水量关系Table1Relationshipbetweenmatrixsuctionandvolumetricwatercontentofsiltyclay/kPa00.4776500.36381000.32242000.30223000.28984000.27435000.2652表2粉土、砂土、砾石土基质吸力和体积含水量关系Table2Relationshipbetweenmatrixsuctionandvolumetricwatercontentofsiltysoil,sandandgravelsoil/kPa0.50.39240.37420.268130.37050.32600.167470.29020.13150.0812100.17140.09220.0692200.11250.08960.0625500.09170.08030.05631000.08620.07850.05401300.08310.07430.0522表3VG模型土水特征参数Table3SWCCparametersofVGmodelθsθrα/cm-1nm/10−4ks/(m·s−1)0.47710.15060.09571.26410.20895.975.78×10−70.35240.06250.12765.32200.81216.254.33×10−60.37440.08180.15224.96400.79861.711.16×10−50.26910.05670.22713.42880.70841.113.47×10−424Fig.2SWCCoffourdifferentsoiltypes2.3NeumanRichards[20](())(())xyHHkhkhQxxyytθ∂∂∂∂∂++=∂∂∂∂∂(5)()xkh()ykhxyHQθt2.3.1边界条件1m/d(6)200m145[0,30d]175[30,60d]ttHt+∈⎧=⎨∈⎩(6)H2.3.2不同土体介质下渗流规律33165m155m124a4d(6)3Fig.3Steadyseepagefield第5期张国超等:库水上升条件下不同土体类型岸坡渗流场特征·59·4a.4b.“V”“V”“V”“V”“V”c.“V”X“V”d.44(d)Fig.4Relationshipbetweenelevationofwatertableinfoursoilsandtime2.3.3监测剖面孔隙水压力的变化13m127512721269126612631260125712541251922m6996966936906876846564556a.564b.5a3m127212516a51d69622dc.5b1275125712751272125712541251125412516b5b6846872·60·煤田地质与勘探第41卷51Fig.5Variationofporewaterpressureateachmonitoringpointwithtimeinfoursoilsshowninsection1表4剖面1各监测点负孔隙水压力转为正孔隙水压力的时间Table4Thetimethatnegativeporewaterpressureateachmonitoringpointchangesintopositiveporewaterpressureinsection1t/dP/kPat/dP/kPat/dP/kPat/dP/kPa1254130.6142.0671257603.065191.05782.2991260535.925220.839111.0521263456.862241.119142.3221266389.32654.07175.33112693217.5254.1472012.791272276.0972450.4122334.9741275200200200200表5剖面2各监测点负孔隙水压力转为正孔隙水压力时间Table5Thetimethatnegativeporewaterpressureateachmonitoringpointchangesintopositiveporewaterpressureinsection2t/dP/kPat/dP/kPat/dP/kPat/dP/kPa684150.36620.65112.612687201.0672.415423.176690193.07694.08764.1966931713.446102.33485.804696510.2941417.23111.738109.271699100100100100第5期张国超等:库水上升条件下不同土体类型岸坡渗流场特征·61·62Fig.6Variationofporewaterpressureateachmonitoringpointwithtimeoffoursoilsshowninsection2d.5c1266“V”“V”“V”126612661126612751272126916c5c222e.5d6d126c45a.b.11263127224d1272(50.412kPa)1263(1.119kPa)c.3结论a.MATLABVGb.“V”“V”“V”c.“V”“V”d.“V”--(下转第65页)第5期陈明生:关于频率电磁测深几个问题的探讨(三)·65·6KFig.6ThephaseofKsectionandapparentresistivitycurves——4结论a.()