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页数:6页
时间:2019-05-31
《浅层地温场中热对流数值模拟》由会员上传分享,免费在线阅读,更多相关内容在行业资料-天天文库。
1、第31卷第4期岩土力学Vb1.31NO.42010年4月RockandSoilMechanicsApr.2010文章编号:1000-7598(2010)O4—1303-06浅层地温场中热对流数值模拟吴志伟,宋汉周(河海大学地球科学与工程系,南京210098)摘要:温度示踪的研究区域大多在地表浅层,浅层地温场主要受气象和水文影响。气温波动可用傅立叶级数精确表示,由此建立了在表层气温和垂向水流共同影响下的浅层地温场瞬态分析模型,用Laplace变换的方法得到其解析解,并用有限元模拟了垂向水流对浅层地温的影响。模拟结果表明:浅层地温有季节波动,在地下水补给区,气温波动振幅衰减速率
2、明显减缓,表现为表层气温波动可以影响到更深的深度;在排泄区,温度波振幅衰减很快。另外,还模拟了水平集中渗漏带附近的瞬态温度场,发现由于热对流的传热能力远大于热传导,强渗漏带温度迅速与补给源温度相一致,温深剖面出现异常,温度异常带形成后,继而通过热传导改变较大范围内地质体热量分布。离低温补给源越近,地质体降温越快,温度改变越多;反之则越慢,温度改变越少。因此,由温深剖面的温度异常,可精确探查渗漏带位置。关键词:温度示踪;浅层地温场;热对流;傅立叶级数中图分类号:O241文献标识码:ANumericalsimulationofthermalconvectioninshallow
3、groundtemperaturefieldWUZhi-wei.SONGHan.zhou(DepartmentofEachScienceandEngineering,HohaiUniversity,Nanjing210098,China)Abstract:Thestudyareasoftemperaturetracermethodaremostlyconcernedwithshallowlayer,itstemperatureismainlyinfluencedbyweatherandgroundwater.Fluctuationofairtemperaturecanbea
4、ccuratelyexpressedbyFourierseries.Howsurfacetemperatureandverticalgroundwaterflowinfluencingtemperaturefieldweredemonstratedwithatransientanalysismode1.TheanalyticalsolutionisobtainedbyLaplacetransformandnumericalsolutionbyFEM.Theresultsindicatethatshallowgroundtemperaturefieldalsohasseaso
5、nalfluctuation;butthedecayrateofamplitudemitigatessingnificantly;andfluctuationofairtemperaturecaninfluencedeeperingroundwaterrechargedistrict:whileindischargedistrict,amplitudeoftemperaturewavesdecaysfaster.Besides,atransienttemperaturefieldnearhorizontalstrongleakagelayerissimulated.Itis
6、foundthatbecauseheattransferabilityofconvectionismuchstrongerthanconduction,thetemperaturewithinstrongleakagezoneisconsistentwithrechargesourcequicklyandthentemperaturefieldinawiderrangeischangedbyconduction.Geologicbodiesnearlowtemperaturesourcearecooledfasterandchangedmore,viceversa,slow
7、erandless.Therefore,thepotentialleakagezoneCallbetracedaccuratelyinthisway-Keywords:temperaturetracing;shallowgroundtemperaturefield;thermalconvection;Fourierseries态分析模型及Bredehoeft和Papadopulos141于同年建1引言立的地下深层区热流稳态分析模型,奠定了地质环在地下水示踪监测技术中,温度示踪具有成本境中温度与渗流作用研究的理论基础
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