简介：Researchonin-channelsandminingisimperativeasitmayhaveasignificantimpactonchannelmorphology.Followingthisquesttoquantitativelycomprehendthephenomenon,experimentalstudiesweredonetoinvestigatethedynamiccharacteristicsofthemigrationofaminingpit.Theevaluationofthemigrationrateofaminingpitinaphysicalscalemodelhasfoundariseinthemigrationrateofthepit'supstreamedgewithincreasingdischarge.Awaveletanalysisappliedforanalyzingscale-dependentmigrationofthebedprofileofaminingpitalsorevealedsimilarfindings.Additionally,thewaveletanalysisexaminedthelength-scaledependentmigrationofaminingpitandadecreaseinthemigrationratehasbeenobservedwithanincreaseinthelengthscale.Theplanformofapit(length-to-widthratio)governstheerosionanddepositionprocessesaroundthepit.Bothphysicalandstatisticalapproachesshowanincreaseinthemigrationratewithanincreaseinthelength-to-widthratioofthepit.Anempiricalformulationhasbeendevelopedforcalculatingthemigrationrateoftheupstreamedgeofaminingpitbasedonpitgeometry(length-to-widthratio),averageflowvelocity,andcriticalshearstressofthebedmaterial.Theresultsalsoshowahigherbedloadtransportrateinthechannelsubjectedtominingascomparedtoaplainbedchannel.

简介：Riversareoneofthemostessentialsourcesofsandandgravelsupplyforcivilworks.However,undesirableeffectsofirregularin-streammininghavebeenreportedonnaturalsources,environmentandinfrastructuresclosetorivers.Therefore,itisnecessarytofindtheeffectsofminingonriversinmoredetails.Thisresearchconcentratesonmining-pitmigrationphenomenonanditseffectsonthechannelbed.Thispaperreportsanexperimentalstudyonthemigrationofrectangularminingpitsandvariationoflongitudinalprofileinthechannelbedcomposedofratheruniformsediments.Differentvaluesofwidthsandlengthswereusedforpitwhilepitdepthsandflowvariableswerekeptconstant.Theresultsshowthatthemigrationspeedchangeswiththelength/widthratioofthepit.Themigrationspeedinconvectionperiodishigherthanthatindiffusionperiod.Inaddition,byincreasingthelengthorwidth,fillingrateofpitincreases,wheretheeffectofwidthismoreimportantthantheeffectofthelength.Alsoisreportedinthispaperafieldstudyonthechangesofthreepitsexcavatedatdifferentlocationsofariver.Somesimilaritiesbetweenthepitmigrationinthestraightreachoftheriverandthatoftheexperimentalworkisrealizedandpresented.

简介：摘要介绍了赞比亚中赞合作区330/66KV变电站内PIT接地井施工，阐述了PIT接地井的主要施工工艺、施工方法及技术要点。

简介：摘要介绍了赞比亚中赞合作区330/66KV变电站内PIT接地井施工，阐述了PIT接地井的主要施工工艺、施工方法及技术要点。

简介：摘要介绍了赞比亚中赞合作区330/66KV变电站内PIT接地井施工，阐述了PIT接地井的主要施工工艺、施工方法及技术要点。

简介：ＴｈｅＳｅｃｏｎｄＰｉｔｏｆＱｉｎｓｈｉｈｎａｎｇ＇ｓＴｅｒｒａ－ｃｏｔｔａＡｒｍｙＵｎｄｅｒｇｏｅｓＥｘｃａｖａｔｉｏｎＢｙｓｔａｆｆｒｅｐｏｒｔｅｒＣＨＥＮＪＩＡＮＩｎｗｈａｔｓｅｅｍｓｔｏｈａｖｅｂｅｅｎａｒａｔｈｅｒｍｅｇａｌｏｍａｎｉａｃａ...

简介：Tosuitaprojectofcapitalconstruction,theLuoyangMunicipalArchaeologicalTeamexcavatedatesttrench(T1)attheintersectionofJiefang解放andWuqi五七roadsinLuoyang洛阳CityinAugust,1982,whichbroughttoarevelationofabronzepitnumbered(C1M395)tolight.ThepitisatthenorthcenteroftheEasternZhouRoyalCity,and30msouthwestofNo.1burialoftheWarringStatesperiod,whichwasexcavatedin1957.

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简介：FordeepfoundationpitdewateringintheYangtzeRiverDelta,itiseasytomakeadramaticdecreaseoftheundergroundwaterlevelsurroundingthedewateringareaandcauselandsubsidenceandgeologicdisasters.Inthiswork,athree-dimensionalfiniteelementsimulationmethodwasappliedintheforthsubwayofDongjiadutunnelrepairfoundationpitdewateringinShanghai.Inordertocontrolthedecreaseoftheundergroundwaterlevelaroundthefoundationpit,thefoundationpitdewateringmethodwasusedtodesigntheoptimizationprojectofdewatering,whichwassimulatedundertheseconditionsthattheaquifersdepositedlayerbylayer,thebottomoftheaquiferswentdeepto144.45m,theretainingwalloffoundationpitshieldwentdeepto65m,thefiltersoftheextractionwellswerelocatedbetween44mto59m,thewaterlevelinthedeepfoundationpitwasdecreasedby34m,andthemaximumdecreaseofwaterleveloutsidethefoundationpitwas3m.Itisshownthattheoptimizationprojectandthepracticalcaseareconsistentwitheachother.Accordingly,thethree-dimensionalfiniteelementnumericalsimulationisthebasictheoryofoptimizationdesignofengineeringstructuresofdewateringindeepfoundationpitinsuchareas.

简介：摘要

简介：PitformationandsurfacemorphologicalevolutioninSi(001)homoepitaxyareinvestigatedbyusingscanningtunnelingmicroscopy.Anti-phaseboundaryisfoundtogiverisetoinitialgenerationofpitsboundbybunchedDBsteps.Theterracesbreakupandarereducedtoacriticalnucleussizewithpitformation.Duetoanisotropickinetics,adownhillbiasdiffusioncurrent,whichislargeralongthedimerrowsthroughthecentreareaoftheterracethanthroughtheareaclosetotheedge,leadstotheprevalenceofpitsboundby{101}facets.Subsequentannealingresultsinashapetransitionfrom{101}-facetedpitstomulti-facetedpits.

简介：摘要目的观察以Pit-Crew心肺复苏（cardiopulmonary resuscitation, CPR）模式的团队复苏对胸外按压质量改善的效果。方法采用对照研究的方法，将64名重症医学科和急诊科医护人员按照医护比例分成角色分工组与未角色分工组，每组各8队，每队4人。角色分工组每队指定一名队长组织协调整个CPR流程，未角色分工组不进行指定。每队利用高级模拟人在CPR质量跟踪反馈系统的监测下，按照《2020年美国心脏协会心肺复苏和心血管急救指南》推荐要求实施标准胸外心脏按压8 min。观察并记录每队实验人员CPR时间、胸外按压比例（chest compression fraction, CCF）、按压中断次数、按压超标中断次数（>10 s）、按压频率、胸廓充分回弹次数等指标。电脑系统记录以上参数，两组间指标的差异比较采用独立样本t检验和Mann-Whitney U检验。结果分析发现，与未角色分工组相比，角色分工组能达到更高CCF[（69.13±1.55）% vs. （59.13±6.08）%，P<0.05]，且角色分工组的按压中断总时间及超标中断次数均显著较少[（79.88±28.76）s vs. （135.25±32.99）s；4（3，5）次vs. 2（1，2）次，均P<0.01]。两组在CPR时间、中断次数及按压总时间方面的均差异无统计意义（均P>0.05），另外两组在按压总次数、按压正确次数、按压频率、按压深度、胸廓充分回弹等按压质量达标方面以及在按压太快、按压太慢、按压太深以及胸廓回弹不足等按压质量未达标方面均差异无统计学意义（均P>0.05）。结论以指定团队领导的Pit-Crew CPR模式有助于实施高质量的CPR，而且CPR质量参数的监测与实施实时反馈系统能有效提高胸外按压的质量。

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简介：摘要：随着旅游城市大理市环保措施的推进，城市建筑物的密集程度大大增加，随之而来的便是建设用地审批的难度越来越大，可以规划的建筑用地也是少之又少，地价也是越来越高。如此唯有在有限且高价的土地上盖出更多的房子方能满足开发商的利益，然而楼层越高，就意味着地下室部分的深度也要越深，方能满足结构稳定性要求。所以，基坑支护，内支撑支护形式在洱海周边建筑得到较大运用。一是深度越挖越深，可占用的面积越来越小，周边高层建筑物密集且距离越来越小。二是只能采用单排或者双排支护桩。三是为防止基坑变形，监测周边建筑物影响，多数情况必须采用内支撑体系，或者内支撑体系与锚索相结合的施工工艺方能满足要求。

简介：摘要：本文由软土地区地铁隧道侧深基坑施工过程相关工况着手，依托隧道段的长期监测数据，对比分析深基坑施工过程中对相邻隧道的变形影响因素分析，以降低深基坑对既有隧道的影响