红粘土临界动应力与高铁无確轨道路堑基床换填厚度刘晓红哄，杨果林1方薇I(1.中南大学土木建筑学院，湖南长沙410075：2•湖南理工学院土建系，湖南岳卩||411000)摘要：针对武广高速诙路无晞轨道红粘土路堑基床长期动力稳定与换填厚度问题，利用改造后的应力控制式动三轴仪，研究了循环荷载作用下原状结构红粘土动应变随振次的变化规律，获得了II种试验条下原状结构红粘土临界动应力。按Illi线龙势特征，红粘土©〜IgN曲线可分为衰减型、临界型、破坏型三类，具有与其它粘性土相同的曲线型式。基于室内动力试验及现场动响应测试成果，采用临界动应力法初步评价了武广高速诙路无磧轨道红粘土路堑基床的长期动力稳定性，给出了相应的基床换填厚度最小值。探讨了含水比、围压、固结比对红粘土临界动应力及路塹基床换填厚度的影响，通过多元线性回归得到了两个简单实用的经验估算公式。红粘土临界动应力随含水比的增大线性减小，随围压、固结比的增大线性增大。基床换填厚度随含水比的增大线性增大，随围压的增大线性减小，固结比对基床换填厚度的影响就木次试验成果而言还不明显。硏究成果为我国高速铁路无磧轨道路塹基床长期动力稳定性评价及换填厚度的确定提出了新的思路和方法，也为红粘土动力特性的深入硏究积累了宝贵的第一手资料。关键词：临界动应力；换填厚度；动力稳定；原状结构红粘土；动三轴试验中图分类号：TU435文献标识码：A文章编号：作者简介：刘晓红(1967-),女，湖南沅江人，聘士研究生，副教授，注册岩土工程师，主要从事土动力学试验及路基动力稳定性评价等方而的研究工作。E-mail:cgcbt@21cn.comCriticaldynamicstressofredclayandreplacementthicknessunderballastlesstrackcuttingbedofhigh-speedrailwayLIUXiao-hongU2,YANGGuo-lin1,FANG-Wei1(1.SchoolofCivilEngineeringandArchitectureofCentralSouthUniversity,Changsha.Hunan410075,China;2.DepartmentofCivilEngineeringandArchitectureofHunanInstituteofScienceandTechnology,Yueyang,Hunan414000,China)Abstract:Inviewofthelong-tenndynamicstabilityandreplacementthicknessofredclaycuttingbedunderballastlesstrackofWuhan・Guangzhouhighspeedrailway,varyinglawsofdynamicstrainwithvibrationtimesarestudiedofredclayinoriginalstructureundercyclicloadingbymeansoftherefonnedstress-controlleddynamictriaxialtestinstrument,andvaluesofcriticaldynamicstressofredclayinoriginalstructurearegottenunder11kindstestconditions・Accordingtocurvestrendfeatures,the£d〜lgNcurvescanbedividedthreetypes:theattenuatedones,criticalonesanddestructiveones,andthereareidenticalcurvetypeswithothercohesivesoils.Basedonresultsofindoorandfieldtests,thelong-termdynamicstabilityofredclaycuttingbedunderballastlesstrackofWuhan・Guangzhouhigh-speedrailwayispreliminaiyevaluatebymethodofcriticaldynamicstress,andthecorrespondingminimalreplacementthicknessisgiven・Influencesarediscussedforwatercontentratio,confiningpressureandconsolidationratiotocriticaldynamicstressofredclayandthereplacementthicknessofcuttingbed,twopracticalempiricalfonnulasareobtainedbythemethodofmultiplelinearregressions.Thecriticaldynamicstressdecreaseslinearlywithwatercontentratioincreasing,andincreaseslinearlywithconfiningpressureandconsolidationratioincreasing.Thereplacementthicknessincreaseslinearlywithwatercontentratioincreasing,decreaseslinearlywithconfiningpressureincreasing,andtheinfluenceisnotobviousforconsolidationrationtoitinaccordancewithtestresultsinthispape匸Anewtrainofthoughtisputforwardforthelong-termdynamicstabilityevaluationandthedeterminationofcuttingbedreplacementthicknessunderballastlesstrackofhigh-speedrailway,andthefirst-handvaluabledataisaccumulatedforthefurtherstudyondynamiccharacteristicsofredclayi...