风积沙填筑铁路路基累积塑性变形及临界动应力试验研究  

Experimental study on cumulative plastic deformation and critical dynamic stress of aeolian sand embankment of railway

作　　者：韦朝 WEI Zhao(Xinjiang Railway Survey and Design Institute Co.,Ltd.,Urumqi 830011,China)

机构地区：[1]新疆铁道勘察设计院有限公司,新疆乌鲁木齐830011

出　　处：《铁道科学与工程学报》2024年第1期138-148,共11页Journal of Railway Science and Engineering

基　　金：中国铁路乌鲁木齐局集团有限公司科技研究开发计划课题(WLMQ-KGHZGS-HRTL-GGB-2020-0032);国家自然科学基金资助项目(51878666)。

摘　　要：目前用于铁路基床的填料大多数为级配优良的填料,而对风积沙作为路基填料在列车荷载作用下的累积塑性变形特性和临界动应力研究不多,但风积沙作为路基填料已在沙漠铁路建设中得到运用。为探究列车荷载作用下风积沙填料填筑铁路路基的累积塑性变形演变特性及临界动应力,考虑围压、动应力幅值、压实系数和含水率等因素的影响,开展一系列动三轴试验。试验结果表明:风积沙累积塑性应变随压实系数、围压的增大而减小,随动应力幅值的增大而增大。以最优含水率为分界点,低于最优含水率时,风积沙累积塑性应变随含水率的增加而减小;高于最优含水率时,风积沙累积塑性应变随含水率的增加而增大。风积沙试样的累积塑性应变曲线可分为:稳定型、临界型和破坏型。根据对累积塑性应变曲线的分类,获得了不同条件下风积沙填料的临界动应力。风积沙临界动应力随围压和压实系数的增大而增大,饱和含水率下风积沙填料的临界动应力明显小于天然含水率和最优含水率下风积沙填料的临界动应力。临界动应力和围压具有较好的线性关系。构建了可考虑围压和含水率影响的风积沙临界动应力经验公式,通过临界动应力公式确定了不同工况下风积沙作为路基填料的适用范围。试验结果可为沙漠铁路的设计、施工以及运营提供经验和理论依据。At present,most of the fillers used for railway subgrade bed are well-graded fillers.There are few studies on cumulative plastic deformation characteristics and critical dynamic stress of aeolian sand as subgrade fillers under train load.But aeolian sand as subgrade filler has been used in desert railway construction.A series of dynamic triaxial tests of aeolian sand samples,considering the influence of confining pressure,dynamic stress amplitude,compaction coefficient and moisture content,were carried out to investigate the evolution laws of cumulative plastic deformation and its critical dynamic stress.The test results are drawn as follows.The cumulative plastic strain of aeolian sand increases with the increase of dynamic stress amplitude,and it decreases with the increase of compaction coefficient and confining pressure.Taking the optimal moisture content as the cut-off point,the cumulative plastic strain of aeolian sand decreases with the increase of moisture content,when the moisture content is lower than the optimal moisture content.The cumulative plastic strain of aeolian sand increases with the increase of moisture content,when the water content is higher than the optimal moisture content.The accumulative plastic strain curves can be classfied into three types:stable,critical and failure.Accordingly,the critical dynamic stress of aeolian sand filler was obtained.The critical dynamic stress of aeolian sand increases with the increase of confining pressure and compacting coefficient.The critical dynamic stress of aeolian sand under saturated moisture content is obviously smaller than that under natural moisture content and optimal moisture content.The relationship between critical dynamic stress and confining pressure could be well fitted by linear function.The empirical formula of critical dynamic stress taking confining pressure and moisture content into account are obtained.The applicability of aeolian sand as subgrade filler under different working conditions were determined by the critical dynamic str

关 键 词：铁路路基 风积沙 累积塑性应变 临界动应力 动三轴试验 基床表层 

分 类 号：TU411.8[建筑科学—岩土工程]