胶新铁路砂土液化区路基沉降规律研究

地震液化常给人们带来巨大损失,而剪切振动和循环荷载作用下的动力学效应常被认为是地震液化的主要原因,人们对剪切荷载作用下饱和砂土的液化问题进行了较多的研究,而对循环荷载作用下砂土液化的动力学效应研究较少。胶新铁路在DK39+000开始为高地震烈度区,DK283+550~DK283+770分布有地震可液化层,工程修建后列车动荷载的影响将会有诱发砂土液化的可能性。为了研究通车前自然沉降特征和通车后循环荷载作用下的路基沉降变形规律,本文在具体分析了砂土液化的概念和准则判别的基础上,重点分析了砂土液化区路基沉降特征,包括测试断面竖向分层沉降变形特征分析和路基水平位移特征分析。最后在试验的基础上,从理论上给出了循环荷载下砂土的本构关系。

SUBGRADE SETTLEMENT BEHAVIOR IN SAND LIQUEFACTION AREA ALONG JIAOXIN RAILWAY

Significant progresses have been made in understanding the development of liquefaction of saturated sand under shear vibration loading.But few researchers paid attention to the sand liquefaction under vertical cyclic loading.Jiaoxin railway is a high seismic intensity area after the alignment DK39+000.From the alignment DK283+550 to the alignment DK283+770,there are seismic liquefaction sand layers.It is highly possible to induce sand liquefaction by the dynamic loading of moving trains.In order to study the subgrade settlement characteristics before and after the commencement of the railway,this paper examines the concepts of sand liquefaction and the criterion of liquefaction at first.The paper further analyzes in details the settlement features of the subgrades in the sand liquefaction area.The analyses include the vertical settlement behaviors of sand layers and lateral displacement behavior.Finally,based on the test results,a constitutive model for the behavior of the sand under the condition of cyclic loading is put forward.