重载铁路基床填料低围压静三轴试验研究

The study on static triaxial test of heavy haul railway filler of subgrade roadbed under low confining pressure

为真实模拟基床表层填料在较低围压下的受力特性,选取朔黄铁路路基基床层填料的低液限粉土,在室内开展一系列不同围压、含水率及不同试验条件下的静三轴试验,探究含水率、围压及试验方法对应力应变曲线及抗剪强度的影响。在试验的基础上,对应变硬化型曲线利用邓肯-张模型进行拟合;对应变软化型曲线利用沈珠江推广双曲线公式进行拟合,拟合结果良好。研究结果表明:峰值强度与围压之间具有良好的线形关系,并且强度对含水率的变化较为敏感;黏聚力与内摩擦角则均随含水率的增加而减小,其中内摩擦角下降的幅度要小于含水率的下降幅度,同时受试验条件的影响,对采取了排水措施的试验,有效应力得到了提高,因此黏聚力较大。

In order to simulate the force characteristics of the surface layer of the bed under low confining pressure,the low liquid limit silt of the base bed of the Shuohuang Railway roadbed was selected,and a series of different confining pressures,moisture content and different conditions were carried out indoors.The static triaxial test under test conditions explores the effects of moisture content,confining pressure and test methods on stress-strain curves and shear strength.On the basis of the experiment,the corresponding hardening curve is fitted by Duncan-Zhang model;the corresponding softening curve is fitted by Shenzhujiang generalized hyperbolic formula,and the fitting result is good.By analyzing the strength of static triaxial test,the results show that there is a good linear relationship between peak strength and confining pressure,and the strength is sensitive to the change of moisture content;the cohesion and internal friction angle are both with the increase of moisture content,the extent of internal friction angle decreases less than the decrease of moisture content.At the same time,due to the test conditions,the effective stress is improved in the test with drainage measures,so the cohesion is large.