红砂岩风化土路基瞬态饱和区动弹性模量和阻尼比试验研究

Experimental Investigation into Dynamic Elastic Modulus and Damping Ratio in Transient Saturated Zone of Red Sandstone Residual Soil Subgrade

连续降雨后的红砂岩风化土路基瞬态饱和区土体骨干曲线、动弹性模量和阻尼比是进行路基动力特性分析的关键因素.为研究红砂岩风化土路基瞬态饱和区在重载列车荷载作用下的动力特性,采用中砂与不同含量红黏土重塑土样进行动三轴试验,探讨了细粒含量、围压对瞬态饱和区土体骨干曲线、动弹性模量和阻尼比的影响.研究表明:含细粒砂土的骨干曲线符合Konder双曲线模型;细粒含量对动弹性模量和阻尼比的影响并不是单调的,而是存在一个临界值,在临界值前后,动弹性模量和阻尼比随细粒含量的变化趋势相反,文中所用试样的临界细粒含量在20%左右;围压对土体动弹性模量和阻尼比有显著的影响,随着围压的增大,动弹性模量增大,阻尼比减小.

The red sandstone residual soil subgrade after a continuous rainfall will form a transient saturated zone,and the soil backbone curve,dynamic elastic modulus and damping ratio are the key factors for analyzing the dynamic characteristics of the subgrade.In order to study the dynamic characteristics of red sandstone residual soil subgrade in transient saturated zone under heavy-haul train load conditions,dynamic tri-axial tests were carried out with sand and different content of red clay remolded soil samples.The effects of fines content and confining pressure on backbone curve,dynamic elastic modulus and damping ratio of soil in transient saturated zone were discussed.The results show that:the backbone curve of sand with fines content conforms to Konder hyperbolic model;the influence of fines content on the dynamic elastic modulus and damping ratio is not monotonic,but there is a threshold(about 20%);the variation trends of dynamic elastic modulus and damping ratio negatively related with fines content around the threshold;confining pressure has a significant effect on dynamic elastic modulus and damping ratio of soil:with the increase of confining pressure,the dynamic elastic modulus increases and the damping ratio decreases.