兰新铁路第二双线盐渍土溶陷特性研究

Study on melt sinking characteristics of saline soil in Lanzhou-Xinjiang second double track railway

结合兰新铁路第二双线建设期间出现的溶陷病害,将该地分布较为广泛的氯盐渍土和硫酸盐渍土作为研究对象,采用自行研制的新型装置进行了室内溶陷试验,以确定初始含水量、初始含盐量、压实度及轴向压力对盐渍土溶陷特性的影响。结果表明:试样首先在轴向压力作用下达到变形稳定,受水浸湿后在很短的时间内有明显溶陷变形,并逐渐趋于稳定;从总体来看,当初始含盐量、轴向压力增大时,盐渍土的溶陷系数随之增大,而当初始含水量、压实度增大时,溶陷系数却呈现减小的趋势;溶陷系数随压力的变化曲线呈抛物线形,但在压力较小和较大时,溶陷曲线变化较平缓;当压力达到200 k Pa时,溶陷系数增量最大。

Melt sinking appeared in Lanzhou-Xinjiang second double track railway. Chlorine saline soil and sulphate salty soil are the research objects in this paper. A new instrument was introduced to conduct laboratory melt sinking tests,aiming to determine the effects of initial water content and salt content,compactness,and axial compression on the saline soil samples. At first,the sample reaches a stable deformation under the action of axial pressure and then a significant collapse deformation occurs within a very short time after soaking,tending to be stable gradually. In general,the collapsibility-coefficient increases with the increase of initial salt content and loads but decreases when the initial water content or com pactness goes up. The curve of the collapsibility-coefficient versus loads is parabolic; the curve is flat when the pressure is small or large. As the pressure comes to 200 kPa,the growth rate of collapsibility-coefficient reaches the maximum.