新建兰新铁路新疆段沿线盐渍土盐胀特性、机理与防治对策

以新建兰新铁路第二双线(新疆段)盐渍土为研究对象,通过室外、室内综合勘测试验,研究哈密地区盐渍土盐胀特性。试验结果表明:从总体规律来看,盐渍土盐胀过程主要集中在-5～10℃,;含水量-盐胀率曲线呈抛物线,盐胀率最大时含水量为15%左右。通过不同压实度状态下盐胀量试验得出:随压实度增大,盐胀量增大,但压实度低于90%时,盐胀量随压实度升高不明显。分析盐渍土盐胀机理:硫酸盐渍土盐胀作用主要由Na2SO4等易溶盐结晶前后体积变化引起。提出盐渍土防治结构模式:采用控制填料含盐量和压实度、路基填高、排水、坡面加固防护、路基包坡、铲除基础底层盐渍土层、换填粗颗粒渗水土、路基本体采用A组填料等综合性防护措施。

Salt Expansion Properties and Mechanism of Saline Soil in Xinjiang Section of Lanzhou-Xinjiang Railway and Preventive Measures

Saline soil in the Xinjiang section of the second double-line of the newly built Lanzhou-Xinjiang Railway was taken as the object of research.Field investigations and lab tests were carried out to study the salt expansion properties and mechanism of saline soil in the Hami area.The results are as follows: The salt expansion process occurs mainly at temperatures in the range of-5℃～10℃;the relation curve of the water content ratio and salt expansion ratio is parabolic,and the water content ratio is 15% when the salt expansion ratio reaches the highest;the salt heaving content increases with enlarging of the degree of soil compaction,however its increment is not obvious when the degree of soil compaction is lower than 90%;salt expansion is caused by the volume changes of soluble salt such as Na2SO4 prior to and subsequent to crystallization.Measures for prevention and cure of saline soil are proposed in respect of control of the salt content & degree of compaction of the filling material,filling subgrade,drainage,slope reinforcement,removal of the saline soil course from the foundation base,replacing of saline soil with coarse-grained water-seepage soil,and filling of subgrade with materials Group A.