南疆铁路路基次生盐渍化试验研究

为了全面地研究重塑盐渍土和改良盐渍土的毛细水上升及次生盐渍化现象,弄清水分盐分迁移规律,结合南疆铁路盐渍土路基病害防治技术研究,自行研发了一套测定土的毛细水上升高度和盐分迁移试验系统。试验结果表明：改良盐渍土试验未见明显泛盐现象,而重塑盐渍土在同样压实度及相同物理环境下,迁移盐分表面析出十分明显,沿土柱高度（模拟土层深度）呈梯度规律变化。K938 Ⅲ-3型改良盐渍土的毛细水上升高度和次生盐渍化平行试验进一步表明,盐渍土经水泥、石灰和粉煤灰等掺入物改良后能有效地抑制次生盐渍化现象的发生,有效地降低毛细水上升高度。

Secondary salinization of subgrade of southern Xinjiang Railway

The defects of saline soil subgrade are obvious along the southern Xinjiang Railway. The most serious cases occur at the railway section between Akesu and Kashi, 108 km in length. This kind of problem has been gradually found since the opening of the railway in 1999. The causes include local natural, engineering and hydrogeological conditions. The main defective forms are salinity exposure, surface expansion, subgrade compaction, sinking, track deformation, and so on. On the one hand, these defects increase the difficulty and workload of maintenance departments; on the other hand, they also seriously affect the traffic safety. An intelligent control test system is designed to study these problems. Its main functions are to investigate the secondary salinization phenomenon and transportation height of capillary water in the soil samples. The transport rules of water and salt are studied by means of the intelligent control test system based on two comparable cases of remolded saline and improved saline soils. The test results show that the secondary salinization phenomenon is not obvious in the improved saline soils. But the secondary salinization phenomenon is very obvious in the remolded saline soils under the same compression degree and physical condition. The secondary salinization degree gradually varies with the depth of soils. The Ⅲ-3 type improved saline soils on K938 are further tested parallelly. The results show that secondary salinization and the transportation height of capillary water can be controlled effectively if the fly ash, lime and cement are mixed into the saline soils with a certain proportion. The research results are successfully employed to solve the secondary salinization problem of the subgrade of southern Xinjiang Railway. There have been no new defects for more than 6 years.