Abstract：Research purposes:The introduction is given to the engineering characteristics of the clay of the upper pleistocene series of the Quaternary System and the improvement of the clay is made by using the different matching ratios of the lime，the cement，the firming agent and the flyash to obtain the change of the grain compositions，the changes of the plastic limit，the liquid limit and the plastic index，the changes of the contractibility and the dilatability characteristics，the change of the parameters of compaction test and the changes of the strength and water stability for making the improved clay meeting the requirement of the filling material for high － speed railway．
Research conclusions: (1)The Xiashu clay is a filling material with relatively special engineering characteristics and its water content has the obvious effects on the soil strength and dynamic modulus．(2) By mixing with the quicklime，the hydrated lime，the ordinary Portland cement and the soil firming agent by certain ratios，the soil strength and water stability can be enhanced and the compressibility，the contractibility and the dilatability of the soil can be reduced，but the targets mentioned above can not be achieved only by mixing with flyash． (3) The research on improvement of the Xiashu clay can provide the reference to choice of the filling material for high － speed railway in the south area of China．
马连强. 第四系上更新统黏土的改良研究[J]. 铁道工程学报, 2013, 30(4): 30-35.
MA Lian － qiang. Research on Improvement of Clay of Upper Pleistocene Series of Quaternary System. 铁道工程学报, 2013, 30(4): 30-35.
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2013, Vol. 30 
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