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| Experimental Research on the Mechanical Properties of Improved Red Soil Subgrade in Rich Water Area |
| XU Hua1, ZHANG Yi-bo1, ZHANG Jie1, YOU Guan-jun 2, WANG Xin-yu1 |
| (1. Southwest Jiaotong University, Chengdu, Sichuan 610031, China; 2. Sinohydro Bureau 5 Co. Ltd, Chengdu, Sichuan 610066, China) |
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Abstract Abstract：Research purposes： To solve the high-water content and uncompacted problems for red clay subgrade in rich water area, improved subgrade material with different water content was made by mixing original soil with weakly weathered red-mudstone gravel, which was sorted by a certain ratio of the particle size. Heavy compaction test, large direct shear test and unconfined compression test were conducted to get the filling material that meet the requirement of the railway subgrade construction. Research conclusions： (1) The water content of original red soil can be reduced effectively through adding weakly weathered mudstone gravel. The optimum water content of the improved material is 10.26%, and the maximum dry density is 2.22 g/cm3. (2) The cohesion c of the improved material is 29.336 kPa and the friction angle φ is 32.86°, when the improved material is at optimum water content. Compared to the natural soil of red layer, the shear strength of the improved material has significantly improved. (3) Unconfined compressive strength of the improved material reaches 518.80 kPa when water content is about 8.85%, and decreases gradually with the increase of the water content. (4) Through mixing the weakly weathered red mudstone gravel with red clay, the characteristics of red clay do not change, and the water content of original soil can be reduced effectively as well, and the shear strength and deformation capacity also are increased. Besides, water content and compaction performance of the improved material can meet the requirements of railway subgrade design criterion. (5) The improved scheme can provide a reference for the southwest rich red layer area in railway subgrade engineering.
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Received: 17 August 2017
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2017, Vol. 34 
