富水红层路基碎石改良填料力学特性试验研究

Experimental Research on the Mechanical Properties of Improved Red Soil Subgrade in Rich Water Area

研究目的:为解决富水区红层黏土路基含水率高、无法压实等问题,本文通过向原状土中掺入一定粒径配比的弱风化红层泥岩碎石,制成不同级配和含水率的改良填料,然后进行重型击实试验、大型直接剪切试验及无侧限抗压强度试验,以获得满足铁路路基填筑要求的填料方案。研究结论:(1)红层原状土通过掺入弱风化泥岩碎石可有效降低原状土的含水率,改良填料的最优含水率为10.26%,最大干密度为2.22 g/cm^3;(2)最优含水率时改良填料的黏聚力c为29.336 k Pa,内摩擦角φ为32.86°,相较于红层天然原状土抗剪强度有明显的提高;(3)改良填料的无侧限抗压强度在含水率为8.85%时最大,达到518.80 k Pa,随着含水率的增加其逐渐降低;(4)通过混合弱风化红层泥岩碎石与红层黏土的改良填料,不仅没有改变红层黏土特性,而且能有效降低原状土填料含水率,增加抗剪强度和抗变形能力,改良后填料的含水率和压实性能满足《铁路路基设计规范》要求;(5)该改良方案可为西南富水红层地区铁路路基基床以下路堤填筑工程提供参考。

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/era3. （2） The cohesion c of the improved material is 29. 336 kPa and the friction angle ~ 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.