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膨胀土遇水膨胀、脱水干缩不能直接填筑路基,因此必须进行改良。改良膨胀土路基施工质量控制主要包括全线取土场土质调查与膨胀土物理性质试验、改良机理分析和方案选择、改良效果比较及参数确定。改良土拌和是使膨胀土与石灰产生理化反应,降低或消除膨胀性,增强水稳性和耐久性。改良膨胀土路基填筑质量控制包括基底处理、基床以下路堤与基床底层填筑、砂填层和复合土工膜铺设、基床表层级配碎石填筑、路桥(涵)过渡段路基填筑等环节。在用改良膨胀土填筑路基过程中,应对填料的液限、塑限、击实、无侧限抗压强度、无荷膨胀率、50kPa荷载下有荷膨胀率、胀缩总率、浸水72h崩解等进行复查试验。
Expansive soil water expansion, dehydration shrinkage can not be filled directly embankment, it must be improved. The construction quality control of improved expansive soil embankment mainly includes the soil survey and physical property test of expansive soil in the whole line, the analysis of the improvement mechanism and the selection of schemes, the comparison of improvement effects and the determination of parameters. Improved soil mixing is to make the expansive soil and lime physical and chemical reactions, reduce or eliminate expansibility, enhance water stability and durability. The quality control of improved expansive soil embankment construction includes basement treatment, embankment and subfloor under foundation bed, laying sand and composite geomembrane, grading of graded gravel on the surface of foundation bed, subgrade filling of road and bridge (culvert) transitional section Building and other sectors. In the course of filling embankment with modified expansive soil, the liquid limit, plastic limit, compaction, unconfined compressive strength, unloaded expansion rate, load expansion rate under 50kPa load, total expansion and contraction rate, immersion 72h Disintegration and other review test.