膨胀土的承载强度特征与机制

本文对湖北襄荆高速公路膨胀土的膨胀潜势等级、含水量与干密度对其加州承载比（CBR）值的影响规律进行了系统研究，获得不同含水量范围内膨胀土CBR值和干密度与压实度的经验相关公式，发现膨胀土的CBR值随其膨胀潜势等级、含水量、压实功变化的规律，CBR峰值对应的含水量大于最佳含水量，其差值随击实功的减小而减小。这些特征与膨胀土的固有膨胀特性以及膨胀潜势等级有关。膨胀土用于路堤填筑时，含水量宜按较最佳水量稍大，并略低于塑限，干密度较最大干密度略低的标准控制，这才有利于路堤的长期稳定。

Characteristics and mechanism of bearing strength of expansive soils

The influences of swelling potential grade, moisture content and dry density on bearing strength (expressed by California Bearing Ratio CBR) of expansive soils is experimentally studied and the empirical formulas expressing the relationship between CBR value and dry density of the soil as well as the relationship between CBR value and compaction degree are derived. It is found that the CBR value of expansive soil varies with the swelling potential grade, molding moisture content and compaction effort. The moisture content of maximum CBR is always higher than the optimum moisture content and this difference decreases as the compaction effort decreases. These characteristics are caused by the inherent property and swelling potential grade of the expansive soil. It is concluded that the optimum moisture content for expansive soil in embankment construction should be slightly lower than the plastic limit and the dry density must be slightly lower than the maximum dry density. This is helpful to the long-term stability of the embankment.