膨胀土胀缩性评价中有关问题的研究

SOME PROBLEMS IN ASSESSMENT OF SWELLING AND SHRINKAGE POTENTIAL OF EXPANSIVE CLAY SOILS

膨胀土吸水膨胀、失水收缩，产生地表变形，进而导致建筑物破坏。本文就现行膨胀土胀缩性指标试验及地基变形量评价计算中有关问题进行了研究，认为以天然含水量为起始含水量测定土样胀缩率是不合适的，建议以缩限为起点进行膨胀试验，以胀限为起点进行收缩试验，采用加荷膨胀量（而非卸荷膨胀量）参加有荷载下的膨胀率计算。膨胀土地基勘察必须结合场地条件分析可能影响土体含水量变化的因素，对同一工程采用几种方法评价，互相对比、参照。

Expansive clay soils swell when wetered and shrink when dried out, and hence give rise to ground movements which can further cause structural damages of buildings. The effects of initial water content and load applying or releasing on the result of laboratory swell shrink indices test are studied. The influence of site conditions on potential volume of an expansive clay foundation, especially these factors causing significant change in water content of underlying soil mass, are discussed in this paper. Instead of natural water content, shrinkage limit and swelling limit should be used as initial water content in laboratory test. Before foundation design, site conditions, such as vegetation, precipitation, groundwater table, water drainage, etc. must be considered carefully. For important structures, different methods should be used and compared with each other to evaluate potential volume change of expansive soil more reasonably.