土建筑遗址表部土体收缩特征曲线测定

DETERMINATION OF SOIL SHRINKAGE CHARACTERISTIC CURVE OF SURFACE SOIL ON ANCIENT EARTHEN ARCHITECTURES

为研究土遗址表面雨蚀泥浆的干缩行为及结皮破坏模式,提出液体石蜡法严格测定土的收缩特征曲线的新方法,并利用该方法对遗址土的收缩特性进行研究。试验结果表明:液体石蜡法比传统方法测量的土收缩特征曲线精度更高,而且试验操作简便易行;初始饱和的糊状重塑土土样,其收缩过程由初始的以重力控制的一维竖向收缩逐渐向三维收缩发展;土中封闭微孔中空气的存在,使得实测收缩曲线与理论收缩曲线发生一定程度的偏移;随着黏粒和膨胀性黏土矿物含量的增大,粉土的体积收缩率增大,而达到最终稳定状态时的孔隙比则减小;3种粉土的缩限与塑限相接近,并且缩限比各自的塑限分别低1.1%,1.4%和1.8%。

The paraffin oil method was proposed and conducted to determine the soil shrinkage characteristic curves（SSCC） for understanding the desiccation behavior of the wet surface of ancient earthen architectures.Test data and the model fitting results show that paraffin oil method is more accurate than the traditional methods.This study indicated that the soil paste shrink vertically at the primary dryings stage by gravity and then came to three-dimensional shrinkage with the further evaporation of the soil water.It was found that the measured SSCC was slightly shifted upward from the theoretical 1：1 saturated line,which can be attributed to the air contained in the isolated micropores.Results of test also indicated that the shrinkage limits of the three silt soils were 1.1%,1.4% and 1.8% lower than the corresponding plastic limit,which was determined mainly by the clay content and the type of clay minerals.