盐渍土盐胀特性与水热状态变化特征试验研究

为了研究外界自然条件下的盐渍土盐胀特性与水热传递变化特征,进行了含盐量和干密度单向控制下的室内膨胀变形试验和为期一年的地基变形、地温和含水率综合监测现场试验。结果表明:盐渍土地基温度传递呈现正弦波式的周期性变化,自然环境温度对地基土体的有效影响深度为1.8 m,在0.8 m附近存在正负温度的过渡交界面;盐渍土地基水分迁移的基本动力来自于土层温度场的变化,距离地表0.6 m以上土体的含水率随温度变化的幅值最大;盐胀变形的主要分布区在地层1 m以上深度范围内,盐渍土盐胀变形主要受温度、分水、含盐量和干密度影响,盐胀变形快速发展的温度区间为10℃^-5℃,严寒期盐胀变形发展受毛细水的冻结影响而减缓,含盐量在2%以上的盐渍土对于温度变化的敏感性增强,盐胀增长趋势更为突出,盐渍土盐胀变形快速发展所需的降温幅值随干密度增大而减小。

Experimental Research on Salt Expansion Law of Saline Soil and the Change Characteristics Under Different Water Thermal Conditions

In order to acquire the salt expansion law of saline soil and the change characteristics under different water thermal conditions,the test of expansive deformation under uniaxial control of salt content and dry density and the field test of ground deformation,ground temperature and water content for one year were carried out.The results show that the periodic change of the saline soil temperature appears a sine wave form and the effective influence depth of natural environment temperature on foundation soil is 1.8 m,there is a transition interface between positive and negative temperatures in the depth of 0.8 m;the basic impetus of moisture migration of saline soil comes from the changes of soil temperature.Soil moisture less than 0.6m depth has the maximum change amplitude;sa]t-expansion deformation mainly oc curs in the depth of 1 meter soil layer,the deformation of salty soil is mainly affected by temperature,water,salt and dry density.The temperature range of rapid development of salt expansion deformation is 10℃ ～-5℃,the development of salt expansion in freezing period is affected by the freezing capillary water.The sensitivity of saline soil with salt content more than 2％ was enhanced and the trend of salt expansion was more prominent,the cooling amplitude required for the rapid development of salt deformation decreases with thc increase of dry density.