干湿循环中膨胀土吸力和膨胀力变化规律研究

Study on the Variation Law of Suction and Expansion Force of Expansive Soil during Dry and Wet Cycle

以江苏省宿迁市某膨胀土航道整治工程为例,通过室内试验,研究膨胀力与基质吸力随含水率与干湿循环次数的变化规律。结果表明,膨胀力随含水率增加而降低,干湿循环后膨胀力整体下降,其中吸湿过程膨胀力大于干燥过程,在一定次数的循环后逐渐稳定;基质吸力随体积含水率增大而减小,干湿循环次数的增加使得基质吸力下降,含水率越大降幅越小,滞回曲线不明显。试验数据拟合发现,膨胀力与含水率关系式用指数函数拟合、土水特征曲线用Gardner模型拟合效果最好。结合相应的非饱和土抗剪强度公式,能用于非饱和膨胀土边坡的相关研究。

Taking an expansive soil waterway regulation project in Suqian City,Jiangsu Province as an example,the variations of expansion force and matrix suction with moisture content and the number of dry-wet cycles are studied through laboratory tests.The results show that,(a)the expansion force decreases with the increase of moisture content,and decreases as a whole after the dry-wet cycle,in which,the expansion force in the hygroscopic process is greater than that in the drying process,and gradually stabilizes after a certain number of dry-wet cycles;and(b)the matrix suction decreases with the increase of volume moisture content,and the increase of the number of dry-wet cycles reduces the matrix suction,in which,the larger the moisture content,the smaller the decrease,and the hysteresis curve is not obvious.Based on the experimental data,it is found that the relationship between expansion force and moisture content is best fitted with exponential function,and the soil-water characteristic curve is best fitted with Gardner model.Combined with corresponding shear strength formula of unsaturated soil,the experimental results can be used for the related research of unsaturated expansive soil slope.