通过一维开放系统的不同温度梯度人工冻土连续冻结试验,采用动态图像采集和数字分析技术,实现了在冻结过程中获取的分凝冰生长信息在空间和时间分布上的一致性。根据试验中获得的即时图像信息,经过二值化处理后,可以定量的确定分凝冰形成的时间、位置、厚度及发展规律等主要信息。结果表明,图像分析获得的分凝冰厚度与位移计测得的冻胀量基本吻合,分凝冰演化过程可以划分为3个主要阶段:初始阶段几乎不产生分凝冰;第二阶段冻结锋面推进速度减缓,分凝冰以不连续薄冰层形式少量出现;第三阶段冻结锋面趋于稳定,分凝冰的产生主要为末透镜体的生长。在连续冻结试验中,温度梯度与末透镜体的形成时间近似成线性关系,温度梯度越大,出现末透镜体的时间越早。
The consistency in position and time of segregation ice in frozen soils is obtained by use of dynamic photograph and image processing in continuously freezing experiments of one-dimensional open system with different temperature gradients.According to the binarization images of frozen soils,the initiation time,position,thickness and evolving rules of segregation ice can be obtained quantitatively.The thickness of segregation ice obtained from the image analysis is consistent with the frost heave tested by displacement transducer.Three phases of evolving process in the ice segregation can be divided according to the results of the image processing: the early freezing,the growth of thin and discontinuous segregation ice and the final ice lens.There is nearly a linear relationship between the initiation time of the final ice lens and the temperature gradient in continuously freezing experiments.The initiation time of the final ice lens will move up with the increase of the temperature gradient.