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土水特征曲线(SWCC)描述的是土体基质吸力与含水率之间的关系,它对于非饱和土的研究具有重要意义。在测定SWCC的各种方法中,渗析法的试验过程较简单、安全且可靠。本文以合肥地区非饱和膨胀土为研究对象,详细介绍了渗析法获得SWCC的试验过程和技术要领,并采用水浴恒温振荡器代替磁力搅拌器改进了渗析试验。结果表明:采用水浴恒温振荡器进行渗析试验是合理可行的,其优点是一次可以进行相同环境条件下多个浓度的渗析试验;使用水浴恒温振荡器对合肥地区膨胀土进行渗析试验时,其渗析平衡时间约为8天。在此基础上,采用Fredlund-Xing模型的3种型式对渗析试验结果进行了曲线拟合,得到了试验土体的SWCC及其拟合参数,可知模型3种型式的区别主要在高吸力部分。
Soil water characteristic curve (SWCC) describes the relationship between soil matrix suction and water content, which is of great significance for the study of unsaturated soils. Among the various methods of determining SWCC, the dialysis test is simpler, safer and more reliable. In this paper, the unsaturated expansive soil in Hefei area as the research object, the experimental process and technical essentials of obtaining SWCC by dialysis are introduced in detail, and the dialysis experiment is improved by using a water bath thermostatic oscillator instead of a magnetic stirrer. The results show that it is reasonable and feasible to use a water bath thermostatic oscillator for dialysis. The advantage of this method is that it can perform dialyzing tests at multiple concentrations under the same environmental conditions at one time. When dialysate is used to dialyze the expansive soil in Hefei area with a water bath thermostatic shaker, The balance time is about 8 days. On the basis of this, three curves of Fredlund-Xing model were used to curve fitting the results of the dialysis test. The SWCC and its fitting parameters of the test soil were obtained. It can be seen that the difference of the three models is mainly in the high suction part.