土-水特征曲线测定过程中潜在影响因素与异常现象研究

Experimental research on potential factors and abnormal phenomenon for measuring soil-water characteristic curve

基于压力板仪对相同制样参数的4个环刀试样与12个三轴试样进行土-水特征曲线(SWCC)试验,研究影响试验的各种潜在因素以及相关的异常现象。试验结果表明:即便是相同条件制备的试样,其SWCC之间也会存在差异性,这种差异与土的颗粒级配不良有直接关系,而与平衡时间无关;蒸发效应在SWCC试验中持续存在,并在平衡后期成为失水的主要因素,因此,对平衡条件应适当修正;试样的侧面防护对试样的SWCC影响显著,特别对于大高径比试样,蒸发效应将因其侧面防护脱离而成为失水的主要因素,严重影响SWCC的试验结果;横向裂纹这一异常现象并未影响SWCC测量结果,但其产生机制却可能反应了轴平移技术的不足,值得进一步研究。根据上述研究结果和其他相关试验成果,对SWCC试验提出建议和改进方法。

In order to improve test method of soil-water characteristic curve （SWCC）, the pressure plate extractor is employed and drying tests are carried out on the basis of four cutting ring specimens and twelve triaxial specimens. The potential factors and abnormal phenomenon in the test are investigated. The results show that there are differences between the SWCC of specimens, even if the specimens are reconstituted at the same condition, and the differences have a direct relationship with the poor particle size distribution. There is the evaporation effect in the drying tests, and the water loss caused by evaporation is dominant with the increasing of time, so equilibrium condition should be adjusted on the basis of evaporation. The SWCC is obviously influenced by side protecting, especially to the specimen with big ratio of height to diameter, evaporation will become main factor of water loss without side protecting. The transverse crack which is an abnormal phenomenon in the specimen does not affect the result of SWCC, but it should be further investigated because the generation mechanism could show the shortage of axis translation technology. Based on the above conclusion and other test results, some suggestions and improving methods for SWCC test are proposed.