干–湿循环过程中吸力与强度关系研究

Test on suction and strength of expansive soil in a desorption-absorption cycle of moisture

针对膨胀土干–湿循环过程中的吸力变化和强度变化特征,开展试验研究。采用体积压力板仪实现脱湿和吸湿并制备不同吸力的试样,通过直剪试验测试不同吸力下的抗剪强度。试验成果显示:①土水特征曲线是不稳定的,它与土体含水率的变化路径有关;②在干湿循环过程中,相同的吸力具有不同的强度贡献。

To study the variation of matric suction and shear strength of unsaturated soils with different water contents, a group of tests were performed to measure the strength of expensive soil during a cycle of desorption-absorption of moisture. Desorption-absorption of moisture was achieved by controlling the suction at different levels. Direct shear tests were conducted to measure strengths of soil samples with controlled suctions in the desorption or absorption process of moisture. From the test results, we could get some insights that： ①soil-water characteristic curve of soil was unstable and related to the variation of soil moisture; ②different variation of soil moisture might lead to different contribution of the same suction to the strength of soil.