SWCC测定时吸力计算公式与最佳离心时间的探讨

On formulas for soil suction and optimum centrifugal time by use of SWCC

采用离心机法测定了南京市栖霞区东阳镇0—20cm，20—40cm，40—60cm3层土壤的水分特征曲线（SWCC），分析了密度变化对吸力的影响、质量含水量与时间的关系、土壤吸力与质量含水量的关系；根据分析结果改进了传统的吸力求解公式，得出了离心机法测定粉砂壤土水分特征曲线时的最佳离心时间．改进公式克服了传统公式计算吸力时没有考虑土壤压缩的弊端，计算得到的土壤体积含水量可以随土壤干密度的变化而变化，土壤水分特征曲线更能合理地反映土壤水分的保持和运动规律．

The soil water characteristic curves for 3 soil strata （0 - 20cm, 20 - 40cm and 40 - 60cm） of Dongyang town of Qixia district of Nanjing City were measured by use of the centrifugal method. The effect of dry density change on suction and the relationship between mass water content and time as well the relationship between soil suction and mass water content were analyzed. Based on analytic results, the traditional formula for computing the soil water suction was modified, and the optimum centrifugal time was obtained to determine the SWCC by means of the centrifugal method. The modified formula overcomes the shortcoming of the traditional one, that is, no consideration of＇compressibility of soil. The volumetric water content of soil calculated by the proposed method changes with its dry density, and the SWCC can reflect the conservation and motion laws of soil water more reasonably.