Abstract:To explore soil shrinkage characteristics during soil drying process, loam soil from Shandong Province (SD) and silty clay loam soil from Shaanxi Province (SX) were selected. The initial bulk density of the two different types of soil was set at 1.30, 1.40 and 1.50g/cm3. A centrifuge method was adopted for soil—water characteristic curve measurement, and the axial and radial shrinkages during drying process were measured and quantitatively analyzed. Results showed that firstly, as for SD and SX soils, soil moisture was decreased with the increase of suction, but the decreasing range was different due to different bulk densities. When suction was increased from 0 to 7000cm, soil moisture was decreased with different rates. Secondly, linear shrinkage ratio increased with decrease of soil moisture during drying process, and the nonlinear relationship between linear shrinkage ratio and soil moisture could be well fitted by the Logistic model, with high determination coefficients (R2) ranged from 0.96 to 0.99. Thirdly, axial shrinkage strain (δs), radial shrinkage strain (δr) and volume shrinkage strain (δV) all decreased with the increase of soil bulk density. And further analyses indicated that the mainly shrinkage characteristics for SD and SX soils were horizontal shrinkage and vertical shrinkage, respectively. Meanwhile, correlation analyses showed that δs, δr and δV were all negatively correlated with sand content and positively correlated with silt and clay contents. And the correlation between the three types of shrinkage strains (i.e., δs, δr and δV) and soil particle content was obviously influenced by bulk density. Detailedly, as for SD soil, δs and δr were significantly correlated with clay and silt contents, however, δV was significantly correlated with sand content; as for SX soil, δs, δr and δV were all significantly or highly significantly correlated with sand and silt contents, but there was no significant correlation with clay content.
