Practical assessment of subgrade settlement induced by train operation requires developing suitable models capable of describing permanent deformation characteristics of subgrade filling under repeated dynamic loading...Practical assessment of subgrade settlement induced by train operation requires developing suitable models capable of describing permanent deformation characteristics of subgrade filling under repeated dynamic loading.In this paper,repeated load triaxial tests were performed on coarse-grained soil(CGS),and the axial permanent strain of CGS under different confining pressures and dynamic stress amplitudes was analysed.Permanent deformation behaviors of CGS were categorized based on the variation trend of permanent strain rate with accumulated permanent strain and the shakedown theory.A prediction model of permanent deformation considering stress state and number of load cycles was established,and the ranges of parameters for different types of dynamic behaviors were also divided.The results indicated that the variational trend of permanent strain rate with accumulated permanent strain can be used as a basis for classifying dynamic behaviors of CGS.The stress state(confining pressure and dynamic stress amplitude)has significant effects on the permanent strain rate.The accumulative characteristics of permanent deformation of CGS with the number of load cycles can be described by a power function,and the model parameters can reflect the influence of confining pressure and dynamic stress amplitude.The study’s results could help deepen understanding of the permanent deformation characteristics of CGS.展开更多
According to the comprehensive tests on the rising height of capillary water for seven kinds of differ- ent coarse grained soil by use of the method of standpipe, the relationship between the rising height of capillar...According to the comprehensive tests on the rising height of capillary water for seven kinds of differ- ent coarse grained soil by use of the method of standpipe, the relationship between the rising height of capillary water and time was obtained, and the influencing factors and rules were analyzed. The data of the steady rising height of capillary water were obtained, and the regression equation of coarse grained soil on steady height and physical indexes （effective grain dl0 and porosity n） was found. Compared with Hazen＇s and other expressions that could estimate the steady height of capillary water of coarse grained soil, the proposed method is satisfactory and the defects of the latter were pointed out.展开更多
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.51878666 and 51678572).
文摘Practical assessment of subgrade settlement induced by train operation requires developing suitable models capable of describing permanent deformation characteristics of subgrade filling under repeated dynamic loading.In this paper,repeated load triaxial tests were performed on coarse-grained soil(CGS),and the axial permanent strain of CGS under different confining pressures and dynamic stress amplitudes was analysed.Permanent deformation behaviors of CGS were categorized based on the variation trend of permanent strain rate with accumulated permanent strain and the shakedown theory.A prediction model of permanent deformation considering stress state and number of load cycles was established,and the ranges of parameters for different types of dynamic behaviors were also divided.The results indicated that the variational trend of permanent strain rate with accumulated permanent strain can be used as a basis for classifying dynamic behaviors of CGS.The stress state(confining pressure and dynamic stress amplitude)has significant effects on the permanent strain rate.The accumulative characteristics of permanent deformation of CGS with the number of load cycles can be described by a power function,and the model parameters can reflect the influence of confining pressure and dynamic stress amplitude.The study’s results could help deepen understanding of the permanent deformation characteristics of CGS.
文摘According to the comprehensive tests on the rising height of capillary water for seven kinds of differ- ent coarse grained soil by use of the method of standpipe, the relationship between the rising height of capillary water and time was obtained, and the influencing factors and rules were analyzed. The data of the steady rising height of capillary water were obtained, and the regression equation of coarse grained soil on steady height and physical indexes （effective grain dl0 and porosity n） was found. Compared with Hazen＇s and other expressions that could estimate the steady height of capillary water of coarse grained soil, the proposed method is satisfactory and the defects of the latter were pointed out.
