Solid-fluid interactions in unsaturated expansive clays can be divided into capillarity and adsorption effects based on their physical mechanisms. Most constitutive models for unsaturated soils are proposed on the bas...Solid-fluid interactions in unsaturated expansive clays can be divided into capillarity and adsorption effects based on their physical mechanisms. Most constitutive models for unsaturated soils are proposed on the basis of the capillarity mechanism, ignoring the contributions of the adsorption effect to mechanical and hydraulic behaviors. For expansive clays, however, the adsorption effect which leads to more complex behavioral characteristics than that in low plasticity clays cannot be ignored. In the light of this, a new binary-medium model for unsaturated expansive clays is proposed, involving a consideration of the solid-fluid interactions stemming from the capillary and the adsorption mechanisms at the same time.Firstly, we assume that expansive clay is a mixture of two ideal parts, i.e. the ideal capillarity part and the ideal adsorption part, and then an ideal capillarity model and an ideal adsorption model, each of which is available for the corresponding ideal part, are established. Furthermore, a participation function is used to reflect the degrees of capillarity effect and adsorption effect. Finally, predictions are performed on the results of the consolidation tests and the cyclical controlled-suction tests published in literature.After comparing predicted results with test results, it is illustrated that the established model can quantitatively predict mechanical and hydraulic behaviors in expansive clays.展开更多
Existing strength criteria are mostly formulated to describe the mechanical properties of reconstituted soils. However, the engineering characteristics of structured soils are different from those of reconstituted soi...Existing strength criteria are mostly formulated to describe the mechanical properties of reconstituted soils. However, the engineering characteristics of structured soils are different from those of reconstituted soils in many aspects, especially in their strength properties, Thus, the influence of soil structure （bonding and fabric） on the mechanical properties of structured soils cannot be correctly described, By analyzing the breakage mechanism of natural soils, the structured soils can be conceptualized as binary medium materials consisting of bonded blocks and weakened bands. On this basis, a new strength criterion is pro- posed for structured soils, The expressions of the strength criterion on both meridian and deviator planes are given to describe the strength properties of structured soils on these planes. The proposed strength criterion is compared with available test data under conventional and true triaxial stress conditions in the literature. It is observed that the proposed strength criterion agrees well with the test data.展开更多
基金supported by the National Natural Science Foundation of China (51278047)Guangxi Science Foundation (2012GXNSFGA060001)
文摘Solid-fluid interactions in unsaturated expansive clays can be divided into capillarity and adsorption effects based on their physical mechanisms. Most constitutive models for unsaturated soils are proposed on the basis of the capillarity mechanism, ignoring the contributions of the adsorption effect to mechanical and hydraulic behaviors. For expansive clays, however, the adsorption effect which leads to more complex behavioral characteristics than that in low plasticity clays cannot be ignored. In the light of this, a new binary-medium model for unsaturated expansive clays is proposed, involving a consideration of the solid-fluid interactions stemming from the capillary and the adsorption mechanisms at the same time.Firstly, we assume that expansive clay is a mixture of two ideal parts, i.e. the ideal capillarity part and the ideal adsorption part, and then an ideal capillarity model and an ideal adsorption model, each of which is available for the corresponding ideal part, are established. Furthermore, a participation function is used to reflect the degrees of capillarity effect and adsorption effect. Finally, predictions are performed on the results of the consolidation tests and the cyclical controlled-suction tests published in literature.After comparing predicted results with test results, it is illustrated that the established model can quantitatively predict mechanical and hydraulic behaviors in expansive clays.
文摘Existing strength criteria are mostly formulated to describe the mechanical properties of reconstituted soils. However, the engineering characteristics of structured soils are different from those of reconstituted soils in many aspects, especially in their strength properties, Thus, the influence of soil structure （bonding and fabric） on the mechanical properties of structured soils cannot be correctly described, By analyzing the breakage mechanism of natural soils, the structured soils can be conceptualized as binary medium materials consisting of bonded blocks and weakened bands. On this basis, a new strength criterion is pro- posed for structured soils, The expressions of the strength criterion on both meridian and deviator planes are given to describe the strength properties of structured soils on these planes. The proposed strength criterion is compared with available test data under conventional and true triaxial stress conditions in the literature. It is observed that the proposed strength criterion agrees well with the test data.
