结合水对软土次固结特性的影响机制研究

结合水对软土的工程特性具有重要影响,为研究结合水对软土次固结特性的影响机制,选取天津软土为研究对象,开展了结合水的等温吸附试验及原状土和不同结合水含量下重塑土的固结蠕变试验.从结合水角度对原状土的固结蠕变特性进行了探讨,并就结合水类型及含量对重塑土蠕变特性的影响机制进行了研究.研究结果表明:等温吸附试验中90％相对湿度...

Mechanism of Bound Water Effects on the Secondary Consolidation Property of Soft Soil

Bound water intimately affects the mechanical properties of soft soil. This study reveals the mechanism of bound water effects on the secondary consolidation property of soft soil. Tianjin soft soil was selected as the research object, isothermal adsorption tests and consolidation creep tests of undisturbed and remolded samples with different bound water contents were conducted. The consolidation creep property of undisturbed soil was examined in terms of bound water, and the controlling effects and mechanism of bound water type and content on the creep property of remolded soil were studied. Results of the isothermal adsorption test show that relative humidity H_R values of 90% and 98% represent the boundaries between strongly bound, weakly bound, and free water in Tianjin soft soil. Correspondingly, the strongly and weakly bound water contents in the soil are 13.2% and 22.6%, respectively. Variation in the hydration site produces a significant lag effect between the adsorption and desorption processes in the strongly bound water sorption stage. When the consolidation pressure p>400 kPa, the secondary consolidation of the undisturbed sample is controlled by weakly bound water. Because the discharge of bound water is much more difficult than that of free water, the secondary consolidation coefficient of undisturbed soil begins to decrease when p>400 kPa. During the consolidation creep process, the displacement of free water and weakly bound water in the undisturbed sample are 12.1% and 9% respectively, and no strongly bound water is discharged. The secondary consolidation coefficient of remolded samples in the range of strongly bound water is not sensitive to an increase in water content. When entering the coexistence state of strongly and weakly bound water, the effect of bound water on the secondary consolidation of the remolded sample can be observed, and the secondary consolidation coefficient increases rapidly with an increase in water content, indicating that the weakly bound water is the dominant factor to affect the creep property of soft soil.