卸荷作用下软黏土回弹吸水试验研究

为了研究软黏土试样在经受卸荷作用后回弹变形中的吸水规律,设计了新的渗透固结试验仪器。以饱和软黏土试样为研究对象,通过室内试验,分析了卸荷作用下软土的回弹吸水特点。试验结果表明,研制的渗透固结仪器密封性能好,可以收集试样固结过程中排出的孔隙水。软黏土试样在大于临界卸荷比的情况下发生回弹吸水,其规律与预压荷载持续时间有关。当预压荷载持续时间为主固结完成时,则软黏土试样回弹变形引起的体积变化等于进入土体的孔隙水的体积;若荷载持续时间为24h,则回弹变形可以分为主回弹阶段与次回弹阶段。在主回弹阶段,土样的体积变化等于吸入土体的孔隙水的体积;在次回弹阶段,试样并未吸水,仍然有少量变形。卸荷后软黏土试样吸入土体的水量与固结沉降排出土体的水量之比普遍小于10%。

Water absorption test of soft clay after rebound under unloading

A newly developed seepage consolidation odometer is designed to investigate the suction discipline of soft clay under unloading after rebound deformation. Taking saturated soft clay as a study object, the suction characteristics of soft clay with the developed seepage consolidation odometer are analyzed. Test results show that the new odometer apparatus designed and manufactured which improves scalability can collects the water discharged from the soft clay when the consolidation happens; when the unloading ratio is greater than critical unloading ratio, the soft clay specimen rebounds and absorbs water, and its characteristics are related to the preloading duration. The volume change of the clay specimen is equal to the volume of water that enters into the soil when the unloading happens at the end of primary consolidation. When the preloading duration is 24 hours, the soft specimen’s rebound deformation is divided into two stages that include primary rebound and secondary rebound. During the primary rebound stage, volume change of the clay specimen with rebound deformation is equal to the volume of water that enters into the soil; during the secondary rebound stage, the specimen has small deformation but doesn’t absorb water. The ratio of the volume of water absorbed by soil-to-the volume of water drained by consolidation is less then 10% generally.