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地基处理和盾构施工都会对土体产生挤压,破坏土体的原生结构和状态,引起土体的扰动,从而改变土体的次固结特性。通过不同预压荷载对土体产生不同程度的挤压扰动,进行分级加载压缩试验。试验结果表明:结构屈服应力随着预压荷载的增大逐渐增大;压缩指数在预压荷载小于结构屈服应力时相差不大,当预压荷载大于结构屈服应力时,压缩指数突然减小,且趋于稳定值;次固结系数随着荷载的增大呈现先增大后减小,再趋于稳定的变化趋势;随着扰动度的增加,次固结系数有所减小。同时,提出了次固结系数的计算模型,对多组试验数据的拟合表明,模型计算结果较好,具有较好的预测能力,对工后沉降的研究有一定的指导意义。
Both foundation treatment and shield construction will squeeze the soil mass and destroy the original structure and state of the soil mass, causing soil disturbance and changing the sub-consolidation property of the soil mass. Through different prestressed load on the soil to produce different degrees of squeeze disturbance, graded loading compression test. The results show that the yield stress of the structure increases with the increase of the preloading pressure. The compressibility index of the structure shows a small difference when the preloading load is less than the structural yield stress. When the preloading load is greater than the structural yield stress, the compressibility index suddenly decreases, And tends to a stable value. With the increase of load, the secondary consolidation coefficient first increases and then decreases, and then tends to a steady trend. As the disturbance increases, the secondary consolidation coefficient decreases. At the same time, a calculation model of secondary consolidation coefficient is proposed. The fitting of multiple sets of experimental data shows that the model has good calculation results and good predictive ability, which is of guiding significance to the study of post-construction settlement.