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采用WF12440型空心圆柱扭剪仪,用反压饱和法对初始饱和度较低的原状黄土进行饱和,进行室内原状黄土饱和液化试验研究,探讨了饱和兰州黄土液化过程中孔隙水压力、轴向应变、应力-应变滞回圈的发展规律。结果表明,对初始饱和度较低的原状黄土,反压饱和法使孔压系数B值达到0.95以上,即土样完全饱和;兰州黄土在均压固结条件下液化的孔压发展,开始时上升速率较缓慢,循环数一定后会出现孔压迅速增高的现象直至达到有效围压;应力-应变滞回特性随着振动次数的增加发生变化,塑性逐步增大;当轴向应变小于2%时,孔压增长缓慢;此后,孔压上升速率加大,3%应变可以出现在初始液化前;接近液化时偏应力为负值时的有效应力大于正值时的有效应力。
Using WF12440 hollow cylindrical torsional shear instrument, saturated original loess with low initial saturation was saturated by backpressure saturation method. The saturated liquefaction experiment of intact loess in interior was carried out. The effects of pore water pressure, axial strain , The development of stress-strain hysteresis loops. The results show that for the original intact loess with lower initial saturation, the pore pressure coefficient B value reaches more than 0.95 by the backpressure saturation method, that is, the soil sample is completely saturated. The pore pressure of liquefaction under Lanzhou loess consolidation under pressure consolidation conditions starts from the beginning When the axial strain is less than 2, the pore water pressure increases rapidly with a certain number of cycles until the effective confining pressure is reached. The stress-strain hysteresis changes with the increase of vibration frequency and the plasticity increases gradually. The pore pressure increases slowly; after this, the pore pressure increase rate increases, 3% strain can appear before the initial liquefaction; close to liquefaction bias stress is negative when the effective stress is greater than the positive value of the effective stress.