基于加载动力效应对孔压滞后现象的一个解释

在底部可测孔压的固结仪内进行单面排水固结试验时，观测到试样底部的孔压可出现滞后现象。为分析其原因，考虑加载引起的动力效应，建立以竖向应变为求解对象的一维动力固结方程，并用有限差分法进行求解。引入新指标CD来综合考虑试样压缩模量、渗透系数、密度以及土样厚度等4个参数对动力效应的影响，探讨了该指标对固结过程中孔隙水压力的影响。计算结果表明，瞬时加载引起的动力效应是引起试样内孔压滞后的一个原因，并且对于压缩模量或渗透系数较大的试样，更易出现孔压滞后现象，同时动力效应对固结度的影响则主要体现在固结的前期。最后讨论了固结分析时可以忽略动力效应的范围。

An explanation of delay of pore water pressure based on dynamic effect due to loading

A phenomenon is found that the pore water pressure in the soil specimen inclines to delay during the single-drainage consolidation test by using the oedometer which can measure the pore water pressure at the bottom of specimen. In order to analyze its cause, a one-dimensional dynamic consolidation equation in which the vertical strain is set as its dependent variable is presented to take into account of the dynamic effect due to instantaneous loading, and the numerical analysis is performed by using the finite difference method. A new parameter CD composed of the modulus of compressibility, coefficient of permeability, density and thickness of specimen is introduced to characterize the dynamic effect; and then its influence on the pore water pressure in the process of consolidation is investigated. The numerical results indicate that the dynamic effect due to loading is a cause of delay of pore water pressure in the specimen, and the phenomenon is easier to appear for the soil specimen with greater modulus of compressibility or coefficient of permeability. In addition, the dynamic effect has a certain influence on the consolidation degree in the early period of consolidation. Finally, the consolidation cases are discussed that the dynamic effect can be negligible.