考虑渗透系数随时间变化及固结状态影响的一维固结计算[

固结系数的不确定性是传统固结理论计算局限性的根本原因,传统固结理论计算忽略了在固结过程中渗透系数k和孔隙比e随固结状态和时间的变化。基于工程常用的5种渗透系数预测模型,结合固结度与侧限压缩量的关系,推导出孔隙比e_t的时间函数,构建渗透系数与时间及固结应力依赖的计算公式。将构建的渗透系数计算式代入固结系数C_v中,同时考虑固结状态、固结应力及时间的影响,对经典Terzaghi一维固结理论进行修正。利用已有的试验数据进行对比,讨论预测公式的适用性。最后通过工程案例计算,与Terzaghi一维固结方程和其他修正固结理论对比,结果表明:当上覆荷载较大时,需要考虑固结系数C_v的变化;同时,对比其他修正固结理论,证明了考虑孔隙比e和渗流系数k随时间变化过程的必要性。

One dimensional consolidation calculation considering the change of permeability coefficient with time and the influence of consolidation state

The uncertainty of the consolidation coefficient is the fundamental reason for the limitation of the traditional consolidation theoretical calculation, which ignores the variation of permeability coefficient k and porosity ratio e with the consolidation state and time during the consolidation.In this paper, the porosity time-history is derived on the basis of five commonly used prediction models of permeability coefficient in engineering, having the relationship between consolidation degree and confined compression.Thus,the calculation formula of permeability coefficient related to both time and consolidation stress is constructed. Here the one-dimensional consolidation theory is modified by substituting the permeability coefficient formula into the consolidation coefficient C_v and considering the consolidation state as well as consolidation stress and time variation. The comparations with the literatures and engineering cases confirm the necessity of the time effect on the porosity. The change of consolidation coefficient C_v cannot be ignored when suffering a larger overlying load. At the same time, it is proved that it is necessary to consider the process of porosity ratio e and seepage coefficient k changing with time by comparing with other modified consolidation theories.