考虑涂抹区压缩及渗透系数变化的堆载预压固结解

Solution of consolidation by surcharge preloading considering compressibility and varying hydraulic conductivities in smear zone

为评估涂抹区土体压缩和渗透系数变化对含竖向排水体地基固结的影响,采用等体积应变假设,考虑涂抹区土体的压缩变形及其水平向渗透系数沿径向分别呈线性和抛物线分布,并考虑井阻作用以及地基附加球应力沿深度任意分布,推导了随时间线性堆载预压条件下固结微分方程的显式解析解答,分析了涂抹区半径、水平向渗透系数的分布模式、以及体积压缩系数对地基整体平均固结度的影响。结果表明,涂抹区土体采用均匀折减的水平向渗透系数明显低估了地基的固结速率,而当涂抹区半径较大时,不考虑涂抹区土体的压缩变形将会高估地基的固结速率。在含竖向排水体地基固结问题的分析中,这些影响不可忽视。

An explicit analytical solution of the partial differential equations of consolidation by vertical drains is derived to assessthe effects of compressibility and varying hydraulic conductivities of soils in the smear zone on ground consolidation. Equalvolumetric strain assumption is adopted. The compressive deformation of soils in the smear zone is considered, together with a linearand a parabolic distribution of the horizontal hydraulic conductivity along the radial direction. Well resistance is also considered,together with an arbitrarily distributed mean stress increasing along the depth of ground. The solution is derived for the consolidationunder a linearly time-varied surcharge preloading. The proposed solution is used to analyze the influences of the radius of smear zone,the distribution of horizontal hydraulic conductivity and the coefficient of volumetric compressibility of smeared soils on the globalaverage degree of consolidation. It is found that the rate of ground consolidation is underestimated by the solution derived byapplying a uniformly reduced horizontal hydraulic conductivity to the smeared soils. When the radius of smear zone is relativelylarge, the rate of ground consolidation is overestimated by the solution derived without consideration of the compressive deformationof the smeared soils. These effects should not be overlooked in the analysis of consolidation by vertical drains.