起始水力梯度对真空预压下砂井地基固结过程的影响

Effect of Initial Hydraulic Gradient on Consolidation of Sand-drained Ground Improved by Vacuum Preloading

针对粘土中孔隙水渗流存在起始水力梯度的现象,将考虑起始水力梯度的非Darcy渗流方程引入传统的砂井固结理论对其进行修正,并给出了真空预压下砂井地基固结近似解。探讨起始水力梯度对真空预压下砂井地基固结过程的影响,包括渗流前锋面的运动规律、孔隙水压力的分布变化规律和平均固结度的变化规律。结果表明,由于存在起始水力梯度,会延缓真空压力的传播,进而影响孔隙水的渗流和整个土层的固结速度。起始水力梯度越大,滞后现象越明显。此外,起始水力梯度的存在将使平均孔隙水压力逐渐趋于某一稳定值,但无法达到真空压力,所以最终平均固结度将小于100%,且其值随起始水力梯度的增大而减小。

Because of the existence of initial hydraulic gradient in clay,non-Darcy equation with initial hydraulic gradient was modified with classical consolidation theories of sand-drained ground.And the approximate solution in the instance of vacuum preloading was presented.Based on this,the effect of initial hydraulic gradient on the seepage front,the pore water pressure and the average degree of consolidation were investigated.It was found that the spread of vacuum pressure was delayed because of initial hydraulic gradient,resulting in the dissipation of pore water pressure and the speed of soil layer consolidation.The hysteresis became more and more evident with the increase of initial hydraulic gradient.In addition,initial hydraulic gradient also caused some residual pore water pressure which could not reach vacuum pressure.Thus,the ultimate average degree of consolidation was less than 100%,which decreased with the increase of initial hydraulic gradient.