上海深部硬土渗透特性试验研究

上海深部硬土层的沉降显著滞后于水位变化, 本文通过一系列渗透试验进行了相关问题的研究, 包括初始水力坡度, 结核对渗透性的影响, 压力对渗透性的作用, 以及孔隙比与渗透系数之间规律的研究。结果表明硬土的渗透速率与水力坡度之间符合良好的线性关系, 满足达西定律; 大量的致密结核对渗透性影响微弱; 应力增加导致渗透性降低, 渗透系数与孔隙比呈指数规律变化。基于试验成果评价了1989～2007年天然硬土的渗透性变化, 此期间硬土层边界水位下降了近30m, 硬土层的沉降造成了该层渗透性的降低, 但土层的平均渗透系数改变不大。

EXPERIMENTAL STUDY ON PERMEABILITY OF HARD CLAY AT DEEP DEPTH IN SHANGHAI

The layer subsidence of hard clay at deep depth in Shanghiai lags behind the water level change.It is necessary to study the permeability of the hard clay.A series of tests on the clay permeability was carried out in order to settle some questions.These questions include initial hydraulic gradient,influence of hard agglutinate to the permeability and relation of permeability to pressure and pore.The result shows that the seepage velocity keeps a linear relation to the hydraulic gradient well,abiding the Darcy law.The compact agglutinate has little influence on permeability.The permeability reduces while the stress increases and changes with pores following the exponential law.Base on the test results,the permeability change of the natural hard clay during 1989-2007 is estimated.The boundary water level dropped almost 30 meters.The hard layer subsidence caused the permeability reduction but the average permeability change was not so much.