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 c lay at deep depth in Shangh iai lags beh ind the w ater level change. It is necessary to study the permeability of the hard c lay. A series of tests on the clay permeability w as carried out in or der to settle some quest ions. These quest ions include initial hydraulic grad ien,t inf luence of hard agg lutinate to the permeab ility and re lation o f permeability to pressure and pore. The result show s that the seepage velocity keeps a linear relation to the hydrau lic grad ientw el,l abiding the Darcy law. The compact agglutinate has little influence on permeab ility. The permeability reduces w hile the stress increases and changes w ith pores fo llow ing the exponent ia l law. Base on the test resu lts, the permeab ility change o f the natura l hard clay during 1989- 2007 is estima ted. The boundary w ater level dropped almost 30 meters. The hard layer subsidence caused the perm eab ility reduction but the average permeability change w as not so much.