Model study of seepage in smear zones around vertical drains in layered soil: further results

In a previous paper (Hird & Moseley, 2000) the effects of disturbance, or smear, on the efficiency of circular vertical drains installed in layered soil were quantified in model tests. The circular drains were driven into the models using a sheathed mandrel, and the sheath was then withdrawn. The models were constructed from alternating layers of preconsolidated kaolin and fine sand. A parametric study was conducted of the influence of clay layer thickness, sand layer thickness, mandrel driving speed and mandrel tip angle.

By measuring the distribution of pore pressure and the flow rate during radial flow tests,...