Experimental Studies

Abstract

The procedure for setting up the 45 soil columns was as follows:

• Soil material containing a high proportion of loess from the illuvial horizon of a soil that has undergone clay translocation during its formation (“Parabraunerde”, “Sol lessivé”, “Alfisol”) is homogenized (site of sampling near Feldbergen, Brunswick region, Germany).

• The material is filled in a dry state into a glass tube lined with paperboard (diameter and height of the soil column approximately 9 cm).

• The column is very slowly saturated with water from below and subsequently dried at 105 °C.

• After removal of the hard soil core from the glass tube, the soil column is burned in a kiln at temperatures rising to a final level of 600 °C, whereby already some voids develop. (The nil test variants were dried slowly and at a lower temperature to prevent the formation of fissures.) The burning prevented a swelling of the soil material during the experimental runs.

• After wrapping the soil columns with wire, further voids are created by driving small nails into the outside surface of the columns.

• The wire wrapping is removed in sections and the soil column is coated with silicon rubber and tape.

• A cylinder with an overflow as well as a base plate made of coarsely woven plastic fibre and wire mesh are fixed to the soil columns with silicon rubber and sealed with putty.