5 Pages


= = = .---.-

If the pore water contains a low concentration of dissolved salts the particles will tend to the dispersed structural arrangement shown in Fig. 2.2(b) (3). Dispersion can be achieved artificially by treating a soil with a deflocculant solution or by mechanical means. An example of the latter is the process of compaction described in Chapter 1. In this case the large deformations imposed on the soil tend to destroy the original structural arrangement of the particles and impose the parallel configuration shown in Fig. 2.2(b) (3). Typically the soil is sub-divided into domains and the parallel orientations in the domains are in random directions. In the case of the Norwegian quick clays in the undisturbed state, the particles are in the flocculated structural arrangement due to their deposition in marine conditions, but the concentration of electrolyte in the pore water is now weak due to the leaching effect of percolating ground-water and would normally be associated with the dispersed structure. When this clay is deformed sufficiently to destroy the relatively strong flocculated structure the particles rapidly rearrange themselves into the much weaker dispersed arrangement. The engineering implication of this quick transformation is discussed in Chapter 4.