Question

In soil consolidation process, the following events take place after loading:

The correct sequence of these events is

• A. 3, 2, 1, 4
• B. 2, 3, 1, 4
• C. 2, 3, 4, 1
• D. 3, 2, 4, 1

Answer 1

The correct option is B 2, 3, 1, 4

• Initial Consolidation : When a load is applied to a partially saturated soil, a decrease in volume occurs due to expulsion and compression of air in the voids. A small decrease in volume occurs due to compression of solid particles. The reduction in volume of the soil just after the application of the load is known as initial consolidation or initial compression. For saturated soils, the initial consolidation is mainly due to compression of solid particles.
• Primary Consolidation : After initial consolidation, further reduction in volume occurs due to expulsion of water from the voids. When a saturated soil is subjected to a pressure, initially all the applied pressure is taken up by water as an excess pore water pressure. A hydraulic gradient will develop and the water starts flowing out and a decrease in volume occurs. This reduction in volume is called as the primary consolidation of soil.
• Secondary Consolidation : The reduction in volume continues at a very slow rate even after the excess hydrostatic pressure developed by the applied pressure is fully dissipated and the primary consolidation is complete. The additional reduction in the volume is called as the secondary consolidation.