Consolidation of Soil: Instrumentation & Monitoring

When constructing projects like highway embankments, bridges, dams, tanks, airport runways, buildings etc, there is a chance of considerable settlement occurring on soft compressible soil. This happens due to the consolidation of soil due to the load application. Immediate settlement occurs in the soil upon load application, which leads to a reduction in void space, and rearrangement of the soil particles in response to the weight.

In order to avoid any expensive or problematic condition due to the settlement, it is advised to cause the consolidation at the commencement of the project, and in the shortest possible time during the construction period.

The construction on top of a soft soil foundation is usually delayed until there is an assurance that there will be no damage due to the settlement that occurs during subsequent consolidation. If the delay cannot happen, the time is reduced by surcharging and/or by the installation of vertical drains.

Soil Consolidation

When a saturated soil undergoes a steady pressure due to the weight of an embankment or overlying soil, its volume is known to decrease with time. Since the soil particles, as well as the water in the void, is compact and firm when the pressure is added, the change in the volume will occur only when the water is forced out of the voids.

As the water is flushed out, the size of the void is reduced, allowing the solid particles to come together closer. The same is shown in the picture below.

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