What happens to the water in a clay soil sample during the consolidation test?

During a consolidation test, the primary focus is on the behavior of water in a saturated soil sample, particularly in clay soils, which are known for their plasticity and ability to retain water. When a load is applied to the clay soil during this test, the voids between the soil particles experience a reduction in volume, leading to an increase in effective stress. This causes the pore water pressure to initially rise, but as the water is unable to move out of the tiny voids immediately, the load is transferred to the soil skeleton.

The consolidation process involves the gradual expulsion of water from the soil pores as the clay particles are compressed under the applied load. This expulsion occurs because the soil particles move closer together, reducing the space for water. The rate at which the water exits the soil is controlled by the permeability of the clay, which is generally low, resulting in a slow rate of consolidation.

As a result, the correct choice describes the expulsion of water under the load applied during the test, which is crucial for understanding the behavior and settlement characteristics of clay soils in civil engineering applications.