A vertical pressure exceeding the s

A vertical pressure exceeding the seating pressure is applied to the specimen. The magnitude of vertical pressure (v0) is usually equivalent to the in situ overburden pressure, or structural loading or both. After the axial deformations under the vertical pressure v0 are complete, the specimen is inundated with water and axial swelling deformations of the speci-men are recorded until primary swell is complete. After completion of primary swell, the specimen is stepwise loaded till the pre-wetting void ratio (ev0) corresponding to the verti-cal pressure v0 is attained (Figure 2.3). The pressure needed to regain the void ratio ev0 defines the swell pressure of the specimen. This test method measures (a) the percent heave for vertical pressure usually equivalent to the estimated in situ vertical overburden pressure and other vertical pressures up to the swell pressure and (b) the swell pressure of the speci-men (Figure 2.3). The swell potential at the vertical pressure v0, relative to ev0 is given as:

(2.2)

where ese is the void ratio after stabilized swell at the vertical pressure v0 and ev0 is the initial (pre-swollen) void ratio at the vertical pressure v0.