Test Results

(Only one average value of k is obtained from this test.) Typical void ratios

encountered in the specimen after completion of this test range from 5 to 12

(from bottom to top of specimen).

The self-weight consolidation test was developed to provide compressibility

and permeability data for material that had been hydraulically dredged and

placed in the disposal site as a slurry; thus the initial void ratios used in this test

were required to be greater than the zero effective stress void ratio. Despite the

fact that dredging methods other than hydraulic dredging will commonly be used

for material placement at subaqueous disposal sites, continued use of this pro-

cedure will ensure that the e- and e-k relationships developed for a particular

material will cover the entire possible range of conditions.

Test Results

Both void ratio-effective stress and void ratio-permeability relationships must

be developed from laboratory test results for each material (cap, contaminated

dredged material, and foundation soil). These relationships should extend across

the entire range of void ratios that may exist in each material. For dredged

material, results obtained from the self-weight and oedometer tests (described in

the previous section) must be combined to yield composite e- and e-k relation-

ships. For the stiffer foundation soils and some mechanically dredged materials,

standard oedometer tests will typically provide adequate data. Tests needed for

capping material will depend upon the type of material and its consistency; if

sand is used for capping, no consolidation test will be required. Example com-

pressibility and permeability curves are shown in Figures I3 through I8.

References

Bromwell, L. G., and Carrier, W. D., III. (1979). "Consolidation of fine-grained

mining wastes," Proceedings of the Sixth Pan American Conference on Soil

Mechanics and Foundation Engineering, Lima, Peru.

Cargill, K. W. (1985). "Mathematical model of the consolidation/desiccation

process in dredged material," Technical Report D-85-4, U.S. Army Engineer

Waterways Experiment Station, Vicksburg, MS.

Cargill, K. W. (1986). "The large strain, controlled rate of strain (LSCRS)

device for consolidation testing of soft, fine-grained soils," Technical Report

GL-86-13, U.S. Army Engineer Waterways Experiment Station, Vicksburg,

MS.

Gibson, R. E., England, G. L., and Hussey, M. J. L. (1967). "The theory of one-

dimensional consolidation of saturated clays, I. Finite, non-linear consolida-

tion of thin homogeneous layers," Geotechnique 17, 261-273.

Appendix I Consolidation Testing