| Abstrakt: |
This paper presents the results of a detailed laboratory investigation undertaken to study the nature and engineering behavior of a fine-grained carbonate soil from off the west coast of India. It highlights the role played by the form of existence of carbonate material in determining the engineering behavior of fine-grained carbonate soils. Grain size analysis, X-ray diffraction, and scanning electron micrograph studies reveal that the calcium carbonate content in this clay ranges from 47% to 55% and exists as inert nonskeletal needles of aragonite and calcite in the clay microstructure. The noncarbonate fraction consists primarily of kaolinite. From the high percentage of calcium carbonate present one usually expects the soil to behave either as cemented material or as granular soil. However, an analysis of the void ratio, e, versus the log of effective stress, σ, relation obtained from consolidation tests as well as stress-strain characteristics, A-factor at failure, and ratio of undrained shear strength, Su, to effective overburden pressure, p0, obtained from shear tests clearly shows that the soil is in a normally consolidated state. Furthermore, compression indices are in most cases higher than those predicted for terrigenous soils having the same liquid limit. The void ratio, e, versus the log of permeability, k, relationship is almost linear. |
