Abstract: The high-water content, high compressibility, and low strength of deep soft soils often pose significant threats to the stability and safety of geotechnical engineering projects. Based on the analysis of physical properties of peaty and organic soils, a comparison was conducted between the coefficient of consolidation calculated by Terzaghi consolidation theory formula and the coefficient of consolidation obtained from laboratory tests to evaluate the applicability of theoretical formula to provide theoretical basis for similar engineering constructions. Results show that the consolidation coefficients of peat soil by Terzaghi formula are 4.3 to 6.8 times the vertical consolidation coefficients obtained from consolidation tests, and 0.8 to 1.4 times the horizontal consolidation coefficients. As for organic soils, the calculated consolidation coefficients using the theoretical formula differ from the consolidation coefficients obtained from consolidation tests by 1 to 3 orders of magnitude, indicating a large deviation. Therefore, it is not recommended to use Terzaghi consolidation theory to calculate the consolidation coefficients of organic soil.

Key words: Deep Soft Soils, Physical Indicators, Coefficient of Consolidation