RESEARCH ON CHARACTERISTICS OF K₀ CONSOLIDATION OF LOESS BASED ON TRIAXIAL TEST

The coefficient of lateral earth pressure(K₀) is a key parameter for calculating lateral earth pressure in geotechnical engineering. The development trend of K₀ value of intact and remolded loess during consolidation is obviously different from that of clay or sand. In order to study the influence of confining pressure and initial void ratio on K₀ value of intact and remolded loess, K₀ consolidation tests were carried out by using the stress path triaxial apparatus, that is also equipped with a high precise internal radial LVDT. The results reveal that: (1)the K₀ value of remolded loess samples is strongly affected by the initial void ratio(e₀), when the initial void ratio decreases from 0.775 to 0.503, the maximum reduction of K₀ value is about 55%. For the intact loess samples it is strongly affected by the effective confining pressure(σ₃^′), the K₀ value is 0.77~0.85 when σ₃^′ < 350kPa and 0.46~0.51 when σ₃^′>350kPa; (2)in the consolidation stage, a sudden drop of K₀ value is found in intact and remolded loess samples. In brief, in dense sample of remolded loess(e₀ < 0.6)the drop takes place at the initial stage of consolidation. In loose sample of remolded loess(e₀ ≈ 0.77)the drop is near the effective confining pressure of 100kPa. For intact loess samples the drop is observed at the effective confining pressure of 350kPa; (3)under otherwise similar conditions in terms of stress level and density, the K₀ value of intact loess is higher than that of remolded loess. By using the nuclear magnetic resonance(NMR)technique, the pore size distributions of remolded and intact loess are obtained. In conjunction with the experimental results in excess pore water pressure and changes of sample volume, etc. The observed discrepancies in the K₀ value is mainly attributed to the characteristics of soil fabric.