EFFECT OF STRAIN RATE ON CONSOLIDATION CHARACTERISTICS OF ARTIFICIAL SILTY CLAY: INSIGHTS FROM MODIFIED CONSTANT RATE OF STRAIN TESTS

Abstract

Soil consolidation behavior is crucial in civil engineering, particularly for construction and foundation design, where settlement and stiffness affect structural stability. However, the effect of strain rate on consolidation, especially in artificial silty clay, remains challenging. This study addresses this by investigating the impact of strain rate using modified constant rate of strain (MCRS) tests. The sample, a mixture of 35% kaolinite clay and 65% fine Baskarp sand, was classified as CL (clay with low plasticity) with a bulk density of 2.062 g/cm³ and a plasticity index of 11.25. MCRS tests were conducted using both a triaxial apparatus and an oedometric cell, applying continuous loading at strain rates ranging from 0.001 mm/min to 0.16 mm/min. Results show that the modulus of stiffness increases with both vertical stress and strain rate, with significant effects observed in stress ranges between 70 kPa and 200 kPa and strain rates between 0.0025 mm/min and 0.064 mm/min. Compared to conventional oedometer tests, higher strain rates lead to smaller settlements and greater stiffness, while lower strain rates result in larger settlements and lower stiffness. MCRS tests align well with conventional oedometer results when strain rates are between 0.012 mm/min and 0.021 mm/min. The findings show that MCRS tests offer more precise consolidation data within specific strain rate ranges, improving engineers' ability to predict settlement in artificial silty clay. This enhances understanding of strain rate effects and underscores the need for further research on clay mineral content sensitivity.