Drainage Properties of Soft Clay Subjected to Intermittent Vibratory Loading: Role of Frequency and Confining Pressure

Abstract

To enhance the drainage performance of soft soil foundations, this study investigated the drainage consolidation behavior of marine soft clay under various confining pressures, intermittencies, and frequencies. A series of laboratory cyclic loading tests were conducted on soft soil specimens, employing a fusion of vibratory drainage consolidation and dynamic drainage consolidation methods. Test results showed that an elevating confining pressure diminishes the drainage rate of soft soil and triggers early-stage soil failure. An optimal pressure of 100 kPa significantly improves drainage efficiency in the test. And in engineering applications when dealing with similar soft soils, it is recommended to explore the optimal confining pressure value under relatively lower pressures. The presence of intermittent periods contributes to improved drainage efficiency, with the optimum drainage intermittent ratio found to be 0.167 in this study. Vibration frequency exerts influence on both drainage rate and maximum drainage rate, particularly evident at 1 Hz, where the resonance effect significantly enhances the drainage rate of soft soil. A numerical fitting formula correlating frequency with the drainage intermittent ratio was developed, effectively predicting the development of vertical strain.