Centrifuge modelling of groundwater variation induced settlement using different scaling methods

Abstract

Groundwater variation is a significant cause for high-fill foundation settlement, which is the main concern of such high-fill projects. In this study, centrifugal model tests were carried out to study the settlement of a high-fill foundation using a wetting-drying system for simulating water level variations. Three scaling methods which are equivalent substitution method, trapezoid similarity method and parallel gradation method, were utilized to prepare the particle size distribution of tested specimens considering the model size. The test process consists four loading cycles and each loading cycle consists of construction, water rise and drainage stages. The analysis results showed that settlement during the construction stage is dominant, and the settlement after construction only accounted for less than 20% of the total settlement. Besides, the settlement of the backfill itself increases with the filling height. The ratio between the settlement and the filling height of the specimen prepared by the equivalent substitution method is higher than the field monitoring data, while those prepared by the trapezoid similarity method or parallel gradation method agree well with the measurements. The settlement after construction with time can be predicted by the three-point method. Furthermore, the total settlement increases as the number of the wetting-drying cycles increases, especially in the initial phase of water table rising. The settlement during the water level rise was remarkably greater than that during the draw-down of the water level in each wetting-drying cycle. The soil gradation curve shift upwards after the tests, especially for the bottom part of soil.