On active and inactive voids and a compression model for granular soils

- We examine the postulate of dividing voids in granular soils into active and inactive fractions.
- This postulate is verified by a linear relationship between de/dp′ and e.
- Based on this postulate, we develop a simple two-parameter model for compression of granular soils.
- We show one of the model parameters is correlated to the minimum void ratio of the soil.
- Model performance is verified for 20 different granular soils with various initial void ratios and mineralogy.

Compression models are widely used in geotechnical and reservoir engineering for the prediction of settlement and void ratio. A desirable compression model should be able to consider the initial density and particle mineralogy of the soil. It should also have a few number of parameters that are easy to be calibrated from tests data, and have clear physical meaning. In order to model the compressibility of granular soils, we examine a simple postulate of dividing the voids in a granular soil into active and inactive fractions. This postulate is verified by a linear relationship between dedp and e, which is valid for various types of granular soil and for wide range of stress levels. Using this postulate, a two-parameter compression model is developed. One of the model parameters is the minimum void ratio of the material, and the other one is related to its particles mineralogy. The proposed model is verified by comparing the predicted results with the measured data for 20 different type of granular soil with various initial density and particle mineralogy. The coefficient of determination is very close to unity, which shows the suitability of our model to predict the compression behavior of granular soils for a wide range of stresses.