Abstract: Sandy pebble soil is a granular media, and the physico-mechanical properties of sandy pebble soil are different from those of sandy soil and intact rock mass. Here sandy pebble soil is considered as a simplified material, namely a two-phase composite material consists of sandy soil as matrix and pebble as ellipsoid inclusion. This paper presents the theoretical derivation of equivalent elastic matrix calculation equation. The derivation process is based on Eshelby tensors and Mori-Tanaka equivalent method within small deformation condition. The process is also considered pebble’s content and distribution, using replacement iterative method. This paper focuses on the calculation of sandy pebble soil equivalent elastic modulus using numerical solution through compile program. Comparison is made between numerical solution and theoretical result. The result shows that the theoretical calculation method has better calculation accuracy than the earlier calculation methods of previous experiment and theory. When the pebble volume fraction less than 50%, the result of theoretical calculation coincides with experiment result, thus the presented method can be used to predict sandy pebble soil’s macroscopic mechanical properties, and it is beneficial to underground engineering application; when the volume fraction more than 50%, the theoretical calculation result may have some error with the experiment result.

Key words: sandy pebble soil, equivalent elastic modulus, self-consistent theory, Eshelby tensor, equivalent stress