Mechanics of Soil, a Dynamically Coupled Solid-Water-Gas System

摘要

One of the main issues in modelling geomechanics is the dynamic coupling between the porous solid skeleton and the water-gas mixture contained in the pores. This article describes some general concepts of this kind of dynamically coupled system. A simple model for the solid-water-gas interaction is introduced that takes into account the variation of compressibility both of pore water-gas mixtures and of the solid mass. The more complex interactions have been simulated in accordance with this model using a dynamic system approach. One of the major factors is how the quantity of free gas influences the compressibility of the water-gas mixture. This influence is substantial, and therefore the exchange process between free and dissolved gas cannot be ignored The isotropic and axial symmetric undrained conditions have also been considered This paper is part 2 of 3, and is concerned with the undrained compression. Part 1 describes the general approach and part 3 describes aspects of the shear compression interaction. The main result to be reported in these papers is that the pore water coefficients A and B can be written as a single parameter, B, which depends on the bulk compressibility of the solid mass, fisd, porosity n, and the degree of saturation S_r Furthermore, B_w can even be greater than 1, and the value B_w=1 does not imply a fully saturated soil condition.