Myths and misconceptions related to unsaturated soil mechanics

Abstract

There have been three main pillars associated with the development of an applied engineering science for both saturated and unsaturated soil mechanics; namely, i) the synthesis of continuum mechanics theories of physical behavior, ii) the laboratory measurement of relevant soil properties, and iii) analyses that illustrate the solution of practical example problems. Geotechnical engineers have, however, been relatively slow in adopting unsaturated soil mechanics into geotechnical engineering practice. There have been several so-called “myths or misconceptions” that appear to have hindered the application of unsaturated soil mechanics. This paper attempts to describe and dispel what are deemed to be misconceptions related to the more general implementation of unsaturated soil mechanics into engineering practice. The so-called “myths” come from the acceptance of false information related to unsaturated soil behavior and a hesitancy to embrace changes to existing empirical protocols. Several misconceptions are identified in the paper that are related to: i) complexity of unsaturated soil mechanics theories, ii) inability to readily measure soil suctions in-situ, iii) the nonlinearity of unsaturated soil property functions, iv) permanency of soil suctions above the water table, v) difficulties associated with assessing ground surface moisture flux conditions, and vi) difficulties associated with numerical modeling that involves solving nonlinear partial differential equations. Each of the above-mentioned items are dealt with as myths or misconceptions in the sense of being impediments to the application of unsaturated soil mechanics in geotechnical engineering practice.

Numeric Simulation of Subsidence of Loess Soil under Wetting in a Limited Area

“…Studies given in [1][2][3][4][5][6][10][11][12][13][14][15][16][17][18] have made a great contribution to the development of construction on loess soils. These studies are mainly experimental and theoretical in nature, revealing the physical essence of the mechanism of the phenomenon of subsidence and its behavior.…”

“…These studies are mainly experimental and theoretical in nature, revealing the physical essence of the mechanism of the phenomenon of subsidence and its behavior. Recently, in the field of construction on structurally unstable soils and in the study of the mechanical properties of loess soils, rich experience and vast experimental material have been accumulated [10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Despite a certain success in the field of foundation engineering on these soils, the calculation models of soil settlements have not been developed and the possibility of a reliable description of the stress-strain state of these soils by methods of continuum mechanics has not been stated.…”

“…According to [4] and from the results obtained in [12][13][14][15][16][17][18], it follows that there is not even a rigorous formulation of this problem, the solution to which is necessary to form a special section in soil mechanics with the involvement of the mathematical apparatus of mechanics of a continuous deformable medium. The existing methods for calculating the stress-strain state of loess soil massif are based on the principle of linear deformability, based on the theory of elasticity and creep [3][4][5][6][24][25][26].…”