Role of unsaturated soil mechanics in geotechnical engineering

Harianto Rahardjo,Yongmin Kim,Alfrendo Satyanaga

doi:10.1186/s40703-019-0104-8

Harianto Rahardjo, Yongmin Kim + Show 1 more

Open Access

https://doi.org/10.1186/s40703-019-0104-8

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Abstract

The understanding of unsaturated soil mechanics principles is of interest to a wide spectrum of geotechnical problems associated with soils above water table and compacted soils. This paper describes the stress state variables and constitutive equations based on the unsaturated soil mechanics principles. In addition, the basic concepts for characterization of unsaturated soils and measurements of matric suction (or negative pore-water pressures) are also explained. The application of unsaturated soil mechanics theories is illustrated through the use of capillary barrier system for minimizing rain infiltration into residual soil slopes.

Highlights

Significant changes in climatic conditions in past decades are affected mostly by the increase in global temperature
This paper presents the principles of the unsaturated soil mechanics, the related apparatuses for measurement of unsaturated soil properties and numerical analyses incorporating unsaturated soil mechanics as well as the application of the unsaturated soil mechanics in engineering practise
The hydraulic properties, i.e., a soil–water characteristic curve (SWCC) and a permeability function are required for seepage analyses or analyses of water flow throughout soil pores with respect to variations in matric suctions

Summary

Introduction

Significant changes in climatic conditions in past decades are affected mostly by the increase in global temperature. Tan φ′ cos α where N = normal force at the bottom of the slice, τ = shear stress, hw = hydraulic head, c′ = effective cohesion, g = gravitational force, c = cohesion, y = elevation, φ′ = effective friction angle, β = the slope length at the bottom of the slice, ρw = density of water, t = time, φb = angle indicating the increase in shear strength due to matric suction, ks = saturated permeability, vw = water flow velocity, kw = water permeability function, ∂hw /∂y = gradient of hydraulic head in y-direction, mw2 = ratio of water volume change against changes in matric suction, W = total weight of the slice, α = the angle between horizontal and tangent to the midpoint of the bottom of each slice representing probability of random pore connections [57], since the region within the pore-suction distribution function defines the degree of saturation.

Results

Conclusion