scholarly journals Application of ‘Estimation Procedures’ in Unsaturated Soil Mechanics

Geosciences ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 364
Author(s):  
Delwyn G. Fredlund ◽  
Murray D. Fredlund
Keyword(s):  
Soil Properties ◽  
Water Content ◽  
Unsaturated Soil ◽  
Soil Mechanics ◽  
Geotechnical Engineering ◽  
Full Range ◽  
New Paradigm ◽  
Engineering Applications ◽  
Estimation Procedures ◽  
Unsaturated Soil Mechanics

The application of unsaturated soil mechanics in routine geotechnical engineering applications requires the determination of unsaturated soil properties. Unfortunately, the cost of direct measurement of unsaturated soil properties goes beyond the financial budget of most clients. A solution has arisen, however, that involves the measurement of two less costly soil properties functions that can be used in conjunction with a series of assumptions and estimation methodologies. The two laboratory tests involve measurement of the: (i) gravimetric water content versus soil suction, referred to as the soil-water characteristic curve (w-SWCC) and (ii) water content versus void ratio, referred to as the shrinkage curve (SC). These two unsaturated soil property relationships can be used along with saturated soil properties to extend unsaturated soil properties over the full range of soil suctions. “Estimation procedures” have been developed and verified for all physical properties of interest in unsaturated soil mechanics. The use of estimation procedures has meant that the geotechnical engineer must operate within a new paradigm. The new paradigm provides sufficient accuracy for most geotechnical engineering applications. The net result is an increased decision-making capability for geotechnical engineers.

Protocol for the assessment of unsaturated soil properties in geotechnical engineering practice

2009 ◽  
Vol 46 (6) ◽  
pp. 694-707 ◽  
Author(s):  
Delwyn G. Fredlund ◽  
Sandra L. Houston
Keyword(s):  
Soil Properties ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Soil Property ◽  
Unsaturated Flow ◽  
Soil Mechanics ◽  
Geotechnical Engineering ◽  
Engineering Practice ◽  
Engineering Project ◽  
Estimation Procedures

The implementation of unsaturated soil mechanics into routine geotechnical engineering practice requires an evaluation of methodologies that may be used for the assessment of “unsaturated soil property functions.” Guidelines and recommendations need to be provided to practicing engineers. The guidelines need to take the form of “engineering protocols” that define acceptable standards for engineering practice. “Engineering protocols” for unsaturated soils engineering practice can be divided into “preliminary design” protocols and “final design” protocols. Both design levels involve the use of a variety of estimation procedures that have been proposed for various classes of geotechnical problems (e.g., unsaturated flow, shear strength, volume change, and distortion). The hierarchy in methodologies is based mainly on the costs and risks associated with a particular engineering project. In this paper, “hierarchical levels” are suggested that take into consideration the cost of various direct and indirect methodologies for the determination of unsaturated soil properties. Recommendations and suggestions are provided for methods for the determination and use of the soil-water characteristic curves (SWCC) and consequently, for the computation of unsaturated soil property functions (USPFs). Primary attention is given to estimation procedures best known to the authors and most appropriate for geotechnical engineering practice.

scholarly journals TERRE project: interplay between unsaturated soil mechanics and low-carbon geotechnical engineering

2020 ◽  
Vol 195 ◽  
pp. 01002 ◽  
Author(s):  
Alessandro Tarantino ◽  
Grainne El Mountassir ◽  
Simon Wheeler ◽  
Domenico Gallipoli ◽  
Giacomo Russo ◽  
...  
Keyword(s):  
Construction Industry ◽  
Unsaturated Soil ◽  
Soil Mechanics ◽  
Geotechnical Engineering ◽  
Infrastructure Development ◽  
Construction Sector ◽  
Low Carbon ◽  
Unsaturated Soil Mechanics ◽  
Low Carbon Technologies ◽  
Industry Sectors

The geotechnical construction industry is a major component of the overall construction sector and is strategically important in infrastructure development (transportation, flood and landslide protection, building foundations, waste disposal). Although industry and research in the overall construction sector have been investing significantly in recent years to produce innovative low-carbon technologies, little innovation has been created in geotechnical construction industry, which is lagging behind other construction industry sectors. This paper discusses the interplay between low-carbon geotechnical engineering and unsaturated soil mechanics based on the research carried out within the project TERRE (Marie Skłodowska-Curie Innovative Training Networks funded by the European Commission, 2015-2019,H2020-MSCA-ITN-2015-675762).

scholarly journals State of practice for use of the soil-water characteristic curve (SWCC) in geotechnical engineering

2019 ◽  
Vol 56 (8) ◽  
pp. 1059-1069 ◽  
Author(s):  
Delwyn G. Fredlund
Keyword(s):  
Soil Water ◽  
Unsaturated Soil ◽  
Soil Mechanics ◽  
Geotechnical Engineering ◽  
Characteristic Curve ◽  
Laboratory Measurement ◽  
Engineering Practice ◽  
Soil Water Characteristic Curve ◽  
Unsaturated Soil Mechanics ◽  
State Of Practice

Routine geotechnical engineering practice has witnessed a significant increase in the usage of unsaturated soil mechanics principles. Laboratory measurement of the soil-water characteristic curve (SWCC) for a soil has been labelled as a primary reason for the improved understanding of unsaturated soil behaviour. Laboratory measurement of the “shrinkage curve” has yielded further insight into the estimation of unsaturated soil property functions (USPFs). The USPFs provide the necessary information for the simultaneous numerical modeling of the saturated and unsaturated portions of the soil profile. This paper presents a state-of-practice summary of the engineering protocols that have emerged amidst the numerous research studies reported over the past couple of decades. It also introduces issues related to hysteresis associated with the SWCC and suggests a pathway forward.

The 1999 R.M. Hardy Lecture: The implementation of unsaturated soil mechanics into geotechnical engineering

2000 ◽  
Vol 37 (5) ◽  
pp. 963-986 ◽  
Author(s):  
Delwyn G Fredlund
Keyword(s):  
Soil Water ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Soil Property ◽  
Soil Mechanics ◽  
Geotechnical Engineering ◽  
Characteristic Curve ◽  
Engineering Practice ◽  
Soil Water Characteristic Curve ◽  
Unsaturated Soil Mechanics

The implementation of unsaturated soil mechanics into geotechnical engineering practice requires that there be a paradigm shift from classical soil mechanics methodology. The primary drawback to implementation has been the excessive costs required to experimentally measure unsaturated soil properties. The use of the soil-water characteristic curve has been shown to be the key to the implementation of unsaturated soil mechanics. Numerous techniques have been proposed and studied for the assessment of the soil-water characteristic curves. These techniques range from direct laboratory measurement to indirect estimation from grain-size curves and knowledge-based database systems. The soil-water characteristic curve can then be used for the estimation of unsaturated soil property functions. Theoretically based techniques have been proposed for the estimation of soil property functions such as (i) coefficient of permeability, (ii) water storage modulus, and (iii) shear strength. Gradually these estimations are producing acceptable procedures for geotechnical engineering practices for unsaturated soils. The moisture flux ground surface boundary condition is likewise becoming a part of the solution of most problems involving unsaturated soils. The implementation process for unsaturated soils will still require years of collaboration between researchers and practicing geotechnical engineers.Key words: unsaturated soil mechanics, soil suction, unsaturated soil property functions, negative pore-water pressure, matric suction, soil-water characteristic curve.

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