PREDICTION OF IN SITU HORIZONTAL STRESSES IN CLAY SOILS FROM THE MEASUREMENT OF UNDRAINED SHEAR STRENGTH, PLASTICITY INDEX AND VERTICAL EFFECTIVE STRESS.

1995 ◽  
Vol 113 (4) ◽  
pp. 206-214 ◽  
Author(s):  
D C SHOHET
Keyword(s):  
Shear Strength ◽  
Effective Stress ◽  
Undrained Shear Strength ◽  
Plasticity Index ◽  
Clay Soils ◽  
Vertical Effective Stress ◽  
Undrained Shear

scholarly journals Theoretical Equations for the Ratio of Undrained Shear Strength to Vertical Effective Stress for Normally Consolidated Saturated Cohesive Soils

2022 ◽  
Vol 28 (3) ◽  
pp. 241-252
Author(s):  
Sugeng Krisnanto
Keyword(s):  
Shear Strength ◽  
Pore Water ◽  
Effective Stress ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Undrained Shear Strength ◽  
Engineering Practice ◽  
Cohesive Soils ◽  
Vertical Effective Stress ◽  
Undrained Shear

Abstract Two theoretical equations are developed to calculate the ratio of undrained shear strength to the vertical effective stress (the ratio of (su/sv’)) for normally consolidated saturated cohesive soils. The effective stress approach is used as the basis in the development of the theoretical equations. The theoretical equations are developed by relating the total and the effective stress paths. The development of the excess pore-water pressure is quantified using Skempton A and B pore-water pressure parameters. The theoretical equations are developed for two initial stress conditions: (i) an initially hydrostatic condition and (ii) an initially Ko (non-hydrostatic) condition. The performance of the theoretical equations of this study is compared with field and laboratory measurement data obtained from the literature. The close results between the theoretical equations and the measurements show that the theoretical equations of this study can compute the ratio of (su/sv’) well. Using the theoretical equations, the values of the ratio of (su/sv’) commonly used in engineering practice can be explained from the soil mechanics framework. Keywords: Saturated cohesive soils, c/p ratio, normally consolidated soil, undrained shear strength, effective shear strength, theoretical equation. Abstrak Dua persamaan teoritis dikembangkan untuk menghitung rasio kuat geser tak teralirkan dengan tegangan efektif vertikal (rasio (su/sv’)) untuk tanah kohesif jenuh terkonsolidasi normal. Pendekatan tegangan efektif dijadikan dasar dalam pengembangan kedua persamaan teoretis ini. Persamaan teoretis tersebut dikembangkan menghubungkan lintasan tegangan total dan lintasan tegangan efektif. Kenaikan tekanan air pori ekses dikuantifikasi menggunakan parameter tekanan air pori A dan B dari Skempton. Persamaan teoretis dikembangkan untuk dua kondisi tegangan awal: (i) tegangan awal hidrostatik dan (ii) teganan awal Ko (non hidrostatik). Kinerja kedua persamaan teoretis tersebut dibandingkan terhadap data pengukuran lapangan dan pengujian laboratorium yang diperoleh dari literatur. Persamaan teoretis dari studi ini memiliki kinerja yang baik dalam memperhitungan rasio (su/sv’) yang ditunjukkan dengan dekatnya hasil perhitungan menggunakan persamaan teoretis dan hasil pengukuran lapangan maupun pengujan laboratorium. Dengan persamaan teoretis tersebut, nilai rasio (su/sv’) yang biasa digunakan dalam rekayasa praktis bisa dijelaskan secara mekanika tanah. Kata-kata Kunci: Tanah kohesif jenuh, rasio c/p, tanah terkonsolidasi normal, kuat geser tak teralirkan, kuat geser efektif, persamaan teoretis.  

Halloysite behaving badly: geomechanics and slope behaviour of halloysite-rich soils

Clay Minerals ◽  
2016 ◽  
Vol 51 (3) ◽  
pp. 517-528 ◽  
Author(s):  
Vicki Moon
Keyword(s):  
Shear Strength ◽  
Bulk Density ◽  
High Mobility ◽  
Undrained Shear Strength ◽  
Field Conditions ◽  
High Peak ◽  
Plasticity Index ◽  
Undrained Shear

AbstractHalloysite-rich soils derived fromin situweathering of volcanic materials support steep stable slopes, but commonly fail under triggers of earthquakes or rainfall. Resulting landslides are slideflow processes, ranging from small translational slides to larger rotational failures with scarps characteristic of sensitive soils. Remoulding of failed materials results in high-mobility flows with apparent friction angles of 10–16°. The materials characteristically have high peak-friction angles (∼25– 37°), low cohesion (∼12–60 kN m−2) and plasticity ( plasticity index ∼10–48%), and low dry bulk density (∼480–1,080 kg m−3) with small pores due to the small size of the halloysite minerals. They remain saturated under most field conditions, with liquidity indexes frequently >1. Remoulded materials have limited cohesion (<5 kN m−2) and variable residual friction angles (15°–35°). Halloysite mineral morphology affects the rheology of remoulded suspensions: tubular minerals have greater viscosity and undrained shear strength than spherical morphologies.

A statistical evaluation of some engineering properties of eastern Canadian clays

1990 ◽  
Vol 27 (3) ◽  
pp. 373-386 ◽  
Author(s):  
Étienne J. Windisch ◽  
Raymond N. Yong
Keyword(s):  
Shear Strength ◽  
Statistical Evaluation ◽  
Undrained Shear Strength ◽  
Plasticity Index ◽  
Engineering Properties ◽  
Plastic Limit ◽  
Liquidity Index ◽  
Marine Clays ◽  
Undrained Shear

Statistics for data collected on eastern Canadian clays (Champlain, Goldthwait, Tyrrell, and Laflamme marine clays and Barlow–Ojibway lacustrine clays) are computed and analyzed. These clays are divided into three groups: eastern Canadian marine clays, Champlain clays (as an important part of the first group), and Barlow–Ojibway lacustrine clays. The analysis reveals significant differences between eastern Canadian clays and Scandinavian clays. Some relationships proposed in the literature and based on plasticity index, liquidity index, and plastic limit are found to be inapplicable to eastern Canadian clays. On the basis of a proposed method for estimating the undrained shear strength of normally consolidated eastern Canadian marine clays, the overconsolidation ratio is found to be equal to the ratio of the in situ undrained shear strength to the estimated normally consolidated undrained shear strength. Key words: undrained shear strength, plasticity index, liquidity index, plastic limit, statistical evaluation, over-consolidation ratio, lacustrian clays.

Some Pile Loading Tests in Stiff Clay

1964 ◽  
Vol 1 (2) ◽  
pp. 63-80 ◽  
Author(s):  
K Y Lo ◽  
A G Stermac
Keyword(s):  
Shear Strength ◽  
Effective Stress ◽  
Undrained Shear Strength ◽  
Load Testing ◽  
Loading Tests ◽  
Stiff Clay ◽  
Vertical Effective Stress ◽  
Set Up ◽  
Timber Piles ◽  
Undrained Shear

Loading tests on two timber piles and a Franki pile, embedded principally in a stiff clay, were carried out. Analysis of the results appear to indicate that the adhesion of the piles is the fully mobilized undrained shear strength of the clay. Reasons for this apparent anomaly with data reported in the literature are suggested.Pore water pressures set up in the soil adjacent to the piles during load testing were very small and calculations in terms of effective stresses, indicated that the ratio of horizontal to vertical effective stress at failure is approximately 1.2.

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