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.

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.  

The adhesion factor: applications and limitations

1992 ◽  
Vol 29 (2) ◽  
pp. 322-326 ◽  
Author(s):  
J. A. Sladen
Keyword(s):  
Shear Strength ◽  
Effective Stress ◽  
Clay Soil ◽  
Horizontal Stress ◽  
Undrained Shear Strength ◽  
Shaft Resistance ◽  
Soil Shear Strength ◽  
Shaft Friction ◽  
Adhesion Factor ◽  
Undrained Shear

The conventional concept of an empirical adhesion factor that relates undrained shear strength of a clay soil to ultimate shaft friction can be shown to have a theoretical basis for vertical piles, even though conditions at the interface are fully drained. The adhesion factor approach and the effective stress approach for shaft resistance are in fact consistent. This is because horizontal stress at the interface and undrained shear strength are both influenced by the same factors. The general implication of the conventional approach that the mechanism is undrained and that the mobilized shear resistance between a structure and clay is a fraction of the undrained soil shear strength is, however, incorrect. This concept can lead to significant errors if it is extrapolated to situations, for which the empirical data were not derived, such as beneath gravity structures on clay foundations, where effective stress normal to the interface is independent of soil undrained shear strength. Key words : piles, clay, adhesion, shaft friction.

Effects of Pile Driving in Clays

1972 ◽  
Vol 9 (1) ◽  
pp. 81-88 ◽  
Author(s):  
Kaare Flaate
Keyword(s):  
Shear Strength ◽  
Undrained Shear Strength ◽  
Pile Driving ◽  
Surface Strength ◽  
Deformation Properties ◽  
Average Water ◽  
Strength And Deformation ◽  
Pile Type ◽  
Timber Piles ◽  
Undrained Shear

This study summarizes the information given in the literature as well as observations made by the author. The effects of driving piles on remolding, stresses, and properties of the clay are considered. It is concluded that timber piles cause strong remolding of a zone extending to 10–15 cm from the pile surface. Strength and deformation properties will undergo changes beyond this zone as well. Pile type, pile density, soil properties, and driving conditions influence the results. There seems to be very small changes in the average water content, since the reduction adjacent to the pile is counter-balanced by an increase between the piles. The undrained shear strength adjacent to the pile is in one case found to be much higher than the skin friction at failure.

scholarly journals Correlations for undrained shear strength of Finnish soft clays

2016 ◽  
Vol 53 (10) ◽  
pp. 1628-1645 ◽  
Author(s):  
Marco D’Ignazio ◽  
Kok-Kwang Phoon ◽  
Siew Ann Tan ◽  
Tim Tapani Länsivaara
Keyword(s):  
Shear Strength ◽  
Undrained Shear Strength ◽  
Liquid Limit ◽  
Regression Analyses ◽  
Plastic Limit ◽  
Soft Clays ◽  
Natural Water Content ◽  
Vertical Effective Stress ◽  
First Time ◽  
Undrained Shear

The study focuses on the derivation of transformation models for undrained shear strength (su) of Finnish soft sensitive clays. Specific correlation equations for su of Finnish clays are presented in this work for the first time. Field and laboratory measurements from 24 test sites in Finland are exploited for this purpose and a multivariate database is constructed. The multivariate data consist of su from the field vane test, preconsolidation stress, vertical effective stress, liquid limit, plastic limit, natural water content, and sensitivity. The main objective is to evaluate the interdependence of su, consolidation stresses, and index parameters and provide a consistent framework for practical use. The new correlations are established through regression analyses. The constructed framework is further validated by another independent multivariate database of clays from Sweden and Norway as well as by empirical equations for Swedish and Norwegian clays. Existing correlations are evaluated for Finnish and Scandinavian clays. Finally, bias and uncertainties of the new correlations are presented.

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