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 Electro Osmotic Consolidation in South West of Johor: Small Laboratory Scale

2014 ◽  
Vol 803 ◽  
pp. 255-264
Author(s):  
Khairul Nizar Mohd Yusof ◽  
Fauziah Ahmad ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Muhammad Faheem Mohd Tahir
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Clay Soil ◽  
Soft Clay ◽  
Soil Improvement ◽  
Undrained Shear Strength ◽  
Engineering Structures ◽  
Vertical Loading ◽  
South West ◽  
Undrained Shear

Clay soil is one of the problematic soils due to its natural states which have low bearing capacity and high compressibility. The effect and problem of the clay soil characteristic creates a problem for construction especially excessive settlement and this can lead to unstable and potential cracks of engineering structures. At presents, there are few of soil improvement types can be carried out to overcome these problems, and electro osmotic consolidation is one of the options. This method has been applied many years ago especially in european countries. The study encompasses the determination of water content, atterberg’s limits and undrained shear strength after electro osmotic consolidation treatment of clay soils taken from 0.5 m and 1.5 m at southwest part of johor. All the samples were tested according to BS1377:1990. An experimental study was implemented in a pvc cylinder tube having dimensions of 300 mm height and 100 mm diameter. In the results of electro osmotic consolidation tests by installing copper spring electrodes, the measured undrained shear strength was increased considerably at the anodes especially compared to the initial undrained shear strength due to electro osmosis process and consolidation. As laboratory studies of its measurement have shown, the application of electro osmotic consolidation after the application of a direct current applied voltage of 10 volts, at the anodes especially: (i) a decrease by approximately 35% in water content; (ii) an increase around 29% in undrained shear strength; and (iii) a decrease about 21% in index plasticity. The results obtained in this study shows that the electro osmotic enhanced 15 kpa vertical loading consolidation is a feasible approach in strengthening of south west soft clay in johor. It can be clearly suggested that the higher the voltage applied in the system, the higher readings of undrained shear strength and the lower of water content especially at the anodes.

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.  

scholarly journals A Study on the Ratio of Undrained Shear Strength to Vertical Effective Stress

1981 ◽  
Vol 21 (1) ◽  
pp. 139-145
Author(s):  
Masuho Inada ◽  
Masaru Akaishi ◽  
Kenya Sagae
Keyword(s):  
Shear Strength ◽  
Effective Stress ◽  
Undrained Shear Strength ◽  
Vertical Effective Stress ◽  
Undrained Shear

scholarly journals EFFECT OF DRYING-WETTING PROCESS ON FRICTION CAPACITY AND ADHESION FACTOR OF PILE FOUNDATION IN CLAYEY SOIL

2015 ◽  
Vol 77 (11) ◽  
Author(s):  
Daniel Tjandra ◽  
Indarto Indarto ◽  
Ria Asih Aryani Soemitro
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Pile Foundation ◽  
Undrained Shear Strength ◽  
Clayey Soils ◽  
Content Change ◽  
Adhesion Factor ◽  
Undrained Shear ◽  
Water Content Change ◽  
Friction Capacity

Clayey soils had a seasonal water content change, which occurred in the zone known as active zone. This change happen due to the seasonal drying and wetting cycles, which affects the fluctuation of water table. The water content variation causes the change in undrained shear strength and these changes have an impact to the friction capacity and adhesion factor of pile foundation. This paper discusses the undrained shear strength, friction capacity of pile and adhesion factor of piles under drying and wetting cycles. Research was conducted on two different types of clayey soils. Laboratory experiments for varying soil water content were done. Soil samples were placed in a cylinder tube, the concrete pile model was then inserted into the soil. The diameter of the tube was about 15 times of the pile diameter. Loading test was carried out to investigate pile friction capacity. The result of this study showed that there was great effect of seasonal water content change on undrained shear strength, friction capacity and also adhesion factor of pile in the clayey soils.

Evaluation of geotechnical property variability

1999 ◽  
Vol 36 (4) ◽  
pp. 625-639 ◽  
Author(s):  
Kok-Kwang Phoon ◽  
Fred H Kulhawy
Keyword(s):  
Shear Strength ◽  
Measurement Error ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Friction Angle ◽  
Horizontal Stress ◽  
Undrained Shear Strength ◽  
Stress Coefficient ◽  
Undrained Shear

To evaluate geotechnical variability on a general basis that will facilitate the use of reliability-based design procedures, it is necessary to assess inherent soil variability, measurement error, and transformation uncertainty separately. The inherent variability and measurement error are addressed in a companion paper, and transformation uncertainty is addressed herein. A second-moment probabilistic approach is applied to combine these uncertainties consistently based on the manner in which the design soil property is derived. The design properties considered in this paper are undrained shear strength, effective stress friction angle, in situ horizontal stress coefficient, and Young's modulus. This paper concludes with specific guidelines on the typical coefficients of variation for these common design soil properties as a function of the test type and the type of correlation used.Key words: transformation uncertainty, undrained shear strength, friction angle, in situ horizontal stress coefficient, Young's modulus, geotechnical variability.

scholarly journals Determination of undrained shear strength and constrained modulus from DMT for stiff overconsolidated clays

2017 ◽  
Vol 49 (2) ◽  
pp. 107-116 ◽  
Author(s):  
Zbigniew Lechowicz ◽  
Simon Rabarijoely ◽  
Tetiana Kutia
Keyword(s):  
Shear Strength ◽  
Horizontal Stress ◽  
Undrained Shear Strength ◽  
Stress Index ◽  
Constrained Modulus ◽  
Empirical Coefficients ◽  
Horizontal Stress Index ◽  
The Relationship ◽  
Undrained Shear

Abstract The paper presents the results of dilatometer and laboratory tests performed on heavily preconsolidated boulder clays and Pliocene clays prevailing in the Warsaw region. Several different correlations available for evaluating undrained shear strength and constrained modulus from dilatometer tests are discussed. Empirical coefficients for multi-factor correlation to obtain undrained shear strength from dilatometer tests for boulder clays and Pliocene clays were determined. The relationship between factor RM and horizontal stress index (KD) for boulder clays was proposed for the evaluation of constrained modulus from dilatometer tests.

Sign in / Sign up

Export Citation Format

Share Document