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 Post-Cyclic Mechanical Behaviors of Undisturbed Soft Clay with Different Degrees of Reconsolidation

2021 ◽  
Vol 11 (16) ◽  
pp. 7612
Author(s):  
Yuan Lu ◽  
Jian Chen ◽  
Juehao Huang ◽  
Libo Feng ◽  
Song Yu ◽  
...  
Keyword(s):  
Shear Strength ◽  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Undrained Shear Strength ◽  
Excess Pore Water Pressure ◽  
Undrained Shear ◽  
Excess Pore

Soft soil is often subjected to cyclic loading such as that imposed during storms, under traffic, or in an earthquake. Furthermore, the cyclic-loading-induced excess pore water pressure can be partially dissipated after cyclic loading. Thus, different reconsolidation processes should be considered. A series of static and dynamic triaxial tests were conducted on undisturbed soft soil to determine the post-cyclic mechanical behavior thereof, such as the variation of undrained shear strength, the development of excess pore water pressure, and the evolution of effective stress path. The effects of consolidated confining pressure, cyclic stress ratio, and degree of reconsolidation were analyzed. Results show that the trend of all stress–strain curves is similar under different conditions. The effect of the degree of reconsolidation is such that, with increasing the degree of reconsolidation, the shear strength is enhanced. Meanwhile, compared with undrained shear strength without cyclic loading, the shear strength after cyclic loading with full reconsolidation is increased. These factors also have a significant effect on the undrained shear strength: the greater both the confining pressure and cyclic stress ratio are, the higher the undrained shear strength. A positive excess pore water pressure is always observed during post-cyclic shearing process, irrespective of different factors. The S-shaped effective stress paths under different test conditions are observed and cross the critical state line. The microstructures of undisturbed soil and post-cyclic specimens with different degrees of reconsolidation were quantitatively investigated. Besides that, the degree of influence of different factors on the post-cyclic undrained strength was analyzed. Based on the test results, the undrained shear strength with cyclic load-history was well predicted by existing models.

scholarly journals Undrained Shear and Pore Space Characteristics of Treated Loose Sands with Lime-Activated Zeolite in Saturated Settings

2020 ◽  
Vol 30 (2) ◽  
pp. 105-132
Author(s):  
Babak Jamhiri ◽  
Mohammad Siroos Pakbaz
Keyword(s):  
Shear Strength ◽  
Pore Water ◽  
Void Ratio ◽  
Pore Space ◽  
Water Pressure ◽  
Undrained Shear Strength ◽  
Alkali Activation ◽  
Unconfined Compression ◽  
Overburden Pressure ◽  
Undrained Shear

AbstractThis research investigates the mechanical behavior of artificially cemented sandy soils formed by lime alkali activation of natural zeolite under saturation settings. In order to verify the bar capability of cemented sands with this new method, an analysis of the undrained shear strength of the soil with pore water pressure ratio measurements was performed from the interpretation of the results of unconfined compression tests. The effect of zeolite-lime blend on treated sands was also visualized by scanning electron microscopy. For the studied soils, it was concluded from the unconfined compression stress values that the soil is fully capable of withstanding compressions due to overburden pressure. Additionally, this study seeks to evaluate the effect of the void ratio on the pore space and undrained shear strength. The results showed that pore water B-ratio increases with the decrease of the void ratio. Moreover, with the increase of zeolite content, confining pressure, and curing age, the peak failure strength increases. The results indicated a promising consistency of treated samples with lime and zeolite under various values of undrained shearing and B-ratios, making this method an ideal treatment for loose sand deposits.

Multivariate Adaptive Regression Spline and Least Square Support Vector Machine for Prediction of Undrained Shear Strength of Clay

2012 ◽  
Vol 3 (2) ◽  
pp. 33-42 ◽  
Author(s):  
Pijush Samui ◽  
Pradeep Kurup
Keyword(s):  
Support Vector Machine ◽  
Shear Strength ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Undrained Shear Strength ◽  
Least Square ◽  
Support Vector ◽  
Regression Spline ◽  
Adaptive Regression ◽  
Undrained Shear

This study adopts Multivariate Adaptive Regression Spline (MARS) and Least Square Support Vector Machine (LSSVM) for prediction of undrained shear strength (su) of clay, based Cone Penetration Test (CPT) data. Corrected cone resistance (qt), vertical total stress (sv), hydrostatic pore pressure (u0), pore water pressure at the cone tip (u1), and pore water pressure just above the cone base (u2) are used as input parameters for building the MARS and LSSVM models. The developed MARS and LSSVM models give simple equations for prediction of su. A comparative study between MARS and LSSSM is presented. The results confirm that the developed MARS and LSSVM models are robust for prediction of su.

Strain-rate-dependent stress-strain behavior of overconsolidated Hong Kong marine clay

2000 ◽  
Vol 37 (6) ◽  
pp. 1272-1282 ◽  
Author(s):  
Jun-Gao Zhu ◽  
Jian-Hua Yin
Keyword(s):  
Shear Strength ◽  
Hong Kong ◽  
Strain Rate ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Undrained Shear Strength ◽  
Rate Dependency ◽  
Marine Clay ◽  
Strain Rate Dependency ◽  
Undrained Shear

A total number of 24 consolidated undrained triaxial shear tests on reconsolidated saturated Hong Kong marine clay (HKMC) have been performed in both compression and extension shear states. The specimens were prepared in four different overconsolidation ratios (OCRs) and sheared at three different axial strain rates. The strain-rate dependency of undrained shear strength, pore-water pressure, stress path, and secant Young's modulus are investigated. The influence of OCR on the stress–strain–strength behavior of HKMC is also examined. The results of all tests are presented and interpreted. The interpreted results are compared with the results in the literature. For the HKMC with OCR varying from 1 to 8, the average value of the strain-rate parameter [Formula: see text] 0.15 is 5.5% for compression tests and 8.4% for extension tests. Most interpreted results are conclusive and consistent with the published results, whereas some results are not conclusive. A new parameter for describing the strain-rate dependency of undrained shear strength of overconsolidated soil is introduced.Key words: strain-rate effects, clay, overconsolidated, triaxial, shear strength, pore-water pressure.

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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