The undrained strength of some thawed permafrost soils

1979 ◽  
Vol 16 (2) ◽  
pp. 420-427
Author(s):  
John F. Nixon ◽  
Alan J. Hanna
Keyword(s):  
Undrained Shear Strength ◽  
Soil Types ◽  
Density Range ◽  
Mackenzie Delta ◽  
Sample Depth ◽  
Wide Range ◽  
Permafrost Soils ◽  
Undrained Strength ◽  
Water Contents ◽  
Undrained Shear

A large number of undrained shear strengths have been measured for thawed, undrained permafrost samples obtained from the Niglintgak Peninsula area of the Mackenzie Delta, N.W.T. The samples are mostly deltaic silts, with a few clay tills, and cover a wide range of depths, water contents, and frozen density. The undrained shear strengths of the thawed samples have been correlated with water content, frozen density, and sample depth. For these soil types, the strength is shown to decrease to zero at frozen densities of less than about 1670 kg/m3 and at water contents greater than about 35–42%. In the Niglintgak area, the undrained shear strength of the thawed samples below a depth of 10 m becomes relatively constant in the range of 23–43 kPa. This corresponds to a frozen density range of 1780–1870 kg/m3, and previous experience with soils of this nature indicates that the corresponding thaw settlement at these depths would be less than 10%.

Determination of the consistency limits of soils by the fall cone test

1986 ◽  
Vol 23 (2) ◽  
pp. 241-246 ◽  
Author(s):  
Y. Wasti ◽  
M. H. Bezirci
Keyword(s):  
Shear Strength ◽  
Key Words ◽  
Water Content ◽  
Strength Criterion ◽  
Undrained Shear Strength ◽  
Wide Range ◽  
Undrained Strength ◽  
Content Range ◽  
Undrained Shear

The liquid and plastic limits for a variety of natural and artificial soils covering a wide range of plasticity, as determined by the Casagrande method and the fall cone test and based on a strength criterion, were compared. To check the validity of the strength criterion, the undrained shear strength of these soils has been determined with a laboratory vane over the water content range between these limits. A limited comparison of the undrained strength values obtained from the vane test and fall cone test is also given. Key words: Atterberg limits, consistency, fall cone, laboratory vane, shear strength.

ANALYSIS OF EMPIRICAL COMPRESSION INDEX EQUATIONS USING THE WATER CONTENT

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Amir W. Al-Khafaji ◽  
Krishnanand Y. Maillacheruvu ◽  
Melissa Hoerber
Keyword(s):  
Water Content ◽  
Empirical Models ◽  
Soil Types ◽  
Data Sets ◽  
Regression Equations ◽  
Compression Index ◽  
Empirical Formulas ◽  
Wide Range ◽  
Compression Data ◽  
Water Contents

This paper proposes a new method to evaluate the reliability of published empirical formulas in terms of accuracy and applicability to different soil types. Different empirical models are proposed to properly approximate the compression index for a wide range of water contents and soil types. They were developed using a unique technique and a substantial number of published regression equations and compression data. Familiar empirical equations were examined for their reliability in predicting the compression index of clay for any water content. A comparison was made between available and newly-proposed empirical formulas using combined regression data sets compiled independently by several authors. The newly proposed empirical compression index equations are applicable to a wide range of clay soils, and in validating other published relationships. The degree of scatter and variations in the computed compression index values are minimized for any water content.

Reconsideration of case histories for estimating undrained shear strength in sandy soils

1999 ◽  
Vol 36 (5) ◽  
pp. 907-933 ◽  
Author(s):  
C E (Fear) Wride ◽  
E C McRoberts ◽  
P K Robertson
Keyword(s):  
Shear Strength ◽  
Sandy Soils ◽  
Standard Penetration Test ◽  
Undrained Shear Strength ◽  
Soil Liquefaction ◽  
Penetration Test ◽  
Case Histories ◽  
Original Case ◽  
Undrained Strength ◽  
Undrained Shear

When sandy soils respond in a strain-softening manner to undrained loading, an estimation of the resulting undrained shear strength (Su) is required to determine the potential for flow liquefaction at a given site. One of the most commonly used methods for estimating the undrained strength of liquefied sand is an empirical standard penetration test (SPT) based chart (originally proposed by H.B. Seed), which was developed using a number of case histories. The original interpretations of these case histories are viewed by many workers and regulatory agencies as the most authoritative measure of the liquefied strength of sand. Consequently, in comparison, other less conservative methods are generally held in an unfavourable light. This paper reexamines the original database of case histories in view of some more recent concepts regarding soil liquefaction. The objectives of this paper are to explore and reassess the issues involved in the original assessment and to offer alternative views of the case records. The conclusions presented here indicate that alternative explanations of the liquefied strength of sand are not inconsistent with the original case histories. Key words: sandy soils, soil liquefaction, undrained strength, standard penetration test (SPT).

Landslide history in a Tertiary sedimentary basin in the Quaternary in Japan

1991 ◽  
Vol 7 (1) ◽  
pp. 671-677
Author(s):  
S. Okusa ◽  
N. Takahama ◽  
Y. Fujita
Keyword(s):  
Shear Strength ◽  
Sedimentary Basin ◽  
Undrained Shear Strength ◽  
Climatic Conditions ◽  
History Of ◽  
Undrained Strength ◽  
Japanese Islands ◽  
Undrained Shear ◽  
Present Activity ◽  
Drained Shear Strength

AbstractThe landslide activities in the Quaternary of the Japanese Islands have been controlled by active neotectonic movements and humid climatic conditions. Most of the present active landslides in Cenozoic muddy sediment in the Japanese Islands occur in the ancient landslides site. In the Musigame landslides site in the Cenozoic Niigata sedimentary basin, the present active landslides are concentrated along the fissures and cracks in the ancient primary landslide blocks. The initial failure of the primary Musigame landslides might have occurred in the mudstone with the intact undrained shear strength and the retrogressive failures with a combination of the intact undrained shear strength and residual undrained strength. Secondary and presently active landslides have occurred in the previously disturbed mudstone in accordance with the residual drained shear strength. The analysis of the occurrence, movement and history of the primary and secondary landslides is essential to understand the present activity of landslide.

Performance of clay samples reinforced with vertical granular columns

2007 ◽  
Vol 44 (1) ◽  
pp. 89-95 ◽  
Author(s):  
J Black ◽  
V Sivakumar ◽  
J D McKinley
Keyword(s):  
Shear Strength ◽  
Ground Improvement ◽  
Stress Path ◽  
Undrained Shear Strength ◽  
Replacement Ratio ◽  
Replacement Method ◽  
Single Column ◽  
Undrained Strength ◽  
Area Replacement Ratio ◽  
Undrained Shear

This paper reports an experimental study in which samples of soft kaolin clay (100 mm in diameter and 200 mm in height) were reinforced with vertical columns of sand and tested under triaxial conditions. Samples were reinforced with either a single column of sand of 32 mm diameter or three columns of sand, each of 20 mm diameter. The replacement method was used to form the columns. The columns were installed in the clay to depths of 120 and 200 mm. Tests were also carried out on samples that were not reinforced with sand columns. The samples were compressed under both drained and undrained conditions. It was found that the undrained shear strength of samples containing full-depth columns was greatly improved compared with that of the unreinforced samples. In the fully drained tests, the sample installed with a single column of 32 mm diameter exhibited better performance than the sample with three columns of 20 mm diameter, although the area replacement ratio in the case of the three 20 mm diameter columns was higher than that of the single 32 mm diameter column. However, the undrained strength of the composite material was not particularly affected by the number of columns.Key words: Ground improvement, undrained shear strength, consolidation, stress path, settlement.

Shear strength of remolded soils at consistency limits

2010 ◽  
Vol 47 (3) ◽  
pp. 259-266 ◽  
Author(s):  
Kamil Kayabali ◽  
Osman Oguz Tufenkci
Keyword(s):  
Shear Strength ◽  
Linear Relationship ◽  
Water Content ◽  
Undrained Shear Strength ◽  
Liquid Limit ◽  
Soil Samples ◽  
Atterberg Limits ◽  
Plastic Limit ◽  
Water Contents ◽  
Undrained Shear

The undrained shear strength of remolded soils is of concern in certain geotechnical engineering applications. Several methods for determining this parameter exist, including the laboratory vane test. This study proposes a new method to estimate the undrained shear strength, particularly at the plastic and liquid limits. For 30 inorganic soil samples of different plasticity levels, we determined the Atterberg limits, then performed a series of reverse extrusion tests at different water contents. The plastic and liquid limits are derived from the linear relationship between the logarithm of the extrusion pressure and water content. The tests show that the average undrained shear strength determined from the extrusion pressures at the plastic limit is about 180 kPa, whereas the average undrained shear strength at the liquid limit is 2.3 kPa. We show that the undrained shear strength of remolded soils at any water content can be estimated from the Atterberg limits alone. Although the laboratory vane test provides a reasonable undrained shear strength value at the plastic limit, it overestimates the undrained shear strength at the liquid limit and thus, care must be taken when the laboratory vane test is used to determine undrained shear strengths at water contents near the liquid limit.

Excavation d'argile sensible au site de l'aménagement hydroélectrique LG-2

1985 ◽  
Vol 22 (2) ◽  
pp. 186-194
Author(s):  
J. J. Paré ◽  
J. G. Lavallée
Keyword(s):  
Shear Strength ◽  
Undrained Shear Strength ◽  
Strength Analysis ◽  
Site Conditions ◽  
Embankment Dams ◽  
Clay Deposits ◽  
Undrained Strength ◽  
Sensitive Clay ◽  
Tailrace Tunnel ◽  
Undrained Shear

This paper is a review of the design adopted to establish the slopes for deep clay excavations (3 000 000 m3) made for founding rockfill embankment dams on bedrock and for clearing the tailrace tunnel portals at the LG-2 hydroelectric site. The design and excavation of soft sensitive clay deposits down to 22 m had been undertaken at a period of time when very few precedents were existing (1974). During the excavation works, only a few minor slides occurred, indicating that the design approach, using undrained shear strength analysis, was appropriate for the site conditions. Methods of excavation and hauling of material to disposal areas are also described. Key words: slope, sensitive clay, undrained strength analysis, safety factor, excavation method, behaviour.

scholarly journals Undrained shear strength of glacial till soils and its determining factors

Baltica ◽  
2021 ◽  
pp. 246-252
Author(s):  
Domas Gribulis ◽  
Kastytis Dundulis ◽  
Saulius Gadeikis ◽  
Sonata Gadeikienė
Keyword(s):  
Shear Strength ◽  
Triaxial Compression ◽  
Undrained Shear Strength ◽  
Test Results ◽  
Fine Silt ◽  
Determining Factors ◽  
Undrained Strength ◽  
Soil Components ◽  
Undrained Shear

This article presents results of the test conducted on the undrained shear strength of till clayey soils of Eastern Lithuania, which are characterized by rigid and very stiff consistency and low plasticity. According to the classification of soils presented in LST EN ISO 14688–2:2018 Geotechnical Investigation and Testing – Identification and Classification of Soil − Part 2: Principles for a Classification, the tested soils are classified as sandy low plasticity clays. The undrained shear strength was tested using the triaxial compression (unconsolidated undrained) method. The test results showed that peculiarities of the particle size distribution had a crucial impact on the undrained strength of these soils, i.e. on the correlation of clay and fine silt fractions with the rest of soil components.

scholarly journals Numerical Analysis of Rapid Drawdown of an Embankment Dam

2020 ◽  
Vol 10 (2) ◽  
pp. 5496-5500
Author(s):  
A. H. Bhutto ◽  
G. S. Bhurgri ◽  
S. Zardari ◽  
M. A. Zardari ◽  
R. Bhanbhro ◽  
...  
Keyword(s):  
Shear Strength ◽  
Numerical Analysis ◽  
Undrained Shear Strength ◽  
Embankment Dam ◽  
Staged Construction ◽  
Different Depths ◽  
Undrained Strength ◽  
Clay Core ◽  
The Stability ◽  
Undrained Shear

Numerical analysis for the safe rate determination of lowering of an embankment dam was performed in this study with the use of the finite element method. Coupled deformation and consolidation analysis were carried out for staged construction and drawdown of a 59m embankment dam for varying undrained shear strength of the clay core. The lowering of the reservoir was performed at different depths between two extreme scenarios, i.e. rapid lowering rate (1m/day) and slow lowering rate (0.1m/day). The reservoir of the dam was lowered to a depth from 10m to 55m in gradual increments. The results indicated that the safety of the dam was satisfactory when the reservoir was lowered at the quick rate for a depth of 10m, 20m, 30m respectively when the undrained shear strength of the clay core was taken as 20, 25 and 30kN/m2. Regarding the case of slow drawdown rate of the reservoir, it was found that the reservoir could be lowered up to a depth of 55m at a rate of 0.1m/day when the undrained strength of clay core was 25kN/m2. The stability of the dam was also found satisfactory even though the reservoir was lowered at a rate of 0.25m/day for a depth of 55m when the undrained shear strength of clay core was 30kN/m2.

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