Modified state parameter for characterizing static liquefaction of sand with fines

2009 ◽  
Vol 46 (3) ◽  
pp. 281-295 ◽  
Author(s):  
D. C. Bobei ◽  
S. R. Lo ◽  
D. Wanatowski ◽  
C. T. Gnanendran ◽  
M. M. Rahman
Keyword(s):  
Critical State ◽  
Volumetric Strain ◽  
State Parameter ◽  
Confining Pressure ◽  
Log P ◽  
Test Results ◽  
Static Liquefaction ◽  
Isotropic Consolidation ◽  
Failure Line ◽  
Soil Behaviour

An experimental study was carried out to investigate the static liquefaction behaviour of sand with a small amount of plastic and nonplastic fines. Five series of tests were conducted in drained and undrained conditions. The drained test results indicate not only that the failure line coincides with the critical state, but also that the development of volumetric strain during shearing was not sensitive to the initial confining pressure. In both isotropically and anisotropically consolidated undrained tests, a so-called “reverse behaviour” was consistently observed. The results were also interpreted in the critical state framework. The critical and steady state (CS/SS) data were found to trace along the same curve in e–log( p′) space, irrespective of the stress history and effective stress paths. A comparison between the isotropic consolidation line (ICL) and critical state (CS) curve showed that a small amount of fines can significantly change the shape and position of the ICL relative to the CS curve. Furthermore, the soil behaviour manifested in both drained and undrained shearing led to the development of a modified state parameter.

Effects of fines on liquefaction behaviour in well-graded materials

2017 ◽  
Vol 54 (10) ◽  
pp. 1460-1471 ◽  
Author(s):  
Katherine A. Kwa ◽  
David W. Airey
Keyword(s):  
Critical State ◽  
Soil Mechanics ◽  
State Parameter ◽  
Triaxial Tests ◽  
Particle Sizes ◽  
Graded Materials ◽  
Fines Content ◽  
Cyclic Resistance ◽  
Wide Range ◽  
Soil Behaviour

This study uses a critical state soil mechanics perspective to understand the mechanics behind the liquefaction of metallic ores during transport by ship. These metallic ores are transported at relatively low densities and have variable gradings containing a wide range of particle sizes and fines contents. The effect of the fines content on the location of the critical state line (CSL) and the cyclic liquefaction behaviour of well-graded materials was investigated by performing saturated, standard drained and undrained monotonic and compression-only cyclic triaxial tests. Samples were prepared at four different gradings containing particle sizes from 9.5 mm to 2 μm with fines (<75 μm) contents of 18%, 28%, 40%, and 60%. In the e versus log[Formula: see text] plane, where e is void ratio and [Formula: see text] is mean effective stress, the CSLs shifted upwards approximately parallel to one another as the fines content was increased. Transitional soil behaviour was observed in samples containing 28%, 40%, and 60% fines. A sample’s cyclic resistance to liquefaction depended on a combination of its density and state parameter, which were both related to the fines content. Samples with the same densities were more resistant to cyclic failure if they contained higher fines contents. The state parameter provided a useful prediction for general behavioural trends of all fines contents studied.

Static liquefaction of sand in plane strain

2007 ◽  
Vol 44 (3) ◽  
pp. 299-313 ◽  
Author(s):  
Dariusz Wanatowski ◽  
Jian Chu
Keyword(s):  
Plane Strain ◽  
Laboratory Tests ◽  
Stress Ratio ◽  
State Parameter ◽  
Intermediate Principal Stress ◽  
Log P ◽  
Loose Sand ◽  
Static Liquefaction ◽  
Testing Data ◽  
Unique Relationship

Experimental results on the static liquefaction behaviour of sand under plane-strain conditions are presented in this paper. Undrained tests on very loose sand under both plane-strain and axisymmetric conditions were conducted and the results compared. The test data show that the undrained behaviour of sand under plane strain is similar to that under axisymmetric conditions. However, the critical-state line (CSL) on both the q–p′ and the e–p′ planes determined under plane-strain conditions is different from that under axisymmetric conditions. The slope of the CSL is different as a result of the influence of the intermediate principal stress. The state parameter (ψ), which is measured with reference to the CSL in the e – log p′ plane, is also different: the ψ value for plane strain is about 0.05 less than that for axisymmetric conditions for the sand tested. The instability behaviour of very loose sand under undrained plane-strain conditions is also studied. Based on the testing data, a unique relationship between the stress ratio of the instability line and ψ is established to enable the triaxial results to be used for plane-strain conditions.Key words: failure, sands, laboratory tests, liquefaction, shear strength.

Influence of state and compressibility on liquefied strength of sands

2013 ◽  
Vol 50 (10) ◽  
pp. 1067-1076 ◽  
Author(s):  
Abouzar Sadrekarimi
Keyword(s):  
Shear Strength ◽  
Critical State ◽  
Soil Mechanics ◽  
State Parameter ◽  
Test Results ◽  
Confining Stress ◽  
Stress Variation ◽  
Laboratory Test Results ◽  
Flow Failure ◽  
Underlying Mechanisms

Critical-state soil mechanics is a useful framework to understand sand behavior. In this paper, a relationship is developed for estimating undrained critical shear strength of sands based on the critical-state framework. The application of this relationship is demonstrated by comparison with laboratory test results and sand liquefied strength from field liquefaction flow failure case histories. Using this relationship, the effects of effective stress variation and density on undrained critical shear strength are studied for different combinations of critical-state line parameters corresponding to several reference sands. The parametric study indicates that depending on sand void ratio, undrained critical shear strength may increase, remain the same or decrease as sand shearing–compressibility (represented by the slope of the critical-state line) increases. The underlying mechanisms of field failures in dense sands and reverse behavior of compressible sands are explained through this relationship. It is suggested that the critical-state parameter alone is insufficient for describing the behavior of liquefiable sands and sand shearing–compressibility should be also taken into account for estimating undrained shear strength corresponding to the changes in density and effective confining stress.

scholarly journals Instability of Compacted Residual Soil

Geosciences ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 403
Author(s):  
Sainulabdeen Mohamed Junaideen ◽  
Leslie George Tham ◽  
Chack Fan Lee
Keyword(s):  
Steady State ◽  
State Parameter ◽  
Triaxial Tests ◽  
Residual Soil ◽  
Test Results ◽  
Residual Soils ◽  
Constant Shear ◽  
Static Liquefaction ◽  
Constant Shear Stress ◽  
Stress Ratios

Static liquefaction of loose sands has been observed to initiate at stress ratios far less than the steady-state stress ratio. Different collapse surface concepts largely based on undrained triaxial test results have been proposed in the literature to explain the above instability phenomenon of loose sands. Studies of the instability behavior of fill material derived from residual soils remain limited. The present study investigated the instability behavior of a compacted residual soil using the conventional undrained triaxial tests and specially equipped constant shear triaxial tests. The test results were characterized in the p’: q: v space using the current state parameter with respect to the steady-state line for the residual soil. A modified collapse surface that has gradients varying with p’ and v was proposed for the loose residual soil to represent the instability states of undrained loading. Under constant shear stress conditions, the soil can mobilize stress ratios higher than those defined by the modified collapse surface. An instability surface was therefore presented for the instability states reached in static loading. Further, an alternative method of deducing the instability surface from the undrained stress paths was introduced.

scholarly journals Investigating the Permeability of Marble under Moderate Pressure and Temperature

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Jianping Yang ◽  
Weizhong Chen ◽  
Diansen Yang ◽  
Hongming Tian
Keyword(s):  
Volumetric Strain ◽  
Strain Curve ◽  
Confining Pressure ◽  
Crystalline Rock ◽  
Mechanical Tests ◽  
Moderate Pressure ◽  
Test Results ◽  
Permeability Evolution ◽  
Confining Pressures ◽  
Linkage Model

The permeability of intact marble samples collected from the depth of 1.6 km in southwestern China is investigated under moderate confining pressures and temperatures. No microcracks initiate or propagate during the tests, and the variation of permeability is due to the change of aperture of microcracks. Test results show a considerable decrease of permeability along with confining pressure increase from 10 to 30 MPa and temperature increase from 15 to 40°C. The thermal effect on the permeability is notable in comparison with the influence of the stress. A simple permeability evolution law is developed to correlate the permeability and the porosity in the compressive regime based on the microphysical geometric linkage model. Using this law, the permeability in the compressive regime for crystalline rock can be predicted from the volumetric strain curve of mechanical tests.

scholarly journals Mechanical state of gravel soil in mobilization of rainfall-induced landslides in the Wenchuan seismic area, Sichuan province, China

2018 ◽  
Vol 6 (3) ◽  
pp. 637-649
Author(s):  
Liping Liao ◽  
Yunchuan Yang ◽  
Zhiquan Yang ◽  
Yingyan Zhu ◽  
Jin Hu ◽  
...  
Keyword(s):  
Critical State ◽  
Void Ratio ◽  
Fine Particles ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
State Parameter ◽  
Confining Pressure ◽  
Dry Density ◽  
Mechanical State ◽  
Gravel Soil

Abstract. Gravel soils generated by the Wenchuan earthquake have undergone natural consolidation for the past decade. However, geological hazards, such as slope failures with ensuing landslides, have continued to pose great threats to the region. In this paper, artificial model tests were used to observe the changes of soil moisture content and pore water pressure, as well as macroscopic and microscopic phenomena of gravel soil. In addition, a mathematical formula of the critical state was derived from the triaxial test data. Finally, the mechanical states of gravel soil were determined. The results had five aspects. (1) The time and mode of the occurrence of landslides were closely related to the initial dry density. The process of initiation was accompanied by changes in density and void ratio. (2) The migration of fine particles and the rearrangement of coarse–fine particles contributed to the reorganization of the microscopic structure, which might be the main reason for the variation of dry density and void ratio. (3) If the confining pressure were the same, the void ratios of soils with constant particle composition would approach approximately critical values. (4) Mechanical state of gravel soil can be determined by the relative position between state parameter (e, p′) and ec–p′ planar critical state line, where e is the void ratio, ec is the critical void ratio and p′ is the mean effective stress. (5) In the process of landslide initiation, dilatation and contraction were two types of gravel soil state, but dilatation was dominant. This paper provided insight into interpreting landslide initiation from the perspective of critical state soil mechanics.

scholarly journals Technical Notoe: Prediction of Static Liquefaction by Nor Sand Constitutive Model

2015 ◽  
Vol 36 (3) ◽  
pp. 75-83
Author(s):  
Krzysztof Sternik
Keyword(s):  
Constitutive Model ◽  
Critical State ◽  
Soil Mechanics ◽  
State Parameter ◽  
Short Description ◽  
Flow Rule ◽  
Saturated Sand ◽  
Hardening Law ◽  
Static Liquefaction ◽  
Associated Flow Rule

Abstract The paper gives a short description of unstable behaviour of saturated sand under undrained monotonic loading. Constitutive model Nor Sand capable to describe static liquefaction is presented. The model is based on critical state soil mechanics and assumes associated flow rule. Hardening law incorporates the state parameter proposed earlier by Been and Jefferies. Results of numerical simulations of undrained element tests have been presented and discussed.

Research on Strength Characteristics of Expansive Soil

2011 ◽  
Vol 109 ◽  
pp. 96-99
Author(s):  
Qian Li ◽  
Le Fu
Keyword(s):  
Critical State ◽  
Expansive Soil ◽  
Confining Pressure ◽  
Experimental Methods ◽  
Dry Density ◽  
Initial Water Content ◽  
Test Results ◽  
Initial Water ◽  
State Test ◽  
Shearing Strength

According to expansive soil, consolidated drained tests and undrained tests are carried on under saturated and remoulded conditions. The stress-strain characteristics of saturated soil are researched systematically under different confining pressure, initial dry density, initial water content, shearing rate and drainage condition. The inherent unity of diversity of shearing strength for the same samples measured by different experimental methods is indicated according to the normalization of critical state test results.

scholarly journals Recommended Procedures to Assess Critical State Locus from Triaxial Tests in Cohesionless Remoulded Samples

Geotechnics ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 95-127
Author(s):  
António Viana da Fonseca ◽  
Diana Cordeiro ◽  
Fausto Molina-Gómez
Keyword(s):  
Critical State ◽  
Review Paper ◽  
State Theory ◽  
Soil Freezing ◽  
Triaxial Tests ◽  
Cohesionless Soils ◽  
Saturation Condition ◽  
Testing Procedures ◽  
Laboratory Procedures ◽  
Soil Behaviour

The critical state theory is a robust conceptual framework for the characterisation of soil behaviour. In the laboratory, triaxial tests are used to assess the critical state locus. In the last decades, the equipment and testing procedures for soil characterisation, within the critical state framework, have advanced to obtain accurate and reliable results. This review paper summarises and describes a series of recommended laboratory procedures to assess the critical state locus in cohesionless soils. For this purpose, results obtained in the laboratory from different cohesionless soils and triaxial equipment configurations are compiled, analysed and discussed in detail. The procedures presented in this paper reinforce the use of triaxial cells with lubricated end platens and an embedded connection piston into the top-cap, together with the verification of the full saturation condition and the measurement end-of-test water content—preferable using the soil freezing technique. The experimental evidence and comparison between equipment configurations provide relevant insights about the laboratory procedures for obtaining a reliable characterisation of the critical state locus of cohesionless geomaterials. All the procedures recommended herein can be easily implemented in academic and commercial geotechnical laboratories.

scholarly journals Prediction of Effects of Geogrid Reinforced Granular Fill on the Behaviour of Static Liquefaction

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
A. Hemalatha ◽  
N. Mahendran ◽  
G. Ganesh Prabhu
Keyword(s):  
Bearing Capacity ◽  
Load Test ◽  
Test Results ◽  
Plate Load Test ◽  
Large Size ◽  
Static Liquefaction ◽  
Granular Fill ◽  
Size Dimension ◽  
Subgrade Modulus ◽  
Different Thickness

The experimental investigation on the effects of granular fill and geogrid reinforced granular fill on the behaviour of the static liquefaction potential of the subsoil is reported in this study. A series of plate load test were carried out with different thickness of the granular fill, number of geogrid layers, and size/dimension of the footing. The test results were presented in terms of bearing capacity and subgrade modulus for the settlement ofδ10,δ15, andδ20. The experimental results revealed that the introduction of granular fill significantly increases the bearing capacity and effectively control the settlement behaviour of the footing. The introduction of geogrid in granular fill enhanced the Percentage of Control in Settlement and Bearing Capacity Ratio by a maximum of 328.54% and 203.41%, respectively. The introduction of geogrid in granular fill interrupts the failure zone of the granular fill and enhances the subgrade modulus of the footing by a maximum of 255.55%; in addition subgrade modulus of the footing was increased with an increase in the number of geogrid layers. Based on the test results it is suggested that the footing with large size has beneficial improvement on the reinforced granular fill.

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