Pre- and post-cyclic behavior of mixed clayey soils

2009 ◽  
Vol 46 (2) ◽  
pp. 115-128 ◽  
Author(s):  
Abbas Soroush ◽  
Hossein Soltani-Jigheh
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Triaxial Compression ◽  
Cyclic Strain ◽  
Cyclic Behavior ◽  
Clayey Soils ◽  
Compression Tests ◽  
Soil Structures ◽  
Number Of Cycles ◽  
Cyclic Strain Amplitude

Soil structures are often comprised or supported by soils that are mixtures of cohesive and granular geomaterials. These soils are termed as intermediate or mixed soils and are widely found in natural deposits and man-made soil structures. The objective of this paper is to study the behavior of mixed clayey soils under monotonic, cyclic, and post-cyclic monotonic loading, with the main focus on the last of these three. For this purpose, a number of strain-controlled monotonic, cyclic, and post-cyclic triaxial compression tests were carried out on “clay–sand” and “clay–gravel” mixtures in undrained conditions. The effects of sand (or gravel) contents, number of cycles, cyclic strain amplitude, consolidation pressure, and grain size on the mechanical behavior of the mixtures are evaluated. The major findings from the laboratory study are: (i) the addition of granular materials to the clayey soils increases excess pore-water pressure during strain-controlled monotonic undrained shearing and cyclic loading and (ii) during post-cyclic monotonic shearing, mixed clayey soils behave similarly to overconsolidated soils; the higher the granular material is, the higher the overconsolidation ratio would be. Based on the research results, an algorithm for estimating post-cyclic mechanical parameters of mixed clayey soils, without conducting cyclic and post-cyclic tests, is suggested.

Cyclic Response and Instability Analysis of Seabed With Cohesionless Soils Due to Surging Waves

2021 ◽  
Author(s):  
Amin Rafiei ◽  
M. A. Gabr ◽  
M. S. Rahman ◽  
Majid Ghayoomi
Keyword(s):  
Finite Element ◽  
Pore Pressure ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Triaxial Compression ◽  
Soil Liquefaction ◽  
Cyclic Behavior ◽  
Cohesionless Soil ◽  
Compression Tests ◽  
Element Analysis

Abstract Surface waves may generate significant loadings on the seabed destabilizing sediments and the supporting marine structures. This threat is more pronounced in shallower water depths where the cyclic wave loading may induce residual pore water pressure in sediments triggering soil liquefaction. In this paper, a coupled numerical framework is presented to evaluate the interaction of waves and horizontal seabed considering nonlinear cyclic behavior of the cohesionless soil. A simple experimental model is employed for concurrent simulation of nonlinear buildup of pore pressure and deformation of saturated sand subjected to the cyclic loadings. The model (in elemental scale) is incorporated into a finite element code to solve the interaction of wave and seabed. Poro-elastoplastic response of the seabed is obtained by modifying the Biot’s coupled flow-and-deformation equations by adding equivalent nodal force terms associated with residual deformations of the soil. Potential flow theory is adopted for the fluid domain to model wave-induced pressure and flow fields. The governing equations and boundary conditions are solved using finite element analysis in time domain. The numerical framework is verified against results of cyclic triaxial compression tests and analytical solutions. Parametric studies are conducted to evaluate the effects of wave characteristics on triggering the residual liquefaction. The numerical results indicate good agreements with experimental measures. The results also show that for large waves, the progressive buildup of pore pressure in sediments may become high enough, leading to residual liquefaction. The details of the numerical model and the potential of residual liquefaction within the seabed soil are discussed.

Static response of fly ash columnar improved ground

2001 ◽  
Vol 38 (2) ◽  
pp. 276-286 ◽  
Author(s):  
A Porbaha ◽  
T BS Pradhan ◽  
T Kishida
Keyword(s):  
Fly Ash ◽  
Stress Concentration ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Triaxial Compression ◽  
Area Ratio ◽  
Stress Redistribution ◽  
Soft Ground ◽  
Compression Tests ◽  
Composite Ground

This study presents the results of a series of monotonic undrained triaxial compression tests on clay specimens improved by columnar reinforcement. The process of loading and stress redistribution of a fly ash – clay specimen (FCS), in comparison with a sand–clay specimen (SCS), is examined in terms of stress–strain characteristics, generation of excess pore-water pressure, effective and total earth pressures, development of stress concentration, and the normalized undrained shear strength of the improved soil. It was found, predictably, that the deviator stress of the composite specimens was influenced by the consolidation stress, replacement area ratio, and properties of the column material. The stress concentration at the top of the composite ground which depends on the loading stage reaches a peak after the consolidation state and is reduced due to stress redistribution between the column and the soft ground. In terms of improvement effects, the mean shear strengths of FCS and SCS relative to the clay specimen are three and seven times greater, respectively, for a replacement area ratio of 49%.Key words: composite ground, fly ash, soil improvement, soft ground, triaxial test.

True Shear Parameters of Saturated Clays

1973 ◽  
Vol 10 (4) ◽  
pp. 652-663
Author(s):  
A. Sridharan ◽  
S. Narasimha Rao
Keyword(s):  
Stress Level ◽  
Pore Water Pressure ◽  
Initial Conditions ◽  
Water Pressure ◽  
Triaxial Compression ◽  
Compression Tests ◽  
Strength Parameters ◽  
Test Procedures ◽  
Stress History ◽  
Triaxial Compression Tests

Ever since Hvorslev proposed a failure criterion incorporating intrinsic parameters, several test procedures have come into practice to determine these ‘true’ strength parameters. Several consolidated undrained triaxial compression tests with pore water pressure measurement were conducted on both montmorillonite and kaolinite clays and the results were analyzed using different existing methods. All the methods through which the data were analyzed fail to assign any unique true strength parameters. Even a particular method yields different values depending upon the initial conditions (stress history, water content) of the sample and stress level during testing. It has been reasoned that these variations are due to the probable differences in fabric between the samples which are involved in various methods. There seems to be a unique linear relationship between tan [Formula: see text] and Cc/pe irrespective of the sample state, stress level, and stress history in both undisturbed and remolded conditions for all the procedures adopted.

Experimental Research of Fine Sandstone Strength and Deformation Characteristics under Different Confining and Hydraulic Pressure

2013 ◽  
Vol 353-356 ◽  
pp. 562-570 ◽  
Author(s):  
Zai Bin Liu
Keyword(s):  
Rock Strength ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Hydraulic Pressure ◽  
Compression Tests ◽  
Exponential Relationship ◽  
Sandstone Rock ◽  
Strength And Deformation

In order to study sandstone rock strength and deformation parameters under pore water pressure conditions, triaxial compression tests of different hydraulic pressure were executed. Fitting equations of fine sandstone confining pressure and hydraulic pressure coupling effects were established. This research show that fine sandstone rock strength increases with confining pressure increases. Rock mass strength and cohesion have negative exponential relationship with hydraulic pressure. When the hydraulic pressure is 3MPa, elasticity and confining pressure fit to logarithmic relationship. Fine sandstone Elasticity modulus decreases with hydraulic pressure increases. Poisson’s ration and hydraulic pressure fit to linear relationship.

TIME TO THE END OF PRIMARY CONSOLIDATION (EOP) OF SOFT CLAYEY SOILS: CONCERNING THE EFFECT OF ATTERBERG’S LIMIT AND CYCLIC LOADING HISTORY

2019 ◽  
Vol 128 (2B) ◽  
pp. 29-41
Author(s):  
Trần Thanh Nhàn
Keyword(s):  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Clayey Soils ◽  
Loading History ◽  
Cyclic Shear ◽  
Wide Range ◽  
Primary Consolidation ◽  
Time Required

In order to observe the end of primary consolidation (EOP) of cohesive soils with and without subjecting to cyclic loading, reconstituted specimens of clayey soils at various Atterberg’s limits were used for oedometer test at different loading increments and undrained cyclic shear test followed by drainage with various cyclic shear directions and a wide range of shear strain amplitudes. The pore water pressure and settlement of the soils were measured with time and the time to EOP was then determined by different methods. It is shown from observed results that the time to EOP determined by 3-t method agrees well with the time required for full dissipation of the pore water pressure and being considerably larger than those determined by Log Time method. These observations were then further evaluated in connection with effects of the Atterberg’s limit and the cyclic loading history.

scholarly journals Mechanical behaviour of calcareous waste under consolidated drained triaxial compression testing in saturated conditions

2019 ◽  
Vol 106 ◽  
pp. 01016
Author(s):  
Jakub Zięba
Keyword(s):  
Mechanical Behaviour ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Triaxial Compression ◽  
Soil Samples ◽  
Excess Pore Water Pressure ◽  
Stiffness Properties ◽  
Construction Purpose ◽  
Strength And Stiffness ◽  
Excess Pore

The article presents the mechanical behaviour of calcareous waste under consolidated and drained condition in Triaxial compression test (CD). The host material currently being considered for the construction purpose of several buildings in Poland. One of the location of calcareous waste is in Łagiewniki area (in Cracow) [1,2]. In this work, particular attention has been paid to the to ensure fully saturation for all the tested soil samples and avoid generation of unwanted excess pore water pressure during shearing stage. The saturation level of soil samples was estimated based on Skempton’s law (B>0.95). CD Triaxial test have been conducted in order to derive information on its strength and stiffness properties.

Aspects of the behaviour of compacted clayey soils on drying and wetting paths

2002 ◽  
Vol 39 (6) ◽  
pp. 1341-1357 ◽  
Author(s):  
Jean-Marie Fleureau ◽  
Jean-Claude Verbrugge ◽  
Pedro J Huergo ◽  
António Gomes Correia ◽  
Siba Kheirbek-Saoud
Keyword(s):  
Water Content ◽  
Pore Water ◽  
Unsaturated Soils ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Dry Density ◽  
Clayey Soils ◽  
Maximum Dry Density ◽  
Optimum Water Content ◽  
Optimum Water

A relatively large number of drying and wetting tests have been performed on clayey soils compacted at the standard or modified Proctor optimum water content and maximum density and compared with tests on normally consolidated or overconsolidated soils. The results show that drying and wetting paths on compacted soils are fairly linear and reversible in the void ratio or water content versus negative pore-water pressure planes. On the wet side of the optimum, the wetting paths are independent of the compaction water content and can be approached by compaction tests with measurement of the negative pore-water pressure. Correlations have been established between the liquid limit of the soils and such properties as the optimum water content and negative pore-water pressure, the maximum dry density, and the swelling or drying index. Although based on a limited number of tests, these correlations provide a fairly good basis to model the drying–wetting paths when all the necessary data are not available.Key words: compaction, unsaturated soils, clays, drying, wetting, Proctor conditions.

Sign in / Sign up

Export Citation Format

Share Document