Simulation on Strain Softening of over-Consolidated Clayey Soil by Binary Medium Model

2011 ◽  
Vol 90-93 ◽  
pp. 1322-1325
Author(s):  
Yong Hong
Keyword(s):  
Nonlinear Deformation ◽  
Strain Softening ◽  
Clayey Soil ◽  
Soil Mass ◽  
Triaxial Tests ◽  
Deformation Analysis ◽  
Silty Clay ◽  
Intensity Attenuation ◽  
Medium Model ◽  
Breakage Mechanics

This paper attempts to simulate the stress-strain relations of Pontida silty clay under triaxial tests in accordance with the latest theory of geotechnical nonlinear deformation analysis-breakage mechanics of geomaterials. The result proves that the binary medium model of over-consolidated clayey soil can effectively reflect the deformation mechanism of soil mass and the brittle break phenomenon, thus possessing good suitability and effectiveness. This also lays down the foundation and provides new ways for the further discussion of establishing the elastic-plastic constitutive model of clayey soil softening properties and intensity attenuation effects with the consideration of large shear displacement.

CFD Simulation on Dynamic Installation of the Light-Weight Gravity Installed Plate Anchor in Clay

2020 ◽  
Author(s):  
Jun Liu ◽  
Nanqiao Bu ◽  
Congcong Han
Keyword(s):  
Strain Rate ◽  
Penetration Depth ◽  
Strain Softening ◽  
Cfd Simulation ◽  
Clayey Soil ◽  
Fluid Model ◽  
Deformation Analysis ◽  
Deep Penetration ◽  
Light Weight ◽  
Plate Anchor

Abstract A light-weight gravity installed plate anchor (L-GIPLA) is put forward in the present study to secure offshore floating structures, such as floating wind turbines, floating net-cages, wave and tidal energy converters, and floating oil and gas platforms. The L-GIPLA is installed with the aid of a booster, which can be connected at the tail of the anchor during dynamically installation and retrieved after installation. The L-GIPLA owns the advantages of dynamically installation, deep penetration depth and high capacity efficiency. In the present study, the dynamic installation process of the L-GIPLA with a booster in clay is modelled by conducting three-dimensional large deformation analysis in commercial software ANSYS CFX, which is a computational fluid dynamics (CFD) software based on the finite volume method (FVM). Non-Newtonian fluid model, incorporating the strain-rate and strain-softening effects, is used to simulate the undrained clayey soil. Various factors influencing the final penetration depth of the anchor have been studied. These factors include the soil strength characterizations (strain-rate and strain-softening effects), and impact velocity. The results show that the L-GIPLA can obtain a relatively deep penetration depth in the seabed, indicating the L-GIPLA is an efficient alternative in offshore engineering.

Determination of Elastic and Plastic Subgrade Soil Parameters for Asphalt Cracking and Rutting Prediction

1996 ◽  
Vol 1540 (1) ◽  
pp. 97-104 ◽  
Author(s):  
G. Behzadi ◽  
W. O. Yandell
Keyword(s):  
Moisture Content ◽  
Constitutive Model ◽  
Permanent Deformation ◽  
Triaxial Tests ◽  
Deformation Analysis ◽  
Soil Parameters ◽  
Dry Density ◽  
Silty Clay ◽  
Exponential Relationship ◽  
Deviator Stress

A preliminary step in the prediction of rutting and cracking in a number of accelerated loading facility trials in Australia is presented. The results of laboratory repeated load triaxial tests were used to characterize the residual and resilient deformation of a silty clay subgrade material. The analysis of permanent deformation indicated that the well-known model ∈p = INS can be used to estimate the accumulated strain at any number of loading cycles. The parameter S (the slope of the line in a plot of log ∈p –log N) was found to be independent of stress and density, but very small increases were observed as moisture content increased. The parameter I (the intercept in a plot of log ∈p –log N) was found to be most sensitive to deviator stress. The test results also indicated that I increased with increasing moisture content and decreased as dry density increased. The analysis revealed that an exponential relationship existed between I and deviator stress. This relationship was used to develop a constitutive model for silty clay based on the previously mentioned well-known model. The constitutive model obtained would be able to predict the plastic strain under any number of loads at any specified stress level. Resilient deformation analysis has shown that resilient modulus initially decreased rapidly with increasing deviator stress and then increased slightly or was nearly constant. The elastic and plastic parameters will be used as input for performance predictors such as VESYS and Mechano-Lattice.

Evaluation on Features of Soft Foundation Engineering and Bearing Layer of Pile in Jiaxing City

2011 ◽  
Vol 90-93 ◽  
pp. 217-221
Author(s):  
Jin Long Zhou ◽  
Qiao Li ◽  
Wei Zhong Cai
Keyword(s):  
Soil Mass ◽  
Shallow Foundation ◽  
Silty Clay ◽  
Foundation Engineering ◽  
Foundation Soil ◽  
Cone Tip Resistance ◽  
Soft Foundation ◽  
Tip Resistance ◽  
Bearing Layer

Through the investigation into composition of major shallow foundation soil mass and the correlation of mechanical indicators in this study, the regression equation of mechanical indicators of the features of local foundation soil mass and the data of in situ testing was obtained. Based on massive quantities of exploration materials, this study analyzed engineering features, distribution status, and the feasibility of silty clay to be used as the bearing layer of the pile in Layer ④2 . The analytical results showed that the silty clay with the uniform depth of over 3.5m and the cone tip resistance in static sounding of over 400MPa could be used as bearing layer of the pile. This study could provide the reference for the accurate understanding of the engineering features of soil mass, and the design and evaluation of foundation in Jiaxing City.

scholarly journals Representative Elementary Length to Measure Soil Mass Attenuation Coefficient

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
J. A. R. Borges ◽  
L. F. Pires ◽  
J. C. Costa
Keyword(s):  
Attenuation Coefficient ◽  
Gamma Ray ◽  
Clayey Soil ◽  
Physical Property ◽  
Soil Mass ◽  
Mass Attenuation Coefficient ◽  
Soil Bulk Density ◽  
Elementary Length ◽  
Increasing Demand ◽  
Mass Attenuation

With increasing demand for better yield in agricultural areas, soil physical property representative measurements are more and more essential. Nuclear techniques such as computerized tomography (CT) and gamma-ray attenuation (GAT) have been widely employed with this purpose. The soil mass attenuation coefficient (μs) is an important parameter for CT and GAT analysis. When experimentally determined (μes), the use of suitable sized samples enable to evaluate it precisely, as well as to reduce measurement time and costs. This study investigated the representative elementary length (REL) of sandy and clayey soils forμesmeasurements. Two radioactive sources were employed (241Am and137Cs), three collimators (2–4 mm diameters), and 14 thickness (x) samples (2–15 cm). Results indicated ideal thickness intervals of 12–15 and 2–4 cm for the sources137Cs and241Am, respectively. The application of such results in representative elementary area (REA) evaluations in clayey soil clods via CT indicated thatμesaverage values obtained forx > 4 cm and source241Am might induce to the use of samples which are not large enough for soil bulk density evaluations (ρs). As a consequence,ρsmight be under- or overestimated, generating inaccurate conclusions about the physical quality of the soil under study.

Micro Parameters Sensitivity of Coarse Grained Material in Mechanics and Deformation Based on PFC3D

2016 ◽  
Vol 873 ◽  
pp. 115-119
Author(s):  
Zhi Hua Zhang ◽  
Xie Dong Zhang ◽  
Hong Sheng Qiu ◽  
Bei Yang Zhang
Keyword(s):  
Weighted Average ◽  
Shear Stiffness ◽  
Coarse Grained ◽  
Triaxial Tests ◽  
Deformation Analysis ◽  
Analysis Method ◽  
Particle Rotation ◽  
Sensitivity Curves ◽  
Coarse Grained Material ◽  
Strength And Deformation

In order to study the effects of various parameters on macro-mechanical and deformational characteristics of coarse grained material based on discrete element method, triaxial tests have been conducted. Weighted average assembling method is used to assemble the numerical model based on PFC3D. The ratio of normal and shear stiffness of particles (kn/ks), shearing rate and friction coefficient are chosen as micro parameters to analyze the influential sensitivity. Curves of stress-strain intensity are taken as the mechanical analytic method. The particle rotation field as deformation analysis method is proposed to sort the sensitivity of these parameters in strength and deformation of coarse grained material. The research shows that the parameters have a certain effect on the strength and deformation of coarse grained material. kn/ks has the greatest influence on both. The sensitive list of the strength and deformation hopefully can be discussed with the relevant scholars, which can provide a reference for the adjustment of micro parameters in numerical field.

scholarly journals Resilient modulus and cumulative plastic strain of frozen silty clay under dynamic aircraft loading

2021 ◽  
Vol 3 (10) ◽  
Author(s):  
Xiaolan Liu ◽  
Xianmin Zhang ◽  
Xiaojiang Wang
Keyword(s):  
Plastic Strain ◽  
Resilient Modulus ◽  
Confining Pressure ◽  
Frozen Soil ◽  
Triaxial Tests ◽  
Silty Clay ◽  
Research Findings ◽  
Cumulative Plastic Strain ◽  
Construction Operation ◽  
Compaction Degree

AbstractThis paper describes an investigation into the factors influencing the resilient modulus and cumulative plastic strain of frozen silty clay. A series of dynamic triaxial tests are conducted to analyze the influence of the temperature, confining pressure, frequency, and compaction degree on the resilient modulus and cumulative plastic strain of frozen silty clay samples. The results show that when the temperature is below − 5 °C, the resilient modulus decreases linearly, whereas when the temperature is above − 5 °C, the resilient modulus decreases according to a power function. The resilient modulus increases logarithmically when the frequency is less than 2 Hz and increases linearly once the frequency exceeds 2 Hz. The resilient modulus increases as the confining pressure and compaction degree increase. The cumulative plastic strain decreases as the temperature decreases and as the confining pressure, frequency, and compaction degree increase. The research findings provide valuable information for the design, construction, operation, maintenance, safety, and management of airport engineering in frozen soil regions.

Combining perennial grass-legume forages and liquid dairy manure contributes to nitrogen accumulation in a clayey soil

2021 ◽  
Author(s):  
Emmanuelle D’Amours ◽  
Martin H. Chantigny ◽  
Anne Vanasse ◽  
Émilie Maillard ◽  
Jean Lafond ◽  
...  
Keyword(s):  
Management Practices ◽  
Clayey Soil ◽  
Perennial Grass ◽  
Dairy Manure ◽  
Nitrogen Accumulation ◽  
Silty Clay ◽  
Soil N ◽  
Mineral Fertilization ◽  
Humid Climate ◽  
Tillage Practices

Repeated applications of liquid dairy manure (LDM) and perennial crops generally favor nitrogen (N) stocks in soils, but in ways that may differ with soil type and other management practices. The objective of this study was to assess the long-term (21 yr) changes in soil N stocks (0–50 cm) of a silty clay soil, in a cool humid climate, in response to mineral fertilization (MIN) or LDM, combined with two tillage practices (chisel plow [CP], or moldboard plow [MP]), and two crop rotations (cereal monoculture [monoculture] or cereal-perennial forage rotation [forage-based rotation].) The forage-based rotation favoured a greater accumulation of N in the first 20 cm of soil (+50 kg N ha-1 y-1) when compared to the monoculture. Tillage practices did not impact N stock in the whole soil profile, but influenced its vertical distribution, with greater accumulation at the surface with CP, and at depth with MP. Annual input of LDM increased N stocks at the surface (0–20 cm) compared to MIN, especially when combined with the forage-based rotation. After 21 yr, soil N stocks (0-50 cm) with LDM were 32% (+2 t N ha-1) higher in the forage-based rotation than in the monoculture, suggesting better retention and more efficient use of manure-N with perennial forages than cereals. Comparisons between the N mass balance computed for each cropping system and the changes in soil N stocks indicated that accumulation of N under the forage-based rotation was largely due to symbiotic fixation by legumes in the forage mixture.

scholarly journals Behavior of Fiber-Reinforced and Lime-Stabilized Clayey Soil in Triaxial Tests

2019 ◽  
Vol 9 (5) ◽  
pp. 900 ◽  
Author(s):  
Yixian Wang ◽  
Panpan Guo ◽  
Xian Li ◽  
Hang Lin ◽  
Yan Liu ◽  
...  
Keyword(s):  
Wheat Straw ◽  
Clayey Soil ◽  
Coupling Effect ◽  
Fiber Reinforcement ◽  
Reinforced Soil ◽  
Triaxial Tests ◽  
Fiber Reinforced ◽  
Microscopic Mechanism ◽  
Lime Stabilization ◽  
Stabilized Soil

The beneficial role of combining fiber reinforcement with lime stabilization in altering soil behavior has been established in the literature. However, the coupling effect of their combination still remains unclear in terms of its magnitude and microscopic mechanism, especially for natural fibers with special microstructures. The objective of this study was to investigate the coupling effect of wheat straw fiber reinforcement and lime stabilization on the mechanical behavior of Hefei clayey soil. To achieve this, an experimental program including unconsolidated–undrained (UU) triaxial tests and SEM analysis was implemented. Static compaction test samples were prepared on untreated soil, fiber-reinforced soil, lime-stabilized soil, and lime-stabilized/fiber-reinforced soil at optimum moisture content with determining of the maximum dry density of the untreated soil. The lime was added in three different contents of 2%, 4%, and 6%, and 13 mm long wheat straw fiber slices with a cross section one-quarter that of the intact ones were mixed in at 0.2%, 0.4%, and 0.6% by dry weight of soil. Analysis of the derived results indicated that the addition of a small amount of wheat straw fibers into lime-stabilized soil improved the intensity of the strain-softening behavior associated with mere lime stabilization. The observed evidence that the shear strength increase brought by a combination of 0.4% fiber reinforcement and 4% lime stabilization was smaller than the summation of the shear strength increases brought by their presence alone in a sample demonstrated a coupling effect between fiber reinforcement and lime stabilization. This coupling effect was also detected in the comparisons of the secant modulus and failure pattern between the combined treatment and the individual treatments. These manifestations of the coupling effect were explained by a microscopic mechanism wherein the fiber reinforcing effect was made more effective by the ways in which lime chemically stabilized the soil and lime stabilization development was quickened by the water channels passing through the surfaces and honeycomb pores of the wheat straw fibers.

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