Modified Duncan-Chang Model Considering Physical Properties of Saturated Clays

2013 ◽  
Vol 416-417 ◽  
pp. 1746-1752
Author(s):  
Xing Chen Wang ◽  
Ri Qing Xu ◽  
Jing Lin Qian
Keyword(s):  
Physical Properties ◽  
Void Ratio ◽  
Confining Pressure ◽  
Deviatoric Stress ◽  
Plasticity Index ◽  
Test Results ◽  
Stress Strain ◽  
Initial Void Ratio ◽  
Proposed Model ◽  
Chang Model

A series of undrained triaxial compression tests of saturated clays under different conditions were performed to study whether it is possible to determine parameters specifying Duncan-Chang model simply by using the physical parameters. The test results show that both the initial tangent modulus and peak deviatoric stress decrease with increasing initial void ratio and plasticity index of the soil under the same confining pressure. Whereas, they increase with increasing confining pressure of the soil with the same initial void ratio and plasticity index. A new synthesized physical parameter λ is defined based on the test results in this work. The functional relationships among the parameters K, peak deviatoric stress in Duncan-Chang model and the parameter λ are established to develop a modified Duncan-Chang model by considering physical properties of soil. In this model, only two input parameters, i.e., λ and the damage ratio Rf, are needed to predict the stress-strain relationships of the soil. In order to check the accuracy of the proposed model, laboratory tests were conducted to evaluate against the predicted results. The results show that the stress-strain relationships of saturated clays can be well described by the proposed model.

Experimental Study on Shear Strength Considering Initial Void Ratio and Plasticity Index

2013 ◽  
Vol 405-408 ◽  
pp. 63-67
Author(s):  
Xing Chen Wang ◽  
Ri Qing Xu ◽  
Jian Feng Zhu
Keyword(s):  
Shear Strength ◽  
Void Ratio ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Deviatoric Stress ◽  
Plasticity Index ◽  
Test Results ◽  
Compression Tests ◽  
Functional Relationships ◽  
Initial Void Ratio

A series of drained triaxial compression tests under different conditions were performed to quantitatively study the influence of the initial void ratio and plasticity index on the shear strength of remolded saturated clays. The test results show that both the peak stress friction angle and peak deviatoric stress decrease with increasing initial void ratio and plasticity index of the soil under the same confining pressure; whereas, they increase with increasing confining pressure of the soil under the same initial void ratio and plasticity index. A new synthesized physical parameter λ, which simultaneously represent both the type and the condition of remolded saturated clays, is defined based on the test results in this work. The functional relationships among the parameters φd and peak deviatoric stress in Mohr-Coulomb equation and the parameter λ are established to develop a modified Mohr-Coulomb equation by considering physical properties of soil. In this equation, only two input parameters, i.e., λ and the confine pressure, are needed to predict the shear strength of the soil. In order to check the accuracy of the proposed equation, laboratory tests were conducted to evaluate against the predicted results. The results show that the peak shear strength of remolded saturated clays can be well described by the proposed equation. Key words: shear strength; Mohr-Coulomb equation; remolded saturated clays; initial void ratio; plasticity index.

Research on Hydraulic Conductivity of Coarse Sandstone under Triaxial Compression

2011 ◽  
Vol 94-96 ◽  
pp. 1146-1151 ◽  
Author(s):  
Guan Rong ◽  
Xiao Jiang Wang
Keyword(s):  
Hydraulic Conductivity ◽  
Circumferential Strain ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Test Results ◽  
Stress Strain ◽  
Deformation And Failure ◽  
Maximum Value ◽  
Strain Process ◽  
Peak Value

Permeability test for complete stress-strain process of coarse sandstone were carried out in triaxial test instrument. On the basis of test results, the influence of confining pressure and strain on the hydraulic conductivity was discussed. It is shown that in the complete stress-strain process, hydraulic conductivity changes in the law that presents the same character with the curve of stress-strain. The hydraulic conductivity reduces slightly with the increase of deviatoric stress in the stage of micro fracture compressing and elastic; In the elastoplastic stage, along with the expansion of new fractures, the hydraulic conductivity increases slowly at first and then reaches sharply to the maximum value after peak point; In the post-peak stage, the fracture which controls the hydraulic conductivity of coarse sandstone is compressed because of the confining pressure and the hydraulic conductivity decreases. During the process of deformation and failure, the hydraulic conductivity is more sensitive to the change of circumferential strain. With the increase of confining pressure, the increased value from initial to peak value and the decreased value from peak to residual value decreases.

scholarly journals Triaxial Testing of Geosynthetics Reinforced Tailings with Different Reinforced Layers

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1943
Author(s):  
Fu Yi ◽  
Changbo Du
Keyword(s):  
Triaxial Compression ◽  
Friction Angle ◽  
Confining Pressure ◽  
Test Results ◽  
Compression Tests ◽  
Strength Index ◽  
Stress Strain ◽  
High Confining Pressure ◽  
Zhang Model ◽  
Triaxial Compression Tests

To evaluate the shear properties of geotextile-reinforced tailings, triaxial compression tests were performed on geogrids and geotextiles with zero, one, two, and four reinforced layers. The stress–strain characteristics and reinforcement effects of the reinforced tailings with different layers were analyzed. According to the test results, the geogrid stress–strain curves show hardening characteristics, whereas the geotextile stress–strain curves have strain-softening properties. With more reinforced layers, the hardening or softening characteristics become more prominent. We demonstrate that the stress–strain curves of geogrids and geotextile reinforced tailings under different reinforced layers can be fitted by the Duncan–Zhang model, which indicates that the pseudo-cohesion of shear strength index increases linearly whereas the friction angle remains primarily unchanged with the increase in reinforced layers. In addition, we observed that, although the strength of the reinforced tailings increases substantially, the reinforcement effect is more significant at a low confining pressure than at a high confining pressure. On the contrary, the triaxial specimen strength decreases with the increase in the number of reinforced layers. Our findings can provide valuable input toward the design and application of reinforced engineering.

The Duncan-Chang Model Parameters for Municipal Solid Waste

2011 ◽  
Vol 48-49 ◽  
pp. 1235-1240
Author(s):  
Zhen Ying Zhang ◽  
Da Zhi Wu
Keyword(s):  
Theoretical Analysis ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Void Ratio ◽  
Practical Method ◽  
Model Parameters ◽  
Mechanical Parameters ◽  
Initial Void Ratio ◽  
The Relationship ◽  
Chang Model

By theoretical analysis and laboratory test, the model parameters of Duncan-Chang for municipal solid waste have been studied. To obtain the mechanical parameters, a new simple and practical method has been established. Research results show that the damage ratio is 0.6, parameter n is about 1.05, parameter F varies between 0 and 0.1, and parameter G varies between 0.3 and 0.4. Besides, the relationship between parameter k and the initial void ratio is linear, and the slope of the line is 5.0.

scholarly journals Proposed Model for Stress-strain Behavior of Fly Ash Concrete Under the Freezing and Thawing Cycles

2020 ◽  
Author(s):  
Ali Hemmati ◽  
Heydar Arab
Keyword(s):  
Fly Ash ◽  
Numerical Models ◽  
Test Results ◽  
Freezing And Thawing ◽  
Stress Strain ◽  
Strain Behavior ◽  
Fly Ash Concrete ◽  
Proposed Model ◽  
The Difference ◽  
Freezing And Thawing Cycles

Fly ash is a supplementary cement material using instead of Portland cement in concrete. Using this material concludes to less emission of greenhouse gas and less water demand of concrete. In this paper, an experimental investigation was carried out on compressive stress–strain behavior of three groups of concrete specimens with different water/cement ratios (0.45, 0.5 and 0.55), containing 0, 10, 20, 30 and 40 percent of fly ash (by weight), after subjecting to freezing and thawing cycles. 0, 45, 100 and 150 cycles of freezing and thawing were applied on these specimens according to ASTM C666 and the results presented. Numerical models for the stress–strain behavior of these frozen-thawed concrete were developed and compared with the available experimental data. Results show that the maximum compressive strength of these concrete specimens exposing cycles of freezing and thawing is gained by using about 10 % of fly ash. Moreover, there is a good agreement between the proposed models and test results and the difference is less than 5 %.

scholarly journals A Stress-Strain Model for Brick Prism under Uniaxial Compression

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Keun-Hyeok Yang ◽  
Yongjei Lee ◽  
Yong-Ha Hwang
Keyword(s):  
Strain Curve ◽  
Peak Stress ◽  
Test Results ◽  
Compression Tests ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Proposed Model ◽  
Relationship Model ◽  
Strain Relationship ◽  
Strain Model

This study proposes a simple and rational stress-strain relationship model applicable to brick masonry under compression. The brick prism compression tests were conducted with different mortar strengths and with constant brick strength. From the observation of the test results, shape of the stress-strain curve is assumed to be parabola. In developing the stress-strain model, the modulus of elasticity, the strain at peak stress, and the strain at 50% of the peak stress on the descending branch were formulated from regression analysis using test data. Numerical and statistical analyses were then performed to derive equations for the key parameter to determine the slopes at the ascending and descending branches of the stress-strain curve shape. The reliability of the proposed model was examined by comparisons with actual stress-strain curves obtained from the tests and the existing model. The proposed model in this study turned out to be more accurate and easier to handle than previous models so that it is expected to contribute towards the mathematical simplicity of analytical modeling.

Experimental Study on Parameters of Duncan-Chang Model for Cement-Soil

2013 ◽  
Vol 641-642 ◽  
pp. 403-409
Author(s):  
Cai Fu Qian ◽  
Xin Jiang Song ◽  
Jie Wu ◽  
Wei Li
Keyword(s):  
Experimental Study ◽  
Calculation Method ◽  
Confining Pressure ◽  
Elastic Theory ◽  
Triaxial Tests ◽  
Stress Strain ◽  
Pressure Decrease ◽  
Cement Soil ◽  
Nonlinear Elastic ◽  
Chang Model

The conventional triaxial tests for cement-soil show stronger soften characteristics of cement-soil under low confining pressure. The soften character is weaken as confining pressure decrease. For adopting Duncan-Chang hyperbola model to obtain parameters of cement-soil, the model cannot include the stress-strain soften characteristics of cement-soil, and must be discussed. The paper studies on parameters of Duncan-Chang model using generalized Hooke law and nonlinear elastic theory. The researches show the parameters of k and n are unrelated to soften characteristics of cement-soil; the relation of Rf and σ3 is given by the soften characteristics, Rf influence the soften process directly. The calculation method could be used in E-u model, and has good practical value.

A reexamination of the permeability index of clays

1993 ◽  
Vol 30 (1) ◽  
pp. 187-191 ◽  
Author(s):  
G. L. Sivakumar Babu ◽  
N. S. Pandian ◽  
T. S. Nagaraj
Keyword(s):  
Void Ratio ◽  
State Parameter ◽  
Paper Analysis ◽  
Liquid Limit ◽  
Test Results ◽  
Permeability Index ◽  
Initial Void Ratio ◽  
Generalized State ◽  
Marine Clays ◽  
Parameter Approach

The permeability index Ck, similar to the compression index, is the slope of the void ratio – coefficient of permeability relationship. Literature shows that, in general, for sensitive clays it can be related to initial void ratio by Ck = 0.5e0. The possibility of obtaining such a relationship for Cochin marine clays in terms of liquid limit void ratio is indicated in this paper. Analysis of permeability behaviour of Cochin marine clays and the test results available in published literature using generalized state parameter approach show that, in principle, these forms of equations for the permeability index are tenable, even though they were obtained based on experimental observation alone. Key words : permeability index, initial void ratio, void ratio at liquid limit, generalized state parameter approach.

scholarly journals Comparative Study in Method of Compaction by Consolidated Drained and Direct Shear Test

2020 ◽  
Vol 78 (2) ◽  
pp. 143-152
Author(s):  
Abdul Samad Abdul Rahman ◽  
N. Sidek ◽  
Juhaizad Ahmad ◽  
N. Hamzah ◽  
M. I. F. Rosli
Keyword(s):  
Shear Strength ◽  
Bearing Capacity ◽  
Triaxial Test ◽  
Direct Shear Test ◽  
Shear Test ◽  
Void Ratio ◽  
Direct Shear ◽  
Test Results ◽  
Stress Strain ◽  
Strain Behaviour

Soil compaction has been a common practice in the construction of highways, embankments, earth dams and other related structures where the condition of the soil is high in void ratio and therefore having a very low in bearing capacity. Therefore, the soil needs to be compacted in order to minimize the void ratio and in the same time would results in having a very high bearing capacity to sustain load. Nevertheless, only a few researches have been done to investigate the method of compaction using different energy on the behavior of shear strength by consolidated drained and direct shear test. In this research, the effect of different compaction in energy of 25 number of blows compared to 40 number of blows on the stress-strain behaviour of drained triaxial test has been done and findings of the data are to be compared with direct shear test. Results reveal that there is an increase in soil unit weight by using different energy in compaction with an increase of 5% from 1790 kg/m3 to 1880 kg/m3 for 25 and 40 number of blows respectively. However, the stress-strain behaviour of the specimens shows differently when compared between consolidated drained triaxial and direct shear test. The shear strength for direct shear-stress is at higher value compared to drained triaxial test. For drained triaxial test, results reveal that the effective friction angles are increase only about 1% from 37° to 38°. This is due to the soil particles rearranging itself with the different applied pressures thus eliminating the effects of different energy on the shear strength of the specimens. However, for direct shear test, the shear strength increases drastically from 29° to 32°. The increase of the shear strength is more likely influence by the soil particle arrangement due to the impact of the energy of the no of blows to the desired specimen.

Duncan-Chang Model Parameters and Normalized Behavior of the Huanggou Pumped Storage Power Station

2014 ◽  
Vol 1065-1069 ◽  
pp. 557-560
Author(s):  
Chun Tan ◽  
Ru Hui Huang ◽  
Yan Ping Li ◽  
Dong He Ma ◽  
Zhi Fa Ma ◽  
...  
Keyword(s):  
Shear Test ◽  
Dielectric Material ◽  
Model Parameters ◽  
Test Results ◽  
Normalization Factor ◽  
Power Station ◽  
Stress Strain ◽  
Strain Characteristic ◽  
Pumped Storage ◽  
Chang Model

In order to describe the stress-strain characteristic of the geotechnical dielectric material in the Huanggou pumped storage power station, using the samples taken from the construct site, the consolidation-drained shear test is carried out. Combined with Duncan-Chang model, the test results are analyzed to obtain the parameters of the model. Based on this, the Normalized Behavior is studied, and The results show that the normalized degree is highest when used (σ1-σ3)ult as normalization factor.

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