Shear strength characteristics of statically compacted unsaturated kaolin

2008 ◽  
Vol 45 (7) ◽  
pp. 910-922 ◽  
Author(s):  
Won Taek Oh ◽  
Vinod K. Garga ◽  
Sai K. Vanapalli
Keyword(s):  
Shear Strength ◽  
Unsaturated Soil ◽  
Confining Pressure ◽  
Strength Characteristics ◽  
Test Results ◽  
Confined Compression ◽  
State Variable ◽  
Variable Approach ◽  
To Come ◽  
Undrained Loading

The shear strength characteristics of statically compacted unsaturated soil specimens of commercial kaolin (Ip = 15%) were determined using conventional triaxial shear testing apparatus extending total stress analysis. The testing program consists of two different types of confined compression shear strength tests on unsaturated soil specimens. In the first series of tests, the specimens were sheared immediately after the application of the confining pressure under undrained loading conditions. In the second series of tests, the specimens were first allowed to come to equilibrium with respect to volume change and suction value under the applied confining pressure and sheared at two different rates of strain. A psychrometer was used for measuring suction values. In addition, conventional consolidated undrained tests were also conducted on specimens that were saturated using the back pressure technique before shearing. Comparisons with respect to the shear strength behavior are provided for both saturated and unsaturated soil specimens. The shear strength contribution towards suction was determined from test results on unsaturated soil specimens extending state variable approach in terms of total stresses. Discussion is presented to understand the influence of the following factors (i) suction, (ii) confining pressure, and (iii) rate of strain on the shear strength.

A Change of Undrain Shear Strength of Soft Ground during Consolidation Process

2014 ◽  
Vol 513-517 ◽  
pp. 269-272
Author(s):  
Yeong Mog Park ◽  
Ik Joo Um ◽  
Norihiko Miura ◽  
Seung Cheol Baek
Keyword(s):  
Shear Strength ◽  
Soft Clay ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Test Results ◽  
Exponential Equation ◽  
Consolidation Process ◽  
Degree Of Consolidation ◽  
Clay Ground ◽  
Strength Increment

The purpose of this study is to investigate the undrain shear strength increment during consolidation process of soft clayey soils. Thirty kinds of laboratory triaxial tests have been performed using undisturbed and remolded Ariake clay samples with different degree of consolidation and 5 kinds of confining pressure. Test results show that well known linear equation proposed by Yamanouchi et al.(1982) is overestimated the strength of undisturbed soft clay ground in the process of consolidation. A new simple and reasonable exponential equation proposed in this paper.

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.

scholarly journals Effect of Geotextile Reinforcement on Shear Strength of Sandy Soil: Laboratory Study

2016 ◽  
Vol 38 (4) ◽  
pp. 3-13 ◽  
Author(s):  
Sidali Denine ◽  
Noureddine Della ◽  
Muhammed Rawaz Dlawar ◽  
Feia Sadok ◽  
Jean Canou ◽  
...  
Keyword(s):  
Shear Strength ◽  
Mechanical Behaviour ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Loose Sand ◽  
Test Results ◽  
Compression Tests ◽  
Confining Stress ◽  
Natural Sand ◽  
Confining Pressures

Abstract This paper presents results of a series of undrained monotonic compression tests on loose sand reinforced with geotextile mainly to study the effect of confining stress on the mechanical behaviour of geotextile reinforced sand. The triaxial tests were performed on reconstituted specimens of dry natural sand prepared at loose relative density (Dr = 30%) with and without geotextile layers and consolidated to three levels of confining pressures 50, 100 and 200 kPa, where different numbers and different arrangements of reinforcement layers were placed at different heights of the specimens (0, 1 and 2 layers). The behaviour of test specimens was presented and discussed. Test results showed that geotextile inclusion improves the mechanical behaviour of sand, a significant increase in the shear strength and cohesion value is obtained by adding up layers of reinforcement. Also, the results indicate that the strength ratio is more pronounced for samples which were subjected to low value of confining pressure. The obtained results reveal that high value of confining pressure can restrict the sand shear dilatancy and the more effect of reinforcement efficiently.

The shear strength of unsaturated soils

1978 ◽  
Vol 15 (3) ◽  
pp. 313-321 ◽  
Author(s):  
D. G. Fredlund ◽  
N. R. Morgenstern ◽  
R. A. Widger
Keyword(s):  
Shear Strength ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Research Literature ◽  
Test Results ◽  
State Variables ◽  
Limited Data ◽  
Laboratory Test Results

The shear strength of an unsaturated soil is written in terms of two independent stress state variables. One form of the shear strength equation is[Formula: see text]The transition from a saturated soil to an unsaturated soil is readily visible. A second form of the shear strength equation is[Formula: see text]Here the independent roles of changes in total stress σ and changes in pore-water pressure uw are easily visualized.Published research literature provides limited data. However, the data substantiate that the shear strength can be described by a planar surface of the forms proposed. A procedure is also outlined to evaluate the pertinent shear strength parameters from laboratory test results.

scholarly journals Effect of different moisture content and triaxial test methods on shear strength characteristics of loess

2019 ◽  
Vol 92 ◽  
pp. 07007 ◽  
Author(s):  
Yong Wang ◽  
Wanli Xie ◽  
Guohong Gao
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Water Content ◽  
Triaxial Test ◽  
Confining Pressure ◽  
Test Methods ◽  
Dominant Factor ◽  
Test Results ◽  
Strength Parameters ◽  
Deformation Parameters

This paper discussed the effect of moisture content on shear strength of loess during different confining pressure firstly. The variation law of deformation parameters, i.e. shear strength and secant modulus is analysed in detail. The results show that moisture content is the dominant factor of shear strength of Loess, with the increase of water content, the strength parameters levelled down, and there is a linear relationship between them to a certain extent. Compared with confining pressure, the effect of water content on shear strength is more obvious. In addition, triaxial test under different drainage conditions were carried out, namely, consolidated drained(CD) test and consolidated undrained(CU) test. Results indicate that the shear damage characteristics are similar during the two test methods.

scholarly journals New Progress in the Study of Intergranular Suction and Shear Strength of Unsaturated Soil

2016 ◽  
Vol 20 (1) ◽  
pp. 1-13
Author(s):  
Liansheng Tang ◽  
Haitao Sang ◽  
Liqun Jiang ◽  
Yinlei Sun ◽  
Muhammad Ashraf
Keyword(s):  
Shear Strength ◽  
Effective Stress ◽  
Unsaturated Soil ◽  
Soil Mechanics ◽  
Influence Factors ◽  
Confining Pressure ◽  
Soil Matrix ◽  
Soil Particles ◽  
Quantitative Calculation ◽  
Matrix Suction

<p>The suction between soil particles is the basis and core problem in the study of unsaturated soil. However, is the suction between soil particles just the matrix suction, which has been widely used since the discipline of unsaturated soil mechanics was established. In fact, the concept of matrix suction is from soil science and reflects the water- absorbing capacity of the soil. Matrix suction characterizes the interaction between soil particles and pore water rather than the interactions between soil particles, which are not in conformity with the principle of the effective stress of soils. The suction of unsaturated soil, in essence, is the intergranular suction composed of absorbed suction and structural suction. In this paper, first, the basic concepts of absorbed suction and structural suction were briefly introduced. Then, with soil mechanics, powder science, crystal chemistry, granular material mechanics and other related disciplines of knowledge for reference, the quantitative calculation formulas were theoretically deduced for the absorbed suction for equal-sized and unequal-sized unsaturated soil particles with arbitrary packing and the variable structural suction for equal-sized unsaturated soil particles with arbitrary packing and unequal-sized unsaturated soil particles with close tetrahedral packing. The factors that influence these equations were discussed. Then, the shear strength theory of unsaturated soil was established based on the theory of intergranular suction through the analysis of the effective stress principle of unsaturated soil. This study demonstrates that the shear strength of unsaturated soil consists of three parts: the effective, cohesive force, the additional strength caused by external loads and the strength caused by intergranular suction. The contribution of the three parts to the shear strength of unsaturated soil depends on the following influence factors: soil type, confining pressure, water content and density. Therefore, these factors must be comprehensively considered when determining the strength of unsaturated soil.</p>

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