Discussion of “A Device for Lateral Strain Measurement in Triaxial Tests with Unsaturated Specimens” by Dimitrios Kolymbas and Wei Wu

1990 ◽  
Vol 13 (3) ◽  
pp. 263
Author(s):  
PC Knodel ◽  
S-CR Lo
Keyword(s):  
Strain Measurement ◽  
Triaxial Tests ◽  
Lateral Strain

scholarly journals The Significance of Local Lateral-Strain Measurement of Soil Specimens for a Wide Range of Strain

1994 ◽  
Vol 34 (2) ◽  
pp. 95-105 ◽  
Author(s):  
Satoru Shibuya ◽  
Choon-Sik Park ◽  
Fumio Tatsuoka ◽  
Fumihiro Abe ◽  
Supot Teachavorasinskun ◽  
...  
Keyword(s):  
Strain Measurement ◽  
Lateral Strain ◽  
Wide Range

New FBG-based Device for Measuring Small and Large Radial Strains in Triaxial Apparatus

2020 ◽  
Author(s):  
Wen-Bo Chen ◽  
Wei-Qiang Feng ◽  
Jian-Hua Yin ◽  
Jie-Qiong Qin
Keyword(s):  
Strain Measurement ◽  
Radial Strain ◽  
Small Deformation ◽  
Working Environment ◽  
Triaxial Tests ◽  
New Device ◽  
Vertical Strain ◽  
Triaxial Apparatus ◽  
Fbg Sensors ◽  
Validation Tests

In triaxial tests, it is of great importance to accurately measure the radial strain of a specimen. However, devices for radial strain measurement are relatively fewer than the ones for vertical strain measurement. In this study, a new measurement device based on fiber Bragg grating (FBG) was developed to determine the small and large radial strains of a soil specimen. The new device includes two yokes and two compass-type mechanisms, which are mounted on diametrically opposite sides of the specimen. Metal strips bonded with FBG sensors were chosen as sensing elements and installed at two ends of two legs of a compass-type mechanism so that the small deformation of the specimen can be amplified by a constant ratio to a more detectable value with a higher signal-noise ratio. Considering the temperature sensitivity of FBG and the real working environment, the new device was carefully calibrated underwater. Validation tests on an intact triaxial specimen demonstrated that the new device can work reliably and accurately under both static and cyclic loadings.

scholarly journals Mechanical Characteristics for Rocks under Different Paths and Unloading Rates under Confining Pressures

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Bing Dai ◽  
Guoyan Zhao ◽  
Longjun Dong ◽  
Chen Yang
Keyword(s):  
Mechanical Characteristics ◽  
Axial Strain ◽  
Initial Point ◽  
Strain Increment ◽  
Triaxial Tests ◽  
Lateral Strain ◽  
Dilatancy Angle ◽  
Peak Point ◽  
Confining Pressures ◽  
D Value

To investigate mechanical characteristics of rocks under different unloading conditions, triaxial tests are carried out with initial confining pressures of 10, 20, and 30 MPa and unloading rates of 0.05~1 MPa/s in three stress paths. Results show that the increment of axial strain is far less than that of the lateral strain. The unloading rates of confining pressures have less influence on variation of strain and lateral increment in path I. The variation of axial increment strain in the same time is slightly larger than the variation of lateral increment; D-value is influenced by unloading rates of confining pressures in path II. The variation of axial strain increment decreases firstly and then increases with the variation of confining pressures. The relation decreases and then increases with unloading rates increases in path III. The dilatancy angle decreases with initial confining pressures increases. The vary rates of dilatancy angle from initial point of dilatancy angle to peak point of dilatancy angle increase with the unloading rates of confining pressures. In the same rates, the vary rates of dilatancy angle from the initial point of the dilatancy angle to peak point of the dilatancy angle in path I are greater than those in path II.

scholarly journals A Nonlinear Constitutive Model for Disintegrated Carbonaceous Mudstone Based on Logarithmic Functions

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Xiang Qiu ◽  
Jinhong Li ◽  
Huangbin Jiang ◽  
Hongyuan Fu ◽  
Shun Yang
Keyword(s):  
Constitutive Model ◽  
Axial Strain ◽  
Confining Pressure ◽  
Deviatoric Stress ◽  
Triaxial Tests ◽  
Lateral Strain ◽  
Logarithmic Function ◽  
Stress Strain ◽  
Nonlinear Constitutive Model ◽  
Nonlinear Stress

To study the mechanical characteristics of the disintegrated carbonaceous mudstone (DCM), consolidated drained triaxial tests were conducted on the DCM with three degrees of compaction (i.e., 90%, 93%, and 96%). Then, the nonlinear constitutive model suitable for the DCM was established based on test results using a logarithmic function. The stress-strain characteristics of the DCM were analyzed. The results revealed that the axial strain of the DCM was positively correlated with the deviatoric stress and lateral strain. The slopes of deviatoric stress-axial strain curves decreased with the increase of axial strain and so did the slopes of the axial strain-volumetric strain curves. The strength of the DCM increased with the increase of the confining pressure and the degree of compaction. In addition, the axial strain induced by dilatancy was also positively correlated with the degree of compaction and the confining pressure. Furthermore, under triaxial loading conditions, the relationship between the stress and strain of the DCM can be expressed by a logarithmic function; based on this, a nonlinear constitutive model with ten material parameters was derived. In addition, the results of numerical tests using the model showed similar stress-strain characteristics of the DCM comparing with the triaxial tests. Hence, it indicated that the nonlinear constitutive model based on the logarithmic function can reflect the nonlinear stress-strain characteristics of the DCM.

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