Axial-Torsional Testing System for Clay with Local Strain Measurement

1998 ◽  
Vol 1614 (1) ◽  
pp. 24-32
Author(s):  
Antonio E. Abrantes ◽  
Dayakar Penumadu
Keyword(s):  
Hollow Cylinder ◽  
Local Strain ◽  
Confining Pressure ◽  
Cohesive Soil ◽  
Local Deformation ◽  
Testing System ◽  
Test Results ◽  
Torsional Loading ◽  
Torsional Shear ◽  
Torsional Testing

An axial-torsional testing system, consisting of an MTS loading frame (9.8 kN/113 N-m) and TestWare-SX control, was developed for evaluating the multiaxial behavior of cohesive soil. The capabilities of the testing system include automated control of three axes (axial load/displacement, torque/rotation, and confining pressure) under static and dynamic conditions. Description of a custom-designed triaxial-torsional shear cell developed for this study is presented. Uniform and reproducible specimens (hollow and full cylinder) were obtained with a slurry consolidation technique. As an example for implementing software control, procedures are described for performing K o consolidation with an electropneumatic transducer in conjunction with an automated volume change device. An optical technique developed by the authors for measuring local strains under axial-torsional loading is also described. Initial test results associated with an undrained constant rate of strain axial and pure torsional shear testing on isotropically consolidated hollow-cylinder kaolin clay are presented. Aspects associated with repeatability are discussed. The test results are being used to evaluate the influence of the inclination of major principal stress on the shear strength and pore pressure behavior of isotropically consolidated clay. A qualitative discussion related to global versus local deformation patterns of hollow-cylinder specimens under axial and torsional loading is also presented.

A New Mesostructural Soft Tissue Testing System With Multiaxial Loading and Local Strain Measurement Capabilities

2004 ◽  
Author(s):  
Todd C. Doehring ◽  
Michael Kahelin ◽  
Ivan Vesely
Keyword(s):  
Feature Tracking ◽  
Soft Tissues ◽  
Local Strain ◽  
Local Deformation ◽  
Fiber Bundles ◽  
Testing System ◽  
Multiaxial Loading ◽  
Computer Controlled ◽  
Key Features ◽  
Measurement Capabilities

A new mesostructural testing system (MSTS) has been developed to measure structural and material properties of soft tissues at an intermediate, or “mesostructural” scale (i.e. ~ .01 to 10 mm). Key features of this new system are biaxial computer controlled loading and synchronized high-resolution microscopic digital imaging. The system uses a marker-less feature tracking algorithm to measure local deformation of mesostructures such as the fiber bundles of the aortic valve. Validation and bioengineering applications are described.

Framework and performance analysis of college English testing system based on data mining technology

2021 ◽  
pp. 1-11
Author(s):  
Liu Narengerile ◽  
Li Di ◽  
Keyword(s):  
Data Mining ◽  
Test System ◽  
Test Time ◽  
Testing System ◽  
Test Results ◽  
System Software ◽  
Examination System ◽  
Mining Technology ◽  
College English ◽  
And Performance

At present, the college English testing system has become an indispensable system in many universities. However, the English test system is not highly humanized due to problems such as unreasonable framework structure. This paper combines data mining technology to build a college English test framework. The college English test system software based on data mining mainly realizes the computer program to automatically generate test papers, set the test time to automatically judge the test takers’ test results, and give out results on the spot. The test takers log in to complete the test through the test system software. The examination system software solves the functions of printing test papers, arranging invigilation classrooms, invigilating teachers, invigilating process, collecting test papers, scoring and analyzing test papers in traditional examinations. Finally, this paper analyzes the performance of this paper through experimental research. The research results show that the system constructed in this paper has certain practical effects.

Promoting positive washforward through personalised test feedback and other benefits: Piloting a computer-based testing system

2020 ◽  
Vol 10 (1) ◽  
pp. 235-244
Author(s):  
Elena A. M. Gandini ◽  
Tania Horák
Keyword(s):  
Foreign Language ◽  
Testing System ◽  
Test Results ◽  
Test Feedback ◽  
Teachers And Students ◽  
Computer Based ◽  
Computer Based Testing ◽  
The University ◽  
Future Learning ◽  
Personalised Feedback

AbstractThis contribution reports on the developing and piloting of a computer-based version of the test of English as a foreign language produced by the University of Central Lancashire (UCLan), where it is currently used for the admission of international students and the subsequent evaluation of their language progress. Among other benefits, computer-based testing allows for better and individualised feedback to both teachers and students, and it can provide a more authentic test experience in light of the current digital shift that UK universities are undergoing. In particular, the qualitative improvement in the feedback available for test-takers and teachers was for us a crucial factor. Providing students with personalised feedback, that is, directly linked to their performance, has positive washforward, because it means we can guide their future learning, highlighting the areas they need to work on to improve their language skills and giving them suggestions on how to succeed in academia. Furthermore, explaining the meaning of test results in detail improves transparency and ultimately washback, as teachers can use the more accessible marking criteria, together with information on how their students performed, to review plans and schemes of work for subsequent courses.

scholarly journals Experimental Investigation of the Mechanical Behavior of NC Linings in consideration of Voids and Lining Thinning

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Zude Ding ◽  
Jincheng Wen ◽  
Xiafei Ji ◽  
Zhihua Ren ◽  
Sen Zhang
Keyword(s):  
Mechanical Behavior ◽  
Local Deformation ◽  
Scale Model ◽  
Test Results ◽  
Load Bearing Capacity ◽  
Normal Concrete ◽  
Failure Characteristics ◽  
Defect Position ◽  
Deformation Properties ◽  
Combined Defects

The presence of voids or lining thinning directly affects the mechanical behavior of linings, and these defects threaten the safety of tunnel operation. In this study, a series of 1/5-scale model tests was used to investigate the mechanical behavior of normal concrete (NC) linings in consideration of voids and combined defects. Test results showed that the void and combined defects substantially reduced the load-bearing capacity and deformation properties of the linings. The inelastic mechanical behavior of the linings was also significantly affected by the defects. The effects of lining defects located at the spandrel were slightly weaker than those of lining defects located at the crown. As the void size or degree of combined defects increased, the tensile strain at the location of the lining defects also increased. Therefore, the defect position of the linings was easily damaged. The defects considerably reduced the overall deformation of the linings but increased the local deformation. The distribution of lining cracks was concentrated at the defect position. In addition, different failure characteristics of the lining were observed due to the differences in defects.

scholarly journals Quantitative 3D imaging of partially saturated granular materials under uniaxial compression

2021 ◽  
Author(s):  
Marius Milatz ◽  
Nicole Hüsener ◽  
Edward Andò ◽  
Gioacchino Viggiani ◽  
Jürgen Grabe
Keyword(s):  
Granular Materials ◽  
Uniaxial Compression ◽  
Water Clusters ◽  
Local Strain ◽  
Confining Pressure ◽  
Mechanical Effect ◽  
Compression Tests ◽  
Initial Water ◽  
Interfacial Areas ◽  
Membrane Effects

AbstractGauging the mechanical effect of partial saturation in granular materials is experimentally challenging due to the very low suctions resulting from large pores. To this end, a uniaxial (zero radial stress) compression test may be preferable to a triaxial one where confining pressure and membrane effects may erase the contribution of this small suction; however, volume changes are challenging to measure. This work resolves this limitation by using X-ray imaging during in situ uniaxial compression tests on Hamburg Sand and glass beads at three different initial water contents, allowing a suction-dependent dilation to be brought to the light. The acquired tomography volumes also allow the development of air–water and solid–water interfacial areas, water clusters and local strain fields to be measured at the grain scale. These measurements are used to characterise pertinent micro-scale quantities during shearing and to relate them to the measured macroscopic response. The new and well-controlled data acquired during this experimental campaign are hopefully a useful contribution to the modelling efforts—to this end they are shared with the community.

Shear Modulus and Damping Ratio of Gravel Material

2011 ◽  
Vol 105-107 ◽  
pp. 1426-1432 ◽  
Author(s):  
De Gao Zou ◽  
Tao Gong ◽  
Jing Mao Liu ◽  
Xian Jing Kong
Keyword(s):  
Shear Modulus ◽  
Shear Strain ◽  
Strain Amplitude ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Dynamic Shear Modulus ◽  
Test Results ◽  
Dynamic Shear ◽  
Data Points ◽  
Shear Strain Amplitude

Two of the most important parameters in dynamic analysis involving soils are the dynamic shear modulus and the damping ratio. In this study, a series of tests were performed on gravels. For comparison, some other tests carried out by other researchers were also collected. The test results show that normalized shear modulus and damping ratio vary with the shear strain amplitude, (1) normalized shear modulus decreases with the increase of dynamic shear strain amplitude, and as the confining pressure increases, the test data points move from the low end toward the high end; (2) damping ratio increases with the increase of shear strain amplitude, damping ratio is dependent on confining pressure where an increase in confining pressure decreased damping ratio. According to the test results, a reference formula is proposed to evaluate the maximum dynamic shear modulus, the best-fit curve and standard deviation bounds for the range of data points are also proposed.

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.

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.

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