Granular Material Radial Deformation Measurements with a Circumferential Extensometer in Repeated Load Triaxial Testing

1998 ◽  
Vol 1614 (1) ◽  
pp. 61-69 ◽  
Author(s):  
Erol Tutumluer ◽  
Navneet Garg ◽  
Marshall R. Thompson
Keyword(s):  
Granular Material ◽  
Material Behavior ◽  
Measuring System ◽  
Triaxial Testing ◽  
Radial Deformation ◽  
Nonlinear Stress ◽  
Wheel Loading ◽  
Repeated Load ◽  
Stress Dependent ◽  
Repeated Load Triaxial

Determination of both axial and radial specimen strains in a repeated load triaxial test is essential for properly characterizing the directional dependency of resilient granular material behavior. Radial deformation measurement is not yet included in the standard AASHTO test procedure. The method of measuring radial strains adopted in this study emphasizes the use of a contact-type specimen instrumentation technique with a circumferential chain extensometer. The circumferential extensometer was successfully used in repeated load triaxial testing to measure radial strains of three aggregate samples with different material types and properties. The accuracy of the measuring system was within 10−5 (in strains) when the smallest strains recorded were on the order of 10−4. Nonlinear stress-dependent models for properly characterizing the anisotropic granular material stiffnesses were developed from measured axial and radial strains. The vertical/horizontal stiffness ratios in the triaxial sample consistently increased with increasing principal stress ratios, which often occurs in pavements under wheel loading. In general, the repeatability in radial strain measurements was deemed to be satisfactory and more reliable strains were measured at low confining pressures.

A technique for measuring radial deformation during repeated load triaxial testing

1978 ◽  
Vol 15 (3) ◽  
pp. 426-429 ◽  
Author(s):  
David M. Cole
Keyword(s):  
Test Data ◽  
Poisson’S Ratio ◽  
Operating Principle ◽  
Poisson's Ratio ◽  
Triaxial Tests ◽  
Triaxial Testing ◽  
Radial Deformation ◽  
Repeated Load ◽  
Displacement Transducers ◽  
Repeated Load Triaxial

A system of non-contacting displacement transducers has been used to record radial deformation in repeated load triaxial tests. Operating principle, system capabilities, and installation technique are discussed. Results of tests on clay and silt subgrade materials are presented and Poisson's ratio is calculated directly from test data.

European Research into Granular Material for Pavement Bases and Subbases

2000 ◽  
Vol 1721 (1) ◽  
pp. 91-99 ◽  
Author(s):  
Andrew R. Dawson ◽  
Michael J. Mundy ◽  
Matti Huhtala
Keyword(s):  
Granular Material ◽  
State Of The Art ◽  
The State ◽  
Material Behavior ◽  
European Research ◽  
Repeated Load Triaxial Test ◽  
In Situ Conditions ◽  
Repeated Load ◽  
Repeated Load Triaxial

Two transnational European research projects in the area of granular materials for road pavements are described. The results are used to illustrate the state of practice as compared to the state of the art and are placed within the setting of a broad picture of national research within Europe. Discussed are the direction of European research, its implementation, those areas that will continue to be problematic, and the findings and strategies that suggest better-practice for non-European users. The use of the repeated-load triaxial test is shown to be an important aspect. Although the test is shown to have limitations for practical purposes, it illustrates the nature of material behavior that may be expected in situ. It is shown that a fundamental engineering understanding has been applied to granular material pavement layer technology but that there remain issues of in situ assessment, analytical methods, and variability of in situ conditions that hinder full application of current understanding.

Geogrid Stabilization of Unbound Aggregates Evaluated Through Bender Element Shear Wave Measurement in Repeated Load Triaxial Testing

2020 ◽  
Vol 2674 (3) ◽  
pp. 113-125
Author(s):  
Mingu Kang ◽  
Joon Han Kim ◽  
Issam I. A. Qamhia ◽  
Erol Tutumluer ◽  
Mark H. Wayne
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Resilient Modulus ◽  
Triaxial Tests ◽  
Triaxial Testing ◽  
Bender Element ◽  
Wave Measurement ◽  
Repeated Load ◽  
Repeated Load Triaxial

This paper describes the use of the bender element (BE) shear wave measurement technology for quantifying the effectiveness of geogrid stabilization of unbound aggregate materials with improved mechanical properties from repeated load triaxial testing. Crushed stone aggregate specimens were prepared with three different gradations, that is, upper bound (UB), mid-range engineered (ENG), and lower bound, according to the dense graded base course gradation specification in Illinois. The specimens were compacted at modified Proctor maximum dry densities and optimum moisture contents. Two geogrids with different triaxial aperture sizes were placed at specimen mid-height, and unstabilized specimens with no geogrid were also prepared for comparison. To measure shear wave velocity, three BE pairs were placed at different heights above geogrid. Repeated load triaxial tests were conducted following the AASHTO T307 standard resilient modulus test procedure, while shear wave velocity was measured from the installed BE pairs. After initial specimen conditioning, and at low, intermediate, and high applied stress states, both the resilient moduli and accumulated permanent strains were determined to relate to the geogrid local stiffening effects in the specimens quantified by the measured shear wave velocities. The resilient modulus and shear wave velocity trends exhibited a directly proportional relationship, whereas permanent strain and shear wave velocity values were inversely related. The enhancement ratios calculated for the geogrid stabilized over the unstabilized specimens showed significant improvements in mechanical behavior for the UB and ENG gradations, and a maximum enhancement was achieved for the engineered gradation specimens stabilized with the smaller aperture geogrid.

Repeated Load Triaxial Testing of Frozen and Thawed Soils

1985 ◽  
Vol 8 (4) ◽  
pp. 166
Author(s):  
VP Drnevich ◽  
DM Cole ◽  
G Durell ◽  
E Chamberlain
Keyword(s):  
Triaxial Testing ◽  
Repeated Load ◽  
Repeated Load Triaxial
Sign in / Sign up

Export Citation Format

Share Document