Author: L. T. Shao Publisher: ISBN: Category : Deformation distribution Languages : en Pages : 15
Book Description
A digital image technique was developed and used to measure the deformation distribution over the entire surface of soil specimens in triaxial tests. The measured deformation process shows that the specimen apparently exhibits three states during the test, i.e., pre-failure, in-failure, and post-failure, in correspondence to the different features of its deformation. The deformation feature in each state is then analyzed by the displacement and strain contours. Additionally, the stress level, S, is calculated to determine whether the soil is in failure at a point (representative element volume (REV)) on the surface of the specimen. Next, the failure zone, namely the shear band, was considered to be enveloped by the curve defined by S = 1 on the stress-level contour map. The stress level is calculated based on the strain, Young's modulus and Poisson's ratio. According to analysis of the deformation feature and the failure process, we recognized the following properties: (i) the deformation of the specimen was approximately uniform in the pre-failure state; (ii) failure occurred from a point and developed gradually until the shear band cleaves the specimen; (iii) in the post-failure state, deformation was exclusively due to the blocks of the specimen sliding along the shear band; (iv) the deformation feature in the shear band was quite different from that outside the shear band. In conclusion, the stress-strain curve of the specimen revealed a structural response, not an elementary response, especially in the in-failure and post-failure states, in which the deformation features of different corner points were different, and the observed deformation for the entire specimen may be the combination of local deformations. Therefore, it is not appropriate to build the constitutive model for soil according to the stress-strain curves of the entire deformation process and to take the specimen as a uniform element in the entire process.
Author: John Q. Ehrgott Publisher: ISBN: Category : Shear strength of soils Languages : en Pages : 88
Book Description
The formulation of constitutive relations for use in computerized analyses of free-field ground shock phenomena is based primarily on laboratory-determined material properties. These properties, as described by stress-strain relations, are not directly determined in the laboratory, but are derived through interpretation of load and deformation data measured by the experimenter. Throughout this paper, one laboratory test, the triaxial shear test, is used to illustrate the extent of interpretation required on raw data and the influence of this interpretation on recommended constitutive properties. Various techniques that have been developed to obtain stress-strain data from the triaxial test are reviewed along with current advances in measurement systems. Typical raw data are presented and calculations of axial, lateral, and volumetric strains are made based on a variety of empirical and theoretical approaches. (Author).
Author: Robert T. Donaghe Publisher: ASTM International ISBN: 0803109830 Category : Anisotropy Languages : en Pages : 896
Book Description
"Although the triaxial compression test is presently the most widely used procedure for determining strength and stress-deformation properties of soils, there have been no books published on triaxial testing since the 1962 second edition of the landmark work The Measurement of Soil Properties in the Triaxial Test by Bishop and Henkel. It is apparent there is a need to document advances made in triaxial testing since publication of Bishop and Henkel's book and to examine the current state of the art in a forum devoted solely to triaxial testing. Because of increasing versatility brought about by recent developments in testing techniques and equipment, it is also important that the geotechnical profession be provided with an up-to-date awareness of potential uses for the triaxial test."--Overview.
Author: Poul V. Lade Publisher: John Wiley & Sons ISBN: 1119106591 Category : Technology & Engineering Languages : en Pages : 424
Book Description
Triaxial Testing of Soils explains how to carry out triaxial tests to demonstrate the effects of soil behaviour on engineering designs. An authoritative and comprehensive manual, it reflects current best practice and instrumentation.References are made throughout to easily accessible articles in the literature and the books focus is on how to obtain high quality experimental results.
Author: J. Paul Guyer, P.E., R.A. Publisher: Guyer Partners ISBN: Category : Technology & Engineering Languages : en Pages : 57
Book Description
Introductory technical guidance for civil and geotechnical engineers interested in laboratory testing of soils. Here is what is discussed: 1. PRINCIPLES OF THE TRIAXIAL COMPRESSION TEST 2. TYPES OF TESTS 3. APPARATUS 4. PREPARATION OF SPECIMENS 5. Q TEST 6. Q TEST WITH BACK-PRESSURE SATURATION 7. R TEST 8. S TEST 9. POSSIBLE ERRORS.
Author: C. K. Januskevicius Publisher: ISBN: Category : Measuring instruments Languages : en Pages : 18
Book Description
Stresses and strains were measured in triaxial specimens of dry sand under slow and dynamic rates of loading. Stress gages employing piezoelectric transducers were found to be sensitive to initial placement conditions, changes in the modulus-of-deformation of the surrounding soil, and lateral deformations of triaxial specimens approaching failure. Reliable stress measurements in triaxial tests below the critical lateral deformation values were made using calibration data of small triaxial specimens approximating the stress-strain relationship of actual tests. Strains were measured with mechanically uncoupled strain-sensing elements operating on the transformer principle. Strains were found to vary through the length of the standard specimens. In special frictionless end specimens, gage-measured stresses and strains were found to be the same as the average stresses and overall strains. At strain rates of 11 in/sec or higher, stress waves were produced with peak stresses a function of the rate of loading.
Author: A. R. Bhandari Publisher: ISBN: Category : Deformation Languages : en Pages : 18
Book Description
This paper describes the development of a new digital image-based deformation measurement system for triaxial tests on soils. Three digital cameras placed on radii at intervals of 120° viewed on plan outside a transparent triaxial cell were used to capture images of a deforming cylindrical soil specimen at various instants. A digital image correlation program was written to analyze the captured images, using ray tracing to take account of image distortion due to refraction at the interfaces between the cell fluid, the cell wall, and the atmosphere. The technique is validated with reference to a sand specimen tested in drained triaxial compression. Typical implementations of the system to study surface deformation characteristics (e.g., barreling, onset of localization, and shear band evolution) of deforming soil specimens are illustrated.
Author: L. T. Shao
Author: John Q. Ehrgott
Author: Robert T. Donaghe
Author: Poul V. Lade
Author: M. W. C. Emerson
Author: R. H. Prysock
Author: J. Paul Guyer, P.E., R.A.
Author: Alan Wilfred Bishop
Author: C. K. Januskevicius
Author: A. R. Bhandari