Measurement of soil stiffness in the triaxial apparatus

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Mostafa A. Ismail ◽  
Yasser E. Ibrahim

Local measurement of deformations of a soil specimen has become inevitable for accurate determination of soil stiffness in triaxial tests. Although there are now many devices that can be used to perform this task, each has its own advantages and limitations that render development of new devices with better desirable features. This paper presents an innovative device called spring deformation gauge (SDG) that has many advantages over many of the existing devices and can be readily manufactured in both research and commercial laboratories. The device is based on using a highly flexible, yet very strong metal strip of spring steel secured between two stiff, stainless steel L-shaped legs; the spring strip is provided with four strain gauges. With this arrangement, local deformation of a specimen is transferred into significant bending in the metal strip and elongation or shortening of the strain gauges. In addition to being very cost effective, the SDG is characterized by the ability to control both range and resolution of measured deformation, its linear output, and a clever pinning mechanism that protects it from being damaged when it goes out of range. Success of the SDG was demonstrated in a true K0 test on carbonate sand.


Géotechnique ◽  
1985 ◽  
Vol 35 (3) ◽  
pp. 378-382 ◽  
Author(s):  
R. J. Jardine ◽  
N. J. Symes ◽  
J. B. Burland

2019 ◽  
Vol 28 (3) ◽  
pp. 405-416
Author(s):  
Zdzisław Skutnik ◽  
Marcin Biliniak ◽  
Wojciech Sas ◽  
Emil Soból

The paper presents an evaluation of the influence of the degree of saturation of soil with water on its stiffness in the range of small deformations. Appropriate analysis of the interaction of the building structure with the subsoil carried out with the use of numerical methods requires the knowledge of parameters, in particular stiffness characteristics in the range of deformations corresponding to the actual conditions of the structure’s work. Usually the deformations of the subsoil caused by the structure do not exceed 10–3, therefore it is particularly important for the geotechnical engineer to determine the soil stiffness in the range of deformations 10–5–10–3. In order to determine the stiffness characteristics of cohesive subsoil, a triaxial compression apparatus equipped with piezoelectric elements of bender type was used, enabling the measurement of the transverse wave velocity inside the sample. The base of the described triaxial apparatus is equipped with high-pressure air entry ceramics (HAEV), which allowed to use the technique of “axis translation” to perform tests for variable (controlled) degree of saturation of the soil sample with water. In the literature, the degree of saturation (Sr) and soil moisture are mentioned as one of many factors which, apart from physical properties, values of effective stresses, voids index, stress history and others, infl uence the velocity of wave propagation in the ground. The publication describes the methodology of research and presents the results of own research.


Author(s):  
Mirosław J. Lipiński ◽  
Małgorzata K. Wdowska

Abstract The paper concerns laboratory methods for determination of soil stiffness. Major criterion for selection of analysed equipment is range of strain in which stiffness can be reliably determined. Substantially, various configurations of triaxial apparatus are referred to i.e. with standard cell and with the modified one. Additional system for internal measurement of strain is described and rational (based on test results) for use of it is presented. As to shear wave velocity measurement as a mean to obtain initial stiffness, requirements for proper measurement and interpretation was given. Finally, an approach to determine Poisson’s ratio on the basis of combined results of cyclic triaxial and resonant column tests was presented.


Géotechnique ◽  
1984 ◽  
Vol 34 (3) ◽  
pp. 323-340 ◽  
Author(s):  
R. J. Jardine ◽  
M. J. Symes ◽  
J. B. Burland

2019 ◽  
Vol 92 ◽  
pp. 02002
Author(s):  
Marcin Witowski

The requirement for implementing local measurements at small strains is well known. Without this type of measurement, it is not possible to accurately identify the soil stiffness characteristics over the entire stiffness degradation curve. The paper presents the results of the use of new sensor based on miniature magnetic encoders for axial and radial deformation measurements in triaxial soil test. Presented results include two types of measurement techniques for radial direction and one for axial deformation.


2021 ◽  
Vol 144 ◽  
pp. 106707
Author(s):  
Zhehao Zhu ◽  
Feng Zhang ◽  
Qingyun Peng ◽  
Baptiste Chabot ◽  
Jean-Claude Dupla ◽  
...  

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