The Influence of Stress History on Stress Paths in Undrained Triaxial Tests on Clay

2009 ◽  
pp. 280-280-12 ◽  
Author(s):  
DJ Henkel ◽  
VA Sowa
Author(s):  
J. H. Atkinson ◽  
J. S. Evans ◽  
D. Richardson

AbstractSoil behaviour is stress history dependent and stress path dependent and soil parameters, particularly those for stress-strain behaviour, measured in conventional triaxial tests may not represent the behaviour of soil in many civil engineering works.To obtain more realistic parameters it may be necessary to conduct laboratory tests which more closely represent in situ conditions before and during construction.The paper describes equipment developed at The City University to carry out stress path tests simply and economically. A series of CU triaxial tests and stress path tests on reconstituted soil illustrate the dependence of measured soil parameters on stress history and stress path.


2012 ◽  
Vol 49 (2) ◽  
pp. 226-243 ◽  
Author(s):  
C.W.W. Ng ◽  
J. Xu

Although the small-strain shear modulus of saturated soils is known to be significantly affected by stress history, consisting of the overconsolidation ratio (OCR) and recent stress history, the effects of suction history on the small-strain shear modulus of unsaturated soils have rarely been reported. In this study, the effects of suction history, which refers to current suction ratio (CSR) and recent suction history, on both the very-small-strain shear modulus (G0) and shear modulus reduction curve of an unsaturated soil, are investigated by carrying out constant net mean stress compression triaxial tests with bender elements and local strain measurements. In addition, the effect of suction magnitude on G0 and the shear modulus reduction curve is also investigated. At a given suction, G0, elastic threshold strain (εe), and the rate of shear modulus reduction all increase with CSR. On the other hand, the effect of recent suction history on G0 is not significant. The effect of direction of recent suction path (θ) on the shear modulus reduction curve is not distinct. However, the magnitude of recent suction path (l) affects the shear modulus reduction curve significantly when θ = –90°.


2021 ◽  
Vol 147 ◽  
pp. 106779
Author(s):  
Zhehao Zhu ◽  
Feng Zhang ◽  
Qingyun Peng ◽  
Jean-Claude Dupla ◽  
Jean Canou ◽  
...  

Geotechnics ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 95-127
Author(s):  
António Viana da Fonseca ◽  
Diana Cordeiro ◽  
Fausto Molina-Gómez

The critical state theory is a robust conceptual framework for the characterisation of soil behaviour. In the laboratory, triaxial tests are used to assess the critical state locus. In the last decades, the equipment and testing procedures for soil characterisation, within the critical state framework, have advanced to obtain accurate and reliable results. This review paper summarises and describes a series of recommended laboratory procedures to assess the critical state locus in cohesionless soils. For this purpose, results obtained in the laboratory from different cohesionless soils and triaxial equipment configurations are compiled, analysed and discussed in detail. The procedures presented in this paper reinforce the use of triaxial cells with lubricated end platens and an embedded connection piston into the top-cap, together with the verification of the full saturation condition and the measurement end-of-test water content—preferable using the soil freezing technique. The experimental evidence and comparison between equipment configurations provide relevant insights about the laboratory procedures for obtaining a reliable characterisation of the critical state locus of cohesionless geomaterials. All the procedures recommended herein can be easily implemented in academic and commercial geotechnical laboratories.


2021 ◽  
Vol 13 (6) ◽  
pp. 3219
Author(s):  
Hynek Lahuta ◽  
Luis Andrade Pais

This contribution presents results from a series of compression and undrained triaxial tests to study the mechanical behavior of dump clay from the north of Bohemia. The use of these materials as a foundation for construction can’t be achieved without the adoption of some precautions. This comes from embankment, formed by digging the ground (altered claystone), up to the level of coal mining which is in a sub horizontal stratigraphic layer. A potential static liquefaction behavior was observed in undrained tests for high confinement stress. A structural collapse was noticed with the results obtained in the triaxial test. This collapse is characterized by an unexpected large decrease in deviator and mean effective stress. The soils formed have strength properties that are potentially dangerous. These concepts can improve the use of these kinds of soils in geotechnical engineering work. It continues and expands the results obtained in previous research, especially the future problematic use of these materials as the foundation soil for line or building structures.


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