Nonlinear Anisotropic Stress-Strain-Strength Behavior of Soils

2009 ◽  
pp. 431-431-25
Author(s):  
JH Prevost
SPE Journal ◽  
2020 ◽  
Vol 25 (05) ◽  
pp. 2582-2600
Author(s):  
Syed Shabbar Raza ◽  
Victor Rudolph ◽  
Tom Rufford ◽  
Zhongwei Chen

Summary A novel, simple, economical, and time-effective method to estimate the anisotropic permeability of coal is presented in this paper. This method estimates the coal’s anisotropic permeability by avoiding the tedious experimentation using triaxial permeameter or history-matching exercises. This method calculates the absolute magnitude of the permeability of the sample. In this regard, it is unlike other analytical permeability models, such as given by Palmer and Mansoori (1998) and Shi and Durucan (2014), that only calculate the permeability ratio (k/k0). The motivation is to find a method by which the permeability of the coal may be determined with reasonable accuracy by using only two easy measurements: mercury intrusion porosimetry (MIP) and anisotropic stress-strain (σ-ɛ) measurement. The main blocks of the method are based on cleat size that is obtained from MIP and randomly allocated to form flow channels/cleats through the coal; these cleats form parallel paths in the orthogonal face and butt cleat directions that provide the permeability; and the cleat width (b) is stress dependent. This method is further validated by comparing with the experimentally measured stress-dependent permeability of Surat Basin (Australia) coal and German coal in face cleat and butt cleat directions.


2020 ◽  
Vol 259 ◽  
pp. 119706
Author(s):  
Shan Feng ◽  
Weibiao Wang ◽  
Kai Hu ◽  
Kaare Höeg

2019 ◽  
Vol 11 (36) ◽  
pp. 33323-33335 ◽  
Author(s):  
Dinara Zhalmuratova ◽  
Thanh-Giang La ◽  
Katherine Ting-Ting Yu ◽  
Alexander R. A. Szojka ◽  
Stephen H. J. Andrews ◽  
...  

2005 ◽  
Vol 42 (2) ◽  
pp. 459-474 ◽  
Author(s):  
Marika Santagata ◽  
John T Germaine

The paper presents the results of an experimental investigation of sampling disturbance in cohesive soils through single-element triaxial tests on resedimented Boston blue clay (RBBC). The first part of the paper discusses the effect of the overconsolidation ratio (OCR) (1–8) of the soil on postdisturbance compression and undrained shear behavior. The results demonstrate that sensitivity to disturbance decreases markedly with OCR. It is also found that for the medium-sensitivity soil tested, the estimate of the preconsolidation pressure is not significantly affected by OCR. The second part of the paper discusses laboratory reconsolidation procedures. For OCR1 RBBC, the recompression method is not effective in recovering the stress–strain behavior of the soil and, for greater disturbance, provides an increasingly unsafe estimate of the strength. For OCR4, provided the reconsolidation path reproduces the path that occurred in the field, this procedure succeeds in recovering the intact stress–strain–strength behavior of the soil. SHANSEP reconsolidation was investigated for normally consolidated RBBC only. For modest levels of disturbance, this is an effective means of evaluating both the stress–strain and the strength behavior of the soil. For greater levels of disturbance, the stress–strain behavior is not fully recovered, but the method continues to provide conservative estimates of the undrained strength.Key words: sampling disturbance, clays, overconsolidation ratio, undrained strength, recompression, SHANSEP.


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