scholarly journals Sample Disturbance Effects on Undrained Shear Strengths—Study from Takuhoku Site, Sapporo—

2011 ◽  
Vol 51 (2) ◽  
pp. 203-213 ◽  
Author(s):  
Vuthy Horng ◽  
Hiroyuki Tanaka ◽  
Hiroshi Hirabayashi ◽  
Ryouzo Tomita
Keyword(s):  
Disturbance Effects ◽  
Sample Disturbance ◽  
Undrained Shear

scholarly journals A Method for Correcting Undrained Shear Strength for Sample Disturbance

1985 ◽  
Vol 25 (1) ◽  
pp. 52-64 ◽  
Author(s):  
Akio Nakase ◽  
Osamu Kusakabe ◽  
Hiroshi Nomura
Keyword(s):  
Shear Strength ◽  
Undrained Shear Strength ◽  
Sample Disturbance ◽  
Undrained Shear

scholarly journals Effect of sample disturbance on triaxial and oedometer behaviour of a stiff and heavily overconsolidated clay

2014 ◽  
Vol 51 (8) ◽  
pp. 896-910 ◽  
Author(s):  
Toralv Berre
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
In Situ Stress ◽  
Undrained Shear Strength ◽  
Stress Strain ◽  
Effective Stresses ◽  
Sample Disturbance ◽  
Oedometer Tests ◽  
Undrained Shear

The tests in this investigation were performed on a natural soft clay with plasticity index around 32%, which was K0 consolidated to a vertical stress of 2942 kPa and then K0 unloaded to a vertical stress of 74 kPa (i.e., to the “in situ” stress). The specimens so created were disturbed in various ways to study the effect of sample disturbance on the stress–strain relationships during undrained shearing and during drained K0 loading (i.e., K0 triaxial and oedometer tests). The results for two testing alternatives may be summarized as follows. Alternative 1: Allow the specimen to swell at the correct in situ effective stresses, but accept an initial water content that is higher than the in situ value. This alternative was found to give the best stress–strain relationships around the in situ effective stresses for undrained triaxial tests, but with undrained shear strength values up to about 20% too low, due to the swelling taking place during consolidation to the in situ effective stresses. Alternative 2: Prevent swelling by starting the test at effective stresses that are higher than the in situ stresses, but with a water content that is closer to the in situ value than if alternative 1 is chosen. Using only isotropic stresses prior to shearing, this alternative was found to give better undrained shear strength values (although up to about 14% too high) but strain values much too small around the in situ effective stresses. For oedometer tests, only alternative 2 was investigated. Also, for these tests, the strains around the in situ stress were too small, but preconsolidation stresses estimated from stress–strain curves were typically only around 60% of the true value.

Sample Disturbance Effects in Silt

2017 ◽  
Vol 143 (9) ◽  
pp. 04017061 ◽  
Author(s):  
Roselyn Carroll ◽  
Michael Long
Keyword(s):  
Disturbance Effects ◽  
Sample Disturbance

Dissipated strain energy method for determining preconsolidation pressure

2004 ◽  
Vol 41 (4) ◽  
pp. 760-768 ◽  
Author(s):  
L B Wang ◽  
J D Frost
Keyword(s):  
Elastic Deformation ◽  
Energy Method ◽  
Strain Energy ◽  
Irreversible Process ◽  
New Method ◽  
Stress Space ◽  
Disturbance Effects ◽  
Preconsolidation Pressure ◽  
Sample Disturbance ◽  
Strain Energy Method

The dissipated strain energy method (DSEM), a new method for determining the preconsolidation pressure, is presented in this paper. Compared with the energy method, the DSEM uses dissipated strain energy and the slope of the unloading–reloading cycle (in the strain energy – effective consolidation stress space) for the plot to minimize the sample disturbance effects and eliminate the effect of elastic deformation. Dissipated strain energy, in terms of micro mechanics, is directly related to the irreversible process of consolidation and can be supported by theories dealing with consolidation and compaction. The use of the unloading–reloading slope to simulate the elastic reloading for the recompression stage can minimize sample disturbance effects. Examples presented indicate that the proposed new method is less operator dependent than most of the existing methods.Key words: dissipated strain energy, preconsolidation pressure, consolidation, energy method, dissipated strain energy method.

scholarly journals An X-ray CT study of miniature clay sample preparation techniques

2019 ◽  
Vol 92 ◽  
pp. 01004
Author(s):  
Christopher Ibeh ◽  
Matteo Pedrotti ◽  
Alessandro Tarantino ◽  
Rebecca Lunn
Keyword(s):  
Sample Preparation ◽  
Shear Plane ◽  
Cohesive Soil ◽  
Image Resolution ◽  
Particle Orientation ◽  
X Ray ◽  
High Resolution Images ◽  
X Ray Computed ◽  
Sample Disturbance ◽  
Relationship Of

The quality and reliability of cohesive soil laboratory test data can be significantlyaffected by sample disturbance during sampling or sample preparation. Sample disturbance may affect key design and modelling parameters such as stiffness, preconsolidation stress, compressibility and undrained shear strength, and ultimately determine particle mobilization and shear plane development. The use of X-ray computed tomography (X-CT) in the study of soil is restricted by the inverse relationship of specimen size and obtainable image resolution. This has led to the testing of miniature specimen sizes which are far less than conventional laboratory sample size in a bid to obtain high resolution images and detailed particle-scale soil properties; however, these miniature soil specimens are more prone to sample disturbance. In this work 2% muscovite was mixed with speswhite kaolin clay as a strain marker for use in X-CT. The clay soil sample was prepared from slurry and either consolidated using an oedometer or a gypsum mould. Specimens obtained from a 7 mm tube sampler were compared to lathe trimmed specimens with a diameter (Ø) of 7 mm. Results from X-CT imaging were used to study the influence of sampler type on specimen disturbance, by analysing the muscovite particle orientation of the obtained 3D images. The results show that; for samples subjected to large consolidation stress (>200kpa) lathe trimmed specimens may be subject to lesser disturbance compared to tube sampled specimens.

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