A Method for Adjusting Strain-Rates to Obtain Pore Pressure Measurements in Triaxial Shear Tests

2009 ◽  
pp. 62-62-16
Author(s):  
Willard Ellis ◽  
W. G. Holtz
Keyword(s):  
Pore Pressure ◽  
Strain Rates ◽  
Pressure Measurements ◽  
Shear Tests

scholarly journals Consolidated and Undrained Ring Shear Tests on the Sliding Surface of the Hsien-du-shan Landslide in Taiwan

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Hung-Ming Lin ◽  
Jian-Hong Wu ◽  
Erik Sunarya
Keyword(s):  
Pore Pressure ◽  
Rock Avalanche ◽  
Excess Pore Pressure ◽  
High Water Content ◽  
Sliding Surface ◽  
Shear Tests ◽  
Typhoon Morakot ◽  
Ring Shear ◽  
Ring Shear Tests ◽  
Excess Pore

A new consolidated undrained ring shear test capable of measuring the pore pressures is presented to investigate the initiation mechanism of the Hsien-du-shan rock avalanche, triggered by Typhoon Morakot, in southern Taiwan. The postpeak state of the landslide surface between the Tangenshan sandstone and the remolded landslide gouge is discussed to address the unstable geomorphological precursors observed before the landslide occurred. Experimental results show that the internal friction angle of the high water content sliding surface in the total stress state, between 25.3 and 26.1°, clarifies the reason of the stable slope prior to Typhoon Morakot. In addition, during the ring shear tests, it is observed that the excess pore pressure is generated by the shear contractions of the sliding surface. The remolded landslide gouge, sheared under the high normal stress, rendered results associated with high shear strength, small shear contraction, low hydraulic conductivity, and continuous excess pore pressure. The excess pore pressure feedback at the sliding surface may have accelerated the landslide.

Delineation of Active Faults, Nucleation Process and Pore Pressure Measurements at Koyna (India)

1997 ◽  
Vol 150 (3-4) ◽  
pp. 551-562 ◽  
Author(s):  
R. K Chadha ◽  
H. K Gupta ◽  
H. J Kumpel ◽  
P. Mandal ◽  
A. Nageswara Rao ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Active Faults ◽  
Pressure Measurements ◽  
Nucleation Process

Controlled displacement-rate in situ shear tests with pore pressure measurements

1985 ◽  
Vol 22 (1) ◽  
pp. 136-142 ◽  
Author(s):  
F. S. Shuri ◽  
D. D. Driscoll ◽  
S. J. Garner
Keyword(s):  
Shear Strength ◽  
Pore Pressure ◽  
Shear Zone ◽  
Large Scale ◽  
Bedding Plane ◽  
Western Canada ◽  
Shear Tests ◽  
Plane Shear ◽  
Clay Seam

Two large-scale in situ shear tests were conducted at a damsite in western Canada. The rock at the site is a Cretaceous shale containing a thin clay seam tentatively identified as a bedding-plane shear zone. The material in this seam is significantly weaker than the intact rock and influences the design of certain features of the dam and structures. In order to provide shear strength data for design, two large blocks of shale were sheared along the clay seam. These tests differed from conventional in situ shear tests in two significant ways: the rate of shear displacement was strictly controlled, and pore pressures (both positive and negative) in the shear zone were carefully monitored throughout the test. This note presents the material properties of the shear zone, describes the test equipment and techniques, and discusses the results obtained. Key words: shear strength, in situ testing, pore pressure, shale.

Permeability heterogeneity during sandstone compaction

2020 ◽  
Author(s):  
Philip Meredith ◽  
Nicolas Brantut ◽  
Patrick Baud
Keyword(s):  
Pore Pressure ◽  
Fluid Pressure ◽  
Initial Permeability ◽  
High Porosity ◽  
Pressure Measurements ◽  
Permeability Heterogeneity ◽  
Compaction Bands ◽  
Local Permeability ◽  
Spatially Distributed ◽  
Cylindrical Samples

<p>Compaction of porous sandstones is generally associated with a reduction in permeability. Depending on porosity and other microstructural characteristics, compaction may be diffuse or localised in bands. Compaction bands have been shown to act as barriers to fluid flow and therefore reduce permeability perpendicular to the band orentiation, and thus also introduce permeability anisotropy. Additionally, the localised nature of compaction bands should also introduce strong permeability heterogeneity. We present new experimental data on sandstone compaction combining acoustic emission monitoring and spatially distributed pore fluid pressure measurements, allowing us to establish how permeability heterogeneity develops during progressive compaction. Three sandstones were tested in the compactant regime: Locharbriggs sandstone, which is microstructurally heterogeneous with beds of higher and lower initial permeability; a low porosity (21%) Bleurville sandstone, which is microstructurally homogeneous and produces localised compaction bands; and a high porosity (24%) Bleurville sandstone, which is also homogeneous but produces compaction in a more diffuse pattern. At regular intervals during compactive deformation, a constant pore pressure difference was imposed at the upper and lower boundaries of the cylindrical samples, and steady-state flow allowed to become established. Following this, local pore pressure measurements were made at four locations, allowing us to derive estimates of the local permeability. In all samples, progressive compaction produced overall reductions in permeability. In addition, localised compaction also produced internal reorganisation of the permeability structure. Localised compaction bands caused local decreases in permeability, while more diffuse compaction produced a more homogeneous overall reduction in permeability.</p><p> </p>

Sign in / Sign up

Export Citation Format

Share Document