A new approach to evaluate effective stress coefficient for strength in Kimachi sandstone

Dassanayake, Anjula Buddhika Nayomi; Fujii, Yoshiyuki; Fukuda, Daisuke; Kodama, Junichi

doi:10.1016/j.petrol.2015.04.015

Cited by 24 publications

(7 citation statements)

References 15 publications

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“…[]. However, the effective stress coefficient could be reduced by plastic/irreversible deformation during loading tests [e.g., Dassanayake et al ., ].…”

Section: Methodsmentioning

confidence: 99%

“…Biot's coefficient is usually determined using experimental data from the elastic region; Biot's coefficient for siliceous mudstone having L values as shown in Tables 1 and 2 is close to 1, based on the . However, the effective stress coefficient could be reduced by plastic/irreversible deformation during loading tests [e.g., Dassanayake et al, 2015].…”

Section: Calculation Of Effective Stressesmentioning

confidence: 99%

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Far‐field stress dependency of the failure mode of damage‐zone fractures in fault zones: Results from laboratory tests and field observations of siliceous mudstone

Ishii

2016

JGR Solid Earth

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The macroscopic failure mode (tensile/hybrid/shear) of damage‐zone fractures in fault zones may influence the hydrogeological properties of the fault zone. Application of the Griffith‐Coulomb failure criterion, combined with the simple assumption that failures are predominantly induced by an increase in differential stresses and/or a decrease in effective normal stresses resulting from stress concentrations generated at the asperities/tips of faults, suggests that (1) only tensile fractures propagate from faults when the effective mean stress is less than the rock tensile strength, (2) tensile/hybrid fractures form when the effective mean stress is less than twice the rock tensile strength, and (3) shear fractures can develop when the effective mean stress is more than twice the rock tensile strength, which suppresses the formation of tensile/hybrid fractures. In this study, thin slots were precut in siliceous mudstone samples and mechanical experiments were conducted under a range of effective confining pressures using core samples with and without precut slots. A comparison of fractures formed in the samples at different applied effective mean stresses gave results consistent with the proposed model. The correspondence of model predictions and results was also corroborated by observations of natural damage‐zone fractures observed in the field, in boreholes penetrating the same siliceous mudstone as used in the experiments. The results indicate that fault zones containing numerous tensile/hybrid fractures are limited to domains that have experienced effective mean stresses of less than twice the rock tensile strength.

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“…[]. However, the effective stress coefficient could be reduced by plastic/irreversible deformation during loading tests [e.g., Dassanayake et al ., ].…”

Section: Methodsmentioning

confidence: 99%

Section: Calculation Of Effective Stressesmentioning

confidence: 99%

Far‐field stress dependency of the failure mode of damage‐zone fractures in fault zones: Results from laboratory tests and field observations of siliceous mudstone

Ishii

2016

JGR Solid Earth

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“…It consists mostly of rock fragments of andesite and crystal fragments of plagioclase, pyroxene, hornblende, biotite, and quartz, as well as calcium carbonate, iron oxides, and matrix zeolite [18]. e porosity of Kimachi sandstone was found to be ranging from 19% to 22% as discussed by Dassanayake et al [19].…”

Section: Kaziwiziwi Rocksmentioning

confidence: 91%

Influences of Water Vapor on Roof Fall Accidents in Selected Underground Coal Mines in Malawi

Yasidu

Fujii

Kodama

et al. 2019

Advances in Civil Engineering

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To develop affordable countermeasures against the roof falls, the accident records of Mchenga Mine were investigated as the first step. Based on the accident records, it was found that roof falls occurred most in April and May. Humidity measurements were taken both in the underground mine and at surface, and humidity peak appeared in April. The accident occurrence and the underground humidity had a positive correlation in which no roof falls could be expected under a humidity of less than a certain value. Effect of humidity on the indirect tensile strength of the rock samples collected from the mine was investigated, and it showed that the indirect tensile strength decreased with humidity. The diffusion coefficient was measured for the rock samples collected from Mchenga Mine as well as from Kaziwiziwi Mine, and the migration of water vapor into rock mass in the roof was calculated for Mchenga case. It was clarified that the weakening of tensile strength was transmitted upward at several centimeters per day from the immediate roof. This could explain the slight difference of the accident peak in April and May from the humidity peak in April. Introducing fresh and dry outside air, if possible, will not only improve the working environment but also contribute to a decrease in roof falls.

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“…Based on the data shown in Dassanayake et al (2015), Biot's effective stress coefficient for Kimachi sandstone is given as follows:…”

Section: Triaxial Cyclic Loading For Triaxially Preloaded Specimensmentioning

confidence: 99%

Tangent modulus method – An original method to measure in-situ rock stress

Fujii

Makasi

Kodama

et al. 2018

Tunnelling and Underground Space Technology

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This paper proposed Tangent Modulus Method (TMM) which is an improved oriented core method to determine in-situ rock stresses. In this approach, the cylindrical specimens prepared along different directions from thick core samples were uniaxially compressed twice to a given stress level. The stress value of the bending point in the first loading cycle of the stress-tangent modulus curve is considered as the normal component of the in-situ rock stress along the drilled direction of the specimen. Four types of rocks from soft porous tuff and sandstone to hard crystalline granite was investigated to evaluate the potential of this method. The effects of changes in strain rate, temperature, water content, confining and pore pressure, and stresses larger than the preload on the stress value of the bending point were experimentally investigated on preload specimens to investigate their influence on TMM.Comparison of the stress measurement results by TMM and an overcoring method at AK tunnel in Hokkaido,Japan was also performed to validate the TMM.

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A new approach to evaluate effective stress coefficient for strength in Kimachi sandstone

Cited by 24 publications

References 15 publications

Far‐field stress dependency of the failure mode of damage‐zone fractures in fault zones: Results from laboratory tests and field observations of siliceous mudstone

Far‐field stress dependency of the failure mode of damage‐zone fractures in fault zones: Results from laboratory tests and field observations of siliceous mudstone

Influences of Water Vapor on Roof Fall Accidents in Selected Underground Coal Mines in Malawi

Tangent modulus method – An original method to measure in-situ rock stress

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