Influences of Sedimentary History on the Mechanical Properties and Microscopic Structure Change of Horonobe Siliceous Rocks

Sanada, Hiroyuki; Niunoya, Sumio; Matsui, Hiroya; Fujii, Yoshiyuki

doi:10.2473/journalofmmij.125.521

Cited by 7 publications

(7 citation statements)

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“…Wakkanai siliceous mudstone is widely found around the Horonobe Underground Research Laboratory of the Japan Atomic Energy Agency. A large number of laboratory tests (but not uniaxial tension tests) have been conducted on this mudstone (Sanada et al 2009;Ishii et al 2011). As the in situ rock for water-saturated conditions, mudstone was adopted for the uniaxial tension test in this study.…”

Section: Sample Rockmentioning

confidence: 99%

“…Okubo and Fukui (1996) proposed a testing method to obtain a complete stress-strain curve from a rock specimen in uniaxial tension. In the test, a cylindrical specimen of the Table 1 Mechanical properties of rocks used in this study a (r dry -r wet )/r dry 9 100, where r dry and r wet are the strength in dry and wet conditions; b Okubo et al (1992); c Sanada et al (2009) same size as that for the uniaxial compression test was bonded with epoxy resin to the upper and lower platens of the test machine. The major advantage of this test is that the specimen accurately self-aligns with the resin and platens.…”

Section: Sample Rockmentioning

confidence: 99%

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Effect of Water on the Deformation and Failure of Rock in Uniaxial Tension

2014

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To design and construct underground structures, it is essential to understand the mechanical properties of rock in not only compression but also tension. It is well known that water is one of the important factors affecting the deformation and failure of rock. In this study, laboratory tests and numerical simulations were conducted to understand the effect of water on rock properties in uniaxial tension. In the experiments, a testing machine previously used for uniaxial tension tests in dry conditions was modified for tests in wet conditions. Using this machine, complete stress-strain curves from the pre-to postpeak regions of water-saturated specimens in uniaxial tension were obtained. The results for granite, tuff, and two types of andesite showed that the stress-strain curves in wet conditions have a lower initial slope and lower strength than those in dry conditions, and they are strongly nonlinear in the prepeak region. Comparing the changes in the results for uniaxial tension versus compression due to water, it was found that the reduction rate of uniaxial tensile strength was greater than that of uniaxial compressive strength, while the ratio between the reduction rates was almost constant for various rocks. In numerical simulations, the stress-strain curves in the prepeak region under dry and wet conditions could be reproduced by crack extension models under uniaxial tensile stress. Numerical analyses indicated that the nonlinearity of the stress-strain curves is probably due to the longer crack extension in wet compared with dry conditions.

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Section: Sample Rockmentioning

confidence: 99%

Section: Sample Rockmentioning

confidence: 99%

Effect of Water on the Deformation and Failure of Rock in Uniaxial Tension

2014

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“…The relationship between C and UCS is as follows: From equations (12) and (13), the value of BRI when X becomes positive (i.e., X ≥ 0) is shown by equation (14), when σ ′ m is assumed to equal σ ′ V (as in section 6.3.2). Here, using ϕ i from the Wakkanai and Koetoi formations in the range 11°–36° [ Sanada et al , 2009], the BRI of equation (14) is about 8–10. This means that major faults with many secondary splay joints can form at BRI >8, and this is consistent with the above observations that (1) joints tend to develop pervasively at shallower depths in the Wakkanai Formation, where present‐day BRI >8 (Figure 6), and (2) packer sections with a log K i‐packer / K i‐lab >3 are restricted to BRI >8 (Figure 13).…”

Section: Analysis and Discussionmentioning

confidence: 99%

“… a Mineralogy is based on normative calculations [ Mazurek and Eggenberger , 2005; Hiraga and Ishii , 2008]. Effective porosity data are from Niunoya and Matsui [2007] and Sanada et al [2008, 2009]. …”

Section: Geological Settingmentioning

confidence: 99%

“…Following the method of International Society for Rock Mechanics [1983], triaxial tests were performed using 30 mm diameter core samples from the Wakkanai and Koetoi formations, to observe deformation behavior under confined conditions [ Niunoya and Matsui , 2007; Sanada et al , 2008, 2009]. When deformation behavior observed in triaxial tests is compared with natural tectonic deformation, the influence of test conditions must be considered, such as drained/undrained conditions, the strain rate, temperature, and the effective confining pressure.…”

Section: Mechanical Datamentioning

confidence: 99%

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The relationships among brittleness, deformation behavior, and transport properties in mudstones: An example from the Horonobe Underground Research Laboratory, Japan

et al. 2011

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[1] Mudstones are low-permeability sedimentary rocks; however, when shear stresses induced by tectonic movement or nonhydrostatic stresses exceed the shear strength of the rock, brittle or ductile deformation occurs. The nature of this deformation is controlled by the brittleness of the mudstone. If brittle deformation occurs, the resulting dilatant structures may increase the permeability and change the transport properties of the strata. This paper addresses the relationships among brittleness, deformation behavior, and transport properties in mudstones at the Horonobe Underground Research Laboratory, Japan. Geological, mechanical, and hydrogeological data from borehole investigations and laboratory tests were systematically interpreted using a brittleness index (BRI), which is the ratio of the unconfined compressive strength to the effective vertical stress. For mudstones under natural strain rates and low temperatures, ductile deformation occurs when BRI <2, brittle/ductile deformation occurs when BRI is 2-8, and brittle deformation occurs when BRI >8, although semibrittle behavior may also occur at the brittle-ductile boundary. When BRI >8 and faulting is well developed, the mudstone behaves hydrogeologically as a fractured medium at the mesoscopic scale, whereas for BRI <8 the mudstone behaves hydrogeologically as a porous medium, even if faulting is extensive. The BRI concept is a useful tool for systematically characterizing the hydromechanical behavior of mudstones; for example, when assessing the effectiveness of mudstone as a long-term barrier in disposal repositories for radioactive waste.Citation: Ishii, E., H. Sanada, H. Funaki, Y. Sugita, and H. Kurikami (2011), The relationships among brittleness, deformation behavior, and transport properties in mudstones: An example from the Horonobe Underground Research Laboratory, Japan,

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