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Volume 52 (2011 - 201･･･
- Issue 6 Pages 213-
- Issue 5 Pages 168-
- Issue 4 Pages 128-
- Issue 3 Pages 88-
- Issue 2 Pages 46-
- Issue 1 Pages 2-
Volume 52, Issue 5
Displaying 1-4 of 4 articles from this issue
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General Article
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—Based on Discussion by the JSEG Research Subcommittee for Initiation of Landslidings and Their Assessment—Tamotsu NOZAKI2011 Volume 52 Issue 5 Pages 168-175
Published: 2011
Released on J-STAGE: March 31, 2013
JOURNAL FREE ACCESSThis article is originally based on the author's idea proposed to the present subcommittee, and concluded with reference to the discussion with the subcommittee members. In the beginning, the relationship between landslides and various kinds of their agents are discussed on the basis of ideas of intellectuals proposed on and after 1970's. The fundamental concept of the idea in this discussion, however, rests with Uemura's idea (1974): primary agents arise from action of the circumstantial agents as external causes to the material agents (internal causes). There are many varieties of landslide agents acting over long to short duration or even in an instant. The author believes that the long-middle ones could be primary agents and the short or instant ones inducing agents. There are various kinds of idea including Terzaghi (1950) on those agents and processes leading to landslides, and those ideas are usually not so easy to understand not only for beginners. In this paper, therefore, the author brought these issues to a comprehensive conclusion and tried to show it in some graphic forms.
The united definition of the subcommittee on the primary landslide fell in line as follows: “Primary landslides originate at a point of time when their potential sliding surfaces have almost completely interconnected with each other” and “Any surface and/or undergound deformation or displacement which are the phenomena of initiation of landsliding in advance of primary landslide are defined as precursors of landslide”. These concept of ideas are also shown as a graphic form, and examples of preparatory landsliding and primary landslide are lastly shown in this paper.View full abstractDownload PDF (5015K)
Original Article
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Yukiyasu FUJII, Naoki TAKAHASHI, Manabu TAKAHASHI, Takato TAKEMURA, Hy ...2011 Volume 52 Issue 5 Pages 176-183
Published: 2011
Released on J-STAGE: March 31, 2013
JOURNAL FREE ACCESSThe confined tri-axial extension test is defined by a compressive stress system in which the maximum principle stress (σ1) is equal to medium one (σ2). Using cylindrical specimens of Kimachi sandstone, the tests were carried out in which radial stress was driven by liquid confining-media as σ1 (=σ2) and axial stress was driven by solid pistons as minimum principal stress (σ3). Test specimens were failed with both shear and tensile fractures, more than 70 MPa radial stress. The surface topography of the fracture was digitized by the stereo-photogrammetry. Using a pair of overlapping digital images of a fracture surface, a three dimensional morphology of the surface can be produced. From the morphology of shear fractures, it is shown that the fracture angles increase with radial stress. Tensile fractures initiate from the shear fractures. In addition, fracture roughness, which is calculated from the morphology of tensile fractures, shows that the one with high axial stress is smoother than the one with low axial stress. Therefore, the formation of tensile fracture follows the shear one and it is influenced with the minimum principle stress (axial stress), which is perpendicular to the tensile fracture surface.View full abstractDownload PDF (5220K)
Report
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Manabu TAKAHASHI, Yukiyasu FUJII, Changwan AHN, Takato TAKEMURA, Naoki ...2011 Volume 52 Issue 5 Pages 184-191
Published: 2011
Released on J-STAGE: March 31, 2013
JOURNAL FREE ACCESSKimachi sandstone is widely used as a standard specimen in rock mechanics field, especially on elucidation of hydromechanical characteristics of rock specimen. In this article, we report mainly the pore structure of intact Kimachi sandstone. Total porosity and pore size distribution obtained with mercury intrusion porosimertry were introduced as a basic information of pore structure. Their distribution were characterized as dominant bimodal distribution less than 1 μm. We showed the original μ focus CT data and an example of medial axis analysis for intact Kimachi sandstone. We verified medial axis distributions, connecting path and tortuosity distributions for three perpendicular directions as 3 dimensional geometric information. These information are rather useful for estimating the underground conditions, and evaluating permeability change induced by stress change and so on.View full abstractDownload PDF (6214K) -
Yuichiro MINAMI, Tatsurou MATSUOKA, Tsuyoshi HARAGUCHI, Kenta MOTOKI2011 Volume 52 Issue 5 Pages 192-198
Published: 2011
Released on J-STAGE: March 31, 2013
JOURNAL FREE ACCESSTo investigate S-wave velocity structures in Osaka plain down to base rock, we carried out long-period microtremor array observations at 5 sites in an east-west direction across the Uemachi fault. Phase velocities of the fundamental-mode Rayleigh wave in microtremors are obtained the spatial autocorrelation method and are converted to S-wave velocity structures using an inversion technique based on genetic algorithm (GA). The estimated S-wave velocity structures were in agreement with geological structures from existing deep wells and profiles from an existing seismic reflection. Moreover, the S-wave velocity structures reveal the difference in the depth to and dip of the base rock surface on the upper and lower brocks of in Uemachi fault.View full abstractDownload PDF (7051K)
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