All issues
Volume 28 (1987)
- Issue 4 Pages 167-
- Issue 3 Pages 101-
- Issue 2 Pages 47-
- Issue 1 Pages 1-
Volume 28, Issue 3
Displaying 1-4 of 4 articles from this issue
- |<
- <
- 1
- >
- >|
-
Norio ENDO, Kazukuni KIMIYA1987 Volume 28 Issue 3 Pages 101-114
Published: September 25, 1987
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSWeathering crust of granitic rocks in the middle part of Abukuma Mountains are divided into five classes, fresh granites, weathered granites, “masa” A, “masa” B and reddish “masa”, according to the weathering degree. Fresh and weathered granites are distributed limitedly and narrowly along large rivers, and “masa” A, “masa” B and reddish “masa” cover extensively all over the area. The thick weathering crusts are distributed restrictedly on the low relief surfaces. The boundary surfaces between weathered granites and “masa” is parallel to the plane connecting the swells of low relief surfaces, and is nearly horizontal. These facts suggest that the weathering crusts of the middle part of Abukuma Mountains are fossil weathering crusts in which were formed from middle Miocene to early Pleistocene.
Clay minerals produced from biotite during the weathering process, were identified by X-ray diffraction examination. The experiment revealed that fresh biotite was first altered into intergradient chlorite-vermicurite, and then changed into interstratified biotite or kaolinite.
Gibbsite exists only along the land surface. This fact suggests that gibbsite has been produced under the present conditions after the current surface was formed.View full abstractDownload PDF (2595K) -
Ryokichi HAMAJIMA, Tadahiko KAWAI, Kiyoaki YAMASHITA, Morito KUSABUKA, ...1987 Volume 28 Issue 3 Pages 115-125
Published: September 25, 1987
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSRock mass usually have cracks and joints, and can be considered anisotropic. Many numerical and experimental studies have been made on the mechanical properties. However the method of numerical analysis which can fully express the behaviour of such anisotropic rock mass with such discontinuities has not yet been developed. Recently the necessity of large scale excurvations and consequently establishment of an effective method of analysis is considered urgent to clarify the mechanical properties of jointed and cracked rock media.
This paper is based on the “rigid body spring models” proposed by Kawai, in which the elements themselves are assumed to be rigid and they are connected by two types of springs distributed over their interfase boundaries. Using the Mohr-Coulomb's failure criterion and considering the effect of contact as well as separation on the two points of interface boundaries of each elements, the perfect elasto-plastic analysis was carried out basing on the initial stress method.
In this paper the following results were obtained.
(1) Homogeneous and anisotropic mechanical characteristics of materials can be obtained by random or anisotropic discretization.
(2) In some cases of cracked rock masses, the crack propagates by slow stable fracture, while such as in splitting tensile test, it causes an instantaneous unstable fracture. This two modes of fracture are verified by numerical analysis.
(3) Fracture pattern results for jointed rock are good agreement with experimental and numerical results.View full abstractDownload PDF (1631K) -
Noboru SAKAI, Kazuhiro DATE1987 Volume 28 Issue 3 Pages 126-140
Published: September 25, 1987
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSWe assembled a thermal shock fatigue testing machine that repeats the cycles of rapid heating by furnace and rapid cooling by water bath. Using this test machine, we investigated the damages of thermal shock fatigue process, in four kinds of rocks, observing the extension of rocks by thermal shock fatigue and the change of strength and physical properties. From the experimental result, we examined the relationship between the strength and other physical properties of the rocks.
The results are;
1. The process of crack extension by thermal shock fatigue could be divided into three stages, that is crack initiation, crack coaleScence and fracturing of the rocks. Let T denote the testing temperature and N the number of repetition cycles of heating and cooling, and we could approximately express the relation as follows;
T=AiN-κ
where κ is the gradient and Ai is the stage of the crack initiation (A1), the crack coaleacence (A2) and the f raturing of the specimen (A3).
By examining the constants in the above expression, we can deScribe the properties of the thermal shock fatigue of the rock.
2. As the repetition cycles of heating and cooling increase, the early part of the stress-strAin curve began to show the non-linearity. This is caused by the initiation and the coaleScence of cracks.
3. Since the non-linear part of the stress-strAin curve is considered to show the damages of thermal shoch fatigue, we examined the validity of √E′/ρ with the velocity of the primary wave, where E′ is the secant modulus at 100kgf/cm2, which is correspond to the slope of early part of stress-strAin curve. The results show that the degree of Vp or by examining the non-linear part of the stress-strAin curves.
4. Contrasting the uni-axial compressive strength (Sc) agAinst the 50% secant modulus (E50) or the velocity of primary wave (Vp) shows that the increase or decrease, respectively, but the better correspondence is seen between Sc and E50 than between Sc and Vp.View full abstractDownload PDF (3790K) -
Stability Decrease of Large Slidemass due to Submergence of Toe and its Remedial MeasuresYasuo NAKAMURA1987 Volume 28 Issue 3 Pages 141-151
Published: September 25, 1987
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSDownload PDF (1724K)
- |<
- <
- 1
- >
- >|