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Volume 44, Issue 1
Displaying 1-6 of 6 articles from this issue
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An Application of Ladanyi's Theory to In-situ Rock MassesTomio TANAKA2003 Volume 44 Issue 1 Pages 2-13
Published: April 10, 2003
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSThis paper presents the results of the studies on the strength of rock masses with discontinuities from the viewpoint of complexity.
Various discontinuities in rock masses are mostly distributed self-similarly and they can be considered as fractal.
Assuming that rock masses which have morphological self-similar discontinuities, are also mechanical self-similar, a numerical formula is derived as follows.
San = (1-Kn) Sjn+KnSin (1) where, San = apparent strength of rock masses which have discontinuities of n-orderSjn = strength of discontinuity of n-orderSin = strength of intact rock of n-orderKn = coefficient of discontinuity of n-order (area ratio of discontinuities to the rock masses) Similarly, the following formula is derived for the apparent strength of rock masses which have discontinuities ofhigher order ((n+1) -order). San+1 = (1-Kn+1) Sjn+1+Kn+1Sin+1 (2)
On the assumption described above, the apparent strength of n-rder (San) can be replaced with the apparent strength of (n+1) -order (San+1) by the nesting effect.
The strength of discontinuity can be considered almost similar in any order, that is San=Sin+1, Sjn≅Sjn+1, formula (3) is derived from formulas (1) and (2).
San+1 = (1-KnKn+1) Sjn+KnKn+1Sin (3)
Formula (3) is generalized to formula (4)
San+m= (1-Kn…Kn+m) Sjn+Kn…Kn+mSin (4) Formula (4) shows that the apparent coefficient of discontinuity of the rock masses which have discontinuities of higher order, Ka = KnKn+m, therefore, if the Ladanyi's theory applied, the apparent strength of rock masses which have discontinuities of higher order is obtained from formula (5). San+m=σ (1-Kn…Kn+m (V+tanφb) + Kn…Kn+mτr/1- (1-Kn…Kn+m) Vtanφb (5)
In the later half of this paper,
1) the coefficients of discontinuities are obtained from the results of block shear tests in situ
2) the strength of rock masses which was calculated using the coefficients of discontinuities as above and ones by the Ladanyi's theory are compared, and
3) the relation of the hierarchy of discontinuities and the strength of rock masses is studied.View full abstractDownload PDF (2109K) -
Kouichi KIKKAWA, Hiroyuki OHNO, Hideki INAGAKI, Natsumi HIRATA2003 Volume 44 Issue 1 Pages 14-24
Published: April 10, 2003
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSRecently, omniscape geology was advocated as one of research fields of the engineering geology used for the environmental problem and disaster prevention. However, this research method has not been established enough, and the method is groped for. In this paper, the environmental problem and disaster prevention in the mountainous terrain of Nepal were examined by the viewpoint of the omniscape geology. The results are the followings.
(1) For landscape of the valley and the terrace paddy field, we examined the form and color of landscape by fractal analysis. As the result, it was shown that the landscape in Nepal is similar to the landscape in Shikoku region of Japan.
(2) Between Nepal and Japan, especially the Shikoku region, there are geographical and geological similarities, and is a climatic similarity. Therefore, the landscape between the two regions is similar.
(3) The similarities of geographical and geological features and the similarity of the climate in two regions have the possibility to cause the similar environmental problem and the similar disaster. Therefore, there is a possibility that the biodiversity will decrease by the dilapidation of the terrace paddy field in the future in the mountainous terrain of Nepal. Moreover, the dilapidation of the terrace paddy field will decrease the flood alleviation function.
(4) In the present, the similarity of the valley landscape has caused slope disasters such as collapses and landslides as similar to Shikoku in Japan. However, enough measures cannot be done in Nepal by an economical problem.
(5) Grasping the region targeted by a viewpoint the omniscape geology contributes to the decision of prior measures by the comparison with a similar region where the problem on the environment and disaster prevention has already been caused.View full abstractDownload PDF (5500K) -
Method of Numerical Calculation and an Application to a Simple SlopeShougo HOSOYA, Tomohide IWAMA, Masashi NAKANE, Daisuke ITO, Masuyuki U ...2003 Volume 44 Issue 1 Pages 25-35
Published: April 10, 2003
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSFor the evaluation of strength and construction area for rock fall protection wall and fence, data related with rock fall characteristics such as falling velocity, rolling angular velocity, falling trajectory, jumping height, horizontal spread. and impact force are necessary. Particularly, jumping height and horizontal spread of rock fall are necessary for the decision of construction height and horizontal width of protection wall and fence. Practical rock fall test is difficult to be carried out because of surrounding conditions, although the practical test is desirable along the relevant slopes. For this reason, 2-dimensional numerical simulation on rock fall has been used for the evaluation of rock fall behaviors. But, 3-dimensional rock fall trajectories could not be obtained by the two dimensional analysis. Recently, authors have developed three dimensional rock fall simulation program and have confirmed that reasonable falling velocity, rolling angular velocity, penetration depth, jumping height, traveling distance and others could be calculated compared with observed data. It was found that falling behaviors of stick shape block were different not a little from those of massive and plate shape blocks. Authors have considered that this 3-dimensional rock fall simulation program could be used practically.View full abstractDownload PDF (2002K) -
[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...2003 Volume 44 Issue 1 Pages 36-47
Published: April 10, 2003
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSThere are some special conditions in the mountain tunneling method, such as 1) the geographical features of the location point is steep and the installation depth is deep, 2) the structure is long in the line, and 3) the geological investigation amount is very limited. Therefore, it can be said that the geological investigation has a difficult, technical, economical condition compared with the dam and the bridge base in a decided site, and is relatively low the forecast conviction level.
However, the uncertainty of such an investigation is not systematically transmitted enough to the post-processing, and the investigation accuracy and the unelucidation point have been succeeded to the design and the construction stage indistinctly. Especially, it is thought that prior geological information is not efficiently used at the construction stage, the case with a great change is generated in the safety management, the cost management, and the production control, etc., and misunderstanding and distrust result easily for the engineer in the investigation field.
On the other hand, enforcement of the law of making to propriety of the tender and the contract, design construction batch order method, and construction CALS are introduced in recent years. It is in the tendency to which the transparency of ground information and making to the data base and system of opening to the public are rapidly promoted in the future.
We report on the current state of the incompleteness of the ground information transmission and of risk communications shortage here. To decrease the ground disaster at the construction stage beforehand, we advocate the introduction of the risk management system which applies at the geological investigation stage.View full abstractDownload PDF (2985K) -
[in Japanese]2003 Volume 44 Issue 1 Pages 48-55
Published: April 10, 2003
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSDownload PDF (5229K) -
Ryohei IMAMURA, Hiroyasu SHIMA, Keisuke SHIMIZU2003 Volume 44 Issue 1 Pages 56-65
Published: April 10, 2003
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSDownload PDF (2421K)
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