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Volume 44 (2003 - 200･･･
- Issue 6 Pages 331-
- Issue 5 Pages 274-
- Issue 4 Pages 213-
- Issue 3 Pages 142-
- Issue 2 Pages 84-
- Issue 1 Pages 2-
Volume 44, Issue 3
Displaying 1-5 of 5 articles from this issue
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Hokkaido Volcanic Ash GroundsKazuyoshi YAGI, Seiichi MIURA2003 Volume 44 Issue 3 Pages 142-153
Published: August 10, 2003
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSThis study aims to clarify mechanical property of volcanic soils with particle crushing. Site investigations using SPT, CPT and SCP tests were conducted at the volcanic ach grounds in Hokkaido. In addition, laboratory tests on disturbed and undisturbed samples taken from the in-situ volcanic ach grounds were also carried out to reveal their static shear strength and cyclic undrained strength. From the results of triaxial compression tests, it was found that there is a remarkable dependency of stress-strain-strength properties of undisturbed and reconstituted volcanic soils on crushing of constituent particles, when the test is performed under the stress system with the increase in effective mean principal stress. Therefore, the effects of cementation and fabric anisotropy on the angle of internal friction are insignificant for undisturbed crushable volcanic soils. On the other hand, the liquefaction strength under low confining pressure is greatly influenced by cementation, grain size and fines content. Furthermore, the correlation between the in-situ sounding data and strength parameters obtained from laboratory test is also discussed in this paper.View full abstractDownload PDF (2098K) -
Discussion of Identifiability of Surface Rock Facies Distribution with DEM-Processed “Roughness Map”Hiroyuki TOSAKA, Takeshi HIRASAWA2003 Volume 44 Issue 3 Pages 154-163
Published: August 10, 2003
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSThe authors present a new type of DEM-processed map, named as “roughness map”, which might reflect the regional rock facies distribution or facies boundaries.
The roughness of a grid point of the DEM, reflecting the degree of point-wise unevenness of the surface excluding the topological undulation, is derived by calculating the difference between the actual elevation value and the value which is interpolated smoothly by using the lineup of adjacent 10 data points except the target point.
The roughness map covering entire Japan has been made, and comparisons of the characteristics of the map with the slope map and the geological map are presented for 3 areas. It is pointed out that: (1) the roughness map can enhance the rock facies difference between limestone and the peripheral sedimentary rocks in Akiyoshidai, Yamaguchi Pref., : (2) the facies difference of the east and west sides along the Mid Techtonic Line is distinguished correspondently by the roughness map in the neighborhood of Ina basin, Nagano Pref., : (3) a banded feature of facies existing in the central part of Shikoku becomes clearly observable by the roughness map.View full abstractDownload PDF (6799K) -
Daijiro UEHARAI, Tsuneari ISHIMARU, Atsushi TANASE, Yasuo OGAWA, Atsus ...2003 Volume 44 Issue 3 Pages 164-174
Published: August 10, 2003
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSMagnetotelluric (MT) survey has been carried out in the southern region of the Kii peninsula, where many anomalous high temperature hot springs are distributed, in order to estimate the influence of the regional noise and the effectiveness on the remote reference method and the rough images of resistivity structure in this region.
The results of this survey are as follows: (1) MT data were contaminated by regional low frequency noise probably caused by leakage current from the electric railway lines in the region. As a result we had to use the far remote reference method to remove the noise sufficiently; (2) Quality of MT data depended heavily on the geomagnetic activity and we had to measure for several days at every site to get high quality data under geomagnetic active condition.
From the two-dimensional analysis of the resistivity structure, we recognize a resistive body in the eastern region of survey area and a conductive layer in the western region. Anomalous high temperature hot springs around the Hongu cho city were located in the extension of the electrical unconformity between the resistive body and the conductive layer. It suggests that the fluid supplied from the lower crust through the fractural zone between the Shimanto super group and Tertiary acidic rocks cause high temperature and high 3He emanation springs in this region.View full abstractDownload PDF (2285K) -
Weiren LIN, Toshiaki NAKAMURA, Manabu TAKAHASHI2003 Volume 44 Issue 3 Pages 175-187
Published: August 10, 2003
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSAfter investigating the distribution features of the orientations of pre-xisting microcracks in Inada granite, anisotropy of thermal properties, ultrasonic wave velocities, strengths and elastic constants were examined by using specimens of the rock material, which were made up in three directions respectively perpendicular to the rift plane, grain plane and hardway plane. The results showed that the linear coefficient of thermal expansion, the permanent strain induced by thermal microcracking, the unconfined compressive strength of the specimens cut in R-direction perpendicular to the rift plane and the Poisson's ratio calculated from lateral strain in R-direction were greater than those of G-and H-directions. Similarly, the ultrasonic wave velocities, the Young's modulus at lower stress level and the tensile strength corresponding to R-direction were less than those of the other two directions. This anisotropy can be attributed to the density of the pre-existing microcracks in R-direction, which was greater than that in the other directions. However, there were some disagreements in the correlation of the microcrack density with the ultrasonic wave velocity or the Young's modulus at lower stress level in G-and H-directions. The measurement results in this study suggested that this characteristic might be caused by other reasons of rock texture except the distribution anisotropy of microcracks.
In addition, degrees of the anisotropy of these physical properties were quantitatively evaluated. It is clear that the degree, which was defined as ratio of difference between maximum and minimum values of a physical property to the average of the values of this property in three directions, varied with the different items of the physical properties. As an example, the degree of the tensile strength was 57% and after all it was the maximum value of all the examined properties. When Inada granite was slowly and homogeneously heated to high temperatures of several hundred degrees centigrade, it was found out, that the degree of anisotropy might be enhanced due to the pre-existing microcracks, which were extended and widened in the heating processes.View full abstractDownload PDF (3681K) -
Tetsuharu YASUOKA, Shigeru MIKI, Yukihiro KAWAHARA, Haruo KITAMURA, Mu ...2003 Volume 44 Issue 3 Pages 188-196
Published: August 10, 2003
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSHorizontal drillings are frequently adopted as geological investigations of the tunnel entrance. Comparative geological investigations among the engineers have made it clear that horizontal drillings are an effective tool to detect weak rock mass conditions such as faults and fracture zone. In addition, geological engineers consider that a horizontal drilling is a powerful method to reveal geological conditions in tunnel investigations. However, the comparative investigations also have shown that horizontal drilling did not bring remarkable performance of rock mass grading in examined tunnels. Therefore, We have utilized a horizontal drilling and a seismic prospecting with tomographic analysis to make accurate rock mass grading. It is suggested that accurate rock mass grading is accomplished to estimate grade values of tunnel geological observation sheet from RQD and seismic velocity.View full abstractDownload PDF (2411K)
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