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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 2
Displaying 1-6 of 6 articles from this issue
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Takahito KUROKI, Hiroyuki HASEGAWA2003 Volume 44 Issue 2 Pages 84-93
Published: June 10, 2003
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSMany slope failures occurred in a valley on 30th June 1999 at Kannondai, Hiroshima city due to heavy rainfall. The slope failures in the valley can be classified into two types, upper slope failure and lower slope failure, according to their geologic, pedologic and topographic features for slide scars, and their setting in the valley. The upper slope failures occurred in head hollow between upper convex break of slope and lower one. The lower slope failures occurred in lower sideslope beneath the lower convex break of slope.
The process of the lower slope failure is presumed that the sand and humus layers above the weathered basement rock were saturated with water by the heavy rainfalls at the lower sideslope, and that the stability of the lower sideslope then decreased, which resulted in the regolith sliding on the basement rock. On the other hand, the process of the upper slope failure is presumed that heavy rainfalls induced piping by saturated through flow in angular gravel layer, and that regolith of the layer and other layers above the fresh basement rock at the head hollow had fallen off the fresh basement rock.
The existence of the four joint systems and the two types of weathering processes on the basement rock affect the geomorphic features of the slope failures and the landforms in the valley.
These two types of slope failures repeatedly occur at the same landforms, and their processes have been maintaining the landforms in the valley.View full abstractDownload PDF (3373K) -
Keisuke KOJIMA, Hiroaki YAMANAKA2003 Volume 44 Issue 2 Pages 94-103
Published: June 10, 2003
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSThe underground structures can be one of the most important factors to elucidate the damage distribution. In this study, the authors propose an inversion procedure of underground structure based on the earthquake observation records, assuming a multi-reflection of vertically propagating SH-wave in a horizontally layering system. The procedure is formulated as an optimization problem to find the thickness and Q-values of each layer which minimize the different between calculated and measured Fourier spectra. Applying this inversion procedure to the actual strong earthquake records observed at the stations deploying in the center of Fukui plain, we calculated 2D S-wave velocity structure beneath the plain up to the tertiary. It was confirmed that the identified underground structure give a fairly good agreement between monitored and calculated responses, and that estimated structure is harmonized with PS-logging data and P-wave reflection survey. By applying the procedure to the sites having little ground condition data, one may be able to predict the strong earthquake response with a good accuracy.View full abstractDownload PDF (3718K) -
Shojirou ARAMAKI, Yoshio KANEKO, Tsutomu ICHIKAWA, Chinobu OKAMOTO, Ki ...2003 Volume 44 Issue 2 Pages 104-111
Published: June 10, 2003
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSSuizenjirori (Aphanothece sacrum (Sur.) Okada) is a one of freshwater unicellular Cyanobacterium. However, there is little academic paper with regard to Aphanothece sacrum (Sur.) Okada, because of the difficulty getting it as experimental material. The purpose of this paper is to describe the groundwater environment for the conservation of Aphanothece sacrum (Sur.) Okada. Recently, spontaneous Suizenjinori has faced to the crisis of extinction by decrease of water flow and water pollution with the city development. The resistivity image profiling obtained from electric prospecting, stratum division picture with ground information database, water quantity and water examination were investigated to get the foundations data for Suizenjinori conservation. The spring rate of Lake Ezu area was ca. 400, 000m3/d and decreased about 10% of the water flow during the experimental period (from 1992 to 1999). There are groundwater come out from three aquifers i. e. most upper aquifer and Togawa lava upper and lower sediment layers in Lake Ezu. It is considered to mix the groundwater of Togawa lava layer and its upper sediment layer in the neighborhood of Lake Ezu. It is marked by a lower concentration of aluminum in Suizenjinori pond than the other spring pond. It is regarded to influence the basement water under Togawa lava to inhabit Suizenjinori.View full abstractDownload PDF (2574K) -
Takeshi KAMEI, Masanori TANAKA, Motofumi KOYAMA2003 Volume 44 Issue 2 Pages 112-118
Published: June 10, 2003
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSResidual effective stress measurement tests, unconfined compressions tests and direct shear tests were performed on undisturbed and remolded Pusan clay to investigate the aging effects on strength characteristics of clay.
Quantitative test results show that strength characteristics of undisturbed samples are greater than those of remolded samples. This difference may be attributed to the fact that the soil structure of the undisturbed samples offers greater resistance to external loading than does the remolded samples, in which the soil structure has been destroyed. In addition, the quantitative relationships between strength and residual effective stress for undisturbed and remolded samples have been investigated, i. e., the residual effective stress of undisturbed samples is larger than those of remolded samples. As a result, when the quality of the unconfined compressive strength is evaluated in making stability analysis of ground, it is effective to measure residual effective stress which remains before unconfined compression tests are carried out.View full abstractDownload PDF (1322K) -
Takeshi KAMEI2003 Volume 44 Issue 2 Pages 119-122
Published: June 10, 2003
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSMost commercial laboratories carry out routine isotropically-consolidated triaxial tests, i. e. specimen is consolidated isotropically and then subjected to undrained compression by increasing axial pressure, lateral pressure being kept constant during compression process. However, in-situ natural clay deposits exist under anisotropic states of stress, corresponding to K0-consolidation with no lateral strain. The anisotropic consolidation phase of triaxial tests is generally time consuming and expensive, especially if K0 conditions are maintained.
This paper describes the effects of different stress paths during anisotropic consolidation to the completion of K0-cosolidation on undrained shear characteristics of anisotropically consolidated cohesive soil. The comparison of triaxial tests obtained from three different paths during consolidation shows no significant difference in undrained shear behaviour evaluation. The present testing procedures require no special cell, and its simplicity, speed and economy are well suited to evaluate the undrained shear behaviour after K0-consolidation. Therefore, it can be readily used by practicing engineers.View full abstractDownload PDF (732K) -
[in Japanese]2003 Volume 44 Issue 2 Pages 123-131
Published: June 10, 2003
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSDownload PDF (6216K)
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