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Hiroyuki HARA, Shigenori HAYASHI, Daisuke SUETSUGU, Masahiro MIZUKI
2010 Volume 66 Issue 1 Pages
21-30
Published: 2010
Released on J-STAGE: January 20, 2010
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In order to investigate the influence of seawater on the properties change of lime-treated soil, laboratory experiments were performed. leaching tests, small cone penetration tests and chemical component analyses were conducted by using different concentration of artificial seawater. It was observed that Ca leaching enhanced in the higher concentration of artificial seawater. In the case of cone penetration test, it was found that the cone penetration resistance decreased with increasing concentration of artificial seawater. The depth of decreasing cone penetration resistance was increased with increasing the duration of immersion under artificial sea water. Ca content of lime-treated soil reduces with increasing concentration of seawater. Reduction of Ca content is remarkable at the surface of specimen.
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Kazuyuki HAYASHI, Sayaka TADANOBU, Hideaki YASUHARA, Mitsu OKAMURA
2010 Volume 66 Issue 1 Pages
31-42
Published: 2010
Released on J-STAGE: January 20, 2010
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A series of drained triaxial tests was performed to clarify the effects of calcium carbonate precipitation on mechanical properties of sand. SEM-EDX was also utilized to examine the quality and quantity of the precipitated, revealing that calcium carbonate is the only mineral precipitated onto grain surfaces. Well-controlled triaxial test results show us that calcium carbonate precipitated within grain aggregate clearly augments Young's modulus and shear strength, and those magnitudes increase with the amount of the precipitated. This augmentation is attributed to increase of surface roughness (i.e., friction), and of positive dilatancy. The test results also demonstrate that intergrain adhesion mediated by the precipitation exerts influence significantly on the elastic deformation, but little on the strength.
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Hiroyuki YAMAMOTO, Tatsuaki NISHIGATA, Shintaro YAO, Kazuhiko NISHIDA, ...
2010 Volume 66 Issue 1 Pages
43-57
Published: 2010
Released on J-STAGE: January 20, 2010
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Vibration tests of the full-sized model of the actual castle masonry wall were executed using the large scale shaking table for evaluating the dynamic characteristics of the masonry wall. A harmonic wave of 3Hz in one axial direction was applied with increasing the input acceleration step by step.
During these tests, the transition of the deformation mode from rocking mode to the swelling mode was observed around 688gal. And it was clarified that this deformation process was triggered by the increasing difference of the magnitude of response acceleration and response phase angle for each material generated by the increase of the earth pressure and the decrease of the friction angle between masonry stones.
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Yuuichi KANNO, Makoto NISHIGAKI, Shiho SAIMEN
2010 Volume 66 Issue 1 Pages
66-77
Published: 2010
Released on J-STAGE: February 19, 2010
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The demand for the biofuel has increased in recent times due to increasing energy demand and the need to reduce global warming. As a result, the use of ETBE (Ethyl Tertiary-Butyl Ether) as a gasoline additive to the bioethanol is also on the increase. In this study, the behavior of ETBE in the saturated zone was investigated. Parameters necessary for the prediction of ETBE behavior in soil were measured by using laboratory test. The results showed that 1) The quality of groundwater could be lowered with respect to odor if the water is exposed to ETBE of even 1mg/L or less. 2) Batch test is examined with three kinds of soil. The relation between amount of adsorption and equilibrium liquid phase concentration is linear when the concentration of ETBE solutions is 500mg/L or less. 3) The result of column test which use Toyoura sand and Masa soil, confirmed that the retardation factor of both soil samples is nearly 1.0 and the longitudinal dispersion length of Masa soil is bigger than Toyoura sand. 4) The column test that is able to set the condition similar to the groundwater flow in the ground is more effective than the batch test as the measuring method to obtain the parameter of the advection dispersion analysis of ETBE.
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Osamu NUNOKAWA, Tomoyasu SUGIYAMA, Naoyuki OTA, Akihito HATA, Michihir ...
2010 Volume 66 Issue 1 Pages
78-88
Published: 2010
Released on J-STAGE: February 19, 2010
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Railway operators invest in measures to prevent rainfall-induced slope failure to secure the safety of train operation. It is important to evaluate a slope disaster risk in order to execute the investment in disaster prevention effectively. We developed a method of establishing the distribution of slope failure probability and the distribution of expected rainfall frequency using rainfall indexes adopted for train operation restriction at rainfall. Using these distributions, we also proposed a method of calculating expected frequency of rainfall-induced slope failure and the events assumed at rainfall. In this paper, we describe these methods, and some calculating examples.
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Ayumu MIYAKAWA, Takeshi TSUJI, Toshifumi MATSUOKA, Tsuyoshi YAMAMOTO
2010 Volume 66 Issue 1 Pages
89-99
Published: 2010
Released on J-STAGE: February 19, 2010
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We propose a classification method to determine the soil type of a river levee using Self-Organizing Maps and k-means method. In order to classify the soil of the levee, electromagnetic waveform, S-wave velocity and resistivity data are acquired by ground penetration radar, surface wave survey, and electrical prospecting, respectively. Envelop and semblance were also calculated from electromagnetic wave reflected waveform. The multi-dimensional data sets are then classified using Self-Organizing Maps and k-means method. The classification results agree very well to the observed nature of the soil properties in the levee. Moreover, we were able to estimate the soil properties from the output of the classification.
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Takeshi SATOH, Takeshi NAGAE, Hirofumi NISHIDA, Kenji HAYASHI
2010 Volume 66 Issue 1 Pages
100-114
Published: 2010
Released on J-STAGE: February 19, 2010
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It's important to consider the life cycle cost (LCC) including the probability of dysfunction risk as well as the initial cost in the hydraulic barrier on the landfill sites. However, it's difficult to estimate correctly probability of dysfunction risk because we do not have enough announcements of dysfunction examples against the hydraulic barrier. In this paper, we have proposed methodology that treat a probability as a variable that influences the decision-making, not as a parameter. Specifically we have made it clear that the structural relation between the dysfunction probability and the LCC about the hydraulic barrier and shown the diagrams that is able to estimate the introducing merit between the double sheets only, the leak detection system and the self selling system.
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Kentaro TABATA, Masayoshi SATO
2010 Volume 66 Issue 1 Pages
115-125
Published: 2010
Released on J-STAGE: March 19, 2010
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To investigate liquefaction-induced lateral spreading and its influence on the failure of structures, the shaking table test of a large-scale model of the liquefiable deposit with caisson-type quay wall and pile-supported structure was performed at the E-Defense. To the model, motions based on the 1995 Hyogoken-Nambu earthquake record were applied, producing liquefaction and lateral spreading of the deposit. The motions also made the caisson's movement and the backfill's large deformation. Such behavior caused the waterside piles bent at the same depth of the caisson's mound. The result explained the effects of inertial force and ground deformation on the behaviors of the caisson and structure.
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Kenzo UEDA, Ryoichi FUKAGAWA
2010 Volume 66 Issue 1 Pages
126-144
Published: 2010
Released on J-STAGE: March 19, 2010
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A simple method to calculate the distribution of contact pressure and displacement at the basement of spread foundations is proposed in this paper. The foundations focused in this paper are symmetrical with the center axis, and consists of rectangular shape foundations. Generally speaking, uneven displacement including partial gap of the basement of spread foundation by the effect of dynamic interaction becomes a severe issue when earthquake occurs, that is lateral large force must be considered in the design. Although conventional methods assume an ideal fixed or pin-structured mechanical bearing on the contact surface between foundation and base ground and require troublesome iteration, the proposed calculation method in this paper is based on a rocking-sway model which is a mechanical system of one degree of freedom and is easily applicable to rather complicated shape foundations. Moreover three dimensional FEM is carried out for a single rectangular shape foundation, and the reliability of the proposed method is evaluated by the comparison with the analytical results.
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Akira ISHIKAWA, Kenjiro TERADA, Takashi KYOYA, Yasuhiro SHAMOTO
2010 Volume 66 Issue 1 Pages
145-155
Published: 2010
Released on J-STAGE: March 19, 2010
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We develop a multi-scale analysis method for partially improved grounds by using the nonlinear elastic constitutive equation, which is newly proposed to characterize the isotropic, three-dimensional, confined-pressure-dependent behavior of an in-situ ground in this study. First, the general framework of the multiscale method based on the homogenization theory is briefly summarized. Secondly, we propose the constitutive model relevant to the numerical algorithm and validate its basic performance. Finally, after demonstrating the macroscopically anisotropic responses with a single macroscopic finite element, we carry out the 3D simulation of an improved ground to demonstrate the capability of the proposed multiscale analysis method and validate the result in comparison with that of the direct analysis in which the heterogeneities of the improving material are directly discretized.
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Shiori TANIZAKI, Akira TATEISHI, Hiroki UNO
2010 Volume 66 Issue 1 Pages
156-171
Published: 2010
Released on J-STAGE: March 19, 2010
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A lattice-shaped ground improvement with a deep mixing soil stabilization is one of the liquefaction mitigation techniques, which prevents sandy soil from liquefaction by constraining its shear deformation. For the design method against level-2 earthquakes, it is very effective to adopt a concept of performance-based design and to assure the external stability of structures allowing a failure of improved walls. Then, aiming at introducing performance-based design concept into the design method, we conducted centrifuge modeling tests and examined the effect on liquefaction mitigation and the earth pressures on improved walls that are important factors for the design. As a result, the authors can see as follows: a potential of liquefaction increases with a decrease in the grid space, the accelerations of improved walls are predominant on the dynamic earth pressures, and the amplitude of dynamic earth pressures sharply rises and the distribution in the vertical direction is clearly changed while the inner sandy soil reaches to liquefaction.
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Tetsuro ISHIDA, Takashi YOSHINO, Toshimi TATSUI, Yukihiro NAKAGAWA
2010 Volume 66 Issue 1 Pages
172-182
Published: 2010
Released on J-STAGE: March 19, 2010
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In order to estimate three componential earth pressure, we have developed an earth pressure cell and a penetration device. These developments were undertaken as part of the project for the build-up of information-based construction management system. This observational system uses boreholes effectively, and enables us to estimate the overall behavior and distribution of stresses within foundation soils. This system consists of two processes. The penetration device is lowered down into the ground to certain depth firstly, and then the earth pressure cell is penetrated horizontally into the cylindrical wall of the borehole. Three componential earth pressure within the ground can be made by changing the directions of the face of the cell. Comparison of the results of labolatory experiment with those of theoretical and analytical estimations demonstrates the utility of the system. This paper also introduces the case history of the tunnel construction in soft ground at Tokyo bay area.
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Yuji KOHGO, Akira TAKAHASHI, Tomokazu SUZUKI
2010 Volume 66 Issue 1 Pages
183-195
Published: 2010
Released on J-STAGE: March 19, 2010
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In this paper we analyzed a real fill-type dam named Minami-Aiki Dam to verify a numerical consolidation method with an elastoplastic model for unsaturated soils. The validities were conducted by comparing the analysis and measurement values during construction and first impounding. The vertical deformations calculated showed good agreements to those observed. Though the changing patterns of the measured and calculated pore water pressures were similar, the dissipation speeds were different. The earth pressures measured at the bottom of the core showed a good agreement with those calculated. This method is valid to estimate behavior of fill-type dams during construction and impounding.
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Atsunori TOMITA, Yoshiaki TASAKA, Takeshi OHMORI, Fusao OKA, Toshihisa ...
2010 Volume 66 Issue 1 Pages
202-214
Published: 2010
Released on J-STAGE: March 19, 2010
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In order to predict the mechanical behavior of an underground cavern, which is constructed in a soft rock ground, it is necessary to study the strain hardening-softening characteristics of soft rock as well as the dilatancy and the effects of pore pressure on the materials. Furthermore, on the large cavern exacavation problem, the confining pressure and the strain rate around the cavern change during the cutting process of the cavern. In this study, an elasto-viscoplastic constitutive model is firstly improved to describe the behavior of soft rock by taking into account the effects of the confining pressure and the strain rate. Using this model, hydro-mechanical coupled analysis carried out to predict the behavior of an underground cavern before its exacavation. When comparing the predicted values with such monitored values as the ground movement, the pore pressure induced in the ground, and the stress induced in the support systems, a good agreement can be seen. Thus, this analytical method is verified as being applicable to predictions of the behavior of underground caverns during construction.
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Masayuki HYODO, Uk-Gie KIM, Yukio NAKATA, Norimasa YOSHIMOTO
2010 Volume 66 Issue 1 Pages
215-225
Published: 2010
Released on J-STAGE: March 19, 2010
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A series of undrained triaxial tests was performed on sand and natural clay mixtures with various fines content. The boundary of the area where sand formed the structural skeleton and the area where clay composed the matrix was examined. The consistency changed drastically on the boundary of fines content about
Fc=20%. The comprehensive undrained shear strengths were presented for materials from sand to clay with various fines content. Although the strength was varied depending on their void rario even if the fines content was indentical for the material in which sand forms skeleton, a unique undrained strength dependent on fines content was observed in material where clay formed the matrix. A unique relationship between equivalent granular void ratio and undrained strength and steady state strength were confirmed for the material which has sand skeleton.
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Hideyuki UTSUMI
2010 Volume 66 Issue 1 Pages
226-235
Published: 2010
Released on J-STAGE: March 19, 2010
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A prediction model for water characteristics curve (SWCC) of clayey soils was derived from the thermodynamic energy balance equation of state. The proposal model contains two independent parameters which are the total pore volume and a constant reflecting the characteristics of the pore size distribution. These two parameters may be obtained by fitting the proposal model to experimental result of mercury intrusion porosimetry. The established equation has been examined by an experimental study for various clayey soils and the UNSODA data base. It is found that a reasonable description of SWCC for clayey soil. This study makes it possible to characterize the SWCC of clayey soils based on the mercury intrusion porosimetry.
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