Japanese Geotechnical Journal
Online ISSN : 1880-6341
ISSN-L : 1880-6341
Volume 9, Issue 4
Displaying 1-24 of 24 articles from this issue
  • Madoka UMINO, Hideo KOMINE, Satoshi MURAKAMI, Kenichi SETOI
    2014 Volume 9 Issue 4 Pages 469-478
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    This paper presents the CO2 fixation properties of steel slag containing calcium, and proposes a geotechnical application for the formation of a sound material-cycle society and a low-carbon society. In order to investigate the properties of CO2 fixation, CO2 fixation test with vented constant flow was conducted. As a result, when the CO2 concentration 4500μL-CO2/L was vented in a specimen by 0.05 L/min, non-aging steelmaking slag amount of CO2 fixed is the maximum, the value was 0.04 g-CO2/g-slag. The amount of CO2 that is fixed in the steelmaking slag was about 20% of water-soluble calcium. Therefore, a possibility that the quantity of CO2 fixation could be evaluated was shown from the viewpoint of the mechanism of CO2 fixation using the quantity of water-soluble calcium.
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  • Yota TOGASHI, Mamoru KIKUMOTO, Kazuo TANI
    2014 Volume 9 Issue 4 Pages 479-493
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    Rock masses often show anisotropic mechanical behavior due to discontinuity or sequence of mineral particle. In a triaxial test, the deformations of these types of rock masses show non triaxial behavior because a condition of axial symmetry is not satisfied. In this study, in order to clarify the deformation properties of transversely isotropic body which is applied for sedimentary rocks by some researchers, two cases of analysis of elements for a triaxial test is conducted. The one is the analysis for the condition which the directions of principal stresses are coaxial with the loading directions and the other analysis is for the condition which the directions of principal strains are coaxial with the loading directions. The results demonstrated two main conclusions: in the case of the former type of analysis, the directions of principal strain are inclined from loading direction; on the other hand, in the case of the latter type of analysis, the directions of principal stress are inclined from loading direction.
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  • Keisuke KITADE, Koji ICHII, Mayumi KAWANO, Ooki KURIHARA, Ikuo TAGUCHI
    2014 Volume 9 Issue 4 Pages 495-510
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    In this study, the applicability of surface-wave methods for health monitoring of port structures were examined. First, the variation of shear wave velocity in the ground due to suffusion and variation in water content is measured by bender element tests. Then, 2D FEM dynamic analysis was conducted for a simulation of surface-wave measurement on a sheet pile quaywall. As the result of the analysis, the estimated results of shear wave velocity profile by a surface wave method agree with the assumed soil profile in general. Finally, surface-waves were measured at a real field of a sheet pile quaywall, and the measured results were consistent with the result of swedish weight sounding test at the site. Furthermore, the difference between the shear wave velocity profiles at ebb tide and that at high tide was successfully measured by the surface wave method. Thus, the applicability of the surface wave method for port structures is demonstrated.
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  • Kazunori FUJISAWA, Akira MURAKAMI
    2014 Volume 9 Issue 4 Pages 511-520
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    This paper presents a theory describing the velocities of soil particles and seepage flow after seepage failures, which have not been understood until now. The theory focuses its target on one-dimensional seepage failures caused by upward seepage flows, whereby the equations of motion of the soil particles and the seepage water are analyzed. Assuming their incompressibility and considering uniform flows, the equations yield the system of ordinary differential equations for their velocities. Herein, the equations are analytically and numerically solved and the approximation of the solutions is discussed with previous experimental results. The results have revealed that the velocities of the soil particles and the seepage water accelerate in proportion to the gravitational acceleration and the increase rate of the pressure gradient and that the difference of the two velocities after the failure is kept slightly greater than the seepage flow velocity at the critical hydraulic gradient.
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  • Kazunori FUJISAWA, Kosuke TSUJIMURA, Akira MURAKAMI
    2014 Volume 9 Issue 4 Pages 521-532
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    When sand reaches the quick condition, it boils and behaves as a fluid because the effective stress vanishes, while the sand can be solid before the seepage failure. This paper proposes a numerical method to simulate the behavior of the sand before and after the seepage failure, during which it experiences the phase transition from solid to fluid. In order to analyze the fluidized sand, Eulerian formulation is applied to the governing equations, i.e., the continuity equations and the equations of motion of the seepage water and the sand. They are categorized into a system of hyperbolic partial differential equations, and the CWENO method (Central Weighted Essentially Non-Oscillated method), which can achieve stable and accurate solutions of hyperbolic systems, is employed. Herein, the seepage failure induced by an upward seepage flow is simulated after the accurate computation of Darcy flows is verified. The numerical results have shown that the computed velocities of the seepage flow and the sand after the seepage failure provides a good agreement with the theoretical solutions and that the proposed method can successfully predict their behavior during the seepage failure.
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  • Kazuo TANI, Katsuya MATSUSHITA, Takao HASHIMOTO, Akira YAMAMOTO, Hidek ...
    2014 Volume 9 Issue 4 Pages 533-553
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    A large number of residential houses suffered from liquefaction-induced damage by the 2011 off Pacific coast of Tohoku earthquake. In this study, the applicability of surface ground improvement to the residential houses was investigated as an economically attractive countermeasure against liquefaction. Based on the case studies, the allowable tilt angles and the differential settlements of houses were proposed for required performance of livelihood against moderate and large earthquakes, respectively. The mitigation effect of the surface ground improvement against liquefaction-induced damage was confirmed by field surveys and centrifuge model experiments. The numerical analyses indicated that the surface layer improved by solidification of no more than three meters thick is needed in order to prevent significant damage of houses. In addition, a cost evaluation on the surface ground improvement for newly-built and existing houses was also carried out.
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  • Toshifumi MUKUNOKI, Toshio FUJIMI, Hidetoshi MATSUMOTO
    2014 Volume 9 Issue 4 Pages 555-567
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    Nowadays, due to the developing the hardware of X-ray Computed Tomography (CT) scanner, it is available to visualize pore structure of geomaterials and to evaluate it quantitatively. The important issue is how to threshold CT-value on X-ray CT image. If the spatial distribution of density is unknown, it should be difficult to define the thresholding value of CT data in an objective way. The purpose of this study is to propose the image segmentation technique for X-ray CT image using Expectation Maximization (EM) algorithm. In this paper, the effectiveness of EM algorithm for histogram segmentation was evaluated and the amount of mixel and its spatial distribution were estimated.
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  • Hiroshi SHINSHA, Toshiyasu UNNO, Noriaki SENTO
    2014 Volume 9 Issue 4 Pages 569-589
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    In order to increase a density of sandy ground for a purpose to mitigate a risk of liquefaction, it is effective to mechanically rearrange the soil structure as well as to drain excess pore water simultaneously. As the methods to rearrange the soil structure, three methods were undertaken, i.e., 1) applying cyclic loads, 2) vibrating and 3) mechanical disturbance by mixing blade. Two kinds of sands were used in laboratory tests. One was clean sand with Dr = 51% (initial) and Fc = 0%, and the other was mixed sand with Dr = 60% (initial) with Fc = 30%. Cyclic loading tests were carried out using cyclic tri-axial testing equipment. Both a vibration model test and a mechanical disturbance model test were carried out using sand specimens of 30cm in diameter and 80cm in height, with vacuum pressure of -60kN/m2. From the result of the tests, it was clarified that a densification from Dr = 51% to Dr = 73 - 94% for clean sand and from Dr = 60% to Dr = 83 - 107% for mixed sand were possible with these methods.
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  • Kaoru KOBAYASHI, Kazunobu MATSUMOTO, Satoru NAKAFUSA, Toshihiro MORII, ...
    2014 Volume 9 Issue 4 Pages 591-602
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    A simple soil layer system composed of a finer soil layer overlaying a coarse soil layer exhibits an excellent property of capillary barrier (CB). Water which infiltrates into the soil is suspended just above an interface between the soil layers and diverted along the interface, with the result that a downward movement of water into deeper soil layers below the interface is restricted within some length along the interface. Because of this diversion of infiltration water, the CB system has been employed in a top cover of waste landfills and mining wastes to reduce water infiltration into the protected waste materials. In designing the diversion capacity and constructing the CB system, a compaction density ρd (degree of compaction Dc) in the sand layer should be quantified because it affects the saturated hydraulic conductivity of the sand layer which determines the length of the diversion capacity of the CB system. In this paper, saturated hydraulic conductivity and soil-water characteristic curve (air- and water-entry pressures) of sand specimen are measured with changing its dry density by using a pressure membrane method, and the effect of the dry density of sand on the hydraulic properties of sand is investigated. A series of laboratory soil tank test is also conducted in order to study the effect of dry density of the sand layer on the diversion capacity of the CB system.
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  • - Case Studies on Various Earthquake Motions and Soil Conditions -
    Yuki MIMORI, Takaji KOKUSHO
    2014 Volume 9 Issue 4 Pages 603-618
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    Liquefaction potential at a site is currently evaluated by a Stress-Based Method (SBM) or FL-Method in almost all engineering practice. An Energy-Based Method (EBM) focusing on dissipated energy as physical quantity controlling liquefaction behavior was already proposed, but is not used in engineering practice. In this paper, Energy-Based Method proposed in a previous paper is applied to a uniform sand model, and evaluates liquefaction potential by different seismic motions to compare with FL-Method. Two evaluation results tend to be consistent with each other in many cases, though in a uniform sand deposit liquefaction always starts from shallow depth in EBM while it depends on dominant period of motions in SBM. Also shown is that EBM intrinsically reflects the effect such as durations and dominant periods in seismic motions without depending on parameters such as the stress reduction coefficient. Then actual liquefaction cases in Urayasu during Tohoku earthquake and in Tanno-cho during Tokachioki earthquake are studied by the two methods and the results are compared to know the applicability of EBM in comparison of SBM.
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  • Tomio TAMANO, Masanobu KANAOKA, Tatsuaki NISHIGATA, Kazuhiko NISHIDA
    2014 Volume 9 Issue 4 Pages 619-632
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    In this study, “stone-wall bulging index” and “temperature-strain coefficient” for analyzing mechanical behaviors of stone-structures are described. “stone-wall bulging index” is defined as a ratio (bulging(cm)/bulging height(m)) of a stone-wall. A relation of strain change for temperature change under a external force uniformly condition is defined as “temperature-strain coefficient”. Two cases of modern age castle masonry wall and one case of arch-type stone bridge were conducted with strain measurements. As the results, “stone-wall bulging index” and “temperature-strain coefficient” in these three cases of strain measurement can be useful for analyzing mechanical behaviors of other modern age castle masonry walls.
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  • Yoshiyasu FURUYA, Yuki HAGIHARA, Masayuki OTA, Shinichi ARAI, Hirohiko ...
    2014 Volume 9 Issue 4 Pages 633-643
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    This paper concerns the liquefaction judgment method of diluvia sandy soil layer. Diluvia sandy soil layers are excepted from the target layers of liquefaction judgment methods in plans for road earthwork. However, a diluvia sandy soil layer (Ds1), which exhibits very low standard penetration test values (N-value) is distributed over the construction site of the Ken-Oh Expressway in Sakai-cho Sashima-gun, Ibaragi Prefecture. This diluvia sandy soil layer has an N-value of almost 1-4. We analyzed the layers using two liquefaction judgment methods. First, the N-value method was used, and then another method which utilizes cyclic undrained triaxial test results was employed. Following that, residual deformation analyses (based on the ALID program) for the event of an earthquake occurring was carried out using the factor of liquefaction value(FL-value).
    The results of these analyses suggest that the liquefaction judgment method using the cyclic undrained triaxial test results is suitable for the evaluation of the FL-value for very low N-value diluvia sandy soil layer.
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  • Tadashi HARA, Hemanta HAZARIKA, Shuichi KURODA, Kentaro KURIBAYASHI, T ...
    2014 Volume 9 Issue 4 Pages 645-658
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    A lot of waterfront structures were damaged due to the 2011 off the pacific coast of Tohoku earthquake and subsequent tsunami. However, many river dikes and embankments display diverse damage patterns different depending on the topography and the types of structures. This paper analyzes the cause of damage to the Yoshihama river dike located in Ofunato city of Iwate prefecture based on several field investigations, in-situ testing, laboratory testing and numerical simulations. Damage analyses were performed for the dike that experienced compound disaster due to earthquake induced liquefaction and the tsunami that followed. Based on the in-situ testing and laboratory testing, it was found that there is likelihood of liquefaction in dike body having smaller modified N value. In addition, stability of the dike was numerically simulated under the action of the main shock, after shock and tsunami forces. Simulations revealed that loss of function and damage to the dike was greatly affected by the liquefaction and post liquefaction dissipation of the pore water pressure developed during the earthquake as well as the external force due to overtopping tsunami.
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  • Shoichi TSUKUNI, Tsutomu NAMIKAWA
    2014 Volume 9 Issue 4 Pages 659-670
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    An embankment approximately 2.5 m in height was planned in an area where an existing 0.6m-diameter, high-pressure gas main was buried (with a preload portion to be dismantled in 20 months). An approximately 8 m-thick, soft, cohesive soil layer (N value = 0) was found under the high-pressure main, and deformation in the vertical direction was restricted at some points at the planned site. Uniform settlement of the high-pressure gas main was thus impeded, generating excessive stress. Though this stress did not exceed the allowable stress, given the importance of the gas main, a stress-reduction measure was designed. An improved structure was designed to accommodate the high-pressure gas main between piles constructed by deep mixing and a gate constructed by shallow improvement. The embankment load was borne by this improved structure, allowing control over the extent of consolidation settlement. To adapt the extent of consolidation settlement to that in an area where this measure was not implemented, three-dimensional FEM analysis was used to design a longitudinal improvement depth. Results from 20 months of field observation following construction of the embankment showed that measured consolidation settlement corresponded well with the value estimated in the design phase, corroborating the effect of the improved structure as designed.
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  • Katsuo SASAHARA, Naoki SAKAI
    2014 Volume 9 Issue 4 Pages 671-685
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    The analysis of the monitoring data on soil-water and deformation in sandy model slope under artificial rainfall was conducted in this study. The analysis revealed that the relationship between the shear strain and the pore pressure and that between the surface displacement and the groundwater level were modified as hyperbolic as the relation between the shear strain and the stress ratio under direct shear condition of loose sand. New prediction method of the time of an onset of rainfall-induced landslide was proposed based on the relationship between the surface displacement and the groundwater level. The procedure is as follows. 1) To make the equation for the prediction of the relationship between the surface displacement and the groundwater level based on the regression analysis at any time before the failure, 2) To make the equation for the prediction of the relationship between the time and the groundwater level based on the regression analysis, and 3) To derive the equation for the prediction of the relationship between the time and the surface displacement by the combination of the former equation to the latter equation. The equation of the relationship between the time and the surface displacement could simulate the actual deformation of the model slope well. It suggests the utility of the method for the time prediction of an onset of the rainfall-induced landslides.
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  • Hirotoshi MORI, Naoki FUKUHARA, Atsushi HATTORI, Reiko KUWANO, Kenichi ...
    2014 Volume 9 Issue 4 Pages 687-696
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    A river levee is an essential flood defense structure. Progressive sliding failure with large deformation is a serious problem which has a possibility to lead to a river levee breach. The SPH method is used for simulating the results of model experiments, which progressive sliding failures were observed. The results of calculation represent the progressive sliding failure with a proposed soil-water coupling. The results also illustrate the diffirence in the process of failures according to the height of a pheriatic line. Besides, it has a possibility for a river levee to lead to progressive sliding failure by the destruction of soil skelton structure at the toe by seepage or the contraction by insufficient compaction from the results of the numerical simulation.
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  • Kengo NAKAMURA, Tetsuo YASUTAKA, Takuro FUJIKAWA, Miyuki TAKEO, Kenich ...
    2014 Volume 9 Issue 4 Pages 697-706
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    In order to standardize an upward style column examination, which is one of evaluation methods on leaching behavior of heavy metal from contaminated soil, nine different conditions examined in this study were based on an ISO/CEN standard and applied to the columns set up in three different organizations. Data on the accuracy of the column and shortening test time were collected. Results showed that maximum concentration rates, integrated elution accounts and shapes of breakthrough curve (BTC) of fluoride, arsenic, calcium, magnesium, sodium, and potassium, with higher concentrations and lower Kd, were obtained with high reproducibility under the same condition in different organization. Moreover, by packing the column with half of the sample, shape of BTC and integrated elution quantity were confirmed with high accuracy. This study also found that the samples under wet or air-dried states had little influence on the results.
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  • Shigeru GOTO, Ikuo TOWHATA
    2014 Volume 9 Issue 4 Pages 707-719
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    Drained cyclic pre-shearing and high temperature consolidation were discussed and evaluated as acceleration of the aging effect that rise liquefaction resistance of sandy soils. The raised liquefaction resistance characteristics, i.e. repeatability, anisotropy and degree of the liquefaction resistance raising were clarified. The acceleration of aging effect of drained pre-shearing was evaluated to several thousand years of consolidation. The high temperature consolidation was evaluated to thousand times of real consolidation period.
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  • Takaji KOKUSHO, Yumika YAMAMOTO, Tomoyuki KOYANAGI, Yujiro SAITO, Taku ...
    2014 Volume 9 Issue 4 Pages 721-737
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    Following previous research finding that not only travel distances but also onsets of seismic-induced slope failure are uniquely determined in terms of energy, model tests on rigid blocks resting on deformable sand slopes have been conducted to clarify the uniqueness of failure initiation in terms of energy. Shaking table tests compared with static loading tests together with Newmark-type analyses indicate that the threshold energy for slope failure initiation is governed by the deformability of slopes before peaks of load versus deformation curves. A simple formula for the threshold energy in evaluating initiations of non-rigid type slope failures has been developed based on the model test findings and applied to two actual failed slopes witnessed by local people during a recent earthquake. It has been demonstrated that evaluated threshold energies are mostly compatible with seismic pulse energies available at the slopes if critical shear strain for failure initiation is assumed to be 3-6% for slope friction angles larger than initial slope angles by 1-10°.
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  • - From prediction of drilling depth to adequacy evaluation for engineering bedrocks -
    Masayuki YAMADA, Yoshihiro ITO, Masahiro MORITA, Koichiro TAKEZAWA, M ...
    2014 Volume 9 Issue 4 Pages 739-746
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    When an investigation drilling work is operated in the area with less survey data in the past, we have suggested the management method for the investigation drilling work using microtremor data that can be easily observed, and illustrated the effectiveness of the method by applying to some test sites. Using both H/V spectral ratio and surface wave phase velocity of microtremor, we have estimated the depth of engineering bedrocks (drilling depth) in advance, and we have drafted the work plan for drilling. While drilling, the investigation management has made possible by reviewing a prior estimate from drilling data. On the occasion of drilling completion, we have been able to evaluate the adequacy for the engineering bedrocks.
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  • Yoshiya HATA, Koji ICHII, Atsushi NOZU, Hisakazu SAKAI
    2014 Volume 9 Issue 4 Pages 747-759
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    Two dimensional non-linear FEM analyses are performed to investigate the dominant frequency components of a ground motion for the seismic performance of high embankments. The seismic performance of the embankments was defined by the residual displacements at shoulder, banquettes and toe. It was found that the displacements are mainly influenced by the intermediate frequency range (0.5-2 Hz). It was also found, however, that the damaging frequency range can be influenced by the natural frequency of the embankment slope. These conclusions are useful in the determination of input motion for seismic performance evaluation at an embankment site.
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  • Shoichi TSUKUNI, Akihiko UCHIDA, Tsuyoshi HONDA, Kazuo KONISHI
    2014 Volume 9 Issue 4 Pages 761-771
    Published: 2014
    Released on J-STAGE: December 31, 2014
    JOURNAL FREE ACCESS
    Liquefaction owing to the 2011 earthquake off the Pacific coast of Tohoku caused heavy damages to private houses in the reclaimed land at the Tokyo Bay area and Tone River basin. A project to prevent liquefaction at housing sites and roads was planned for this area, and the city of Urayasu adopted the grid-form ground improvement technique. A study focusing on the settlement of houses was conducted using under-ground modeling parameters considered by the “Urayasu Feasibility Study Committee for Measures Against Liquefaction” and the dynamic centrifuge model tests of sand mounds eruption. The study investigated the effect of grid-form ground improvement in controlling liquefaction in the event of a magnitude 9.0 earthquake with ground surface acceleration of 200 -gal. The results suggest that the grid-form ground improvement minimizes the settlement of houses by decreasing grid intervals whereas increases in pore water pressure directly under the houses increase the settlement.
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