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Daiki HIRAKAWA, Yoshihisa MIYATA
2012 Volume 27 Pages
11-18
Published: 2012
Released on J-STAGE: January 21, 2013
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A series of laboratory model tests were performed to investigate the methodology of improvement of the structural stability of embankment on slope against rainfall. In this study, the effects of geosynthetic-reinforced soil as well as drainage and filtration technologies on the stability of soil structure against rainfall were focused. As the results of experimental investigation, it was confirmed that the stability of soil structure against rainfall can be improved effectively by applying the geosynthetic-reinforced retaining wall to the toe of the embankment with drainpipes which can be maintained in working period to keep the function.
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Luky HANDOKO, Noriyuki YASUFUKU, Harya DANANJAYA
2012 Volume 27 Pages
19-24
Published: 2012
Released on J-STAGE: January 21, 2013
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To evaluate the mechanism of hydraulic barrier system by using geotextile, more precise hydraulic properties of geotextile are needed. This paper describes the modification method based on capillary rise principle to obtain geotextile water retention curve. This method is mainly purposed to obtain more data to draw the curve in both drying and wetting process. Detail procedure will be explained and the result will be presented and verified using conventional method. Obtained geotextile water retention curve was used to evaluate one dimensional infiltration ponding in soil-geotextile columns as hydraulic barrier in unsaturated condition.
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Takeo UMEZAKI, Takashi KAWAMURA, Kengo NISHIDA, Masaru HAYAKAWA, Daigo ...
2012 Volume 27 Pages
25-30
Published: 2012
Released on J-STAGE: January 21, 2013
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Sand of well quality is difficult to be supplied for horizontal drain to accelerate consolidationvelocity. On the other hand, pre-fabricated drain is recognized as the alternative major material.However the conventional drain design manual is insufficient in order to take the variousmaterials into consideration. In this paper, two layers horizontal drain model and its discretizationtreatment by differentiation for computing is presented to promote the horizontal drain design.After comparing the consolidation delay induced by the presented model with Yosikuni.s matresistance concept, and confirming approximation, the design procedure for horizontal drainusing pre-fabricated drain is presented for reduction of consolidation delay.
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Takeo UMEZAKI, Takashi KAWAMURA, Akira KAWASAKI, Masashi OODERA, Kengo ...
2012 Volume 27 Pages
31-38
Published: 2012
Released on J-STAGE: January 21, 2013
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The multi-drain vacuum aspirating system was proposed for dewatering of high water content soil and filtering of turbid water. And the outline and feature were discussed. Field dewatering tests were carried out for dredge bed mud in Lake Suwa. Moreover, comparison with the high-pressure filter press dewatering of 4MPa was also performed. Furthermore, laboratory filtrating tests of turbid water were conducted. Main conclusions are follows. High water content soil can be dewatered to liquid limit by operation of less than 1 hour using small-scale and simple equipment. In the case of the same filtering area and amount of soil, the throughput of the proposed method is more than 3.3 times the filter press dewatering. In turbid water treatment, the soil particles adhering to the drain surface can serve as a duty of a filter, and can raise the transparency of discharge water.
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Angelica NAKA, Takeshi KATTSUMI, Takehiro OHTA, FLORES Giancarlo, Toru ...
2012 Volume 27 Pages
39-46
Published: 2012
Released on J-STAGE: January 21, 2013
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=Geosynthetic Clay Liners(GCLs) have the potential to immobilize cations present in solution. Due to this, GCLs have been considered suitable materials not only in landfill bottom liners, but also in rock containments eith the potential of acid rock drainage(ARD) generation.However,the bentonite inside GCLs dose not have affinity towards anions such as aresenic, which is one of the toxic components present in ARDs. Based on the authors' previous research on swelling, sorption, and hydraulic conductivity of GCL against ARD, through discussion on the role of Fe in As immobiliation was done in this paper.Swelling test showed that the presence of metals, especially a high concentration of Fe(4500 mg/L approximately) due to its high concentration, negatively impact the swelling of bentonite by increaing the hydraulic conductivity value. The hydraulic conductivity remained low during the test duration but was one order of magnitude higher in the ARD permeation case(5.0×10-10 m/s)than in the water permeation case(1.4×10-11 m/s)。Single metal sorption tests showed that Fe was sorbed by the betonite while As was As sorption.Considering that GCLs do not retain As, but Fe does, an additional Fe layer could be placed in the bottom liner system in order to immobilize it. However, if the ARD contains high Fe concentration, this additional layer would not be neccessary as the Fe in solution will prevent As mitigation.
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Masaki NISHIMURA, Tomoyuki AKAI, Masashi KAMON
2012 Volume 27 Pages
47-54
Published: 2012
Released on J-STAGE: January 21, 2013
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Landfill cap cover that simultaneously suppresses water infiltration to the waste and promotes rapid gas permeation is demanded. We have developed gas-permeable/waterproof sheet (GPWS), comprising a micro-porous sheet which is waterproof but have gas permeability, coated with nonwovens to protect it, and investigated characteristics and applicability of GPWS as a landfill cap cover. In this study, durability and characteristics on seam of GPWS were evaluated. Results showed that waterproof, gas permeability, and tensile properties of GPWS, which has been laid in test slope for 3 years, remained their original level. In addition, it was demonstrated that water impermeability in seam of GPWS can be achieved under 100 cm hydraulic head.
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Takayuki SHIMAOKA, Hirofumi NAKAYAMA, Takeshi KATSUMI, Shigeo UEDA, Ta ...
2012 Volume 27 Pages
55-60
Published: 2012
Released on J-STAGE: January 21, 2013
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Geomembranes are an important structure in landfill sealing systems, because they are hydraulically impervious and deterioration resistant. However, the durability evaluation of a geomembrane is mainly based on accelerated weatherability tests. Therefore, the Japan Chapter of the IGS investigated four types of geomembranes at six locations in Japan with the objective of evaluating geomembrane durability. First, several geomembrane test samples were collected from each landfill. Then, the samples were evaluated by laboratory tensile tests. Based on the test results, the relationship between total solar radiation and geomembrane elongation is discussed. The results revealed that the geomembrane elongation ratio is linearly related to in-situ total solar radiation. Finally, a durability evaluation method of geomembrane is suggested based on the results of this research.
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Shimpei YAMAGUCHI, Maimi YANAGISAWA, Syohei KAWABE, Fumio TATSUOKA, Ya ...
2012 Volume 27 Pages
61-68
Published: 2012
Released on J-STAGE: January 21, 2013
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During the 2011 Great East Japan Earthquake, at many places, fill-type coastal dykes fully collapsed by over-flowing tsunami current by two mechanisms. Mechanism A: the subsoil in front of the downstream slope was scoured, which destabilized the concrete facing on the downstream slope. Mechanism B: the concrete panels on the crest and the downstream slope were lifted up and flowed away by the tsunami current. The backfill was then quickly eroded. Based on small-scale model tests in the laboratory, to prevent Mechanism B, as well as to increase the seismic stability, it is proposed to reinforce the backfill,cover the slopes and crest with concrete panels connected to each other and to the reinforcement layers.
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Kazuya YASUHARA, Takayoshi USUI
2012 Volume 27 Pages
69-76
Published: 2012
Released on J-STAGE: January 21, 2013
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We explored the potential of employing geosynthetics for the restoration of the coastal area in Tohoku where tectonic movement during the 2011.3.11 Great East Japan Earthquake caused large land subsidence. Based on the preliminary investigation, we have found that: i) The flexible structures reinforced with geosynthetics are available not only for urgent remediation but also as permanent countermeasures against inundation increased by climate change-induced storm surges. ii) The long-term monitoring of ground surface movement and sea-level rise is essential for determining what kinds of adaptive measure is most suitable at the objective site and when they should be taken in order to avoid inundation.
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Tomohiro FUJITA, Hidetoshi KOHASHI, Masayuki YABU, Atsushi NAKANE, Yos ...
2012 Volume 27 Pages
77-83
Published: 2012
Released on J-STAGE: January 21, 2013
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The 8m-high geogrid reinforced wall monitored since 1995 has been damaged due to the 2011 earthquake. The authors analyzed the seismic wave and investigated the damage. These activities are useful for developing the limit state design based on reliability design concept. This paper reports the seismic wave analysis result, investigation results on the base foundation and facing deformation, and results of seismic stability analysis based on the current design method developed by Public Work Research Center
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Akihiko OKAMURA, Masahiro KURATA, Hiroyuki SAEKI, Masayoshi SUGIMOTO, ...
2012 Volume 27 Pages
85-88
Published: 2012
Released on J-STAGE: January 21, 2013
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Disaster restoration work was worked with the ECO-TUBE METHOD. There are many water ways in Ishinomaki. The water way using for agriculture and waste water way were dredged. But this dredged sediment contains lot of sand and it is difficult to pump up sand. Then we mixed this dredged sediment carefully. After that this dredged sediment pump up easily and geo-tube which sized 1.0m3 was packed approximately 2000m3 on site. Geo-tube were dehydrated for 20 days and moved to where land subsidence place using for embankment.
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Shinichiro TSUJI, Naoki TATTA, Tsutomu ISHIGAKI, Hideki OHTA
2012 Volume 27 Pages
89-92
Published: 2012
Released on J-STAGE: January 21, 2013
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This paper shows the results of the full scale field test on the confined-reinforced earth method (called CRE method) for asphalt pavement to confirm restraint efficacy of bumps occurring to road surface between concrete and soil structures due to earthquake. It consists of granular bed, geogrid reinforcement and expansion anchor. The structural characteristics of CRE method obtained form the test are as follows; 1) it restrains bumps occurring in road surface by laying CRE layer under the asphalt pavement, 2) it keeps good trafficability of vehicles after earthquake. This paper reports the structure of CRE method, restraint efficacy of bumps of asphalt pavement and its mechanism obtained from the test.
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Takahiro NONAKA, Kenichi KOJIMA, Toyoji YONEZAWA, Takashi SATO, Tatsuy ...
2012 Volume 27 Pages
93-100
Published: 2012
Released on J-STAGE: January 21, 2013
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We have developed the pile slab track embankment which makes use of the material of poor quality, but can support concrete slab by soil improvement piles. Up to now, we have confirmed the effect of this method by the shaking table test. As a result, the method can reduce seismic settlement of concrete slab compared with that of concrete slab without the support by the piles. However, it was confirmed that concrete slab subsided rather than expected by slipping out of the macadam existing between a pile head part and concrete slab. This paper describes, based on the loading test results, of the gabion laid between the head part of improvement pile and concrete slab, with was devised in order to prevent slipping out of macadam
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Kyohei SATO, Hideo KOMINE, Satoshi MURAKAMI, Kazuya YASUHARA, Masahito ...
2012 Volume 27 Pages
101-108
Published: 2012
Released on J-STAGE: January 21, 2013
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Some portions of levee in the Red River delta, located in north of Vietnam, have frequently been damaged by seepage failures. Therefore, a countermeasure of reinforcement for seepage failures are needed to be applied. The countermeasure using natural fiber material is considered to be effective in the Red River delta, because rice farms are flourishing and natural fiber material such as the straw is available at low cost. The purpose of this study is to evaluate the countermeasure of reinforcement by examining the resistance against seepage failure of short fiber mixture soil with natural material. Due to the shortage of soil material in the Red River delta, material was prepared under the simulation of grain size distribution in the Red River delta. The resistance against seepage failure of short fiber mixture soil and fiberless mixture soil are prepared ,respectively. As a result, reinforcement in soil material was confirmed to be effective when the percentage content of sand was over 68.
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Munehiko KAGA, Takashi SASAKI
2012 Volume 27 Pages
109-112
Published: 2012
Released on J-STAGE: January 21, 2013
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Three-axial net reinforcement in which the projections are put was developed. We investigated the pull-out strength by using modeled steel reinforcement. Modeled steel reinforcements of 2 types were used. Pull-out strength increased by installing the protrusion in the reinforcement. And, the pull-out strength of the projecting reinforcement increased in proportion to loading stress. As a next step, we examined the prediction method of pull-out strength which introduced the projection coefficient. These results can be utilized for design of three-axial net reinforcement in which the projections.
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Kenji WATANABE, Ryosuke KURIYAMA
2012 Volume 27 Pages
113-120
Published: 2012
Released on J-STAGE: January 21, 2013
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In this study, pullout tests of geogrid embedded in well-graded gravel were performed, in order to establish the design procedure of GRS integral bridge which was proposed as a new type of bridge abutment using reinforced-soil method. The pullout tests were focused on the effect of confining pressure and stiffness of geogrid on the pullout stiffness characteristic of geogrid. The experiments revealed that the pullout stiffness was largely affected by the confining pressure. This is due to the increase of friction and inter-rocking resistance mobilized between the geogrid and the gravel as well as the decrease of free length of geogrid. The pullout stiffness of geogrid was also affected by the relative displacement between the geogrid and the gravel.
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Kohichi YAMANAKA, Ryosuke KURIYAMA, Satoru SHIMOBE
2012 Volume 27 Pages
121-126
Published: 2012
Released on J-STAGE: January 21, 2013
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This study investigated lightweight geomaterial mixed with expanded polystyrol beads as subgrade soil about the design parameters. The base material of composit geomaterial in this study used high moisture content volcanic cohesive soil (Kanto loam). The base material was mixed with super-lightweight EPS beads and with portland cement.After each specimen is compacted, they are cured in the laboratory for 7 days before the tests. This study, as a part of our studies to make clear the design parameter of lightweight geomaterial mixed with EPS beads as subgrade soil, conducts the CBR test, the resilient modulus test, to find out the design parameter of lightweight geomaterial mixed with EPS beads.
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Shigeaki NOZOE, Yoshio KASAI, Kenji KANEKO, Kazumi MATSUI, Koji KUMAGA ...
2012 Volume 27 Pages
127-132
Published: 2012
Released on J-STAGE: January 21, 2013
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The strength and deformation characteristics of sand are improved by mixing the flexible short fibers. Many factors such as the mixture ratio, fiber materials, ?ber length and orientation a?ect the improvement e?ect of short ?ber reinforcement sands. Especially, the mixture ratio of short fiber is very important for the improvement and the design. In this study, we discussed the relationship between mechanical properties and the ?ber mixture ratio by the laboratory tri-axial compression tests. From the results, we could recognize the existence of optimum mixture ratio for the shear strength clearly. Moreover, we understood that the initial sti?ness becomes small according to the mixture ratio increasing.
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Nozomu KOTAKE, Shouhei URAYAMA, Saburou MATSUBARA
2012 Volume 27 Pages
133-140
Published: 2012
Released on J-STAGE: January 21, 2013
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The fiber reinforced cement treated soil was originally developed as a geomaterial that improves toughness of brittle cement treated clay by inclusion of fibrous materials. The bending strength was increased by fiber inclusion irrespective of the physical properties of soils and more significantly in the case of soils having larger sand fractions. A series of simple tension tests was additionally conducted to clarify the reinforcing mechanism more in detail for the purpose to apply the soil stabilization technique for reinforcement of soil structures and effective utilization of surplus soils. It was observed that the tensile failure was very progressive. The bending and tension strength characteristics were obtained to establish the design model for the member in bending mode.
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Fumio TATSUOKA, Tetsuya KURODA, Shinpei YAMAGUCHI, Shohei KAWABE, Masa ...
2012 Volume 27 Pages
141-148
Published: 2012
Released on J-STAGE: January 21, 2013
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To alleviate several serious problems with conventional type bridges, geosynthetic-reinforced soil (GRS) integral bridges for new construction and nail-reinforced soil (NRS) integrated bridges to reinforce existing conventional type bridges have been proposed. Model tests showed that the backfill settlement and destabilization by cyclic lateral displacements due to thermal expansion and contraction of the girder integrated to the abutments is restrained by reinforcing the backfill with reinforcement connected to the abutment. The seismic stability of these two new bridge types is very high due to increases in: 1) the initial stiffness; 2) the stiffness maintained during dynamic loading; 3)the damping ratio; and 4) the ultimate dynamic strength against response acceleration. By factors 1) and 2), the approaching speed to the resonance state becomes slower. By factor 3), the response acceleration becomes lower.
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Ryosuke KURIYAMA, Kenichi KOJIMA, Tatsuya MORINO, Kazuyuki WATANABE, H ...
2012 Volume 27 Pages
149-156
Published: 2012
Released on J-STAGE: January 21, 2013
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Authors developed Geosynthethic-reinforced soil integral bridge, which made to unify the Geosynthethic-reinforced soil structure and integral bridge, as construction method solves a problem of subsidence of back banking generated with expansion and contraction of beam by temperature change. Now, Geosynthethic-reinforced soil integral bridge is constructed with the Hokkaido Shinkansen. Authors are measuring during construction and long-term action in order to check an effect to the above-mentioned problem. As a result, it checked carrying out the action of the Cement improvement backfill and the integral bridge as one through the geotextile. Therefore, it is conceivable that the problem of subsidence of back banking, which arises with expansion and contraction of beam is solvable. In addition, it checked that the big displacement to a structure had not arisen until present.
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Motoaki SUGA, Takahiro NONAKA, Ryosuke KURIYAMA, Kenichi KOJIMA, Masay ...
2012 Volume 27 Pages
157-164
Published: 2012
Released on J-STAGE: January 21, 2013
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Integral bridge of rahmem construction can omit shoe. And integral bridge can slim concrete section of bridge. Follow, integral bridge is built in America and Europe as highway bridge. But integral bridge has problem of settlement of back banking generated with expansion and contraction of beam by temperature change. Authors developed Geosynthethic-Reinforced Soil integral bridge, which made to unify the Geosynthethic-Reinforced Soil structure and integral bridge as construction method solves above problem. In this paper, authors did lateral loading test of actual size scale bridge supposing earthquake and the temperature change this time. As a result, the stability and high earthquake resistance of this structure has been checked.
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Jinsuk HUR, Satoru SHIBUYA
2012 Volume 27 Pages
165-172
Published: 2012
Released on J-STAGE: January 21, 2013
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Case study was carried out into the causes and countermeasures against excessively deformed concrete culverts during and immediately after the construction in the embankment. And this case study dealing with the issue of typical backwards problem in geotechnical engineering was examined. In this paper, first of all, the outline of the damaged culvert as well as the surrounding embankment is in detail described. The background, together with the cause of damage, is discussed based on the results of site investigation. Secondly, it was attempted to elucidate the deformation mechanism of the embankment by means of numerical analysis, and the countermeasures are proposed. Finally, the stability of the embankment with the countermeasures was evaluated.
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Seiji KONDO, Naruto TERADA, Ryu-tarou SHIRAYANAGI, Junichi HIRONAKA
2012 Volume 27 Pages
173-176
Published: 2012
Released on J-STAGE: January 21, 2013
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Large mattress using high strength geogrids for river or marine applications has been used to protect the erosion around the reasons for construction performance with its simple execution. The feature of this mattress is to perform lifting construction, underwater construction. This paper explains the five applications of this mattress at river and marine.
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Takashi HARA, Shinichiro TSUJI, Masaki YOSHIDA
2012 Volume 27 Pages
177-182
Published: 2012
Released on J-STAGE: January 21, 2013
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This study aims to achieve a new type of independent reinforced soil wall (Piled Geo-wall) that can be substitute for one made up of concrete with similar scale, and to contribute to sustainable development. In order to confirm the practicability of the novel structure, three experimental studies with static and impact loading tests and a dynamic centrifuge model test were carried out in the past years. Simple design methods of the novel structure, which can reproduce the results of the experiments, are introduced in this paper.
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Shuji ITO, Naoki TATTA, Shinichiro TSUJI
2012 Volume 27 Pages
183-188
Published: 2012
Released on J-STAGE: January 21, 2013
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The geotextile-reinforced soil wall with double facing system has a vertical layer to absorb the deformation between the facing concrete panels and reinforced backfill. Authors carried out field observation for several walls and confirmed static stability of the walls. Additionally, in order to evaluate static stability of the wall, numerical analysis is carried out. This paper reports that results of field observation and numerical analysis of the wall, which the maximum height of 14.2m and the back-slope is continued to a height of 25m, and the wall is stability state after construction.
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Atsuko SATO, Teruyuki SUZUKI, Tetsuya KUBO, Satoshi NISHIMOTO
2012 Volume 27 Pages
189-192
Published: 2012
Released on J-STAGE: January 21, 2013
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Recent reports have detailed the deformation of geotextile-reinforced earth walls due to frost heaving in cold regions. The results of related studies conducted so far indicate that replacement with gravel ? a frost heave-resistant material ? is highly effective in preventing such deformation. Toward the further reduction of the depth of frost penetration into embankments, compost was mixed into gravel in view of the former’s expected insulation effects. The adoption of this approach was found to reduce the depth of frost penetration, slightly reduce the depth of frost heave, and enable the planting of trees on gravel-based ground.
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