Japanese Geotechnical Society Special Publication
Online ISSN : 2188-8027
ISSN-L : 2188-8027
Volume 2, Issue 64
Displaying 1-7 of 7 articles from this issue
THE 15TH ASIAN REGIONAL CONFERENCE ON SOIL MECHANICS AND GEOTECHNICAL ENGINEERING
Ground improvement - Earth reinforcement
  • Tugba Eskisar, Selim Altun
    2016 Volume 2 Issue 64 Pages 2159-2163
    Published: January 31, 2016
    Released on J-STAGE: January 29, 2016
    JOURNAL FREE ACCESS
    In this study, unconfined compression tests have been performed to investigate the effect of freeze–thaw cycles on strength properties of kaolin reinforced with fibers. Kaolin was mixed with bentonite in percentages of 10, 30, and 50 in terms of the dry mass of soil. Bentonite admixed kaolin specimens were prepared at optimum moisture contents and reinforced with varying fiber contents. The specimens were subjected to 0, 1 and 5 freeze–thaw cycles. It was found that, fiber inclusion to soil improved the mechanical properties of the soil; the peak strength increased by the existence of fibers and the strength loss after the peak strength decreased. It was also seen that the increment of the plasticity index required more fiber content to achieve a similar amount of compressive strength with the specimens that had a lower plasticity index. The unconfined compressive strength of unreinforced specimens decreased with increasing the number of freeze–thaw cycles, whereas reinforced specimens showed better performance and the strength reduction decreased with the optimum amount of reinforcing content. The lowest values of compressive strength are obtained after the 5th cycles of freezing-thawing of the specimens.
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  • Daiki Hirakawa, Yoshihisa Miyata
    2016 Volume 2 Issue 64 Pages 2164-2169
    Published: January 31, 2016
    Released on J-STAGE: January 29, 2016
    JOURNAL FREE ACCESS
    In pavement structure, short fiber reinforcing technique is hoped as an effective method for improving the stability of the subbase or subgrade layers against traffic load. In this paper, compaction behavior of short fiber reinforced is discussed by the results of laboratory compaction tests. As the results of roller compaction tests, it was confirmed that the value of dry density stably increases with an increase in the number of roller passing even if initial value of dry density at spreading was lower. At 8 passing of roller compaction, the value of realized dry density around the optimum water content become higher than the maximum dry density obtained from the Proctor test. This results shows that the current compaction control method for the subbase of pavement structure can also be applied to short fiber reinforced soil.
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  • Chennarapu Hariprasad, Balunaini Umashankar
    2016 Volume 2 Issue 64 Pages 2170-2173
    Published: January 31, 2016
    Released on J-STAGE: January 29, 2016
    JOURNAL FREE ACCESS
    Removal of unsuitable soil and replacement with a strong material is one of the oldest and simplest ground improvement techniques. During this process, a layered soil system with a strong layer overlying a weak layer is achieved. Studies on the load-settlement response of footing on such layered system are limited. An experimental study is carried out to obtain the load-settlement response of a model circular footing resting on (a) unreinforced aggregate layer overlying a sandy soil layer, and (b) geogrid-reinforced aggregate layer overlying a sandy soil layer. A large-scale test chamber of size equal to 1m x 1m x 1m is used to perform the experiments. Actuator of 10T capacity is used to apply the loads in a displacement-rate controlled mode. A plate vibrator is used to prepare uniform sand and aggregate layers inside the test chamber. Relative density equal to 70% is maintained for both the layers during the entire test program. The improvement in the load carrying capacity of model footing with the increase in the thickness of aggregate layer and with the introduction of geogrid reinforcement in the aggregate layer is proposed in the study.
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  • Rajyalakshmi Kurapati, Venkata Abhishek Sakleshpur, Madhira R. Madhav
    2016 Volume 2 Issue 64 Pages 2174-2179
    Published: January 31, 2016
    Released on J-STAGE: January 29, 2016
    JOURNAL FREE ACCESS
    The paper presents the effect of shape on bearing capacity of footings on reinforced foundation bed over soft non-homogeneous ground. The model considered for study consists of a two-layered system of granular fill over soft non-homogeneous ground with a single horizontal layer of geosynthetic reinforcement in the granular fill. Meyerhof’s punching mode of failure for footings on dense sand overlying soft homogeneous clay is extended to include the effects of non-homogeneity of soft ground and the axial resistance of the reinforcement to pullout. Shape of footing is an important parameter that influences the ultimate bearing capacity of ground/soil. Solutions are given for strip, square, circular and rectangular footings on both unreinforced as well as reinforced granular beds. A parametric study quantifies the contributions of various parameters on the improved bearing capacity of footings upon consideration of non-homogeneity, embedment and reinforcement. Predictions compare well with experimental results in literature.
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  • C. Yoo, S. M. Shin
    2016 Volume 2 Issue 64 Pages 2180-2185
    Published: January 31, 2016
    Released on J-STAGE: January 29, 2016
    JOURNAL FREE ACCESS
    Global warming has become a global issue in recent years. Korean peninsula has been no exception in terms of global warming. The direct consequence of the temperature increase due to the global warming is an increase in the annual precipitation. Since the rate and amount of precipitation has of paramount implications on short and long-term performance of geo-structures, geo-engineers should pay attention to the issue of global warming. In this paper, the results of numerical investigation on a geosynethic reinforced soil wall (GRSW) are presented. A two dimensional stress-pore pressure coupled finite element model was adopted which can realistically simulate the interaction between rainfall and a GRSW within the framework of unsaturated soil concept. Practical implications on the findings of this study will also be discussed.
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  • Motoyuki Suzuki, Ryohei Asada, Yoshinori Otani, Naoki Shimura
    2016 Volume 2 Issue 64 Pages 2186-2191
    Published: January 31, 2016
    Released on J-STAGE: January 29, 2016
    JOURNAL FREE ACCESS
    Reinforced retaining walls were slightly damaged during recent Japanese earthquakes. Therefore, it is important to clarify the post-earthquake loading capacity of reinforced retaining walls to evaluate the safety, stability, and availability of damaged walls. Using displacement and/or loading-controlled pullout tests, we examined the pullout behaviour of a strip under constant pullout loading in a compacted soil layer that was subjected to various pullout histories. This paper evaluates the post-earthquake loading capacity of a steel reinforced retaining wall based on these test results. The primary conclusions are as follows: 1) when the pullout load did not exceed peak value, the resultant pullout displacement was only 3 to 6 mm; 2) the pullout behaviour of the strip was not significantly affected by the previous pullout; 3) unless the pullout load did not surpass peak or yield values in the relation between pullout load and displacement, even after the earthquake, the reinforced retaining wall maintained its loading capacity to some extent.
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  • Wen guang Fu
    2016 Volume 2 Issue 64 Pages 2192-2195
    Published: January 31, 2016
    Released on J-STAGE: January 29, 2016
    JOURNAL FREE ACCESS
    The soil nailing wall is a retaining structure widely used all over the world, while the composite soil nailing wall is a composite retaining structure developed on the basis of it, and it is so popular in China as to be used in thousands or more of foundation pit supporting projects each year. The composite soil nailing wall is made up of soil nailing wall and one or more type of the composite components such as ground anchor, cement-soil wall and mini pile, it could be applied to almost all kinds of soil, especially to soft soil layer. Like soil nailing wall, it gets many advantages such as rational construction, low cost, short construction period, convenient installation, simple mechanical equipment, etc. When ground anchor, cement-soil wall or mini pile works separately with soil nailing wall, it will form the three basic composite structures, and when two or three of them work together with soil nailing wall, the other four composite structures will be formed. The concepts, structural features, the overall stability check formulas of the seven structure types of the composite soil nailing wall, and a successful cases about foundation pit with the depth about 21 m are described in this paper.
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