Japanese Geotechnical Society Special Publication
Online ISSN : 2188-8027
ISSN-L : 2188-8027
2 巻, 69 号
選択された号の論文の7件中1~7を表示しています
THE 15TH ASIAN REGIONAL CONFERENCE ON SOIL MECHANICS AND GEOTECHNICAL ENGINEERING
Geosynthetics - Mechanical and general aspects of barriers (Organized by IGS TC on Barrier Systems)
  • K. von Maubeuge, T. Egloffstein, L. Vollmert
    2016 年 2 巻 69 号 p. 2347-2351
    発行日: 2016/01/31
    公開日: 2016/01/29
    ジャーナル フリー
    Worldwide more and more road noise and view-blocking barriers are being built along roads, motorways and railway lines, with a core that is made from mineral waste. This waste material can be in the form of slag, ash from municipal waste incineration plants or contaminated soil from the rehabilitation of contaminated sites, residue from construction waste recycling or industrial processing residue (slag, ash, foundry sands, conditioned sludges etc.). These waste products have to meet certain environmental-chemical requirements and must be provided with a surface sealing for groundwater protection. This sealing system can be designed as a mineral sealing (compacted clay liner, CCL) or it can be made of geosynthetic material (geosynthetic clay liners GCL, geomembranes). The commonly required drainage layer can also be of gravel or crushed stone or it can comprise geosynthetic materials (geosynthetic drainage system). Many noise barriers have relatively steep slopes because there is limited space and the higher the barrier and the steeper the slope the greater the noise protection. The sealing and drainage systems therefore frequently require reinforcement in the form of geogrids to ensure slope stability.
  • Nozomu Kotake, Masashi Kamon
    2016 年 2 巻 69 号 p. 2352-2356
    発行日: 2016/01/31
    公開日: 2016/01/29
    ジャーナル フリー
    The interfaces of geosynthetic barrier are considered to be structurally weak surfaces when the barrier is installed in the slope of landfill. However, dynamic behaviors of geosynthetic barrier under seismic excitation have not been clarified sufficiently. In the present study for the purpose to assess the seismic risk of the landfills with respect to the sliding failure along the geosynthetic barriers, the dynamic behaviors of geosynthetic barrier slope were investigated experimentally by means of shaking table tests. Firstly the dynamic behaviors of geosynthetic interfaces were investigated by sliding block experiments to evaluate dynamic friction. Secondly, the surface and global sliding failure modes of the geosynthetic barrier slope were observed depending on the thickness of bottom protection layer. Finally the stability analysis method was proposed so as to predict the failure of geosynthetic barrier slope reasonably.
  • Akinori Saito, Jin-Chun Chai
    2016 年 2 巻 69 号 p. 2357-2361
    発行日: 2016/01/31
    公開日: 2016/01/29
    ジャーナル フリー
    A series laboratory large scale direct shear tests were conducted to investigate interface shear strength between geomembrane (GM) and clayey soils. Two types GMs tested were made of polyvinyl chloride (PVC) (GM-1) and polyethylene (PE) (GM-2) respectively with a thickness of 1.0 mm. Two types soil used were mixture of Ariake clay and passing 425 μm sieve decomposed granite (mixed soil), and Na-type bentonite. For all cases investigated, the interface shear strength (τf) was lower than the shear strength of the soil (τfs) and the lowest τf /τfs ratio was about 0.55. GM-1 is softer and resulted in higher apparent interface adhesion. The test results also show that the higher the water contents of the soil, the lower the τf value. GM-2/bentonite interface only had a friction angle of 3° ~ 4°. The results from this study can be applied for design liner system of landfill.
  • B.V.S. Viswanadham, Dipankana Bhattacherjee
    2016 年 2 巻 69 号 p. 2362-2367
    発行日: 2016/01/31
    公開日: 2016/01/29
    ジャーナル フリー
    Slope instability due to rainwater infiltration is a common problem in many parts of the world, and causes thousands of deaths and damages to infrastructures annually. The problem becomes severe if the soil within the slope has low permeability, and cannot dissipate the pore water pressure generated during the rainfall event. In recent times, the unavailability of good quality backfill material has led to the use of locally available low-permeability soil in reinforced slopes/walls construction. A viable alternative is the inclusion of geocomposites within the slope, to provide the drainage and reinforcement actions necessary to maintain slope stability against rainfall. In the present paper, the effect of rainfall on the seepage characteristics and global stability of slopes with and without geocomposites was investigated numerically using Geostudio (2012). For this purpose, a typical low-permeable slope having 2V:1H inclination and 7.2 m height was considered, and the change in matric suction in the slope with time was studied by subjecting it to a medium rainfall of intensity 22 mm/hr for a duration of 24 hours. It was observed that, the low-permeable slope exhibited high pore water pressures and low factor of safety under the applied rainfall intensity. However, the same low-permeable slope when provided with geocomposite layers, showed significant lowering of phreatic surface and reduced pore pressures, and was stable even 24 hours after completion of duration of rainfall. A parametric study was also conducted to determine the optimum position of placement of geocomposite layers within the low-permeable slope subjected to rainfall. The results indicated that the placement of gecomposite layers at bottom portion of the slope was found to be most effective, as compared to middle and top positions. The use of dual-function geocomposites within slopes subjected to rainfall thus eliminates the necessity of procuring expensive high-permeability fill materials, thereby economizing the project.
  • B.M. Sunil
    2016 年 2 巻 69 号 p. 2368-2372
    発行日: 2016/01/31
    公開日: 2016/01/29
    ジャーナル フリー
    Considerable development has taken place in the area of geosynthetics and their applications since their first use in 1980s in the construction of safe containment of hazardous wastes. Geosynthetic clay liner (GCL) and High density polyethylene (HDPE) geomembrane (GM) liners are widely used in municipal solid waste landfills as a barrier system on the base of the landfill. Satisfactory performance of geosynthetic materials when buried under soil depends on several factors. Geosyntetic liners are subjected to degradation by variation in temperatures or settling of landfills or they will be disintegrated by leachate. Several studies on monitored landfills have shown that geosynthetic liners in municipal solid waste landfills have performed extremely well at controlling leakage in field applications for a couple of decades. However, there have also been some problems reported on the very long term performance these materials. To ensure that long-term contamination does not occur, it is important that the durability of GCL and GM is maintained over the contaminating lifespan of the landfill. Some of the factors that influence very long term performance of GCL/GM/composite liners are particle size, strength and initial water content of subgrade soil, desiccation, the effect of daily thermal cycles etc. This paper examines some of these factors and the mechanisms of performance of geosynthetic liners were reviewed in order to supply reference to the study in this field.
  • Jacob L. Risken, James L. Hanson, Nazli Yesiller
    2016 年 2 巻 69 号 p. 2373-2378
    発行日: 2016/01/31
    公開日: 2016/01/29
    ジャーナル フリー
    A laboratory investigation was conducted to determine moisture-suction relationships for geosynthetic clay liners (GCLs) as a function of GCL type and hydration solution. The moisture-suction relationships were then used to estimate various engineering properties of the GCLs under unsaturated conditions. Predictions of the permeability function and the shear strength function for the GCLs are presented herein. The shapes of the permeability and shear strength functions were influenced by the air-entry suction value and the hysteresis of the corresponding moisture-suction relationships. Significant variations were observed in the estimated engineering behavior of the GCLs as a function of hydration solution, whereas relatively insignificant variations were observed as a function of GCL type. Moisture-suction relationships determined under representative test conditions may be used to estimate field performance of GCLs for applications such as barrier systems for solid and liquid waste containment facilities; liner systems for liquid containment structures such as ponds, impoundments, reservoirs, and water conveyance canals; covers for various containment systems; as well as for agricultural applications.
  • Angelica Naka, Giancarlo Flores, Takeshi Katsumi, Hirofumi Sakanakura
    2016 年 2 巻 69 号 p. 2379-2384
    発行日: 2016/01/31
    公開日: 2016/01/29
    ジャーナル フリー
    Evaluating the factors that affect hydraulic conductivity and metal retention in geosynthetic clay liners (GCLs) becomes crucial in order to decide whether or not GCLs can be used as barrier material in rock containments with acid rock drainage potential generation. This study presents a state-of-the-art review of the factors that impact the hydraulic conductivity and heavy metal retention on GCLs: Effect of type of bentonite inside GCLs, prehydration, confining pressure, pH, metal concentration, and type of metal ion in ARDs. ARDs affect the hydraulic performance of GCLs because of their characteristic low pH (usually lower than pH 3) and presence of different heavy metals and concentrations (especially the presence of divalent and trivalent metals). The retention of metals present in ARD through GCLs are governed by the pH (higher retention at pH higher than 3.5), the metals that are present in the ARD as well as the buffering capacity of the bentonite (determined by the cation exchange capacity of bentonite). Ion exchange constitutes the main mechanism for metal uptake, but other mechanisms also take place. Secondary sorption on ferrihydrite or gypsum (formed through precipitation of metals present in ARD) of metalloids such as As, which cannot be sorbed by bentonite directly, may also occur.
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