Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
ABSTRACT: Geotextiles are currently specified in many different ways. Engineers specify geotextiles by brand name, mass, type, and/or any mix of properties including strength, puncture resistance, "G" Rating, EOS, and hydraulic properties. However, in Australia, no unified method exists of specifying geotextiles in a simple manner. Some specifications are unnecessarily biased against certain types of geotextiles, particularly wovens. Each State road authority has its' own method. This causes unnecessary confusion and complexity to engineers, manufacturers and contractors alike. This paper presents a case for adopting a simple, unified method of specifying geotextiles. Current Australian specifications are reviewed against worlds best practice. BACKGROUND Geotextiles have been used in Australia for over 30 years, beginning with the introduction of Terram, or "Terra-Firma" as it was widely known, imported by ICI many years ago. The key development in the local industry throughout the 1980"s was the setting up of a local Bidim non-woven manufacturing facility at Albury by Geofabrics Australasia in July 1987. Standards Developments In the late 1980's Standards Australia Committee CE/20 Geotextiles released the Draft Australian Standards for Geotextiles - series AS3706 which addressed general requirements, strength tests, hydraulic tests and durability tests. In 1990 Austroads published its' Guide to Geotextiles (Austroads 1990) which covered topics including Geotextiles Properties and Functions, Applications and Design, Durability, Construction and Testing. Due to lack of interest and funding there has been little further development work by Standards Australia or Austroads to standardize specifications for geotextiles. In Australia only the NSW RTA (Roads & Traffic Authority) has continued work in this area (RTA 1998 R63 Geotextiles, Separation and Filtration). In America AASHTO (the American Association of State Highway Transport Organisations) released its Standard Specification for Geotextiles M 288–96 (Ref.4) recently, which is widely recognised as worlds best practice.
- Transportation > Infrastructure & Services (0.54)
- Transportation > Ground > Road (0.54)
Abstract Geosynthetics engineering has made phenomenal advances during the last decade in areas of manufacturing as well as practical applications. As a result, geosynthetics are now being recognized as essential construction materials that can be used to facilitate construction, ensure better performance of the structures and reduce the long-term maintenance in routine civil engineering works. The creative use of geosynthetics in geo-engineering practice is expected to continuously expand as innovative materials and products are becoming available. In this paper, a wide variety of geosynthetic products available to geoengineers to solve a wide range of problems are briefly presented along with their functions and possible applications. Fundamentals of geotextile filter design principles are then introduced for use in the tunnel drainage system. Practical applications of geosynthetics relevant for tunnel engineering are also highlighted with emphasis on the issues associated with the geotextile filter application for use in the tunnel drainage system. Introduction Geosynthetics have emerged as essential engineering materials in a wide range of civil engineering applications, e.g., transportation, geotechnical, geoenvironmental, hydraulics, and private development since the first geosynthetic conference in Paris, 1977 (Koerner 2012). Due to their costeffectiveness, ease of installation, and well established mechanical and hydraulic properties, geosynthetics are now playing important roles in the field of geo-engineering. As indicated in the 9 Bucahanan Lecture paper by Holtz (2001), major developments in civil engineering have only been possible with the parallel developments in the technology of construction materials. For example, larger scale structures became possible with the help of developments in concrete, reinforced concrete, and prestressed reinforced concrete technology which replaced wood and building stone as construction materials. The best example of a parallel development in geo-engineering between the material and the geotechnical application may perhaps be the soil reinforcement technology which has a direct analogy with reinforced concrete as a polymeric reinforcement material provides added level of tensile resistance and stability to soils that have little to no tensile strength, thus giving additional margin of safety.
- North America > United States (1.00)
- Europe (0.68)
- Materials > Construction Materials (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Construction & Engineering (1.00)
- (2 more...)
ABSTRACT: Geosynthetics have revolutionalized many aspect of geotechnical design and construction. Modern geosynthetic engineering involves identifying the function(s) of the geosynthetic in a given application, establishing the required engineering properties based on rational design methodologies, and selecting a cost effective solution that meets the engineering requirements. When appropriately designed and installed, geosynthetics provide a cost effective alternative to more traditional techniques. This paper highlights a few examples. The potential for Geosynthetic Clay Liners (GCL's) serving as an alternative to a conventional compacted clay liner or as a means of augmenting the performance of a compacted clay liner as part of a composite liner system in the base of municipal solid waste landfills is examined. It is shown that basal reinforcement can be an efficient and effective means of allowing the construction of embankments over soft soil deposits. It is noted that while basal reinforcement can increase stability and reduce short term shear deformations, it can not prevent long term consolidation and creep settlements. However when the use of basal reinforcement is combined with the use of prefabricated vertical drains, it is possible to reduce long term deformations by appropriate surcharging of the soft deposit. Using geosynthetic reinforcement to support structures over man-made or naturally occurring voids is a developing application. How to design for this condition is the subject of current studies, and it can be shown that strong stiff reinforcement is efficient and effective and that multiple layers of extensible material of medium strength can also be used. Recent developments in composite materials include reinforcement with inbuilt drainage; these have been shown to accelerate the reduction in porewater pressure and permit more rapid construction of reinforced embankments using poor quality fill. Further developments include a new range of geosynthetic materials which are electrically conductive.
- Europe (1.00)
- North America > United States > Texas (0.46)
- North America > Canada > Ontario (0.28)
- Geology > Geological Subdiscipline > Geomechanics (0.95)
- Geology > Mineral > Silicate > Phyllosilicate (0.92)
- Water & Waste Management > Solid Waste Management (1.00)
- Materials (1.00)
- Energy > Oil & Gas > Upstream (1.00)
ABSTRACT Geotubes are made from permeable, soil-tight geotextiles that are filled with dredged soil. The performance of pilot scale field tests using a geotube is presented. The geotube was made from a woven geotextile. It was filled by hydraulically pumping dredged silty clay material into it. The variations of the shape of the geotube and the dry unit weight, moisture content, and vane shear strength of the soil at various locations in the geotube with time are summarized. Based on this study, it appears that geotubes are feasible construction materials for use in coastal engineering projects. INTRODUCTION Geotubes are made of permeable, soil-tight geotextile. They are hydraulically filled with dredged soil. Essentially a geotube is a single construction unit block containing soil. Attempts are now being made to use geotubes in coastal engineering projects such as shore protection and breakwaters. Geotubes also help store and isolate contaminated materials obtained from dredging. Results of studies regarding geotextile containers are found in the work of Koerner and Welsh (1980). Botzan et al. (1982) and Harris (1987, 1989, 1994) reported the use of geotextile containers in erosion control. Bogossian et al. (1982) and deBruin and Loos (1995) evaluated the effectiveness of geotubes for erosion control. Environmental dredging and backfill technology using geotubes was reported by Fowler et al. (1994) and Pilarczyk (1996). This paper summarizes the observations made on the performance of a pilot scale field test using a geotube in the land reclamation project for the Songdo New City construction site in South Korea. PROPERTIES OF GEOTUBE USED The geotextile more commonly used to construct geotubes are either woven geotextile or composite geotextile (i.e., an external layer of woven geotextile and an internal layer of non-woven geotextile). For the present study only one woven geotextile was used.
- North America > United States (1.00)
- Europe > United Kingdom > North Sea (0.16)
- Food & Agriculture > Agriculture (0.91)
- Construction & Engineering (0.67)
- Energy > Oil & Gas > Upstream (0.55)
- Government > Regional Government > North America Government > United States Government (0.32)
ABSTRACT: Unpaved roads built over soft, weak subgrade have been used extensively in the Southeast Asian region as temporary site access roads, forest roads and low volume roads. Trafficking of vehicles on un-reinforced unpaved roads will cause severe rutting and mud-pumping problems especially in the rainy season. In addition, stones will get pushed into the weak subgrade. Geotextiles have been successfully used to improve the overall stability and trafficability of unpaved roads. Placed at the interface of the base layer and the subgrade, geotextiles perform separation, reinforcement, filtration and drainage functions, hence, improving the performance of weak subgrade. This paper presents the performance of geotextiles in the stabilisation of unpaved roads in a laboratory model tracking test. The effect of anchoring and pre-tensioning of geosynthetics is examined. Seven laboratory-tracking tests have been carried out for this purpose: one control test, three composite geotextile tests (un-anchored, anchored and with pre-tensioning) and three non-woven geotextile tests (un-anchored, anchored and with pre-tensioning). During loading, subgrade settlement of each test was carefully monitored. To evaluate the performance of each stabilisation system, rut resistance of each test was evaluated and compared with the performance of the control test. INTRODUCTION Unpaved roads built over weak, soft subgrade (less than 3% CBR) are prone to rutting, stone loss and mud-pumping problems. Placing geotextiles at the subgrade-base interface performs the desired separation, reinforcement, filtration and drainage function. Geotextiles when used as separators prevent stone loss into the soft subgrade and minimise base contamination induced by mud pumping. One of the key mechanisms of reinforcement function in geotextiles is the membrane effect. The vertical component of the tension developed in the geosynthetics will distribute the wheel loading over a larger area in the subgrade, avoiding overloading beyond the bearing capacity of the soil.
- Transportation > Infrastructure & Services (0.35)
- Transportation > Ground > Road (0.35)