Published on July 22, 2014

Author: srinivasangadi71



Role of Geosynthetics in Infrastructure Projects: Role of Geosynthetics in Infrastructure Projects A presentation by SRINIVAS ANGADI M Tech JNTU College of Engineering Hyderabad PowerPoint Presentation: "In the beginning, O Lord, you laid the foundations of the earth, and the heavens are the work of your hands.” “When He made this Earth very thing is perfect and beautiful” Earth becomes problematic place to live when Men disobeyed Creator. Construction in difficult sites becomes a tough job for engineers My present topic give glimpse of new technology how they are dealing with weak soils. Introduction: Introduction In the past, when dealing with difficult sites for construction purposes, the conventional practice was limited to either replacing the unsuitable soils, or bypassing them with costly deep foundations. Additionally, the age-old problem of land scarcity and the need to rebuild aging infrastructure in urban areas, increased realization of seismic hazards, and regulations mandated for various environmental problems, have been the impetus for the evolution of a number of ground improvement techniques during the past 25 years. Introduction: Introduction Innovative ground modification approaches are routinely used now to solve unique soil-related problems, and often are considered to be the most economical means to improve an undesirable site condition Geosynthetics have proven to be among the most versatile and cost-effective ground modification materials . Their use has expanded rapidly into nearly all areas of civil, geotechnical, environmental, coastal , and hydraulic engineering. Genesis of Geosynthetics..: Genesis of Geosynthetics.. Inclusions of different sorts mixed with soil  have been used for thousands of years. They were used in roadway construction in  Roman  days to stabilize roadways and their edges. These early attempts were made of natural fibres, fabrics or vegetation mixed with soil to improve road quality, particularly when roads were built on unstable soil. They were also used to build steep slopes as with several pyramids in Egypt and walls as well. Genesis of Geosynthetics..: Genesis of Geosynthetics.. A fundamental problem with using natural materials (wood, cotton, etc.) in a buried environment is the biodegradation that occurs from microorganisms  in the soil. With the advent of polymers in the middle of the 20th century a much more stable material became available. When properly formulated, lifetimes of centuries can be predicted even for harsh environmental conditions. R & D..: R & D.. Work Related to Geo-synthetics started in 1960.  The International Geo-synthetics Society (IGS) founded in 1982. At present there are more than 20 Universities teaching various courses on Geo-synthetics. Geo-synthetics are available worldwide and the activity is robust and steadily growing. Global Scenario of Geo-synthetics: Global Scenario of Geo-synthetics Worldwide demand for geo-synthetics is projected to rise 5.3 percent annually to more than 4.7 billion square meters in 2014. Strong growth in China is demonstrated by use of geo-synthetics in almost all government sponsored/controlled projects in various areas while such is not the case in India. USA dominates the consumption, China Catching up quickly but India consumes less than 1.5% There is a lot of scope and necessity to enhance the use of Geo-synthetics in India. Types of Geosynthetics: Types of Geosynthetics 1. Geotextile Functions of Geotextiles: Functions of Geotextiles   Geotextiles  are basically textiles in traditional sense made from synthetic fibers . So this material is flexible, porous in nature and bio- undegradable . There are at least 80 specific application areas for geotextiles that have been developed to fulfill following major functions: 1. Separation 2. Reinforcement 3. Filtration & Drainage 4. Moisture barrier (when impregnated) Filtration: Filtration Drainage- Function: Drainage- Function Separation - Function: Separation - Function Reinforcement - Function: Reinforcement - Function Separation Filtration and Drainage Functions of Geotextiles in Road Construction: Separation Filtration and Drainage Functions of Geotextiles in Road Construction Embankment Failure Modes and Reinforcement: Embankment Failure Modes and Reinforcement PowerPoint Presentation: 2. Geogrids Geogrid -Functions: Geogrid -Functions The use of geogrids in roadway and railroad construction to reinforce the base of the structure over soft soils The geogrid helps to increase the bearing capacity of the subgrade soil while greatly reducing the loss of the aggregate cover material into weak, wet, or saturated subgrade soils. Geogrid -Functions: RETAINING WALLS The use of geogrids in retaining wall applications is viewed as an extremely efficient and cost saving method of design application Geogrid -Functions Geogrid -Functions: Geogrid -Functions REINFORCED EMBANKMENTS OVER SOFT FOUNDATIONS A popular technique for creating stable foundations over soft soils is termed reinforced embankments over soft foundations 3. Geomembranes & Geosynthetic Clay Liner: 3. Geomembranes & Geosynthetic Clay Liner Geomembranes & GCL’s Functions: Water Conveyance(Canal Liners) Geomembranes and GCLs can be economically employed to reduce the seepage through unlined irrigation canals or waterways. They are effective alternatives to concrete, asphalt or compacted clay soils and can be used as an expedient method to repair poorly performing existing linings or those that are rapidly deteriorating. Geomembranes & GCL’s Functions Geomembranes & GCL’s Functions: Solid Waste Landfill Containment Landfill applications for geomembranes and geosynthetic clay liners (GCLs) include their use as bottom liners for waste and leachate containment, cut-off walls as well as landfill closures or covers. Geomembranes & GCL’s Functions Geomembranes & GCL’s Functions: Other Uses… Coal Ash Storage Sites Geomembranes & GCL’s Functions Surface Impoundments/ Liquid Containment ( Pond Liners) 4. Geofoam: 4 . Geofoam Geofoam - Functions: Geofoam - Functions Geofoam is used in geotechnical applications such as lightweight fill for construction on soft ground, for slope stabilization, and retaining wall or abutment backfill; From foundations to theatre seating to road embankments geofoam is inherently multi- functional Geofoam - Functions: Geofoam - Functions Geofoam - Functions: A major advantage of using geofoam as fill material in embankments is that it is up to 50 times less massive than other lightweight fills Geofoam - Functions 5. Geocell: 5. Geocell Slope erosion control: Slope erosion control The use of Geocell for erosion control applications eliminates complicated and expensive construction techniques. Geocells 3D structure provides a blanket of 'cells' on the slope surface which can be in-filled with a variety of materials depending on the application; either topsoil, aggregates, from sands and gravels to larger stones and cobbles. Slope erosion control: This improves resistance to erosive forces such as rainwater run-off on steep or unstable slopes, or slopes exposed to severe hydraulic or mechanical stresses. Slope erosion control 6. Geocomposites: 6 . Geocomposites Geocomposite - Functions: Geocomposite - Functions Geocomposite are basically combinations of two or more different types of geosynthetic . Examples include: geotextile- geonet ; geotextile- geogrid ; geonet-geomembrane ; or geosynthetic clay liner (GCL ) The three main geocomposite material types are: drainage geocomposites , reinforcement geocomposites and fluid barrier geocomposites . Usage of Geosynthetics in India: Usage of Geosynthetics in India At Delhi Metro Rail Corporation Ltd Used for Protection , Separation, Drainage between Top Shotcrete Lining & Yellow Geomembrane sheet Usage of Geosynthetics in India: Usage of Geosynthetics in India Constructing Protection Wall against sea erosion of coast at Kolak , Gujarat . Usage of Geosynthetics in India: Usage of Geosynthetics in India Open Air Auditorium At Kharghar , Navi Mumbai, Non Woven Geotextile Is used as Separator between Top Soil & Drainage Layer Usage of Geosynthetics in India: Meghalaya State ElectricityBoard , Shillong Function: • Flexible Earth Retaining Wall. • River / Coastal Erosion Control Usage of Geosynthetics in India Advantages of Geo-synthetics: Advantages of Geo-synthetics Cheaper in product cost, transport and installation. Can be designed (predictability) Can be installed quickly with flexibility to construct during short period. Consistent over a wide range of soils Space Savings Material Quality Control - More homogeneous than soil and aggregates. Better Construction Quality Control at site Easy Material Deployment Advantages of Geo-synthetics: Advantages of Geo-synthetics Less Environmentally Sensitive Improved performance and extended life Increased safety factor Compatible with field conditions Increased service life of flexible pavement section by a factor of 2.5 to 3.0 for weak subgrades and by 2.0 to 3.3 for moderate subgrades Increase in allowable load bearing capacity by 40 to 50 % Geo-Synthetic at Economic Edge: Geo-Synthetic at Economic Edge The cost of geo-synthetics applied usually between 3 to 5 per cent of the total cost of projects. For a number of projects, savings of 30 per cent in total project costs have been reported. Minimizes the regular repair and maintenance costs directly. Increase efficiency of structures, minimize pollution and leads to efficient use of natural resources. Geo-Synthetic at Environment Edge: Geo-Synthetic at Environment Edge Geo-synthetics are difficult or impossible to degrade. However, in view of their inert nature they can be disposed off without the danger of contamination. Geo-synthetics assist the environment by acting as a containing barrier for toxic materials. Geo-synthetics provide sealing and capping of pollution due to chemicals released after road and rail accidents into groundwater areas Disadvantages of Geo-synthetics: Disadvantages of Geo-synthetics Long-term performance of the particular formulated resin being used to make the geo-synthetic must be assured by using proper additives including antioxidants, ultraviolet screeners, and fillers. Clogging of geotextiles, geo-nets , geo-pipes and/or geo-composites is a challenging design for certain soil types or unusual situations. For example, loess soils, fine cohesion less silts, highly turbid liquids, and microorganism laden liquids (farm runoff) are troublesome and generally require specialized testing evaluations. Handling, storage, and installation must be assured by careful quality control and quality assurance Hindrances for the use of Geo-synthetics in India: Hindrances for the use of Geo-synthetics in India Lack of desired legislation Lack of required standards on geosynthetic products as well as on design, construction and installation guidelines Lack of policy / regulatory initiatives by the central and state governments Lack of awareness of standards and guidelines by the site engineers / field staff Lack of national certifying and accreditation agencies for geo-synthetics in the country Lack of R&D facilities Incompleteness of existing standards and guidelines Conclusion: Conclusion It is essential to made the use of Geo- synthectics mandatory in India in order to have increased efficiency with potential large cost saving, safety of structures and minimum environmental pollution including large saving of natural resources Thank You: Thank You

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