Limited design life in geosynthetic materials

THE BOOK: Discusses the fundamentals of geosynthetics. Examines various applications in areas such as filters, separators, landfills and foundation materials. Reviews quality assurance and the service life of geosynthetics. Geosynthetics are man-made polymer-based materials which facilitate cost effective building, environmental, transportation and other construction projects. Given their versatility, geosynthetics are a vital material in all aspects of civil engineering. Part 2 examines the various applications of geosynthetics in areas such as filters, separators, landfills, barriers and foundation materials. THIS CHAPTER: - Introduction - Limited life of geotextile concept - Natural fibres as industrial materials - Agro-industrial fibres - Vegetable fibre characteristics - Erosion control - Basal reinforcement of embankments on soft soil - Conclusions - References

Geosynthetics in Civil Engineering

Discusses the fundamentals of geosynthetics. Examines various applications in areas such as filters, separators, landfills and foundation materials. Reviews quality assurance and the service life of geosynthetics. Geosynthetics are man-made polymer-based materials which facilitate cost effective building, environmental, transportation and other construction projects. Given their versatility, geosynthetics are a vital material in all aspects of civil engineering. The first section of the book covers the fundamentals of geosynthetics. Chapters discuss the design and durability of geosynthetics together with their material properties and international standards governing their use. Building on these foundations, Part 2 examines the various applications of geosynthetics in areas such as filters, separators, landfills, barriers and foundation materials. The book concludes by reviewing methods of quality assurance and the service life of geosynthetics. Written by an international team of contributors, Geosynthetics in civil engineering is an essential reference to all those involved in civil engineering. (Woodhead Publishing

Use of 'Limited Life Geotextiles' (LLGs) for Basal Reinforcement of Embankments Built on Soft Clay

Polymeric technical fabrics have long working lives and are sometimes used in practical situations where a geosynthetic is only needed to be fully functional for a relatively short period of time, e.g. a separator layer beneath a temporary access road. This article concerns the use of ‘Limited Life Geotextiles’ (LLGs), i.e. high specification geotextiles, which are designed on the basis of having a limited working life, as basal reinforcement for an embankment built on soft clay. A method is given for defining the allowable progressive loss of tensile strength of the foregoing basal LLG as a result of improvement of the shear strength of the foundation soil due to consolidation. It is shown that the derived relation between required reinforcement strength and consolidation time (the Time-Strength-Envelope) can be represented by a simple exponential equation. Vegetable fibres are natural candidates for use in the manufacture of LLGs since they are a renewable resource and their degradation with time is accounted for in the design of the LLG. Combinations of vegetable fibres growing in tropical regions which are capable of satisfying the Time-Strength-Envelopes for several embankment slopes are presented. (Elsevier

Construction for a sustainable environment

Proceedings of the Green5 Conference, Vilnius, Lithuania 1 July - 4 July 2008The past fifty years have seen rapid development of public and governmental awareness of environmental issues. Engineers and scientists have made tangible contributions to environmental protection. However, further theoretical and practical developments are necessary to address mankind’s growing demands on the environment. Construction for a Sustainable Environment includes recent developments relating to construction and the environment, including: (1) engineered disposal of wastes; (2) treatment of contaminated and derelict land; (3) sustainable construction and infrastructure; (4) supporting the natural environment. Construction for a Sustainable Environment presents clear evidence that common sustainability issues are encountered throughout the world and that only a concerted, international and interdisciplinary approach can tackle these issues

Empirical Relationship between Rock Structure Rating and Modulus of Deformation

Site investigation data used for the establishment of the reported relationships were provided by railway authorities in India and the relationships were subsequently used throughout a 65km section of railway line in the Eastern Ghats.During the early stages of construction of a railway line in southeast India, the tunneling works encountered numerous problems, such as rock falls, major water inflow, etc. In order to progress the works, it was necessary to undertake thorough classification of the rock masses and to obtain values of the in situ modulus of deformation for inputting into numerical analyses. It was not feasible to conduct a large number of in situ determinations of the modulus of deformation. Hence, an attempt was made to establish an empirical relationship between rock structure rating and modulus of deformation (Em) for the rock masses through which the railway passed. This was done using data from tests conducted on rock samples taken from 45 boreholes at various locations along the railway line, particularly in tunnel sections where distress was observed. (ASCE

Geotechnical and Environmental Aspects of Waste Disposal Sites: Proceedings of Green4, International Symposium on Geotechnics Related to the Envionment, Wolverhampton, UK 28 June - 1 July 2004

Despite the importance of preserving the environment in out developing world, activity involving the extraction of natural resources and the disposal of waster continues to increase. Such operations need to be conducted in a carefully-controlled manner, protecting both the natural environment and the communities who live in the vicinity. Drawing expertise from 19 countries around the world, this book discusses the engineered disposal of waste in landfills as well as how to manage land contaminated by waste disposal and fluid flows. It provides an integrated view of the latest research and practice in waste disposal as well as environmental management. (CRC Press)Over the past 25 years large quantities of vegetative matter (particularly gardening waste) have been deposited in engineered landfills. The fibrous nature of this type of waste initially creates a form of 'soil reinforcement' within the refuse mass. With time the fibres will degrade and the reinforcing effect will be lost and this could have a serious effect on the stability of refuse slopes. Laboratory tests have been conducted to investigate the effect of pore water composition on the strength properties of fibrous vegetable matter and individual vegetable fibres. This preliminary assessment of whether the stability of 'as-constructed' landfill slopes is likely to be affected significantly by decomposition of vegetable matter within the refuse was conducted using a 'typical' vegetable fibre

The contribution of biogeotextiles to sustainable development and soil conservation in European countries: The BORASSUS Project

Field and laboratory experiments has shown that geotextile mats made from palm leaves are an effective, sustainable and economically-viable soil conservation method, with huge global potential. The EU-funded BORASSUS Project (2005-09; Contract Number INCO-CT-2005-510745) is evaluating the long-term effectiveness of biogeotextiles in controlling soil erosion and assessing their sustainability and economic viability. These experiments are in progress in 10 countries, both in the ‘industrial north’ (in Europe) and in the ‘developing south’ (Africa, South America and South-East Asia). This paper discusses the significance of geotextile palm mats in European countries (Belgium, Hungary, Lithuania and the UK). Geotextile mats were effective in reducing splash erosion, runoff and soil erosion on arable sloping land in Shropshire, UK. The use of Borassus-mats on bare soil reduced soil splash height by ~31% and splash erosion by ~42%. The application of Borassus-mats as complete cover on bare soil reduced runoff by ~49% and soil erosion by ~75%. Borassus and Buriti mats as 1 m buffer strips reduced runoff by ~56 and 34%, respectively, and soil erosion by ~83 and 77%, respectively. Results from selected types of vineyards in Hungary suggest that the geotextile mats are effective in reducing soil erosion, particularly erosive rainfall. The geotextiles mats are also helpful in maintaining moisture and temperature conditions in the surface soil at levels particularly conducive to the establishment and growth of young plants. Experiments in Lithuania show that geotextile mats are effective in encouraging the establishment and growth of natural vegetation, thereby reducing erosion on roadside slopes. Simulated experiments in controlled laboratory conditions in Belgium suggest that palm-leaf geotextiles are effective in increasing infiltration rates and reducing interrill runoff and erosion rates on medium (i.e. 15%) and steep (i.e. 45%) slope gradients. The effectiveness of geotextile mats when used as technical materials for the construction industry in ground strengthening was investigated. Generally, the tensile strength of the Buriti mats was approximately twice that of the Borassus mats. The tensile strength of the palm-leaf geotextile mats is influenced by the mat strip formation pattern. Research and development activities of the BORASSUS Project have improved our knowledge on the effect of palm geotextile mats on the micro- and macro- soil environments and at larger scales through controlled laboratory and field experiments in diverse environments

Using palm-mat geotextiles for soil conservation on arable loamy sands in the United Kingdom

To date, most studies on the effectiveness of geotextiles on soil erosion rates were conducted in laboratory experiments for <1 h. Hence, at Hilton, East Shropshire, UK, this study investigated the effectiveness of palm-mat geotextiles (Borassus and Buriti mats) in reducing rainsplash erosion, runoff and soil loss and changing selected soil properties under field conditions over two years (January 2007-January 2009). Mat-cover effects on rainsplash erosion were studied in two sets on a loamy sand soil (0o slope). In both sets, six randomly-selected plots (each 1 m2) were completely matcovered and six were bare. Unlike Buriti mats, Borassus mat-cover on bare soil significantly (P<0.001) decreased rainsplash erosion (by ~89%). Duplicate runoff plots (10 x 1 m on a 15o slope) had five treatments (bare, permanent grass, Borassus completely-cover, Borassus buffer strip and Buriti buffer strip). Using Borassus buffer strips (area coverage ~10%) on bare soil decreased runoff by ~71% (P>0.05) and soil erosion by ~92% (P<0.001). Borassus buffer strip, Buriti buffer strip and Borassus completely-covered plots had similar effects in decreasing runoff and soil loss. However, the longevity of Borassus mats was ~twice that of Buriti mats. Despite physical protection, runoff control and sediment entrapment, biomat buffer zones may considerably alter and protect flow direction by presenting barriers and creating several cross-drains. Except Borassus completely-covered plots, all plots had significant (P<0.05) increases in topsoil (0-5 cm) bulk density and decreased aggregate stability. However, buffer strips were more effective in trapping fine particles than Borassus completely-covered plots. No treatments had significant (P>0.05) effects on changes in pH, soil organic matter, total soil carbon or N. Plots with Borassus mats significantly (P<0.05) increased total P and decreased total Ca. Treatments had no significant effects on changes in total S, Mg, Zn, Cu, Fe, Mn, Mo or Cl concentrations. Borassus buffer strips can effectively conserve soil and water and improve and maintain selected soil properties, with results similar to Borassus completely-covered plots. The mechanisms explaining the effectiveness of buffer zones require further studies under varied pedo-climatic conditions.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Rainfall simulator study of the erosion control potential of palm geotextiles for mine dam slope stabilization

Proceedings of the Green5 Conference, Vilnius, Lithuania 1 July - 4 July 2008Mining has been the backbone of the South African economy since the late 19th century. Large volumes of mine waste, such as tailings, have been generated in some areas. Mine waste is highly susceptible to both water and wind erosion, it may create moderate to severe chemical imbalances or toxicities and has a severe abrasive effect on seedlings, a low water-holding capacity and is prone to compaction and crusting. Biogeotextiles are potentially effective and economically-viable erosion control products. The main objective of the study reported herein was to establish the erosion control properties of palm-mats by determining erosion-related variables via rainfall simulation. The textiles were manufactured from the leaves of the Lala palm (Hyphaene coriacea) and covered about 40% of the tailing surface. Ten representative samples of South African mine waste materials were collected for the rainfall simulator studies. Measured erosion parameters included; runoff, sediment load in runoff and interrill erodibility. Seven samples were sand-textured and three were silty. Sediment load was not dependent on exchangeable sodium or organic matter contents, but prominently associated with pH, silt percentage and the quartz content in the clay fraction. When the samples were covered with palm-mats the amount of runoff was similar to that of bare materials, but sediment yield was reduced by about 55%. These results confirm the suitability of palm geotextiles for erosion control on tailing dam slopes