http://hdl.handle.net/10204/2901 2013-06-19T12:32:01Z http://hdl.handle.net/10204/6180 Title: The CSIR contribution to the Revision of the SA Road Pavement Design Method (SAPDM) Authors: Maina, J Abstract: In this presentation the author outlines the CSIR contribution to the Revision of South African Pavement Design Method. Description: 4th CSIR Biennial Conference: Real problems relevant solutions, CSIR, Pretoria, 9-10 October 2012 2012-10-01T00:00:00Z http://hdl.handle.net/10204/5598 Title: A spatial assessment of riverine ecosystems and water supply in a semi-arid environment Authors: Smith-Adao, LB; Nel, JL; Le Maitre, D; Maherry, A; Swartz, ER Abstract: A spatial assessment was conducted in the semi-arid area of South Africa, to: (1) identify priority areas for the conservation of river and groundwater ecosystems; (2) examine surface and groundwater quality for human consumption and (3) investigate the rehabilitation of degraded areas to highlight ‘win-win’ situations for both environmental and human use. A systematic conservation plan was produced, highlighting river conservation areas (river types, fish species and connectivity areas), moderate-impact management areas (groundwater-surface water interaction and recharge areas) and river rehabilitation areas. The proposed river selections would achieve the biodiversity targets of 33 (66%) of the 50 river types; feasible rehabilitation would increase this to 92%. The greatest groundwater-surface water interaction and recharge (30 to>50mm -1) values are concentrated around the mountainous regions of the Little Karoo. This is because the main aquifers in the mountains, table mountain group (TMG) quartzites, yield naturally good quality water for human consumption. River reaches of unacceptable surface water quality were classified as degraded water resource delivery areas where the poor water quality was primarily due to saline return flows from irrigation and the impacts of other anthropogenic activities including abstraction of freshwater which otherwise would have diluted the return flows. Only the middle reaches of the Gouritz and Groot Rivers represent a possible win–win situation for both the environment and human use. Description: Copyright: 2011 Wiley 2011-12-01T00:00:00Z http://hdl.handle.net/10204/3773 Title: Fracture mechanics in pavement design Authors: Denneman, E; Wu, R; Kearsley, EP; Visser, AT Abstract: Pavement materials are subjected to high-cycle loading regimes. Conventional design methods employ the Palmgren-Miner damage hypothesis to predict the fatigue life of pavement materials. The material itself is usually characterized in the analysis by a measured material parameter. This approach is practical and can readily be calibrated, but does have some known shortcomings. The aim of the paper is to discuss some of the limitations of empirically based, Palmgren-Miner type, damage laws. The paper also seeks to promote the use of size independent material properties to characterize pavement materials. Some material properties used in current methods, such as the concepts of strain at break and flexural strength are known to exhibit size effects. Examples of the use of fracture mechanics providing an alternative to these conventional design parameters are given in the paper. The paper shows that although much further development is required before fracture mechanics can be relied upon to fully replace the Palmgren-Miner type damage laws, some of the concepts can already be applied to improve pavement design methods. Description: Sustainable Transport: 28th Annual Transport Conference (SATC) 2009, Pretoria, South Africa, 6-9 July 2009 2009-07-01T00:00:00Z http://hdl.handle.net/10204/3736 Title: Load equivalency factors (LEFs) for abnormal vehicles (AVs) and mobile cranes in South Africa based on the mechanistic-empirical (M-E) design methodology Authors: De Beer, M; Sallie, IM; Van Rensburg, Y; Kemp, M Abstract: This paper describes the proposed new methodology for the determination of the Permit Mass Fees for Abnormal road Vehicles (AVs) based on the estimation of road damage. The existing South African mechanistic-empirical (M-E) pavement design methodology is used to estimate the Load Equivalency Factors (LEFs), based on critical pavement layer life, under static loading conditions. The proposed methodology is not based on the traditional Equivalent Single Wheel Load (or Mass) ESWL (or ESWM), nor on the well known 4th power law for relative pavement damage but on the latest South African Mechanistic-Empirical Design Method (SAMDM) which has been used in practice for pavement design and analysis since 1996. The LEFs were calculated from estimated ratios of critical pavement layer life for each individual AV relative to the Standard Axle (80 kN, 520 kPa) bearing capacities of a range of nine (9) typical standard pavement structures found in South Africa. This was done for both relatively dry and wet pavement conditions. This paper includes examples of eleven (11) selected Mobile Cranes and eight (8) typical selected AVs. The new methodology also includes the effect of tyre inflation (or contact pressure) (TiP), including a sensitivity analysis over a range of 520 kPa to 1200 kPa for all the above vehicles and pavements. It is clear that there appears to be a wide range in the new LEFs for the different vehicles based on the new and what is considered a more rational and fully mechanistic approach (i.e. the SAMDM). Although the new LEFs (hence the associated Mass Fees) are found to be different compared to those calculated according to the existing ESWL method, they are in principle, considered to be based on a more rational (mechanistic) methodology than before and it is suggested that they be refined and applied with draft TRH 11 as soon as possible, but phased in over time. Description: Sustainable Transport: 28th Annual Transport Conference (SATC) 2009, Pretoria, South Africa, 6-9 July 2009 2009-07-01T00:00:00Z