Soil-reinforcement pull-out tests are essential for evaluating the strength, integrity, and effectiveness of the soil-reinforcement system. In this paper, a new pull-out test model that calculates the soil-geosynthetic reinforcement interface shear stress for highly extensible geosynthetic reinforcement is proposed. Based on a new bilinear interface shear model, the geosynthetic pull-out test results are calculated with regard to the variation of the mobilised geosynthetic tension with distance, geosynthetic pre-yield and post-yield behaviour, and the effective and extended length of the geosynthetic reinforcement. The resulting nonlinear equation for the soil-geosynthetic interface shear stress pull-out mechanism is nondimensionalised, expressed in a finite difference form, and solved numerically using the Gauss-Siedel technique. A parametric study is carried out for a range of relative stiffness values and interface shear stresses. The normalised load-displacement relationship and the variation of the pull-out force and reinforcement displacements, with distance along the reinforcement, are presented. The values calculated using the proposed model are compared with experimental pull-out test results for a needle-punched, nonwoven geotextile, polyester fibres coated with polyethylene, and nylon reinforcements.

In this study, a model on the basis of artificial neural networks is developed to predict the peak horizontal acceleration. The neural network model provides an objective analysis method which requires neither specifying predictive functional forms nor the independence of the inside variables. The Joyner and Boore data set (BSSA, Vol. 71, pp. 2011-2038, 1981, was used for analysis. For comparison, one-and two-step regression procedures were also applied to the same data set. Various fitness criteria have been considered. Finally, the proposed procedure showed an agreeable capability for the required prediction of ground motion parameters.

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SUMMARYA formulation for the analysis of pullout test on highly extensible planar reinforcement is presented. The non-linear di!erential equation for pullout mechanism was expressed in non-dimensional form and solved numerically using the Gauss}Siedel technique. Parametric study was carried out for various ranges of relative sti!nesses, and relative bond resistances. Normalized load}displacement relations and the variations of pullout force and reinforcement displacements along the length of reinforcement are presented graphically. A method for the estimation of the interface interaction parameters from a pre-failure test is also given. The numerical predictions compare well with the available experimental pullout test results for various geotextiles, polymers and nylon geosynthetics.

This paper compares the effects of adding fertilizer in nitrate pollution of groundwater in the Udunuwara area in Sri Lanka and the Shiroishi Plain in Japan. Excessive application of nitrogen fertilizers to soils contributes to contamination of groundwater by nitrates. As nitrate is one of the most identified contaminant in groundwater several environmental protection agencies maximum contamination level for nitrate is 10 mg/l as NO 3 -N. The problem becomes severe in rural areas where people depend entirely on dug wells in the shallow groundwater table for their drinking water supply. Several locations were selected from the Udunuwara area of Sri Lanka for the detailed study. Nineteen shallow dug wells and 4 deep tube wells were selected for water sampling beginning of January to March 1998. Shiroishi Plain in Japan reclaimed from the Ariake Sea has a soil layer consisting of Ariake clay. The total 82 drug wells of average depth 1.5 m had been drilled around the area. Sample were collected in December 2000 and continued for one year around. Nitrate concentration in groundwater was measured by Cadmium reduction method.The results showed a varying nitrate distribution pattern compared to that the Udunuwara area. The effect of fertilizer application on groundwater depends on soil type, fertilizer type and amount used, crop type and climatic condition. The highly permeable soil around Udunuwara area showed that shallow groundwater is highly vulnerable for nitrate than the poorly drained soil of the Shiroishi Plain in Japan. As the people living in Shiroishi Plain use deep groundwater for domestic purposes, drinking water is safe (less than Maximum Contaminated Level for nitrate in drinking water for Japan-10 mg/l as NO 3 -N) as far as the nitrate contamination is concerned. The results of these studies suggest that applying the correct rate of N fertilizer at the optimum time would have a substantial effect on reducing nitrate-N losses.

This technical note describes the analysis of reinforcement pull-out tests using a shear model that incorporates a hyperbolic shear stress-displacement relation for the soil-reinforcement interface. Numerical studies of pull-out tests were performed for small to large strains in inextensible and extensible reinforcements. Predictions based upon a hyperbolic model of shear mobilisation are compared with a theoretical bilinear model presented by Madhav et al. in 1998. Comparative parametric studies using both models were carried out for ranges of relative stiffness and bond resistance values. Normalised load-displacement relations and the variations of pull-out force and displacements with distance, are presented for comparative evaluation. The finite difference equations of the hyperbolic model result in a faster convergence than the bilinear model. The incorporated hyperbolic model estimates the pre- and post-yield deformations, and shear stress and tensile force variations along the length of the reinforcement. Predictions of laboratory and field pull-out results from the available theoretical and experimental tests for inextensible steel straps, and extensible geotextiles, polymers, and nylon geosynthetics are also presented.

A pullout test model is proposed using hyperbolic relation for highly extensible soil-reinforcement. The non-linear equation for interface pullout mechanism was non-dimensionalised, expressed in finite difference form and solved numerically using the Guass-Siedel technique. A parametric study was carried out for various ranges of relative stiffness and relative bond resistance. The normalised loaddisplacement relations and the variations of pullout force and reinforcement displacements with distance, are presented. The interface pullout response of the model is compared with the available experimental pullout test results for geotextile, polymer and nylon geosynthetic reinforcements.

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