Paola Bandini

Prediction of Pavement Performance through Neuro-Fuzzy Reasoning

: Government agencies and consulting companies in charge of pavement management face the challenge of maintaining pavements in serviceable conditions throughout their life from the functional and structural standpoints. For this, the assessment and prediction of the pavement conditions are crucial. This study proposes a neuro-fuzzy model to predict the performance of flexible pavements using the parameters routinely collected by agencies to characterize the condition of an existing pavement. These parameters are generally obtained by performing falling weight deflectometer tests and monitoring the development of distresses on the pavement surface. The proposed hybrid model for predicting pavement performance was characterized by multilayer, feedforward neural networks that led the reasoning process of the IF-THEN fuzzy rules. The results of the neuro-fuzzy model were superior to those of the linear regression model in terms of accuracy in the approximation. The proposed neuro-fuzzy model showed good generalization capability, and the evaluation of the model performance produced satisfactory results, demonstrating the efficiency and potential of these new mathematical modeling techniques.

Effects of Silt Content and Void Ratio on the Saturated Hydraulic Conductivity and Compressibility of Sand-Silt Mixtures

The hydraulic conductivity, the coefficient of consolidation, and the coefficient of volume compressibility play major roles on the pore pressure generation during undrained and partially drained loading of granular soils with fines. This paper aims to determine how much these soil parameters are affected by the percentage of fines and void ratio of the soil. The results of a large number of flexible wall permeameter tests performed on 60 specimens of two poorly graded sands with 0, 5, 10, 15, 20, and 25% nonplastic silt are presented and discussed. Hydraulic conductivity measurements were done at effective confining stresses of 50–300 kPa. The evaluation of the data shows that the hydraulic conductivity and the coefficient of consolidation of sands with 25% silt content are approximately two orders of magnitude smaller than those of clean sands. The coefficient of volume compressibility of the sand-silt mixtures is affected in a lesser degree by void ratio, silt content, and confining stress. The influence of the degree of saturation on the laboratory-measured k values is also discussed.

Use of tire bales for erosion control projects in New Mexico

The use of tire bales in civil engineering and transportation projects is receiving growing attention because of its potential to safely and economically dispose a large number of scrap tires. In recent years, tire bales have been successfully used as fill material in several erosion control and bank reconstruction projects in New Mexico. This paper describes two tire bale projects conceived and constructed by technical support engineers and maintenance crews of District 1 of the New Mexico Department of Transportation (NMDOT). In these projects, 160 to 610 tire bales (approximately 16,000 to 61,000 scrap tires) were used. The materials and construction details adopted in these projects and the standard practice resulting from the experience of NMDOT District 1 personnel are described. Some construction considerations in these projects include anchoring the bales to the ground, wrapping the layers of bales with gabion wire, and backfilling.

Numerical Approach to Model the Effect of Moisture in Adobe Masonry Walls Subjected to In-Plane Loading

ABSTRACT This article proposes a numerical modeling approach to account for the weakening effect of moisture on the in-plane (lateral) resistance of adobe masonry walls. The approach uses a variable that links the water content of the soil to its strength properties, with varying locations of a moist region in the wall (i.e., length across the wall). A nonlinear, isotropic finite element model was used to study adobe walls at the macro scale. The adequacy of the proposed approach was examined numerically through finite element (FE) analysis for I-shaped adobe walls with varying length and water content of a moist region along the base. The analysis showed that the lateral strength of adobe walls, defined as the maximum force required to cause a given displacement, may drop considerably (up to about 40% for the cases considered) depending on the length, location, and water content of the moist (weakened) region of the wall.