RAINFALL INTENSITY EFFECTS ON Flexible PAVEMENT LAYERS

Abstract

The main objective of this work is to study of effect of rainfall intensity on the thickness of pavements layers of flexible pavement structure. This is using Maple 13 software for modeling of this problem and calculation the rainfall intensity and pavement infiltration. It was found that pavement infiltration increases with increasing rainfall intensity because of, the increase in the rainfall intensity caused an increase in the infiltrated water to the base and sub-base layers. Accordingly an increase in pore water pressure resulted which intends cause an increase in porosity and decrease of base and subbase degree of compaction. Accordingly which leads to increase in time-to-drain, decrease in drainage coefficient for base and sub-base, and subsequently, request to increase their thickness. For flexible pavement, rainfall intensity 256 mm/hr is giving pavement infiltration, thickness and drainage coefficient 3.2m/day, 46 cm, 0.57 respectively and rainfall intensity 25 mm/hr is giving pavement infiltration, thickness and drainage coefficient 0.4 m/day, 18.5cm, 1.7 respectively. Drainage of accumulated water on pavement is accordingly drained rapid in as short time as possible due to minimize potential moisture damage to a pavement structure. It was found that soil type effects of moisture in pavement based on conditions of total saturation with loss of pavement strength from through affect the state of stress through suction (effective porosity) or pore water pressure and affect the structure of the soil through destruction of the cementation between soil particles because of, soil types difference in coefficient of permeability. Where, soil types have been used in this study Well-graded sand, Uniform dense sand and Fine-grain soil.