T b = T-t sb-t s Cross section of flexible pavement: Then we can easily calculate the value of thickness of the base course, Or otherwise assume the thickness of surface course (t s) = 5 cm The combined value of thickness of base and surface course can be found out from above chart form dotted curve with the help of group index value and traffic volume. Thickness of surface and base course = total thickness – sub-base thickness (Note: thick line indicates the total thickness value and the dotted line indicates thickness of surface and base)Ĭalculation thickness of sub-base course (t sb):įrom the below chart for given group index of soil subgrade select appropriate curve value of “thickness of sub base only” which will give the thickness of the sub-base course.Ĭalculation of thickness of base and surface course (t b & t s): Based on number of vehicles per day.īefore going to design the pavement we must know the structure of flexible pavementįrom the below chart for given group index of soil subgrade and traffic volume value select appropriate thick curve value of “combined thickness of surface, base and sub-base line” which will give the total thickness of pavement. It is denominated by commercial vehicles/day or CVPD. It is the measure of Annual average daily traffic, peak-hour traffic. Group index value range of different soils is given below Group Index Method of Flexible Pavement Design Data Required for Flexible Pavement Design 1. It varies from a value of 0 to 20, lower the value higher is the quality of the sub-grade and greater the value, poor is the sub-grade.īy sieve analysis test we can determine Group index value of soil subgrade from below equationĪ= percentage of soil passing 0.074 mm sieve in excess of 35 per cent, not exceeding 75.ī= percentage of soil passing 0.074 mm sieve in excess of 15 per cent, not exceeding 55.Ĭ= Liquid limit in per cent in excess of 40. Group Index is a number assigned to the soil based on its physical properties like particle size, Liquid limit and plastic limit.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |