Question

Flexible Pavement Design Homework Based on the data presented in following pages, determine structural layers' thickness (asphalt concrete, base, and subbase layers) for 15 years (Skip stage construction) Some hints to solve the problem 1- Calculate effective roadbed soil resilient modulus 2- Assume related drainage coefficient 3- Calculate layer coefficients 4- Make a good assumption for data that are not directly mentioned. Some of the important graphs and charts that you may need are also presented

Answer 1

you dont have provided the charts and data for design. Please upload again here I am providing you a general approach by California bearing ratio design of flexible pavement :

CBR method recommended by California state of highways:

Data required for flexible pavement design:

. CBR value of soil subgrade

b. CBR value of sub base course

c. CBR value of base course

d. Wheel load in KG or KN

Wheel load is classified into three groups based on traffic conditions.

Light traffic(3175 KG)

Medium traffic(4082 KG)

Heavy traffic (5443 KG)

Calculation of total thickness (T):

From the below chart for given CBR value of soil subgrade and Wheel load value select appropriate thick curve value of “combined thickness of surface, base and sub-base line” which will give the total thickness of pavement.

Calculation of sub base course thickness (tsb):

By using the above chart, for give CBR value of sub base course material and for wheel load read the thickness of pavement which is above the soil sub base. It is denoted as (Tsb). Which is highlighted by circle in the below fig. but here we have to find tsb.

Therefore, thickness of sub base course tsb =T – Tsb

Calculation of base course thickness (tb):

Similar to the above procedure, from the CBR value of base course and wheel load read the value of thickness of pavement which is above the base course (ts). From this we can find out the value of tb. tb = Tsb – ts

Therefore all the values of pavement are known and cross section of pavement is as follows.