Page 106 - Lecture Notes DCC3113
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viii. Define equivalent thickness, TA’ using Nomograph Thickness
Based on subgrade CBR, ESA and TA values (Using Figure 2)
In case of varying CBR for 1m depth of sub-grade, mean CBR is determined as follows:
CBR m = [(h 1CBR 1 + h 2CBR 2 + … + h nCBR n ) / (1000)]
3
1/3
1/3
1/3
Where:
CBRm = mean CBR for that location
CBR1, CBR2, … CBRn = CBR of soil strata
h1, h2, … hn = thickness of soil strata (mm)
h1 + h2 + … + hn = 1000 mm
Make sure TA ≥ TA’
vii. Sketch the designed thickness
99
