Prediction based Subgrade Moisture Thornthwaite Moisture Index

Abstract:

Subgrade moisture has critical effect on performance of pavement structure and life of highway. Selection of indexes appropriately suggests influence factors are important for prediction of moisture. First, the factors of subgrade moisture were merged into climate condition and groundwater. Furthermore, thornthwaite moisture index(TMI), which comprehensively reflects influence of climate and latitude was introduced. Then, the calculation process of TMI was divided into three steps including calculation of potential evapotranspiration, moisture balance and calculating annual value of TMI. Moreover, example was presented to validate calculation procedure of TMI. Finally, values of TMI calculated on the basis of the meteorological data collected from 400 weather stations of China were tabled according to climatic zoning of highway. The results show that TMI can be used as new criterion to classify climatic zoning for highway.

Key words:moisture of subgrade; climate factor; thornthwaite moisture index (TMI); potential evapotranspiration; moisture balance; climatic zoning