Pavements founded on expansive soils are damaged because of seasonal wetting and drying of the foundation soils. the magnitude of the damage is controlled by the wettest and driest moisture content profiles that occur at the site. the moisture profiles are altered with the removal or replenishment of soil moisture by the meteorological conditions. because weather conditions cannot be predicted accurately, the extreme moisture content profiles are stochastic. the purpose of this study is to characterize the wettest and driest moisture content profiles that have the desired probability of occurrence during the lifetime of the pavement. the wettest and driest profiles are associated with the respective annual maximum and minimum depths of water stored in the soil profile. the stored depth of water in thesoil profile is obtained by using a daily water balance to calculate the accumulation or depletion of water in the profile. the replenishment is due to rainfall and runoff from the adjacent pavement surface. the depletion of the profile is due to the actual evapotranspiration. the daily water balance is calculated using a consecutive series of annual events. each year is characterized by the maximum and minimum water depths stored in the soil profile. the fact that both the maximum and minimum depths of stored water have distributions oftheir probability of occurrence makes it possible to define the probabilistic "design event." the design events are the maximum and minimum water depths that have the desired probability of not being exceeded in the lifetime of the pavement. illustrated in this paper is this method for the climatic areas of houston, dallas-fort worth, and san antonio, texas. this paper appeared in transportation researchrecord no. 1137, soil mechanics considerations in arid and semiaridareas. for covering abstract see irrd no 817740.
Samenvatting