Abstract
This paper studied the application of 2-D Plaxis (v8.6, 2011) software on a pavement layer structure set on unsaturated subgrade soil. An axisymmetric finite element (FE) model was used to analyze the behavior of pavement layers subjected to dynamic loadings. The model was loaded with an incremental contact pressure from 50 to 550 kPa with different variable such as water table level (1,2 and 3m), suction of soil and degree of saturation (100, 90, 80, 70 and 20%). The results indicated that during loading on pavement layer with increases water table level and different degree of saturation the vertical settlement was decreased by about (11, 15, and 18%) for water table level= 1m, (9, 13, 16%) for water table level= 2m and (28%) for water table level= 3m (dry soil) respectively. The effect of degree of saturation on the vertical settlement is apparent at the lower value for water table level (1 and 2m) and the vertical settlement is decreased with increasing soil suction. The results also show the negative pore water pressure decreased with decreased of degree of saturation and development increases with depth and beginning of dynamic load. The effect of unsaturation greater at the center line of pavement layer and limited far away the center line.
Highlights
1.IntroductionCompacted soils that are typically unsaturated with degrees of saturation varying from 75 to 90%
Compacted soils that are typically unsaturated with degrees of saturation varying from 75 to 90%The vertical loading that is dissipated through the wheel of the moving vehicles causes compressive stress in the pavement structure
From the analysis carried out plaxis program on pavement system layer the following points can be draw: 1. The vertical settlement closely similar at the beginning time increased with time for water level at depth 1m and 2m
Summary
Compacted soils that are typically unsaturated with degrees of saturation varying from 75 to 90%. An attempt has been made to investigate the influence of soil suction, degree of saturation and change in water table on the behavior of unsaturated subgrade soil within the asphalt concrete pavement through the application of 2D Plaxis software program. Clays contain salts and these salts cause a reduction in the vapour pressure This results in an increase in the total suction, and this increase is the energy needed to transfer water into the vapour phase (i.e. the osmotic suction) [10]. Two constitutive models were used to characterize the load settlement and time settlement relations of the unsaturated subgrade soil under dynamic load. Linear elastic model was used for the asphalt layer while elastic plastic with Mohr-Coulomb failure under undrained condition for unsaturated subgrade soil layer and drained condition for sub-base layer
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