Behaviour of Unsaturated Subgrade Soil Under Highway Load

Hanan Adnan Hassan Afaj; Hadeel Amaar Mohammed; Ghassan  Nasser Jaffer

doi:10.24237/djes.2019.12104

Authors

Hanan Adnan Hassan Afaj Department of Highway and Transportation Engineering, Al-Mustansiriayah University, Iraq
Hadeel Amaar Mohammed Department of Highway and Transportation Engineering, Al-Mustansiriayah University, Iraq
Ghassan Nasser Jaffer
ghassan_hanan@yahoo.com
General company for trade construction material, Baghdad, Iraq

Keywords:

Unsaturated Soil, Soil Suction, Pavement, FE Analysis, Dynamic Loading

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.

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