An Assessment of Vertical and Lateral Resistance to Deformation of Reinforced Earth Model

Abstract

Gypseous soil exhibits suitable strength after compaction but it loses the strength when subjected to the environment. This can cause hazard when it is implemented in the construction of roadway embankment. The studies on the mechanical properties of reinforced embankments during service stage are so few, and lack of measured data. In the present investigation, Gypseous soil with 84.2 % of gypsum content was obtained from Tikret region, (180 km north of Baghdad) at middle north part of Iraq. It was compacted to 95 % of its maximum dry density to the pre-determined dry unit weight of (16.4 kN/m³ ) in six layers in the metal box with the dimensions of (50 x 50 x 30) cm and each layer is of 5 cm thickness to form a control embankment model, and subjected to vertical stress. Test was carried out using proving ring of 5 kN capacity. The vertical and lateral deformations of the embankment model were monitored until failure. Another embankment model was constructed using an aluminum reinforcing strips spread at five layers of the embankment height. The aluminum reinforcing strips was laid at equal spaces between each of them, which means that each layer was reinforced with four strips at a spacing of 10 cm center to center. The vertical and lateral deformations were also monitored until failure. It was observed that the reinforced embankment model exhibit lower vertical deformation of 40 % as compared with the control embankment. On the other hand, the lateral deformation at the third and fifth embankment layers declines by (36.8 and 76.7) % respectively when the earth reinforcements were implemented. However, the lateral deformation at the fifth layer was (66.6 and 50.5) % lower than that at the third layer for reinforced and control embankment models respectively. It was concluded that the earth reinforcement can better sustain the vertical stresses applied on the embankment surface by 336 % as compared with the control embankment.