İnvestigation of retaining walls and retaining earth walls constructed in highway projects

In this study, retaining wall and reinforced earth structures used at highways were investigated according the real project values. The change in internal friction angle of backfill material behind the wall (Ø), internal friction angle (Ø) and cohesion (c) of natural soil behind the wall, natural soil slope (α), height of wall (H), surcharge load (q), ground water level were considered during the design stage of cantilever wall. While the height of retaining wall changes between 4 m and 19 m with a one meter intervals, natural soil slope behind the wall was taken as 0o and 18o to represent the real ranges. A surcharge load was applied from 5 kN/m2 to 20 kN/m2 in addition to unloaded case as well as the assumption of various frost depth values ( 0,5 m, 1,0 m, 1,5 m). Rankine active and passive earth pressure theories were used to make static analysis of cantilever walls. The limit factor of safeties of retaining walls against overturning, sliding and bearing capacity were considered as 2.0, 1.5 and 3.0, respectively. Increasing of surcharge load, natural soil slope, wall height and ground water level decreases the factor of safeties against overturning, sliding and bearing capacity of retaining wall. While frost depth increment increases factor of safeties against sliding and bearing capacity, it does not effect that of overturning. Steel strip reinforcements and real project parameters mentioned above were used to design of reinforced earth structures. Similarly, wall heights were taken from 1 m to 19 m with a one meter intervals and horizontal distance of strips were taken as 0.25, 0.50, 0.75 and 1.00 meters. While increments of life span of strips increase the thickness of strips, it does not affect the length of strips. Key Words: Centilever Retaining Wall, Reinforced Earth Wall, Height of Wall, Surcharge Load, Frost Depth, Ground Water Level.