Effect of Skewing and Splaying on Pullout Capacity of Steel Reinforcements in Mechanically Stabilized Earth Structures

Structures embedded in the reinforced fill of mechanically stabilized earth (MSE) retaining walls often prevent the soil reinforcements from being placed in their proper design configurations. Such conflicts are generally addressed with alternative reinforcement layouts that circumvent the obstructions. The most commonly used strategies include the skewing of strip-type reinforcements and the cutting and splaying of grid-type reinforcements. This research investigated the impact of skewing and splaying on the pullout resistance capacity of these two types of reinforcement. The research involved a series of pullout tests that were conducted in a specially designed large-scale pullout resistance test system. This MSE pullout load test system included an MSE test box with dimensions of 12 by 12 ft (3.66 by 3.66 m) in area and 4 ft (1.22 m) in depth. In this test system, the action of the soil overburden pressures on the embedded earth reinforcement were simulated with a reaction frame assembly that consisted of nine 4- by 4-ft (1.22- by 1.22-m) pressure plates that were hydraulically jacked against three wide-flange cross beams. The reaction frame assembly allowed the simulation of overburden pressures up to 40 ft (12.2 m) of fill. The pullout test program included (a) tests conducted on strip-type reinforcements with skew angles of 0°, 15°, and 30° and (b) tests conducted on grid-type reinforcements with splay angles of 0°, 15°, and 30°. The pullout loads obtained were then compared to determine the impact of skewing and splaying on the pullout resistance.