Civil Engineering May 2021 | Vol 29 No 4

Civil Engineering May 2021 5 strips provides a coherent gravity block when subject to working loads (Figure 1). 3. High adherence The strips are ribbed which mobilises the full angle of internal friction of the backfill. The shear plane is in the backfill on top of the ribs and not between the reinforcement and the backfill (Figure 2). A granular backfill dilates during shear. The apparent coefficient of friction increases significantly towards the top of the structure. 4. Padded HAR strips are padded, enabling the strength at the connection to the clad- ding to be greater than the strength in the strip length. This ensures that the full elongation after yield will occur and an indeterminate structure is created (Figure 3). 5. Robust and durable Coarse, rocky backfill material will not damage the strips (Figure 4). 6. Constructability The strips are stiff and consequently there is no need to tension them before backfill is placed (Figure 5). For more information contact Reinforced Earth South Africa www.recosa.co.za | +27 (0)11 726 6180 resa@recosa.co.za No cracking ACTIVE ZONE RESISITIVE ZONE Line of maximum tension failure plane does not develope Idealized limit of active zone (AASHTO) Limiting shear stress for pullout Significant tension over full length Zero tension Maximum tension INEXTENSIBLE REINFORCEMENTS Location of maximum tension Cracking possible Active wedge RESISITIVE ZONE Maximum tension Strain in the reinforcement allows failure plane to develop Limiting shear stress for pullout Tension near zero Location of maximum tension over short length EXTENSIBLE REINFORCEMENTS Figure 1 Inextensible and extensible reinforcements Figure 2 Ribbed strips mobilise the full angle of internal friction of the backfill Figure 5 Installation of steel reinforcing strips of varying lengths, according to the design Figure 4 The strips are durable enough not to be damaged by coarse backfill material Figure 3 HAR strips are padded