9.2.9 Shear Keys


Shear keys are sometimes used to provide additional sliding resistance for a counter term to rock/soil buttress. The main purpose of a shear key is to force the critical slip circle deeper into a stronger underlying formation, thereby increasing the resistance along the slip surface (Figure 9 & 10). This method is very practical and cost effective if the stronger formation is only a few meter below the overlying soft soil. Construction of such shear keys require excavation of a trench at the toe of the slope.  

Figure 9: Working mechanism of shear keys. 

Figure 10: making of shear key by replacing loose soil with strong and resists soil