RETAINING WALLS 



343 



wall, increasing the base by the same amount that the top width 

 is decreased. 



A wall with a battered face may be made to give the same 

 stability with a materially smaller volume and average thickness 

 than would be required if a vertical wall were used. 



Rules for Surcharged Walls. When the surcharge runs 

 over the top of the wall, as in Fig. 3, there is a slight increase in 



SURCHARGED VERTICAL WALLS RATIO OF THICK- 

 NESS TO HEIGHT 



the weight resisting overturning by the addition of the triangle 

 of earth dcz, as well as the larger increase in the weight of the 

 wedge of backing pressing against the back of the wall. For a 

 height of surcharge less than about a quarter of the height of the 

 wall, the additional weight of the filling resting on the top of the 

 wall will offset the extra weight of the overturning wedge; but, 

 as the height of the surcharge increases, the overturning pres- 

 sure increases rapidly, while the increased resistance due to the 



