STRESS RELATIONSHIPS ON A 

 PLANE PARALLEL TO THE GROUND 

 SURFACE WITHIN AN INFINITE SLOPE 



The term, infinite slope, is defined as a slope of constant inclination of unlim- 

 ited extent. For practical purposes, a slope that has a length to depth ratio of 20:1 

 or greater has been considered an infinite slope. 



The classical' infinite slope analysis requires that soil properties be constant at 

 any and all vertical sections along the slope. If this requirement is met, the slope 

 can be studied by analyzing the stress conditions within an elemental volume of soil. 



Figure 1 shows the basic assumed geometry of the infinite slope. In figure 1, Z 

 is the depth to the plane of investigation, Z w is the depth to the water table, and 

 (Z-Z w ) is the vertical distance from the water table to the plane of investigation. 

 The total unit weight of the soil material above the water table is denoted as y , an d 

 Y sa t is the saturated unit weight of the soil. The angle the ground surface makes with 

 the horizontal is denoted as 6. It is assumed that the planes representing the ground 

 surface and the water table are parallel. 



Figure 1. --Pro file of an infinite slope. 



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