Question

What is relation of bearing pressure on soil nail head to ratio La/Lb, where La is length of soil nail before potential slip circle as Lb is length of soil nail beyond potential slip circle?

Answer

Unstable soil mass before potential circular slip is resisted by two components- soil nail head bearing pressure and friction of soil nail in unstable soil mass. Therefore, longer is length of soil nail previous to potential slip circle La; higher is proportion of forces being resisted by frictional forces and therefore smaller amount is to be opposed by soil nail head. Therefore, smaller the ratio La/Lb, the greater is resistance provided by soil nail head.