Dear reader we are discussing here about basis of analysis and necessary assumption taken in analysis of slope stability of proposed soil mass. We know that shear strength is the key issue that determines stability of slope.
Slope of soil mass should be such that soil mass is safe against failure of slope along any conceivable (plane or circular) surface. Now elastic or plastic theories are using increasingly to establish method of analysis. But common methods of analysis are developed base on the limiting equilibrium.
Now what is limiting equilibrium? Here it is assumed that soil mass is on the brink of failure. The method (limiting equilibrium) is statically indeterminate.
Due to indeterminacy, we cannot predict stress-strain relationships working along assumed surface and as usual we need some assumptions. With the help of assumption we will try to make the system statically determinate. This facilitated to produce sufficient equilibrium equation to solve the problem conveniently.
The forces that are active along failure surface and trying to result failure and their resultant are determined in analysis. The shear strength available in system is also determined. The assumptions that make the system determine will be discussed in next part, please stay with us. Till then good bye.