Scoring of subgrade : Scour highly reduces lateral soil support and Lateral soil support is very essential to bear maximum bending stress.
When the ultimate lateral pressure is lower then it was caused by decreased vertical effective stress and indirectly decreased the initial modulus of subgrade reaction.
How to reduce scour in subgrade :
Here I am discussing some points, through that we can easily reduce scour in the the the subgrade, they are as follows;
By the installation of geotextile carpet Using 3D geogrid By effective slope formation process By doing soil stabilization
I hope so your doubt is clear.