How to stop C# from replacing const variable with their values?

I think usage of static readonly modifiers fits your needs:

public static class Consts
{
    public static readonly string a = "a";
    public static readonly string b = "b";
    public static readonly string c = "c";
}

Constants are hard-coded on the call-site, so that is your problem. Static readonly variable can be modified only in variable declaration or static constructor of Consts class, and it will not be inlined on the call-site.