We are estimating lateral deflections for a socket in yielding rock and have developed p-y curves to take into account the potential for lateral shifting at the top of rock. I am uncertain as to what to enter for the soil modulus parameter k (pci) because I do not know how the program uses the factor. According to the program documentation at Chapter 4, k is the slope of the modulus E versus depth. This may be useful for soil, but the modulus is relatively insensitive to depth for rock. Examples included with the program show higher k factors with increased soil material stiffness, e.g., 90 for medium dense sand but 2000 for weak limestone. This would suggest a greater increase in mudulus with depth, not a lesser increase. I have access to relevant subgrade modulus values tabulated from plate loading tests, etc. for rock, but am hesitant to specify a k-factor that may mean something in the program that does not mimic reality. Does anyone know how to get COM624 to resolve this?