One important parameter that influences rock strength variation is compaction rate. The rate of penetration of drill bit will vary in Strongly compacted rocks and under compacted rocks.

Dear Sir,

I agree compaction rate is one of the parameter for variation of rock strength. But please let me clarify, I have performed rock drilling operations on CNC machine. In this case constant penetration rate, constant speed and fixed drill bit diameter was used from rock drilling.

Q. If we fixed constant penetration from rock drilling operations, Is it valid reason compaction rate causes for rock strength variations?. Can you send any reference regarding compaction rate cause for rock strength variation.

Thanking you,

Ch.Vijaya Kumar

NITK Surathkal.

"Rock strength" depends on frictional forces and hence confinement stress. Two important factors here are pore pressure (determines effective stresses) and Poisson's ratio (determines horizontal stress).

Thank you for your valuable suggestions.

Regards

Ch.Vijaya Kumar.