Based on the view of distribution laws of internal forces of pile and internal forces keep in a balance between rock-socketed pile and pile rock interface, pile shaft resistance strengthening effect — rock-socketed pile shaft resistance increased with the increasing of pile tip rock uniaxial compressive strength or elastic modulus and load at pile top was analyzed; mathematical expression of quantitative indicators of pile shaft resistance strengthening effect was established, including pile shaft resistance strengthening coefficient to pile shaft rock internal friction angel, uniaxial compressive strength or elastic modulus and load at pile top; The concept of the expression was...