According to the mechanical characteristics of rock-socketed anchoring rods under pile toe in the system of vertical load-bearing capacity test of pile foundation by the self-anchored technique

a new load transferring function suitable for anchoring rods under pile toe is set up based on the dilatancy effect between anchorage-body and surrounding rock; and an analytical solution of the critical anchorage length is obtained as well. Then

the distribution of frictional resistance along the anchorage length and the influencing factors are discussed in detail based on the obtained analytical solution; and a parameter ? is introduced to consider the comprehensive influencing effect of various factors approximatively. Comparative analysis result of an engineering example shows that the calculated values by the present method agree well with the measured data.