In foundation excavating

upright post piles and engineering piles form a long -short pile composite foundation. According to the variation of shaft resistance around piles simulated by software ANSYS

we regard that short piles(engineering piles) will affect shaft resistance distribution around long piles(upright post piles). Based on shear displacement method，calculation formula for short piles’ influence is obtained. The affected shaft resistance distribution around a long pile is simplified at equal value

thus it can suit Geddes-stress theory. A new settlement calculation method of the long- short pile composite foundation is advanced; and a program PLS for settlement calculation of the upright piles is written. The calculation results accord with the engineering practice basically.