Model test study of impact of pile length on long-short piles composite foundation

In order to study the impact of pile length on the bearing properties of long-short piles composite foundation, distribution of the axial force and skin friction along pile, the bearing mechanics of long-short-pile composite foundation with long and short piles were studied based on laboratory tests in three different conditions: 60-centimeter-long long piles with 20-centimeter-long short piles, 60-centimeter-long long piles with 30-centimeter-long short piles and 60-centimeter-long long piles with 60-centimeter-long short piles in this paper. Keeping the length of long piles 60 centimeters, conclusions were as follows: the axial force of long piles decreased a little with the increasing of short piles length and the axial force of short piles increased obviously with the increasing of short piles length; No matter how the length of short piles changed, long and short piles always followed the law that the value of axial force of corner piles were the largest, followed side piles and then center piles; The value of long and short piles skin friction both decreased with the increasing of short piles length; No matter how the length of short piles changed, long and short piles always followed the law that the utilization degree of the skin fiction of center piles were the largest, followed side piles and then corner piles.