Model test of vertical bearing capacity of cast-in-situ X-shaped concrete piles

To study the load settlement characteristics and load-transfer mechanism of cast-in-situ X-shaped concrete piles,full-scale model pile load test of X-shaped pile is carried out by using the large-scale test trench of Hohai University.The interaction behavior of the vertical loaded X-shaped piles is obtained by means of the reinforcement stress gauges set in the pile and earth-pressure boxes embedded in the pile bottom.The experiment results show that: X-shaped pile load settlement curve is an adjustment curve;pile side friction and tip resistance show incremental development with the increasing pile settlements;but with the increase of pile top load,the ratio of pile side resistance sharing pile head load is regressive,its sharing ratio decreases from the initial load of about 90% to 70% of the limit state,while the ratio of tip resistance sharing the load is incremental,the pile top load-sharing ratio of about 10% from the initial state up to 30% of the limit.The research results are useful for the design and analysis of X-shaped piles under vertical load.