REINFORCEMENT TECHNIQUES OF ANCHOR PILES FOR PILE BEARING CAPACITY TEST WITH LARGE VERTICAL LOADS

Pile bearing capacity is an important parameter in foundation design.One of the key means to determine the pile bearing capacity is the conventional static load test at construction site.A pile testing project at Luohe Bridge along Huangling-Yanan Highway employs the piles of the bridge as the anchor piles.The anchor piles are stressed to form an anchor-pulling system.The test pile stress,the anchor pile stress and the displacement on top of the pile measured during the loading test show that it is feasible for the anchor-pulling system to use pre-stress technique and to take the piles of bridge as anchor piles for the static pile load test.At the same time,the equation is developed to determine the value of prestressing force applied to the anchor piles.Essential measures to make sure that those piles still have sufficient bearing capacity for the bridge after being used as anchor piles are also put forward.The results of this paper are of significance to shorten the construction period,reduce the test cost and broaden the application scope of prestressing techniques.