PRD공법으로 시공한 암반 근입된 현장타설말뚝의 지지력 연구

Abstract

With the recent trend on the structures to be larger and heavier, large-size cast-in-place pile or mid-size cast-in-place pile, which provide bearing support for structures such as long span bridges or building foundations, are commonly produced. Small-size precast pile does not provide enough bearing capacity especially for skyscrapers, therefore, the usage of cast-in-place pile in rocks, which satisfies the requirement of bearing capacity, is increasing. In this study, it is discussed, with putting the design allowable bearing capacity to the minimum value which is measured and calculated by the method proposed by many other researchers, that the construction process of injection of a pile, which is produced by the method of P.R.D(Percussion Rotary Drill), into the hole with 800 mm diameter and 2 m depth, and compared and analyzed the design allowable bearing capacity of the pile by measuring, calculating, and adapting the minimum value of the designing resources proposed by many other researchers, and also, it is researched and examined that if it is able to establish the bearing capacity and stability by comparing and analyzing the result of dynamic pile loading test. From the result of dynamic pile loading test, it was showed that skin friction bearing capacity was much bigger than point bearing capacity. Also, point bearing capacity of the dynamic pile loading test was much less than those proposed by many other researchers. It is because the load, which delivers the weight to the tip, is not bigger than the skin friction bearing capacity. That means, point allowable bearing capacity can bear more than the maximum of load tested and so the foundation will still be safe, and it can bear as far as the inside strength of pile can bear. It was also observed that skin friction allowable bearing capacity from dynamic pile loading test was close to the calculation proposed from Poulos & Davis, D'Appolonia et al. With these observations, the interrelation between skin friction bearing capacity and point bearing capacity was analyzed.