OasisLMS

Abstract: Precast nodular piles have been used in Japan for close to 100 years. In recent years, nodular piles consist of precast high-strength concrete (PHC) spun piles having nodules at fixed intervals over the pile shaft. Early on, nodular piles were installed by driving through a pile of crushed stones such that the stones filled up and packed the space abound the pile shaft between nodules. Due to regulations governing vibration and noise control enacted around 1970, installation of nodular piles has changed to a bored precast pile method in which the pile is placed in the drilled hole and then grouted with cement milk.

In the case of the bored pile method, the integration of soil cement and a nodular pile results in high shaft friction resistance along the outer soil cement interface, so it has been mainly used as friction piles in many low to mid-rise buildings in Japan. At present, nodular piles are used not only as friction piles, but also as end bearing piles. For higher end bearing capacity, a base enlarged pre-boring method has been developed. The enlarged base part is constructed at the pile toe which can be up to 2 times the nodule diameter. Bored PHC nodular piles in combination pre-boring with enlarged base has been widely used in Japan to provide high axial load bearing resistance to support buildings. In this paper, we will present the background and development of nodular piles in Japan together with the load transfer mechanism and design practice concerning bored PHC nodular piles.

Engr. Dr. Yujiro Tanaka; Dr. YUSUKE HOMMA

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