The present invention relates to a front-end extendable pile and a construction method therefor, the front-end extendable pile capable of increasing the allowable bearing capacity of a pile by rapidly enlargedly cutting the ground at the front end of the pile and simultaneously forming a pile expansion part in various stratums using simple equipment without a separate reaming drill. The front-end extendable pile of the present invention is installed in a perforated hole formed under the ground and comprises: a pile main body; and an enlargement part which is coupled to the lower section of the pile main body and of which the diameter expands when rotating, wherein the enlargement part comprises: an upper guide member which is coupled to the lower section of the pile main body; a lower guide member which is provided at the lower section of the upper guide member so as to be spaced apart from the upper guide member at certain intervals; a cylindrical connection member which connects the centers of the upper guide member and the lower guide member to each other and has a plurality of entry and exit holes formed on the outer circumferential surface thereof; and a plurality of extension bodies which are installed between the upper guide member and the lower guide member at the outside of the connection member and comprise: arc-shaped blade portions having cutting tips coupled to the outsides thereof; and pressurizing portions which are provided at the rear ends of the blade portions and are inserted in the entry and exit holes of the connection member.

La présente invention concerne un pieu à extrémité avant extensible et un procédé de construction associé, le pieu à extrémité avant extensible étant capable d'augmenter la capacité portante admissible d'un pieu grâce à sa capacité de pénétrer rapidement dans le sol et s'élargir à sont extrémité avant ainsi que de former une partie à dilatation pieu dans différentes couches au moyen d'un équipement simple ne nécessitant pas de foret d'alésage séparé. Le pieu à extrémité avant extensible de la présente invention est placé dans un trou perforé formé dans le sol et comprend : un corps principal de pieu ; une partie à élargissement couplée à la section inférieure du corps principal de pieu et dont le diamètre s'agrandit lors de la rotation, la partie à élargissement comprenant : un élément de guidage supérieur couplé à la section inférieure du corps principal de pieu; un élément de guidage inférieur ménagé au niveau de la section inférieure de l'élément de guidage supérieur de manière à être espacé de l'élément de guidage supérieur à une certaine distance ; un élément de raccordement cylindrique qui relie les centres de l'élément de guidage supérieur et l'élément de guidage inférieur l'un à l'autre et comporte une pluralité de trous d'entrée et de sortie formés sur sa surface circulaire externe ; une pluralité de corps à dilatation est installée entre l'élément de guidage supérieur et l'élément de guidage inférieur au niveau de l'extérieur de l'élément de raccordement et comprennent: des parties de lame en forme d'arc ayant des pointes de coupe couplé à l'extérieur de celui-ci; et des parties sous pression prévues aux extrémités arrière des parties lame et insérés dans les trous d'entrée et de sortie de l'élément de raccordement.

본 발명은 별도의 확공드릴 없이 간단한 장비를 이용하여 다양한 지층에서 신속하게 말뚝 선단 지반을 확경 절삭함과 동시에 말뚝 확대부를 형성함으로써, 말뚝의 허용지지력을 증가시킬 수 있는 선단 확장 말뚝 및 이의 시공 방법에 대한 것이다. 본 발명의 선단 확장 말뚝은 말뚝 본체 및 상기 말뚝 본체의 하부에 결합되는 것으로 회전하면서 지름이 확장되는 확경구로 구성되어, 지중에 형성된 천공홀에 설치되는 것으로, 상기 확경구는 상기 말뚝 본체의 하부에 결합되는 상부가이드부재; 상기 상부가이드부재 하부에 상부가이드부재와 일정 간격 이격되도록 구비되는 하부가이드부재; 상기 상부가이드부재와 하부가이드부재의 중앙을 서로 연결하는 것으로 외주면에 복수의 진출입공이 형성된 통 형상의 연결부재; 및 상기 연결부재 외측의 상부가이드부재와 하부가이드부재 사이에 설치되는 것으로 외측에 절삭팁이 결합된 호 형상의 날개부 및 상기 날개부 후단에 구비되는 것으로 상기 연결부재의 진출입공에 삽입되는 가압부로 구성되는 복수의 확장체; 로 구성된다.