Method of constructing underground pile having expanded bulb and underground pile having expanded bulb constructed by the method

Abstract

Disclosed herein is a method of constructing an underground pile having an expanded bulb on a lower end or an intermediate portion thereof. In the method of the present invention, liquefied grout is charged into a hole bored in the ground, and a rapidly expanding metal compound of metal powder and a metal salt is inserted into the grout. Thereafter, the rapidly expanding metal compound is exploded in the grout before the grout is cured, so that a portion of the hole is widened and the grout is charged into the widened portion. According to the present invention, the expanded bulb which protrudes outwards can be easily formed at a predetermined position of the underground pile and, simultaneously, the soil around the pile can be hardened. Furthermore, the construction period and construction cost of the pile having the expanded bulbs are markedly reduced. As well, the underground pipe having the expanded bulb according to the present invention can exhibit superior supporting force despite having reduced length and diameter compared to the straight pile. Therefore, the present invention makes it possible to provide superior ground reinforcing ability despite using a reduced number of piles compared to the conventional art.

1 . A method of constructing an underground pile having an expanded bulb, comprising: charging liquefied grout into a hole bored in ground; inserting a rapidly expanding metal compound of metal powder and a metal salt into the grout; and exploding the rapidly expanding metal compound in the grout before the grout cures, so that a portion of the hole is widened and the grout is charged into the widened portion. 
   
   
       2 . The method as set forth in  claim 1 , wherein the rapidly expanding metal compound is contained in an outer casing made of steel, fiber reinforced plastic or polycarbonate and is inserted into the grout. 
   
   
       3 . The method as set forth in  claim 1 , wherein the rapidly expanding metal compound comprises a compound in which the metal powder and the metal salt that oxidizes the metal powder at a high temperature using oxygen atoms thereof are mixed in a weight ratio of 0.1:99.9 to 99.9:0.1. 
   
   
       4 . The method as set forth in  claim 1 , wherein the metal salt is one selected from among a metal nitrate, a metal perchlorate, a metal peroxide, a metal oxide, a metal oxalate, a metal carbonate and a metal sulfate, or is a compound of at least two thereof. 
   
   
       5 . The method as set forth in  claim 1 , wherein the metal powder is one selected among aluminum (Al) powder, sodium (Na) powder, potassium (K) powder, lithium (Li) powder, magnesium (Mg) powder, manganese (Mn) powder, barium (Ba) powder, chromium (Cr) powder and silicon (Si) powder, or is a compound of at least two thereof. 
   
   
       6 . An underground pile having an exploded bulb constructed through the method according to  claim 1 . 
   
   
       7 . An underground pile having an exploded bulb constructed through the method according to  claim 2 . 
   
   
       8 . An underground pile having an exploded bulb constructed through the method according to  claim 3 . 
   
   
       9 . An underground pile having an exploded bulb constructed through the method according to  claim 4 . 
   
   
       10 . An underground pile having an exploded bulb constructed through the method according to  claim 5 .