Method of constructing underground pile having expanded bulb and underground pile having expanded bulb constructed by the method
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. Field of the Invention
The present invention relates generally to methods of constructing underground piles for reinforcing the ground and, more particularly, to a method of constructing an underground pile having an expanded bulb on a lower end or an intermediate portion thereof.
2. Description of the Related Art
As well known to those skilled in the art, when structures, such as buildings, railroad lines, bridges, etc., are constructed on soft ground, pile foundations are widely used to prevent the structures from sinking and to ensure supporting force for the structures.
In methods of constructing a pile foundation, there are a method of driving or embedding a premanufactured concrete pile into the ground, and a method of boring a hole in the ground, and charging grout, such as mortar, concrete, molten glass and asphalt, into the hole, thus forming an underground pile. The present invention relates to the method of boring a hole in the ground at a construction site and charging grout such as mortar into the hole, thus forming an underground pile.
The inventor of the present invention proposed, in Korean Patent Registration No. 10-0213577 and in Korean Patent Laid-open Publication No. 2003-6083, rapidly expanding metal compounds, which comprise metal salt as an oxidizing agent, metal powder that is oxidized by the metal salt and is thus increased in volume by an exothermic reaction due to the oxidation, and a promoter that promotes the oxidation reaction between the metal salt and the metal powder. Here, metal nitrate, metal oxide, metal oxalate, metal carbonate and metal sulfate can be used as the metal salt. Aluminum, manganese, magnesium and metal, which can be used as reducers, are used as the metal powder. Furthermore, the inventor of the present invention proposed, in Korean Patent Laid-open Publication No. 2003-37707, a room temperature antioxidized rapidly expanding metal compound, in which oil or inorganic antiseptic is added to a rapidly expanding metal compound including metal salt and metal powder.
In the present invention, a rapidly expanding metal compound means the rapidly expanding metal compound proposed in Korean Patent Laid-open Publication No. 2003-6083 or Korean Patent Laid-open Publication No. 2003-37707.
When the rapidly expanding metal compound is detonated using a high temperature spark or shock heat in a sealed space, a sequence of momentary oxidation-reduction reactions results, so that superhigh pressure metal and metallic oxide steam is generated, thus rapid expansion occurs. After the rapidly expanding metal compound has been rapidly expanded, when the expansion volume and expansion pressure reach predetermined levels, expansion energy is lost, so that it instantly contracts into a liquid or solid phase of metal or metallic oxide. The reason for this is that, because the coefficient of expansion is relatively small, power thereof is exhibited merely within a relatively small range. Using such characteristics of the rapidly expanding metal compound, a noiseless, vibrationless and spatterless rock fracturing operation can be conducted.
Furthermore, the inventor of the present invention developed a method and device for contact-detonating a rapidly expanding metal compound, which were registered in Korean Patent Registration Nos. 10-283505 and 10-442551. In Korean Patent Registration Nos. 10-283505 and 10-442551, when high voltage is applied to a conducting wire (a resistor wire), which is embedded in the rapidly expanding metal compound, the conducting wire is rapidly heated and a spark is caused. Thus, the rapidly expanding metal compound is ignited by the spark.
The inventor of the present invention has conducted many rock fracturing operations in the world using the rapidly expanding metal compounds and the contact-detonating devices therefor. The present invention represents a new use for the rapidly expanding metal compound.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an underground pile constructing method in which an outward expanded bulb can be formed around the pile at a lower end or at an intermediate position, and an underground pile having an expanded bulb constructed by the method.
Another object of the present invention is to provide a method of constructing an underground pile, which has a relatively superior supporting force, at reduced cost and in a short period.
Another object of the present invention is to provide an underground pile having an expanded bulb which can exhibit superior supporting force despite having reduced length and diameter compared to a straight pile, thus providing superior ground reinforcing ability despite the use of a reduced number of piles compared to the conventional art.
In order to accomplish the above object, the present invention provides a method of constructing an underground pile having an expanded bulb, including: charging liquefied grout into a hole bored in the 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 is cured, so that a portion of the hole is widened and the grout is charged into the widened portion.
Preferably, 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.
The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
Hereinafter, a method of constructing an underground pile having expanded bulbs according to a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.
First, a rapidly expanding metal compound 101 used in the present invention and the capsule 100 containing the rapidly expanding metal compound 101 therein will be explained herein below.
The rapidly expanding metal compound 101 is a compound in which metal powder and a metal salt, which oxidizes the metal powder at a high temperature using its own oxygen atoms, are mixed at a weight ratio of 0.1:99.9 to 99.9:0.1. It is preferable that the metal salt be 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 be a compound of at least two of them. Furthermore, it is preferable that the metal powder be one selected from 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 be a compound of at least two of them.
The rapidly expanding metal compound 101 is contained in an inner casing 103, which is made of synthetic resin such as PVC (polyvinyl chloride), and is contained in an outer casing (105, 107a and 107b), which is sealed and is made of steel, fiber reinforced plastic or polycarbonate, thus forming the capsule 100. Carbon fiber reinforced plastic and glass fiber reinforced plastic are representative examples of the fiber reinforced plastic used in the present invention. Furthermore, the carbon fiber reinforced plastic and the glass fiber reinforced plastic, which are high-strength plastic, and polycarbonate have superior plasticity despite having strength similar to steel. Therefore, the outer casing is preferably made of the above high-strength material rather than steel. Furthermore, for oxidation-reduction reaction of the rapidly expanding metal compound 101, a high oxidation detonating temperature and a sealed space ensuring a predetermined pressure are required. Therefore, the above high-strength material is preferably used as the material of the outer casing. Although the outer casing is illustrated in
Meanwhile, a resistor wire 109, which generates a spark for creating an oxidation reaction, is embedded in the rapidly expanding metal compound 101. The resistor wire 109 is connected to power supply wires 111, which extend outside the inner casing 103 and the outer casing (107a, 107b) of the capsule 100. The power supply wires 111 are connected to a contact-detonation device 113, which generates high instantaneous voltage. When high voltage is applied to the resistor wire 109 by the contact-detonation device 113, heat is supplied, and the resistor wire 109 fuses, thus inducing a high current discharge. Then, a spark is generated by the high current discharge, thereby the rapidly expanding metal compound 101 explodes.
Hereinafter, the method of constructing the underground pile having expanded bulbs using the rapidly expanding metal compound capsule 100 having the above-mentioned construction and operation will be explained with reference to
As shown in
After the process of inserting the rapidly expanding metal compound capsules 100 into the grout 7 has been completed, the power supply wire 111 is connected to the contact-detonation device 113, and high voltage power (3,000V or more) is applied. Then, the rapidly expanding metal compounds and the capsules 100 containing them explode and expand, so that portions of the ground 5 around the rapidly expanding metal compound capsules 100 are widened and the grout 7 is instantaneously charged into the widened portions, as shown in
Thereafter, as shown in
As described above, according to the present invention, expanded bulbs which protrude outwards can be easily formed on predetermined portions of an underground pile and, simultaneously, the soil around the pile can be hardened. Furthermore, the construction period and construction cost of the underground pile having the expanded bulbs are markedly reduced. As well, the underground pipe having the expanded bulbs 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.
Although the preferred embodiment of the present invention has been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
Claims
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.
Type: Application
Filed: Jun 12, 2007
Publication Date: Dec 20, 2007
Inventor: Chang Sun Kim (Incheon)
Application Number: 11/808,757
International Classification: E02D 13/00 (20060101);