KR900005913B1 - Base stake inflated in bump state at lower end there of and its construction - Google Patents

Abstract

The method comprises excavating the soil at the lower end of the shell to an extent larger than the shell in its cross-section, for forming an enlarged base. The method then involves forcing a second charge of concrete through a pressurising tube, the open end of which is extended to the lower end of the excavated portion. This allows for penetrating the second charge of concrete into the region surrounding the base and the shell after a first charge of concrete fills and sets in the excavated portion and the shell.

Description

Foundation piles and their construction

1 is a cross-sectional view showing a state of driving the foundation pile.

2 is a cross-sectional view showing a state of hitting the head of the pile down with a core rod (봉).

3 to 5 are cross-sectional views showing a process of cutting between the pile tip and the head into a cavity as a cutting device.

6 is a cross-sectional view showing a state in which a cavity is detected.

7 is a cross-sectional view schematically showing the skeleton hypothesis.

8 is a cross-sectional view showing a state in which the pressure pipe (H) is inserted.

9 is a cross-sectional view showing a state in which the reinforced concrete is formed in a conical shape in accordance with the concrete injection.

10 and 11 are cross-sectional views showing the injection state of the soil stabilizer and mortar, respectively.

* Explanation of symbols for main parts of the drawings

P: pile body H: rotating body

10: pile head 11: mandrel

12: rotating body 13: cutting member

14: circumferential wall 15: sand gravel

16: cavity 17: ultrasonic device

18: skeleton 19: exit

20: concrete part 21: rough ground

22: mortar

The present invention relates to a foundation pile in which the lower end is inflated into a conical shape, and a method thereof. In particular, a PC (Prestressed Concrete) pile is driven into the soil, and then a large cone-shaped concrete body is formed at the lower end thereof. The present invention relates to a foundation pile and a method for stabilizing the ground by hardening and injecting mortar.

In the past, the problem of pile foundations was to put the support piles in the ground and to fix them on the hard soil layer.

Prior to this foundation work, the grounding point of the pile was determined by boring, sampling, penetration testing, and the like, but the anchorage point of the pile was determined.

In other words, a solid hard soil layer is preferable to support the upper structure and prevent settlement, but since the soil layer is hidden to a depth of several tens of meters underground or even less than 100 meters depending on the location, construction is difficult and construction cost is high. Because of the high cost, the piles were often increased to adopt subhard soil layers close to the surface, and in inevitable cases, soft soil layers having a relatively small bearing force qa were to be selected.

In addition, since the supporting pile is almost loaded at the front end of the pile, the bottom of the pile should reach the hard ground, but if it is a solid hard ground, it is inevitable to select a sandy or sandy clay layer. It was planned to increase the number of piles and the pile diameter to lower the allowable bearing force qa value of the soil at the pile end support surface.

This, of course, increases the cost of materials and construction costs, which makes the profitability unsuitable, and disturbs the soil structure of the pile circumference due to excessive pile impact and swing vibrations, resulting in foundation settlement and even floating settlement. It was also the cause of the cause.

In addition, in the design of the pile foundation, the number and diameter of piles suitable for the allowable bearing force qa value of the soil of the pile front end support surface are required, and the number of piles is appropriately designed within the allowable capacity of the pile material. It is desirable that the pile be fully utilized within the allowable bearing capacity of.

In practice, however, it is very difficult to satisfy both of them and the pile support surface is not able to fully utilize the pile bearing capacity because of the low bearing force qa value. This causes a waste of materials and is a problem to be solved in the future.

In addition, it is boring with PC piles and steel piles and turning cutting devices that are directly driven into the soil using conventional driving machines, and they form pillar-shaped holes in the soil and inject concrete into them to form piles. The material of the pedestal pile and the method of embedding the pile, which is one of the field production methods in which the steel pipe is embedded in the soil and extracted while replacing it, filling the space with concrete mortar The same problem can be mentioned.

In other words, the first purpose of the foundation pile is to transfer the load from the top to a certain depth in the ground. For this reason, the bearing strength of the support surface becomes a problem and it is as mentioned above to select the position of a support surface well.

In addition, if the sub-hard soil layer close to the surface is inevitably selected, the foundation of the pile and the steel pile is not necessarily superior to the pier foundation in basic engineering, so that the diameter of the pile is physically limited and the load on the supporting surface ( This is because it acts as iii) and is more likely to settle or float than the peer foundation.

Secondly, the foundation pile described above is characterized in that the working surface is formed in the shape of a surface by the formation of concrete bulbs, but rather the depth of the field-made concrete pile is rather than to compensate for the aforementioned drawbacks. Because of the limitation, it is thought that the lower end of the pile is formed into a bulb shape so that the allowable bearing force qa value can cope with a small support soil layer.In addition, since the bearing capacity of the pile itself is limited, it is difficult to support a large load except for economic reasons. Not desirable.

The present invention has been proposed to solve the above-mentioned drawbacks or the above-mentioned unsuitable points. That is, it is an object of the present invention to provide a foundation pile and a method for reducing the bearing pressure of the support surface by forming the pile lower end in a large cone-shaped concrete body.

Another object of the present invention is to inject soil stabilizer and mortar to strengthen the rough soil around the ground, and to provide a foundation pile and a method for increasing the bearing capacity and frictional force of the ground due to the closeness of the pile peripheral surface and the ground .

Therefore, the present invention injects a PC pile with a hollow conical pile head with a hollow core and a removable core at the bottom of the core to a predetermined ground, and separates the pile head from the pile body with a mandrel. The cutting device is inserted through the hollow part of the pile, and the cutting member of several rigid flexible cords attached to the rotating shaft of the pile is rotated at high speed near the top of the pile head. The soil circumference wall is cut by centrifugal rotation.

In addition, water is injected to assist cutting operations, while shaved soil is formed in the form of a hydrated sol. According to the bottom of the pile to form a substantially circular cavity, the reinforcing bar and the angle of the steel frame is assembled into the above-mentioned cavity, and expanded in the cavity, then hypothesized, and the pressure pipe together to fill the concrete mortar Finally, when the concrete mortar condenses after a certain curing time has elapsed and the concrete is formed into a conical shape, the above-mentioned pressure pipe is used to inject the soil stabilizer into the pile and the rough ground around the hump to harden the mortar. It is characterized by making a stable ground by filling the gap around the pressure by injecting upward from the bottom of the furnace It is.

The above-described foundation pile is formed in circular concrete, preferably in the shape of a fan-shaped cone or a bell, and the manufacturing method is performed by appropriately adjusting the length of the soluble cord for cutting attached to the rotating shaft.

The foregoing and other objects and features will become more apparent by reference to the accompanying drawings in accordance with the embodiments.

In FIG. 1 and FIG. 2, "P" is a pile body whose core is hollow, and "10" is a hollow conical pile head attached to the bottom of the pile body P to be detachably attached. After driving into the predetermined ground to continue to hit the pile head 10 with a hammer through the mandrel (11) to separate the pile head.

The pile head 10 hit in FIG. 3 is settled about 2m below the pile apart from the pile body P. FIG. "12" is a round bar-shaped cutting device in which the front end portion is connected to the cutting member 13 in the wire rope group as a rotating body, and is inserted near the upper portion of the pile head 10 through the hollow portion of the pile.

"I" is a ballast that supports the cutting device to rotate. 4 and 5, the soil circumferential wall 14 is cut and crushed by centrifugally rotating the cutting member 13 having the length of the cord lowered downward in accordance with the high speed rotation of the rotary shaft of the cutting device 12 described above. It is.

In addition, water is injected to assist the cutting operation, and at the same time, the cut soil is formed in the form of a hydride sol, and these are sucked out of the pile with an aspiration pump (not shown), and the sand fine grains which do not solute are settled downward (15). A large conical cavity 16 is formed at the bottom with a radius of the length of each wire rope.

In Figures 6 and 7, "17" is an ultrasonic device used to probe the volume and shape of the cavity through the cavity 16 after taking out the cutting device described above.

"18" refers to the above-mentioned cavity (16) through the hollow part of the pile in a bent state as a freely bent and assembled steel frame which can be expanded in the cavity by manipulating the reinforcement or the angle through a pipe or the like from the top. After inserting it in, spread it out in an umbrella shape as shown in FIG.

8 and 9, "H" is a pressurized pipe vertically fitted into the corner of the cavity 16, which is pressurized and equilibrated with water so that the pipe outlet 19 is not blocked when filling concrete mortar. The concrete mortar is filled in the cavity 16 through the hollow core around the pressure pipe while maintaining the outlet flow.

In FIG. 10 and FIG. 11, an oblique line part shows the concrete part 20 filled in the cavity 16, and condenses after 4 to 5 hours, and is formed in the conical concrete body of a large downward side.

At this time, the soil stabilizer is pressurized from the above-mentioned pressure pipe (H) to the coarse ground 21 around the pile and the concrete body so as to harden, and then hardened with mortar, as indicated by the "X" symbol in "22". Press to send upward and fill the gaps around.

Thus, when the pile is formed according to the above-described method, the working surface of the pile tip becomes the surface at the point, and as the supporting pressure of the soil support surface is reduced, the subhard soil layer near the ground surface without increasing the number of piles or the diameter of the pile In addition, it is possible to settle in the soil or soft soil layer, which greatly reduces the basic construction cost and contributes to the safety of the ground.

In addition, the foundation pile according to the present method combines the advantages of the conventional pile and the field-made concrete pile, and maintains the high bearing capacity of the conventional pile and at the same time has a tip portion that is multiplied more than the tip of the field-made bulb pile. It is possible to support relatively large loads with relatively few piles on the ground with low bearing capacity.

In addition, by adopting a cutting member made of a strong flexible cord, and by properly rotating the shaft, the wall is easily cut so that it is not restricted by the ground situation at the bottom of the pile like a conventional bulb pile.

In addition, since it is possible to directly insert a frame assembled with reinforcing bars or angles into the concrete body at the bottom of the pile, the concrete body is reinforced to form a solid pillar root, thereby improving the transfer function of the upper load.

In addition, the pressurized tube can be sandwiched between the permeable sand gravel deeply in the corner of the cavity at the bottom of the pile, so that soil stabilizers and mortar can be easily injected to not only harden all coarse soil around the ground but also fill gaps. Ground stability is greatly increased.

Claims (7)

The core is embedded with a PC (Prestressed concrete) pile which is hollow and longer than the above-mentioned pile radius dimension through the hollow portion, and is a cutting member made of a flexible flexible group of cords, one end of which is connected to the rotating shaft. According to the foundation pile, characterized in that the bottom of the bulge formed by filling the concrete mortar in a circular cavity having a radius of the above-described length of the cord formed by cutting and expanding the soil around the bottom of the pile. The foundation pile according to claim 1, wherein the above-described forming portion of the lower end of the pile is formed in a conical shape or a bell shape. 2. The foundation pile according to claim 1, wherein the aforementioned circular cavity has a steel frame which is previously unfolded in an umbrella shape and is built in the cavity to form a reinforced concrete structure. The core is a hollow body, and the PC pile with a hollow cone-shaped pile head attached to the bottom is driven into a predetermined ground, and the pile head is separated from the pile body along the hollow body with a core rod and is about 2m below the pile. The cutting device is inserted into the hollow core of the pile, and then the cutting member, which is connected with a number of strong flexible cords, is centrifugally rotated at the high speed of the rotary shaft near the upper part of the pile head along the tip of the rotary shaft. While cutting and crushing walls, water is injected to assist cutting operations, while the cut soil is formed in the form of a hydrate so that they are sucked out so as to sink the non-solking sand gravel downwards. Form a circular cavity, assemble the steel frame by assembling the reinforcing bars or angles, and expand the hypothesis Filling the concrete mortar in the cavity while using the pressure pipe, and after the predetermined curing time has elapsed, when the concrete mortar is condensed and formed into a circular concrete body, the soil stabilizer is piled and A foundation pile method, characterized by forming a stable ground by pressurizing and injecting into rough ground around the concrete body to be hardened, followed by pressurizing and injecting upward from the lower end with mortar to form a stable ground. 5. The foundation pile method according to claim 4, wherein the cord of the cutting member linked to the lower end of the rotating shaft of the cutting device is a wire row and has a length larger than the size of the pile radius according to a predetermined cone shape. The steel frame according to claim 4, wherein the steel frame obtained by assembling the aforementioned reinforcing bars or angles is freely bent and assembled in the form of a miscarriage. Foundation pile method, characterized in that the loss. The foundation pile method according to claim 4, wherein the cord length of the cutting member is formed in a conical or bell-shaped cavity by appropriately adjusting the cord length to be lowered downward.

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