JPS61254716A - Setting of in-place concrete pile - Google Patents

Abstract

PURPOSE:To obtain an in-place pile having high strength by preventing the mixture of mud water into concrete by a method in which a double tube having a given interval between its inner and outer walls is penetrated into a pit and concrete is driven into the aperture of the double tube. CONSTITUTION:While jetting high-pressure water from the tip of an auger rod, a pile pit 1 is excavated down to a bearing stratum 12 by the auger, and inner and outer tubes with an aperture held by a close plate 8 on the lower end and a spacer in the intermediate are penetrated into the pile 1. Concrete 11 is then packed into the space between the inner and outer walls to set up a concrete pile 13. An in-place concrete pile having high strength can thus be obtained without mixture of mud water into the concrete 11.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention belongs to the field of installing concrete piles during foundation construction.

(Conventional technology) Conventionally, when concrete is poured on site and concrete piles are installed, a hole is drilled at the site where the pile is to be installed, and a reinforcing bar cage is inserted into the hole. After that, concrete was being poured into the pile hole.

(Problems to be Solved by the Invention) According to the conventional method, it is not only unclear whether the poured concrete has evenly buried the reinforcing bar cages, but also the residual mud or mud in the pile hole. , there was a risk that it would mix with the poured concrete and deteriorate the quality of the concrete. In addition, it is difficult to predict and detect the condition of the installed piles, such as irregular shapes or uneven strength of the prepared concrete due to partial collapse of the pile wall, making it difficult to improve reliability.
Therefore, there were problems such as having to use more concrete than necessary (for example, conventional site piles were solid piles). Furthermore, since the reinforcing bar cage is naturally buried within the thickness of the concrete, there is a problem that the resistance to bending moment is small compared to the amount of reinforcing bar.

(Means for solving the problem) However, in this invention, the inner and outer double pipes are inserted into the pile hole, and concrete is poured into the gap between the inner and outer double pipes. Not only is it possible to construct a concrete structure, but it also uses the necessary iron effectively, and the amount of concrete used is almost the same as in the case of conventional prefabricated piles, all of the problems of the conventional method have been solved.

That is, in this invention, after drilling a hole with a predetermined outer diameter at a site where the pile is to be installed, an inner and outer double pipe is inserted into the hole while maintaining a predetermined gap between the inner and outer walls, and the inner and outer double pipe is Concrete is poured into the gap between the pipes and concrete piles are installed on site.

In the above, when digging a pile hole, the hole wall is strengthened by rubbing some of the mud excavated by the auger on the hole wall as the hole is dug, and the hole is made solid during the work (especially when inserting a double pipe). This method effectively prevents the collapse of soil and does not discharge a large amount of excavated soil, which significantly improves the workability of soil disposal. Regarding this excavation method, conventional methods may be used depending on the depth of the hole, soil quality, and other reasons. It is preferable to form the inner and outer double pipes in advance on the ground and insert the inner and outer double pipes at the same time after closing the bottom, but it is also possible to insert the inner and outer pipes separately if necessary. be. However, when inserting the inner pipe and the outer pipe separately, it is necessary to pour concrete after or while removing muddy water that has entered between the inner and outer double pipes.

When excavating a hole that is extremely difficult, if an empty hole can be excavated due to reasons such as the absence of spring water and the use of injected water in large numbers, it does not matter how the inner and outer double pipes are inserted.

In addition, when the expanded bottom method is adopted, a hole with a specified outer diameter is excavated at the site where the pile is planned to be installed, an expanded bottom section is provided at a specified height below the hole, and cement is poured into the expanded bottom section. After injecting milk to make soil cement, insert the inner and outer double pipes into the hole so as to maintain a predetermined gap between the inner and outer walls, and pour concrete into the gap between the inner and outer double pipes. , install on-site concrete piles. In this construction method, the insertion depth of the inner and outer double pipe bottoms is at an intermediate position of the expanded bottom part or a position close to the bottom surface of the expanded bottom part.

Regarding this point, concrete piles will be installed according to the standard of the conventional wide-bottomed foundation construction method.

In addition, in order to integrate the soil cement for expanding the bottom with the poured concrete, holes may be made in the closing plate at the bottom of the inner and outer double-walled pipe, or the closing plate may be removed.

(Operation of the invention) That is, according to this invention, since concrete is poured into the gap between the inner and outer double pipes, the length, thickness and shape of the completed pile are as designed, and reliability is high. At the same time, piles with large bending resistance can be created.

In addition, since there is no collapse of the pit, workability is extremely good, and the poured concrete can maintain the same quality as previously mixed on the ground.

(Example 1) In the present invention, a pile hole 1 having a predetermined outer diameter is excavated at a site where a pile is to be installed using an auger 2. In this case, auger rod 3
When the auger rod 3 is rotated while injecting pressurized water from the tip of the auger rod 3, the excavated soil is crushed by the stirring rod 4 fixed to the auger rod 3, and the crushed soil is crushed by the drum 5 fixed to the auger rod 3. Hole wall 1a
Practice it. Therefore, the wall of the pit can be firmly shaped, and by kneading the excavated soil, the amount of soil removed can be reduced. As described above, when the auger 2 reaches the supporting ground 12 and excavates the supporting ground 12 to an appropriate depth, the auger rod 3 is removed from the hole. Insert the steel inner tube 7 into the steel outer tube 6, which has an outer diameter approximately equal to the inner diameter of the hole, while maintaining a predetermined gap S (the gap S is the thickness of the concrete pile). A closing plate 8 is fixed to the lower end of the outer tube 6, and an appropriate spacer 9 (for example, a reinforcing bar formed in a truss shape, or a piece for maintaining a gap between the inner and outer tubes) is inserted at an appropriate position in the gap to separate the inner and outer tubes. A heavy pipe 10 is formed. Insert the double pipe 10 into the hole 1, and
Concrete 11 is filled between the inner and outer walls of 0. In this case, since the space between the inner and outer walls is hollow (there is no muddy water or mud inside), the filled concrete 11 maintains the mixing ratio on the ground, maintains its design strength, and hardens within the scheduled time. etc., reliability can be maintained.

As described above, the concrete piles 13 equipped with steel inner and outer tubes could be installed on the inner and outer walls. 16 in the diagram
is the surface of the earth.

(Example 2) After drilling and forming the borehole 1 in the same manner as in Example 1, the auger rod 3 is rotated in the opposite direction, the auxiliary blade (not shown) of the auger is expanded, and the auger is directly inserted. While rotating the rod 3, the specified vertical range (for example, about 3 m)
When the auger rod 3 is moved up and down over this period, an enlarged hole 14 is drilled below the borehole 1 above and below the supporting ground surface.

Therefore, after rotating the auger rod 3 in the normal direction and storing the auxiliary blade, the cement milk is injected from the tip of the auger rod 3, and the auger rod 3 is rotated and pulled up to fill the soil cement 15 inside the expanded hole 14. to fill up. Thereafter, a double pipe 10 consisting of an outer pipe 6 and an inner pipe 7 made of steel is inserted into the hole 1, and concrete 11 is filled between the inner and outer walls of the double pipe 10. In this case, the lower end of the double pipe 10 is located approximately in the middle of the expanded hole 14 and is buried in the soil cement 15. In this way, we were able to install concrete piles 13 with steel pipes attached inside and outside.

(Effect of the invention) That is, according to the present invention, an inner and outer double pipe is inserted into a pile hole, and the gap between the double pipes is filled with concrete. It has a similar effect. In addition, since concrete is poured into the space of the double pipe, there is no risk that the poured concrete will mix with muddy water or mud and deteriorate the quality of the concrete piles, and the design strength can be reliably maintained. . However, with respect to bending moment resistance, which is a characteristic of steel pipe piles, it has the effect of having strength proportional to the thickness of the steel pipe.

Furthermore, the installation method of the present invention is technically simple, and even non-skilled workers can install foundation piles with high reliability as long as the method is carried out correctly.

[Brief explanation of the drawing]

The figures show the pile installation order of this invention. Figure 1 is a diagram of the start of excavation with an auger, Figure 2 is a diagram of the planned completion of excavation, Figure 3 is a diagram of the double pipe insertion flow, and Figure 4 is a diagram of concrete pouring. Figure 5 is a diagram showing the completion of concrete pouring in another embodiment. 1... Socket hole 2... Auger 3... Auger rod 4... Stirring rod 5... Drum
6...Outer pipe 7...Inner pipe 10...Double pipe 13...Concrete pile

Claims (1)

[Scope of Claims] 1. After drilling a pile hole with a predetermined outer diameter at the site where the pile is to be installed, insert an inner and outer double pipe into the pile hole while maintaining a predetermined gap between the inner and outer walls, and A method for installing concrete piles on-site, characterized by pouring concrete into the gap between double pipes 2. A method of installing concrete piles on site, characterized by pouring concrete into the gap between double pipes. 2. A method of installing concrete piles on site, characterized by pouring concrete into the gap between double pipes. Method 3 for installing concrete piles on-site according to claim 1. Method 4 for installing concrete piles on-site according to claim 1, in which the inner and outer double pipes are double pipes that are formed in advance and have their bottoms closed. At the planned installation site, a hole with a predetermined outer diameter is excavated, an enlarged bottom section is provided at the bottom of the hole over a predetermined height, and cement milk is poured into the enlarged bottom section to form soil cement. On-site concrete pile installation method 5, characterized by inserting an inner and outer double pipe into the pile hole so as to maintain a predetermined gap between the inner and outer walls, and pouring concrete into the gap between the inner and outer double pipes. The method for installing on-site concrete piles according to claim 4, in which the insertion depth of the inner and outer double pipe bottoms is set at the middle part of the expanded bottom part or close to the bottom of the expanded bottom part.