JPS6110625A - Process of settling concrete pile - Google Patents

Abstract

PURPOSE:To decrease a construction cost, by a method wherein a mixture layer of cement milk and soil is formed in a vertical shaft, and after an excavation securing layer containing bentonite and soil is formed thereon, a pile provided at the lower end with an enlarged part is penetrated into the vertical shaft and is buried by rotation. CONSTITUTION:An excavation securing layer 11 is formed through excavation of a ground as a securing solution, in which bentonite and water are mixed together, is injected through the forward end of an auger. Thereafter, after a ground is excavated down to a depth arrested by a support ground A, an auger is lifted as, instead of the solidifying solution, cement milk is poured, and a cement milk mixture layer 12 is formed to the lower part of the securing layer 11. Thereafter, a concrete pile 10 is penetrated into a vertical shaft 5 as the pile is rotated, and an enlarged part 10b is forcibly pressed in the mixture layer 12.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a concrete pile sinking method.

``Conventional technology'' In order to prevent noise and vibration during construction, concrete piles are generally placed using a method in which a hole is formed by excavating the ground using an auger, and the concrete pile is rotated and inserted into the hole. is often used. In such construction methods, the supporting capacity of the pile at the tip is determined by the size of its cross-sectional area. Therefore,
Conventionally, as shown in FIGS. 3 and 4, an excavator 2 and a helical blade 3 each have an excavator blade 2a at its tip that can be opened and closed in forward and reverse directions.
A sinking hole 5 is excavated in the ground by an auger 1 equipped with a stirring blade 4 and a stirring blade 4, and when the supporting ground A is reached, the digging blade 2a is opened at the bottom of the sinking hole to form an enlarged hole 5a. Cement milk 6 is injected into the lower part of the sinking hole 5, and a fixing solution 7 made of cement, bentonite, and water is injected into the upper part. And Auger 1
After pulling up the hollow concrete pile 8 into the sinking hole 5 while rotating it, the lower end is inserted into the enlarged hole 5a.
into the cement milk 6. As a result, the concrete pile 8 is supported in a large-diameter nodule made of cement milk combined with the supporting ground A, and it has been thought that a large supporting force can be obtained.

However, in this construction method, it is questionable whether the drilling blade of the drilling device 2 of the auger 1 used can be opened to a predetermined position and the drilling can be performed reliably when drilling the enlarged hole 5a. Since this cannot be confirmed, in reality, the bearing capacity of this large-diameter nodule is calculated based on the diameter of the concrete pile, assuming that it is uncertain. Therefore, the diameter of the concrete pile becomes larger than necessary, resulting in an increase in construction costs.

y Problems to be Solved by the Invention The present invention solves the drawbacks of the conventional construction method described above, makes it possible to easily excavate a pile sinking hole and penetrate the pile, and to obtain a predetermined supporting force while reducing the diameter of the concrete pile. Another object of the present invention is to provide a concrete pile sinking method that can substantially save weight and reduce construction costs.

``Means for Solving the Problems'' The present invention involves drilling a hole in the ground for depositing a concrete pile, forming a mixed layer of cement milk and earth and sand at the bottom of the hole, and forming a mixed layer of cement milk and soil on the top of the hole. A fixed layer containing bentonite and earth and sand is formed in the hole, and
The present invention is characterized in that the concrete provided with the enlarged diameter portion at the lower end is rotated and penetrated, and the enlarged diameter portion is buried in the mixed layer.

"Embodiments" Examples of the present invention will be described below with reference to FIGS. 1 and 2.

In the construction method of the present invention, an expanded-bottom concrete pile 10 as shown in FIG. 2 is used as the concrete pile to be sunk. This expanded-bottom concrete pile 10 is provided with an enlarged diameter portion 10b having a larger outer diameter than the pile body 10a at the lower end thereof, and the upper and lower ends of the enlarged diameter portion 10b are each formed into a tapered shape.

The prepared hole 5 for sinking the concrete pile 10 is excavated using an ordinary auger which is not provided with an opening/closing excavation blade 2a as shown in FIG. 3. The diameter of the hole adjustment 5 is made slightly larger than the diameter of the enlarged diameter portion 10b of the concrete pile 10. During excavation, a fixative solution of bentonite + water or bentonite + cement + water is injected into the hole from the tip of the auger to fix the hole wall, and the fixative solution is mixed with the excavated soil. Then, the excavated fixed layer 11 is formed. When the auger excavation has been carried out to a predetermined depth reaching the supporting ground, the auger is pulled up, but at the beginning of the auger pulling up, cement milk is injected instead of the fixing fluid and mixed with the excavated soil to form the hole. A cement milk mixed layer 12 of a required height is formed at the bottom.

After the auger is pulled up, the concrete pile 10 is penetrated into the prepared hole 5 and deposited as shown in FIG. When penetrating the concrete pile 10, there is resistance due to the existence of the excavated fixed layer 11 and the cement milk mixed layer 12 in the hole, and the penetration cannot be made only by the own weight of the concrete pile 10, so the upper end of the concrete pile 10 is While connected to a device and applying a load.

The concrete pile 10 is rotated to advance its penetration. Then, the enlarged diameter portion 10a of the concrete pile 10 is pushed into the cement milk mixed layer 12 to complete the laying work.

"Function" When purchasing the concrete pile 10 according to the construction method of the present invention, if the tip end is tapered as shown in the figure, even if the penetration direction is slightly inclined, the bottom of the pile 10 will be Since the hole wall is not cut down by the end and the enlarged diameter portion 10b having the required length slides along the hole wall, the directionality of pile penetration is improved. In addition, the hollow part of the concrete pile 10, the hollow part of the lower part where the enlarged diameter part 10b is located *, is filled with the mixture of the cement mill mixed layer 1z, so that the supporting cross-sectional area of the concrete pile 10 is reduced. is substantially proportional to the diameter of the enlarged diameter portion 10b, and a large supporting force can be obtained.

"Effects of the Invention" As explained above, the construction method of the present invention excavates a prepared hole in the ground for laying concrete piles, forms a mixed layer of cement milk and earth and sand at the bottom of this prepared hole, and
An excavated fixed layer containing bentonite, earth, etc. is formed on top of the hole, and a concrete pile with an enlarged diameter section at the lower end is rotated and penetrated into this prepared hole, and the enlarged diameter section is buried in the mixed layer. As a result, the concrete pile can obtain a large supporting force according to the cross section of its enlarged diameter part, whereas the pile body can be formed with a small diameter.
Material costs and transportation costs for piles can be reduced, and construction costs can be significantly reduced. In addition, since the pile body has a smaller diameter than the tip, the negative frictional force can be reduced compared to normal piles, and the actual strength of the pile is improved. Since only the pile is subjected to a large amount of stress, the torsional stress caused by the application of rotational force to the pile is small overall, there is no risk of damaging the pile, and construction is easy, reliable, and efficient.

It has many advantages, such as the ability to

[Brief explanation of the drawing]

Figures 1 and 2 show an embodiment of the construction method of the present invention, where Figure 1 is a side sectional view showing the state in which the pile sinking hole is formed, and Figure 2 is a side sectional view showing the state in which the pile is sunk. , FIG. 3 is a side sectional view showing a state in which a pile sinking hole is excavated in a conventional construction method, and FIG. 4 is a side sectional view showing a state in which a pile is similarly sunk. 1... Auger 5... Hole adjustment for pile sinking 10... Concrete pile 10a... Pile body 10b... Enlarged diameter portion 11.
...Excavation fixed layer 12... Cement milk mixed layer Fig. 1 Fig. 2 Δ Δ Fig. 3 Fig. 4

Claims (1)

[Claims] A hard hole for depositing concrete piles is dug in the ground, and a mixed layer of cement milk and earth and sand is formed at the bottom of this hole, and an excavated fixing layer containing bentonite, earth and sand is formed above it. . A method for sinking a concrete pile, characterized in that a concrete pile having an enlarged diameter portion at its lower end is inserted into the vertical hole, and the enlarged diameter portion is rotatably buried in the mixed layer.