JP3932069B2 - Construction method for hollow ready-made piles - Google Patents

Description

【表−２】

【表−３】

[0001]
[Industrial application fields]
The present invention relates to a construction method for embedding a hollow ready-made pile such as a concrete pile by a digging method.
[0002]
[Prior art]
As a method for embedding hollow ready-made piles such as concrete, there is a medium digging method. In this construction method, as shown in FIG. 2, an auger screw 2 is inserted into the hollow portion of the pile 1 in advance, and the auger driving device 4 and the auger screw 2 mounted on the pile driving tower 3 are connected to rotate the auger screw. In this method, the ground at the tip of the pile is excavated, and the pile is laid while discharging the excavated soil from the pile head through the pile hollow portion.
[0003]
In addition, the medium digging method includes a medium digging batting method and a medium digging press-fitting method. The medium excavation method is a method in which the auger screw 2 is pulled up and hit by a hitting device such as monken when the tip of the pile reaches a predetermined hit depth. On the other hand, in the middle digging press-in method, a folding head is provided at the tip of the auger screw 2, this is inserted into the pile, the head is expanded and excavated, and the tip of the pile is close to the predetermined stop depth. In this method, after rooting cement milk is injected to form a root consolidation nodule, the head is folded, the auger screw 2 is pulled up, and the pile is pushed into a predetermined position using a press-fitting device.
[0004]
[Problems to be solved by the invention]
The advantages of each of the above digging methods are that the amount of excavated soil can be reduced and that the frictional support force of the pile can be increased, but in the digging method, soil is pressed into the hollow part of the pile when it is stopped. As a result, it causes vertical cracks in the pile, and the supporting force is only an annular cross section of the pile, so that the supporting force as a whole is small. In addition, in the digging press-in method, the cement milk injected into the lower end of the pile is easy to flow in the groundwater, it is not possible to confirm from the ground whether the cement milk nodules have been formed in the shape as designed, and the folding head However, there is a disadvantage that the diameter of piles to be buried is limited and cannot be applied to small-diameter piles.
[0005]
Moreover, the problem common to each digging method is that the excavated earth and sand is discharged using the hollow part of the pile, so if there is large gravel or cobblestone, they will be engaged between the auger screw and the pile, It may be impossible or the pile may be damaged by internal pressure. Therefore, when carrying out the medium excavation method, the diameter of the gravel that can be constructed varies depending on the depth of the pile and the gravel and the shape of the gravel, etc. The target value is determined as shown in Table 1, and in the case of the ground where there is a gravel layer with a gravel diameter equal to or greater than this target value, construction is impossible.
[0006]
[Table-1]
[0007]
The present invention has been made to solve the above-mentioned problems in the medium excavation method. The auger head is attached to the projecting lower end of the auger screw inserted into the pile, and the lower end of the pile is auger head after excavation is completed. It is possible to prevent damage to the pile by adopting a method in which the auger screw is lifted by leaving it in contact, and it is possible to construct a layer with gravel of any gravel diameter by the medium excavation method Is something to try to do.
[0008]
[Means for Solving the Problems]
The configuration of the present invention for achieving the above object will be described with reference to the drawings corresponding to the embodiments. The present invention is arranged at the projecting lower end of the auger screw 2 inserted through the hollow ready-made pile 1 and outside the pile. This is a construction method in which a pile is buried while maintaining an interval L between the pile 1 and the excavation head 6 with the excavation head 6 having the same diameter as the diameter, and in a formation such as a gravel layer containing a lot of gravel, If the maximum gravel diameter in the formation is greater than or equal to the maximum workable gravel diameter determined in advance corresponding to the diameter of the pile 1 to be buried, the interval L is adjusted to be equal to or less than the maximum workable gravel diameter. If the maximum gravel diameter in the formation is smaller than the maximum gravel diameter that can be constructed, the interval L is larger than the maximum gravel diameter that can be constructed and 0.5 times the pile diameter. It is characterized by adjusting the following length and proceeding with the construction.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows one embodiment of the present invention in sequence, and FIGS. 3 to 8 show one embodiment of an excavator using an auger screw or the like used in the present invention.
[0010]
As shown in FIG. 1, the excavator used in the present invention comprises an auger screw 2 having a screw 4 on an auger shaft 3 and an auger head 6 detachably attached to a lower end of the auger screw via a joint 5.
[0011]
As shown in FIGS. 6 to 8, the joint 5 has a square shaft 8 fitted to the lower end of the auger shaft 3 at the upper end of the shaft rod 7, and can be engaged with and disengaged from an auger head 6 described later at the lower end. An engaging body 9 is provided, and a large diameter abutting plate 10 joined to the upper end of the auger head 6 is provided at the upper and lower intermediate portions, and a screw 11 is provided above the abutting plate 10 of the shaft rod 7. ing. The engaging body 9 is formed of a thick plate, and has a shape in which locking pieces 9a protruding in a plurality of sectors are provided on the peripheral surface.
[0012]
As shown in FIGS. 4 and 5, the auger head 6 has an inverted mountain-shaped excavation blade 13 having many pits 14 on the lower surface of a circular substrate 12 having the same diameter as the outer diameter of the pile 1 to be embedded. A cylindrical body 15 having a diameter through which the engaging body 9 of the auger joint 5 can be inserted is provided at the center of the upper surface of the substrate 12. An engagement hole 16 similar to the engagement body 9 through which the engagement body 9 can be taken in and out is provided at a position in the cylinder 15 of the substrate 12. The excavating blade 13 is provided with a notch recess 17 in the upper part of the central portion thereof, into which the engaging body 9 can be inserted and which can hit the side end of the locking piece 9a.
[0013]
The auger joint 5 has its square shaft 8 inserted into a square hole at the lower end of the auger shaft 3 and is attached to the auger screw 2 by a stopper 18, and the excavation head 6 is detachably coupled to the auger joint 5. For this connection, the engaging body 9 of the auger joint 5 is inserted into the notch recess 17 through the engaging hole 16 of the substrate 12 so that the abutting plate 10 is brought into contact with the upper end of the cylindrical body 15. When the auger screw 2 is rotated forward in the excavation direction, the locking piece 9a of the engagement body 9 is stopped against the end side surface 19 of the notch recess 17 of the substrate 12. Therefore, if the auger screw 2 is rotated forward, the excavation head 6 rotates and the ground can be excavated. At the time of excavation rotation, the engagement body 9 and the engagement hole 16 are displaced in the rotational direction, so that the state where the auger joint 5 and the excavation head 6 cannot be separated vertically is maintained.
[0014]
In order to separate the auger joint 5 and the excavation head 6, the auger joint 5 is reversely rotated to a position where the engagement body 9 matches the engagement hole 16, and then the auger screw 2 is pulled up to engage the engagement body 9. It comes out of the entrance hole 16 and rises so that it can be separated.
[0015]
The excavator is not limited to the one having the above configuration. In short, when the auger head 6 attached to and detached from the lower end of the squeegee auger 2 can be rotated in a state where it cannot be separated by the forward rotation of the screw auger 2 and the screw auger 2 is rotated slightly backward. Any structure that can be separated is acceptable.
[0016]
Next, the pile embedding process according to the present invention will be described with reference to FIGS. First, as shown in FIG. 1 (a), the excavation head 6 is fixed, and on the other hand, the auger screw 2 is inserted into the pile 1, and this is built at the burial point of the pile 1, that is, immediately above the excavation head 6. . In this state, the auger screw 2 and the excavation head 6 are coupled as described above. Then, a predetermined pressure is applied to the auger screw 2 by a rotary press-fitting device (not shown) to rotate it forward in the excavating direction, and if the pile 1 is pushed down, excavation of the ground proceeds, and the pile 1 enters the ground. It will penetrate.
[0017]
In the present invention, when excavating and penetrating, as shown in FIG. 1 (b), a required interval L exists between the excavation head 6 and the pile 1 in the ground. As a result, the earth and sand that has been excavated and pushed to the side of the head 6 enters the pile 1 through the gap 20 between the excavation head 6 and the lower end of the pile 1 and is conveyed upward by the action of the rotating screw 4. It is discharged to the outside (ground) from the upper end of. According to this method, during excavation and subsidence, the earth and sand are pressed to the side of the excavation head 6 and are compacted by the side ground, so that the disturbance of the earth and sand is reduced, and the remaining earth and sand are placed in the pile hollow portion. Since it is transported and discharged, the amount of discharged soil can be reduced to about half compared to a general conventional digging method.
[0018]
And in this invention, it constructs, adjusting the space | interval L of the excavation head 6 and the pile 1 according to soil quality, ie, the magnitude | size (gravel diameter) of gravels, such as gravel and cobbles contained in the stratum. Try to proceed. The adjustment is made corresponding to the gravel diameter at each depth by the soil column diagram created by the survey prior to construction.
[0019]
That is, the distance L between the excavation head 6 and the pile 1 corresponds to the outer diameter φ of the buried pile as shown in Table 2 in the formation where the gravel diameter is smaller than the target value shown in Table-1. The construction is to be carried out with a length within approximately one half of the diameter. In addition, in the formation (gravel layer) when the gravel diameter is equal to or greater than the target value shown in Table 1, the distance L is not longer than the length corresponding to the target value of the maximum gravel diameter with respect to the outer diameter φ of the pile to be buried. Adjust and install. The range of the space | interval L with respect to the diameter of this pile is shown in Table-3.
[0020]
[Table-2]
[0021]
[Table-3]
[0022]
As described above, in the present invention, the interval L is sufficiently long in the normal ground smaller than the target maximum gravel diameter with respect to the diameter of the pile to be buried, from the intermediate layer A to the support layer B of the ground in which the pile is buried. However, in the gravel layer where gravel is larger than the maximum gravel diameter, even if the distance L is below the target maximum gravel diameter, the gravel will not enter the pile hollow part. The construction is proceeded with adjustment. As a result, damage to the piles can be eliminated, and it is possible to construct a gravel layer with any gravel diameter.
[0023]
As described above, the construction is advanced while maintaining the distance L between the excavation head 6 and the pile 1, and when the lower part of the pile 1 penetrates to the support layer B as shown in FIG. The auger joy is slightly lifted by bringing the engaging body 9 of the auger joint 5 and the engaging hole 16 of the excavation head 6 together slightly, and the coupling between the two is released. As a result, the excavation head 6 is left in the support layer B.
[0024]
In this state, since there is a predetermined gap 20 between the lower end of the pile 1 and the excavation head 6, the pile 1 is pushed down from the upper end of the pile 1 by light striking or pressing to make contact with the excavation head 6. Thereby, the excavation head 6 becomes a support part of the pile 1. Next, as shown in FIG. 1 (D), the pile 1 is further penetrated by further applying a light stroke or pressing from the upper end of the pile 1. Then, the auger screw 2 is pulled out from the pile 1 and the burying construction of the pile is completed.
[0025]
【The invention's effect】
As described above, according to the present invention, a detachable excavation head is attached to the projecting lower end of an auger screw inserted into the pile, and the pile is buried while maintaining a distance between the pile and the excavation head. As a result, the excavated soil is discharged into the excavated hole wall while a part of the earth and sand is discharged, the hole wall becomes stronger, and the discharged excavated sand is about half as small as the general medium digging method. The cost required for soil disposal can be greatly reduced.
[0026]
In addition, in strata containing gravel, the construction is carried out by adjusting the distance between the pile and the excavation head, so it is possible to prevent the gravel from getting caught between the auger screw and the pile and damaging the pile. Therefore, piles can be buried reliably and easily even for gravel layers that could not be constructed by the general digging method.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 shows the steps of construction according to an embodiment of the present invention method in sequence, (A) shows a state where a pile is built on the ground, (B) shows an embedded state in an intermediate layer, (C) shows the state of penetration into the support layer, and (D) shows the auger screw pulled out state.
FIG. 2 is a side view showing an embodiment of an apparatus used in the present invention.
FIG. 3 is a sectional side view of the excavation head.
FIG. 4 is a plan view of the same.
FIG. 5 is a side view of an auger joint.
FIG. 6 is a plan view of the same.
FIG. 7 is a bottom view of the same.
[Explanation of symbols]
1 Pile 2 Auger Screw 5 Auger Joint 6 Excavation Head 9 Engagement Body
12 Board
13 Drilling blade
14 pits
16 engagement hole
17 Notch recess
20 Gap A Middle layer B Support layer L Distance between pile and excavation head [Table-1]

[Table-2]

[Table-3]

Claims (1)

An excavation head with the same diameter as the outer diameter of the pile is attached to the projecting lower end of the auger screw inserted into the hollow ready-made pile, and the pile is buried while keeping the distance between the pile and the excavation head. In strata such as gravel layers that contain a lot of species, when the maximum gravel diameter in the strata is greater than the maximum gravel diameter that can be constructed in advance corresponding to the diameter of the pile to be buried , If the maximum gravel diameter is adjusted to be less than the maximum gravel diameter that can be constructed and the maximum gravel diameter in the formation is smaller than the maximum gravel diameter that can be constructed, the above interval is set to the maximum gravel that can be constructed. A method for embedding hollow ready-made piles, characterized in that the construction is carried out by adjusting the length to be larger than the diameter and not more than 0.5 times the pile diameter .

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