JPH11158871A - Method for embedding hollow existing pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hollowing method by which a pile can be embedded in a gravel layer. SOLUTION: A hollowing method involves mounting a drilling head 6 freely removably at the lower end of an auger screw passed through a hollow existing pile 1, and embedding the pile 1 while performing digging. Then construction work proceeds while securing the required interval L between the drilling head 6 and the pile 1 in the soil. During the construction work, if the drilling head 6 comes into contact with a gravel layer containing gravel and boulders, etc., the construction work proceeds while the interval L is adjusted to a length within the range of 0.1 to 0.5 times of the diameter of the pile embedded, i.e., the desired value of a gravel diameter permitted to match the diameter of the pile embedded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of embedding a hollow prefabricated pile such as a concrete pile by a middle digging method.

[0002]

2. Description of the Related Art As a method of burying a hollow prefabricated pile made of concrete or the like, there is a hollow digging method. In this method, as shown in FIG. 2, an auger screw 2 is inserted into a hollow portion of a pile 1 in advance, and an auger screw 4 is connected to an auger driving device 4 mounted on a pile driver 3 and the auger screw 2 is rotated. Excavating the ground at the tip of the pile, and excavating the excavated earth and sand from the pile head through the hollow part of the pile to lay the pile.

[0003] There are two types of digging methods: digging hitting and digging. The underground hitting 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 near a predetermined hitting depth. On the other hand, the auger screw 2
A foldable head is provided at the tip of the pile, inserted into the pile, the head is expanded and excavated, and when the tip of the pile reaches a predetermined depth, the consolidation cement milk is injected and the root is poured. This is a method in which the head is folded up, the auger screw 2 is pulled up, and the pile is pushed to a predetermined position by using a press-fitting device after forming a consolidated nodule.

[0004]

The advantages of each of the above-mentioned excavation methods are that the amount of excavated soil can be reduced and the frictional supporting force of the pile can be increased. At the same time, the soil is pressed into the hollow portion of the pile, which causes a vertical crack in the pile, and the supporting force is only the annular cross section of the pile, so that the supporting force as a whole is small. In addition, in the excavation method, the cement milk injected into the lower end of the pile is easily washed away by the groundwater, it is not possible to check from the ground whether the cement milk nodules are formed as designed, and the folding head There is a drawback that the diameter of the pile to be buried is restricted due to the use of, and cannot be applied to a small diameter pile.

[0005] Moreover, a problem common to all the digging methods is that the excavated earth and sand is discharged using the hollow portion of the pile. It may cause meshing, construction failure, and damage to piles due to internal pressure. Therefore, the diameter of gravel, etc. that can be constructed depends on the depth of piles and gravel, the shape of gravel, etc. The target value is determined as shown in Table 1. In the case of ground with a gravel layer with a gravel diameter greater than this target value, construction is not possible.

[Table 1]

The present invention has been made in order to solve the above-mentioned problems in the underground digging method. An auger head is attached to a lower end of an auger screw inserted into a pile, and the lower end of the pile is excavated after completion of excavation. Against the auger head,
A method of raising the auger screw with this remaining is used to prevent damage to the pile, and to make it possible to construct a layer with gravel of any gravel diameter by the inside excavation method Things.

[0008]

The structure of the present invention for achieving the above object will be described with reference to the drawings corresponding to the embodiments. The present invention relates to an auger screw inserted into a hollow precast pile 1. 2 is a method of mounting a digging head 6 having substantially the same diameter as the outside diameter of the pile at the lower end of the stake, and burying the pile while maintaining the interval L between the stake 1 and the digging head 6, and contains a large amount of gravel. In geological layers such as gravel layers, the above interval L is adjusted to a length within the range of 0.1 to 0.5 of the pile diameter, which is the target value of the maximum gravel diameter corresponding to the diameter of the pile 1 to be buried. It is characterized by proceeding.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 sequentially shows one embodiment of the present invention, and FIGS. 3 to 8 show one embodiment of an excavator using an auger screw or the like used in the present invention.

As shown in FIG. 1, the excavator used in the present invention includes an auger screw 2 having an auger shaft 3 provided with a screw 4 and an auger head 6 removably attached to a lower end thereof via a joint 5. Consisting of

As shown in FIGS. 6 to 8, the joint 5 has, at the upper end of a shaft rod 7, an angular shaft 8 fitted to the lower end of the auger shaft 3, and at the lower end thereof an auger head 6 to be described later. An engaging body 9 that can be engaged and disengaged is provided, and a large-diameter contact plate 10 that is joined to the upper end of the auger head 6 is provided in the upper and lower middle part. A screw 11 is provided above the contact plate 10 of the shaft 7. Is provided. The engaging body 9 is formed of a thick plate, and is provided with a plurality of fan-shaped projecting locking pieces 9a on the peripheral surface.

As shown in FIGS. 4 and 5, the auger head 6 has a circular substrate 12 having a diameter substantially equal to the outer diameter of the pile 1 to be embedded.
Inverted hill 13 with many pits 14
Is provided at the center of the upper surface of the substrate 12, and a cylindrical body 15 having a diameter through which the engaging body 9 of the auger joint 5 can be inserted is provided. An engagement hole 16 similar to the engagement body 9 is provided at a position in the cylinder 15 of the substrate 12 so that the engagement body 9 can be taken in and out. The excavation wing 13 is provided with a cutout recess 17 in the upper part of the center portion thereof, into which the engagement body 9 can be inserted and which can strike the side end of the locking piece 9a.

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 stop rod 18. To the auger joint 5, a cutting head 6 is detachably connected. You. The engagement is performed by inserting the engagement body 9 of the auger joint 5 into the cutout recess 17 through the engagement hole 16 of the substrate 12, and bringing the abutment plate 10 into contact with the upper end of the cylindrical body 15. Then, when the auger screw 2 is rotated forward in the excavation direction, the locking pieces 9 a of the engagement body 9 are stopped against the end side surface 19 of the cutout recess 17 of the substrate 12. Therefore,
If the auger screw 2 is rotated forward, the excavating head 6 rotates and the ground can be excavated. During this excavation rotation, the engagement body 9 and the engagement hole 16 are displaced in the rotational direction, so that the auger joint 5 and the excavation head 6 cannot be separated vertically.

In order to separate the auger joint 5 from the excavating head 6, the auger joint 5 is engaged with the engagement body 9 by the engagement hole 16.
When the auger screw 2 is pulled up after the reverse rotation to the position corresponding to the above, the engagement body 9 comes out of the engagement hole 16 and rises, so that separation can be performed.

The excavator is not limited to the one described above. In short, as an excavator, when the auger head 6 attached to and detached from the lower end of the screw auger 2 can be rotated in a state where it cannot be separated by the forward rotation of the screw auger 2, and when the screw auger 2 is slightly rotated in the reverse direction Any structure can be used as long as the structure can be separated.

Next, the burial process of the pile according to the present invention is shown in FIG.
This will be described with reference to FIG. First, as shown in FIG. 1 (a), the excavating head 6 is fixed, and on the other hand, the auger screw 2 is inserted into the pile 1, and this is inserted into the pile 1 at the burial point, that is,
It is built just above the excavation head 6. In this state, the auger screw 2 and the excavating head 6 are connected as described above. Then, a predetermined pressure is applied to the auger screw 2 by a rotary press-fitting device (not shown) to cause the auger screw 2 to rotate forward in the excavation direction, and the pile 1 is pushed down. It will penetrate.

In the present invention, when excavating and penetrating, as shown in FIG. 1 (b), a required distance L exists between the excavating head 6 and the pile 1 in the ground. As a result, the excavated earth and sand extruded to the side from the head 6 enters the pile 1 from 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 the pile 1. According to this method, at the time of excavation and subsidence, the earth and sand is pressed against the side of the excavation head 6 and is compacted on the side ground to reduce the turbulence of the earth and sand. Since it enters and is conveyed and excavated, the amount of excavated earth can be reduced by about half compared with the general conventional digging method.

In the present invention, the excavating head 6 and the pile 1
The construction is proceeded while adjusting the distance L between them to the soil quality, that is, the size (gravel diameter) of the gravel such as gravel and boulders contained in the stratum. The adjustment is performed according to the gravel diameter at each depth in the soil column diagram created by the survey prior to construction.

That is, the distance L between the excavating head 6 and the pile 1
Indicates that in the stratum where the gravel diameter is below the target value shown in Table 1,
As shown in Table 2, corresponding to the outer diameter φ of the pile to be buried,
The construction will proceed with a length of approximately one-half the diameter. In the stratum (gravel layer) where the gravel diameter is equal to or greater than the target value shown in Table 1, the interval L is set to a length not exceeding the target value of the maximum gravel diameter with respect to the outer diameter φ of the pile to be buried. Adjust and construct. Table 3 shows the range of the interval L with respect to the diameter of the pile.

[Table 2]

[Table 3]

As described above, according to the present invention, in the normal ground where the diameter of the pile to be embedded is smaller than the target maximum gravel diameter from the intermediate layer A of the ground where the pile is embedded to the support layer B, the spacing L Is taken long enough to improve the efficiency of soil removal, but in gravel layers with gravel larger than the maximum gravel diameter,
The gap L is kept below the target maximum gravel diameter, and the construction is advanced so that gravel does not enter the hollow part of the pile. Thereby, the damage of the pile can be eliminated, and it is possible to construct a gravel layer having gravel of any gravel diameter.
Also,

As described above, the construction is carried out while maintaining the interval L between the excavating head 6 and the pile 1, and as shown in FIG. The screw 2 is slightly reversely rotated in the opposite direction to the conventional one, and the auger joy is slightly pulled up by aligning the engaging body 9 of the auger joint 5 with the engagement hole 16 of the excavating head 6 to release the connection between the two. As a result, the excavating head 6 becomes
Will be left behind.

In this state, the lower end of the pile 1 and the excavation head 6
Since there is a predetermined gap 20, the pile 1 is pushed down from the upper end of the pile 1 by light tapping or pressing to make the pile 1 abut against the excavation head 6. Thereby, the excavating head 6 becomes a support portion of the pile 1. Next, as shown in FIG. 1 (d), the pile 1 is further penetrated by further tapping or pressing the pile 1 from its upper end.
After that, the auger screw 2 is pulled out from the pile 1, and the embedding of the pile is completed.

[0025]

As described above, according to the present invention,
A detachable excavation head is attached to the lower end of the auger screw that penetrates the pile, and the pile is buried while maintaining the space between the pile and the excavation head. Part of the earth and sand is discharged while the hole wall is strengthened, and the amount of discharged earth and sand is about half less than that of the ordinary middle digging method, and the cost required for earth removal can be greatly reduced Become like

In a stratum containing gravel, construction is performed by adjusting the distance between the pile and the excavation head, so that the pile is prevented from being damaged by gravel entering between the auger screw and the pile. Therefore, piles can be reliably and easily buried even in a gravel layer that could not be constructed by a general middle digging method.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view sequentially showing construction steps according to an embodiment of the present invention, (a) shows a state where a pile is built on the ground, (b) shows a state of being buried in an intermediate layer, (C) shows a state penetrating the support layer, and (d) shows a state where the auger screw is pulled out.

FIG. 2 is a side view showing one embodiment of an apparatus used in the present invention.

FIG. 3 is a side sectional view of a drilling head.

FIG. 4 is a plan view of the same.

FIG. 5 is a side view of the auger joint.

FIG. 6 is a plan view of the same.

FIG. 7 is a bottom view of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pile 2 Auger screw 5 Auger joint 6 Drilling head 9 Engagement body 12 Substrate 13 Drilling wing 14 Pit 16 Engagement hole 17 Notch recess 20 Gap A Middle layer B Support layer L Distance between pile and drilling head

[Table-1]

[Table-2]

[Table-3]

Claims (1)

[Claims] At the projecting lower end of the auger screw inserted through the hollow ready-made pile,
This is a method of burying piles with a drilling head of almost the same diameter as the outer diameter of the pile and keeping the space between the pile and the drilling head. The burying of hollow precast piles, characterized in that the spacing is adjusted to a length within the range of 0.1 to 0.5 of the pile diameter, which is the target value of the maximum gravel diameter corresponding to the diameter of the pile to be buried. Construction method.