JP3965451B2 - Pile burying method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pile burying method, and more particularly to a burying method for building a ready-made pile in a pre-bored pile hole.
[0002]
[Prior art]
As one of the methods of burying ready-made piles, in order to minimize the amount of soil discharged by excavating pile holes, a method of mixing and agitating excavated earth and pile circumference filling liquid to form a slurry-like pile circumference solidified material is used. Are known. In such a construction method, in general, in order to increase the tip support force, the tip portion of the pile hole is enlarged and excavated, and also in this enlarged excavation portion, the excavated sediment and root-solidification liquid are mixed and stirred to Forming and rooting the tip of the ready-made pile.
[0003]
However, although the above-mentioned conventional method can be expected to increase the tip support force due to the enlarged root-solidified portion, the length is usually as short as about 2 m, and therefore an increase in peripheral frictional force due to the root-solidified portion can hardly be expected. In fact, the design surface calculation does not take into account the peripheral frictional force of the root portion.
[0004]
Further, for excavation of a pile hole, an auger screw having an excavation head of a type that expands a blade by reversing is used at the tip. When forming the enlarged excavation part for the root consolidation part, the expansion blade is expanded by reversing the excavation head, and when moving to the pile hole above it, the blade is closed by normal rotation. However, the expansion blade may not open depending on the soil quality such as clay. In such a case, an enlarged rooting portion having a required size is not formed, and the desired tip support force cannot be obtained.
[0005]
[Problems to be solved by the invention]
The present invention has been made based on the technical background as described above, and achieves the following object.
An object of the present invention is to provide a pile embedding method capable of increasing the peripheral frictional force in addition to the tip supporting force.
[0006]
Another object of the present invention is to provide a pile embedding method capable of preventing occurrence of a situation in which an enlarged blade does not open and reliably obtaining a desired support force.
[0007]
Still another object of the present invention is to provide a pile embedding method in which a slurry-like saw does not overflow from a pile hole when an ready-made pile is built in the pile hole.
[0008]
[Means for Solving the Problems]
The present invention employs the following means in order to achieve the above object.
That is, this invention is a process of expanding the lower part of the pile hole formed in the ground, forming an expanded excavation part having a predetermined length,
Injecting the pile circumference filling liquid into the enlarged excavation part, mixing and agitating with excavated earth and sand, forming a pile circumference solidified material by soil cement,
Injecting a root-setting liquid into the tip of the enlarged excavation part, mixing and agitating with excavated earth and sand to form a root-solidified part by soil cement;
A prefabricated pile is built in the pile hole so that a tip portion of the pile is embedded in the solidified portion, and the soil cement raised thereby is filled around the prefabricated pile and cured. It is in the pile burial method.
[0009]
In the above construction method, the total soil cement length for forming the root consolidation part and the pile circumferential solidification material is the following formula,
Ls = L (1-Vp / Vh)
However, L: Pile hole length Ls: Total soil cement length Vp: Pile volume Vh: Pile hole volume before expanded excavation is preferably substantially satisfied. In this case, the formation length of the said expanded excavation part can take the aspect consistent with the said soil cement length, and the aspect smaller than the said soil cement length.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG.1 and FIG.2 is sectional drawing which shows the construction procedure of the pile burying construction method by this invention. As shown in the figure, an auger screw 1 having an auger head 2 at the tip is used as an excavator. Although not shown in detail in the auger head 2, the auger screw 1 has an enlarged blade that closes in the forward rotation state and expands when the auger screw 1 rotates backward. The auger screw 1 is capable of discharging excavation liquid, pile circumference filling liquid, and root hardening liquid supplied from the ground.
[0011]
Using such auger screw 1, as shown in FIG. 1 (a), while confirming the excavation core, the pile hole 3 is made to a predetermined depth at a speed suitable for the ground while feeding the excavation liquid as appropriate. Excavate.
[0012]
Next, as shown in FIG.1 (b), the auger screw 1 is reversely rotated by the front-end | tip part of the pile hole 3, and an expansion blade is expanded. Then, by raising the auger screw 1, the enlarged excavation part 4 is formed by performing an enlarged excavation from the hole bottom to a predetermined length range. At that time, the excavation liquid is switched to the pile circumference filling liquid, and this pile circumference filling liquid is discharged to the enlarged excavation part 4 excluding the distal end portion 4a which will be described later, and mixed and agitated with the excavated soil. Cement milk having a predetermined water-cement ratio is used as the pile circumference filling liquid.
[0013]
Further, as shown in FIG. 1 (c), the auger screw 1 is switched to normal rotation, closed and lowered. Then, the blades are reversed again to expand the blades, and while the auger screw 1 is raised, mixing and stirring of the pile circumference filling liquid and the excavated earth and sand is performed again. Thereafter, such mixing and agitation is repeated as many times as necessary, and thus the pile excavated portion 4 is formed with the pile circumference solidified material 5 made of slurry soil cement.
[0014]
Next, as shown in FIG. 2 (d), the expanded blade is expanded and mixed with the excavated sediment while discharging the rooting liquid in the range (about 2m) from the bottom of the excavation hole to the tip 4a of the expanded excavation part. Stirring is repeated to form the enlarged root hardening portion 6. As this root hardening liquid, cement milk is used like the pile circumference filling liquid, but its water-cement ratio is set smaller than the pile circumference filling liquid. After the formation of the enlarged root fixing portion 6, the auger screw 1 is rotated forward to close the enlarged blade, and the auger is pulled up from the pile hole 3. With this pulling up, most of the excavated earth and sand in the pile hole 3 above the enlarged excavation part 4 is discharged.
[0015]
Next, as shown in FIG. 2 (e), while confirming the verticality, the ready-made pile 7 is built in the pile hole 3, and the tip portion thereof is rooted in the enlarged rooting portion 6. The ready-made pile 7 is an open-ended hollow pile. By building the ready-made pile 7, the slurry-like soil cement forming the expanded root-solidifying portion 6 and the pile circumference solidifying material 5 is raised, and the entire periphery of the ready-made pile 7 is filled with the soil cement. . By hardening this soil cement, the soil cement pillar 8 is formed in the outer periphery of the ready-made pile 7, and the synthetic pile 10 with which both were united is built.
[0016]
According to the above construction method, the soil cement column 8 forming the composite pile 10 is further enlarged on the enlarged rooted portion 6 at the tip portion and having an enlarged portion 11 (FIG. 2 (e) or FIG. 3 (b). The enlarged portion 11 is integrated with the surrounding ground and has a large peripheral surface, so that the peripheral frictional force can be increased.
[0017]
In addition, during construction, even if a situation occurs in which the expansion blades do not open due to the soil quality, the expansion excavation section 4 has a length longer than the expansion root consolidation section 6, so that the auger screw 1 is being raised. There are many opportunities to expand the blades, and it is possible to prevent harmful effects caused by the non-expanded blades of the expanded blade.
[0018]
In the said embodiment, the length of all the soil cements which respectively form the enlarged root solidification part 6 and the pile periphery solidification material 5 has a fixed relationship with respect to the length of the pile hole 3. FIG. That is, as shown in FIGS. 3 (a) and 3 (b), the length of the pile hole 3 is L, the length of the entire soil cement is Ls, the volume of the pile 7 is Vp, and the pile hole 3 before expanded excavation (FIG. 3) If the volume of 3 (a) is partially indicated by a chain line is Vh, the length Ls of the entire soil cement is expressed by the following formula: Ls = L (1-Vp / Vh) (1)
Almost satisfied. When the length Ls of all the soil cements satisfies the above formula, when the ready-made pile 7 is built in the pile hole 3, the soil cement rising thereby does not overflow from the pile hole 3, but over the entire circumference of the pile. Filled. Here, Vp is the actual volume that does not include the hollow portion in the case of the open-ended pile, and the volume that includes the hollow portion in the case of the closed-end pile.
[0019]
Note that the total soil cement length satisfies the above equation “almost” because the depth of penetration of the tip of the ready-made pile 7 depends on the construction conditions as shown in the figure. This is because there is a case where the intermediate portion does not reach the bottom portion or a case where the intermediate portion does not reach the bottom portion or the bottom portion of the root hardening portion 6 is reached. In short, the meaning of the above formula is that the soil cement is filled in the outer periphery of the ready-made pile built in the pile hole 3 without excess and deficiency, and the soil cement does not overflow from the pile hole.
[0020]
In the above embodiment, after substantially satisfying the expression (1), the total soil cement length Ls and the length Le of the expanded excavation part are matched (Ls = Le). That is, only in the length range of the expanded excavation part 4, cement milk is injected, mixed with the excavated earth and sand, and the pile circumference solidified material 5 made of soil cement is formed. If it does in this way, since mixing and stirring will be performed only in a wing expansion state, construction management becomes easy.
[0021]
However, in order to obtain the required peripheral frictional force with the expression (1) almost satisfied, it may be sufficient that the length Le of the expanded excavation part 4 is smaller than the total soil cement length Ls. obtain. 4A and 4B show an embodiment in such a case. In the case of this embodiment, the pile periphery solidification material 5 by soil cement will also form soil cement also in a part of pile hole 3 above the expanded excavation part 4.
[0022]
【The invention's effect】
As described above, according to the present invention, since the soil cement pillar formed integrally with the periphery of the ready-made pile has the enlarged portion on the root-solidified portion, the peripheral frictional force is increased. be able to. Further, it is possible to prevent occurrence of a situation in which the expansion blade does not open, and to surely obtain the desired support force.
[0023]
In addition, the soil cement overflows from the pile hole when the ready-made pile is built in the pile hole by making the total soil cement length that respectively forms the root consolidation part and the pile circumference solidification material almost satisfy the predetermined formula. Can be prevented.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a construction procedure of an embodiment of the present invention construction method.
FIG. 2 is a cross-sectional view showing a construction procedure subsequent to FIG.
FIG. 3 is a cross-sectional view for explaining the relationship between the length of all soil cement and the length of pile holes.
FIG. 4 is a cross-sectional view for explaining the relationship between the length of all soil cement and the length of pile holes in another embodiment.
[Explanation of symbols]
1: Auger screw 2: Auger head 3: Pile hole 4: Expanded excavation part 5: Pile circumference solidified material 6: Expanded solidification part 7: Ready-made pile 8: Soil cement pillar 10: Synthetic pile 11: Expanded part

Claims (4)

Expanding and excavating the lower part of the pile hole formed in the ground, and forming an expanded excavation part having a predetermined length;
Injecting the pile circumference filling liquid into the enlarged excavation part, mixing and agitating with excavated earth and sand, forming a pile circumference solidified material by soil cement,
Injecting a root-setting liquid into the tip of the enlarged excavation part, mixing and agitating with excavated earth and sand to form a root-solidified part by soil cement;
A prefabricated pile is built in the pile hole so that a tip portion of the pile is embedded in the solidified portion, and the soil cement raised thereby is filled around the prefabricated pile and cured. Pile burial method. The total soil cement length forming each of the root consolidation part and the pile circumference solidification material is
Ls = L (1-Vp / Vh)
However, L: Pile hole length Ls: Total soil cement length Vp: Pile volume Vh: Pile hole volume before expansion excavation is substantially satisfied, The pile embedding method according to claim 1 characterized by things. The pile embedding method according to claim 2, wherein a formation length of the expanded excavation portion is equal to the total soil cement length. The pile embedding method according to claim 2, wherein a formation length of the expanded excavation part is smaller than a length of the entire soil cement.

Images