JP5484018B2 - Pile construction method using Yatco - Google Patents

Description

  The present invention relates to a method for constructing a pile using a yatco. More specifically, the present invention relates to an improvement in the structure of the yatco and the construction method of the pile.

  As a construction method for piles with spiral blades (for example, steel pipe piles), the steel pipe piles are rotated by a pile rotating device (auger) while the vicinity of the lower end of the steel pipe piles is kept steady by a pile driving machine. There is something. Moreover, in such a construction method, the pile head is directly rotated by a pile rotating device, and the power of the pile rotating device is transmitted to the pile via a Yatco (temporary pile made of steel pipe) between them. (See, for example, Patent Document 1).

  By the way, when constructing a pile, if there is soft ground near the pile head, the displacement of the pile increases with respect to the horizontal force acting during an earthquake, which may adversely affect the superstructure. Therefore, in order to reduce the influence by improving the horizontal strength in the vicinity of the pile head in particular, as a method of expanding the periphery of the pile head, an enlarged diameter drilling hole is first built before the pile is buried. And a method of improving the ground by excavating the periphery of the pile head after burying the pile (see Patent Document 3). Furthermore, there is also proposed a method of excavating a hole for improving the periphery of a pile without excavation, and excavating with the same diameter over the entire length without performing expanded excavation (see Patent Document 4).

Japanese Patent No. 3828731 Japanese Patent No. 4223780 Japanese Patent No. 3127276 Japanese Patent No. 3532247

  In the pile construction method as described above, if the number of steps can be reduced, it is advantageous in terms of cost and quality control. However, when constructing a pile using a Yatco as described above, there is a limit to reducing the number of steps. In addition, it is desirable that the horizontal resistance of the pile buried in the ground can be further improved from the current level.

  Then, an object of this invention is to provide the construction method of the pile using a Yatco which makes it possible to improve the horizontal proof stress of a pile while reducing the number of processes, considering the subject in a prior art.

  In order to solve this problem, the present inventor has made various studies. In order to improve the horizontal strength of the pile, as described above, a construction method such as building a drilling hole with an enlarged diameter in advance or excavating the periphery of the pile head to improve the ground has been adopted, The current situation is that it has undergone various processes such as excavation process, pile burying process, and ground improvement process.

  Moreover, in order to improve the horizontal proof stress of a pile, the surroundings of a pile head are expanded and excavated as mentioned above, and also the ground is improved by filling the pile periphery with a ground improvement material. In this case, it is desirable that the horizontal proof stress of the pile be exhibited evenly, but in reality, the pile moves in the expanded excavation hole until the improved material solidifies, and the center of the pile and the improved material center There was a possibility that it would shift. Such shift of the center of the pile is not desirable from the viewpoint of improving the horizontal strength because the horizontal strength of the pile is not uniform.

  The present inventor who has repeatedly studied these current technologies has come to obtain new knowledge that leads to the solution of such problems. The present invention is based on such knowledge, and uses a Yatco comprising an outer frame body for expanding and excavating the ground, and a guide for maintaining a state in which the pile core of the pile is substantially aligned with the rotation center of the Yatco, Is held substantially in line with the center of rotation of the yatco, the pile is buried in the ground using the yatco, and the periphery of the pile is enlarged and excavated by the outer frame body. The ground is improved around the pile by placing a ground improvement material on the part.

  In such a construction method, by burying the pile in the ground using the above-described yatco, an enlarged excavation hole can be built around the pile by the outer frame simultaneously with the embedding step. For example, in the case of the conventional method, it is necessary to pass through various processes sequentially such as building an enlarged excavation hole first, then burying the pile, and then improving the ground around the pile. According to this construction method, it is possible to collectively perform different processes of burying piles and constructing an expanded excavation hole.

  Moreover, in this construction method, since the ground is expanded and excavated while holding the pile in a state of being substantially coincident with the center of rotation of the Yatco, an expanded excavation hole can be built around the buried pile. For this reason, it becomes possible to perform ground improvement in a state in which the center of the pile and the center of the ground improvement material are made more consistent. Therefore, according to the construction method concerning this invention, it becomes possible to reduce the bending moment which may act on a pile, and to improve a horizontal proof stress conventionally.

  In the construction method of the pile as described above, it is preferable that another pile is connected to the upper part of the pile to which the Yatco transmits the rotational force and is held by the guide. When the rotational force is transmitted to the lower pile in this way, the rotational force (torque) does not act on the connection portion with the upper pile, so for example, the mechanical joint structure for connecting the pile and the pile is simplified. Can contribute to cost reduction.

  Moreover, in this construction method, the ground improvement material can also be placed in the part that has been expanded and excavated during or after the Yatco is pulled up from the ground. For example, in the case where multiple piles are constructed in sequence with a single pile driving machine, the process of burying one pile and building an expanded excavation hole and placing ground improvement material in the expanded excavation hole Thus, if the step of solidifying can be carried out separately and independently, each step can proceed in parallel at different locations. In this regard, according to the construction method according to the present invention, after finishing the process of burying one pile and constructing the expanded excavation hole, the ground improvement material is placed in the portion where the expanded excavation has been lifted up once after that. Since the process and the process of burying other piles and building an expanded excavation hole can be performed in parallel, it is possible to improve the construction speed and shorten the construction time required for the whole. In addition, the ground improvement material may be placed on the expanded excavated part either during or after the Yatco is pulled up from the ground, and the main point is the space for placing the ground improved material on the expanded excavated part. If there is, it is enough.

  According to the present invention, it is possible to reduce the number of steps and improve the horizontal strength of the pile.

It is a side view which shows an example of the pile driving machine utilized for implementation in this invention. It is a perspective view which shows the structural example of the yatco in the 1st Embodiment of this invention. It is sectional drawing which expands and shows the structure of the movable cover of Yatco, and its periphery. It is a bottom view (however, only a pile and an internal steel pipe are shown in figure) which shows a mode that the protrusion for pile engagement engaged with the pile engaging part of the inner steel pipe lower end of Yatco. It is a figure which shows an example of the construction procedure of a steel pipe pile in order of (A)-(I).

  Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.

  FIG. 1 shows an embodiment of a pile construction method using a yatco according to the present invention. The Yatco 20 is a steel material jig for embedding the steel pipe pile 10 in the ground G, and an outer frame body that is a steel material jig capable of digging the ground G and placing the ground improvement material 30. It has a structure that is integrated with. Below, the structure of the common pile driver 1 utilized for pile construction is demonstrated easily first (refer FIG. 1), and embodiment of this invention is described after that.

  The pile driving machine 1 is a machine that has a leader 2, an auger 3, a steadying device 4, and the like, and rotates a pile (for example, a steel pipe pile 10) while standing and embeds it in the ground G (see FIG. 1). In addition, in FIG. 1, the cap which may be attached to the base end (upper end) of the steel pipe pile 10 is shown with the imaginary line.

  The auger (pile rotating device) 3 is provided so as to be movable along a leader 2 standing in the vertical direction during pile driving, and moves up and down along the longitudinal direction of the leader 2 (see FIG. 1). A steel pipe pile 10 is connected to the auger 3 directly or via a Yatco 20, and when the auger 3 is driven to rotate, the steel pipe pile 10 also rotates. In this embodiment, the steel pipe pile 10 provided with the spiral blade 12 for excavation at the tip is used, and propulsion to the ground generated by the spiral blade 12 by rotating the steel pipe pile 10 in this way. Using the force, the steel pipe pile 10 is dug while biting into the unexcavated ground G. When the steel pipe pile 10 is excavated with respect to the ground G, the auger 3 also descends along the leader 2.

  The steady rest device 4 is a device that guides the steel pipe pile 10 to be struck and suppresses the lateral runout (shake in the horizontal direction) of the steel pipe pile 10, and is provided, for example, at the lower portion of the leader 2 (see FIG. 1). ). Further, the steady rest device 4 includes a guide portion 5 that surrounds and guides the steel pipe pile 10 around the axis of the steel pipe pile 10. For example, in the case of the present embodiment, the guide portion 5 has a pair of open / close guides (not shown) provided so as to swing horizontally with respect to the vertically standing leader 2.

  Then, the example of the construction method of the steel pipe pile 10 using the structure of the Yatco 20 and the said Yatco 20 is demonstrated below.

  The Yatco 20 according to the present embodiment is a steel pipe temporary pile for burying a pile including an outer frame body 21, a guide 22, a pile engaging portion 22b, and the like, and at the same time the steel pipe pile 10 is buried, the steel pipe pile 10 in the ground. A space for ground improvement is formed around the area.

  The outer frame body 21 of the YATCO 20 functions as a hopper capable of expanding the ground G and storing the ground improvement material 30 (hereinafter also referred to as a hopper). For example, in the present embodiment, the hopper 21 is formed of a cylindrical portion and a tapered portion provided at a lower portion of the cylindrical portion (see FIG. 2 and the like). The hopper 21 having a tapered lower portion is preferable in that the ground G can be easily excavated.

  The guide 22 is a member that maintains a state in which the pile core of the steel pipe pile 10 to be buried is substantially aligned with the center of rotation of the yatco 20. For example, in the present embodiment, a steel pipe having an inner diameter larger than the outer diameter of the steel pipe pile 10 to be constructed (hereinafter also referred to as an internal steel pipe 22) is used as a guide.

  The internal steel pipe 22 and the hopper 21 are integrated by a connecting member 23 so that the axis of the internal steel pipe 22 substantially coincides with the rotation center of the hopper 21. Although the specific configuration of the connecting member 23 is not particularly limited, for example, in the present embodiment, a total of two connecting members 23 made of spoke-like arms having a cross-like shape in plan view are used for each of the upper and lower stages. The inner wall of the hopper 21 and the internal steel pipe 22 are connected at two locations near the upper portion and near the lower portion of the cylindrical portion of the hopper 21 (see FIG. 2). If the spokes 23 having the same configuration can be used in two places, it is advantageous in terms of cost.

  At the upper end of the internal steel pipe (guide) 22, an engagement protrusion 22 a for connecting to the auger 3 is formed. The engaging protrusions 22a are composed of, for example, two protrusions of the same shape arranged at equal intervals (every 180 degrees) (see FIG. 2), and function as a detent when the auger 3 is rotationally driven. If the shape of the upper end portion of the internal steel pipe 22 including the engaging protrusion 22a is the same as the shape of the upper end portion of the pile 10, both the pile 10 and the internal steel pipe 22 are directly connected to the auger 3 without using an auxiliary tool or the like. Can be attached.

  Further, a pile engaging portion 22 b for connecting the pile 10 is formed at the lower end of the internal steel pipe (guide) 22. The pile engaging portion 22b in the present embodiment includes a notch 22c into which the engaging protrusion 11 of the pile 10 is fitted, and a notch cover 22d that covers the notch 22c from the outside and reinforces the strength. (See FIG. 4). The notch 22c of the pile engaging portion 22d and the engaging protrusion 11 of the pile 10 fitted in the notch 22c function as a detent in the circumferential direction of the pile 10 with respect to the internal steel pipe 22. Therefore, when the Yatco 20 is rotated with the internal steel pipe 22 and the pile 10 engaged, the pile 10 also rotates by the same amount. Note that the engagement protrusion 11 of the pile 10 is positioned in contact with the wall (per degree) of the notch 22c at a predetermined position, and cannot enter deeper than the predetermined position (see FIGS. 3 and 4). . The notch cover 22 also functions as a hit for defining a stroke end of the movable lid 24 described later.

  Further, for example, at the bottom of the hopper (outer frame) 21, an outflow hole 21a through which the ground improvement material 30 stored in the hopper 21 can flow out is provided (FIGS. 2 and 3). reference). For example, in the present embodiment, the bottom of the tapered cylindrical portion at the bottom of the hopper is opened to form an annular outflow hole 21a centering on the internal steel pipe 22 (see FIGS. 2 and 3).

  Furthermore, the YATCO 20 may include a movable lid (open / close lid) 24 that opens and closes the outflow hole 21a. For example, the yatco 20 of the present embodiment includes a movable lid 24 that opens and closes the outflow hole 21a by receiving resistance in the ground when the yatco 20 is propelled into the ground and pulled up from the ground ( (See FIGS. 2 and 3).

  The movable lid 24 of the present embodiment has a size that can close the outflow hole 21a with a pipe portion 24a that can slide around the inner steel pipe 2 along the axial direction and can rotate around the inner steel pipe 2. For example, a circular flat plate portion 24b is integrated. The movable lid 24 has a position where the flat plate portion 24b is in contact with the edge of the outflow hole 21a (upper stroke end), and an edge of the pipe portion 24a is in contact with the notch cover (per degree) 22d of the pile engaging portion 22b. It is possible to stroke at a predetermined interval between the position (lower stroke end).

  The movable lid 24 is preferably provided with a resistance increasing portion that increases the resistance of the movable lid 24 in the ground when the Yatco 20 is pulled up from the ground. In the present embodiment, a spiral blade 24c is formed around the pipe portion 24a, and when the steel pipe pile 10 is buried, the spiral blade 24c is bitten into the ground G like an anchor, and the resistance at the time of pulling is increased to be movable. The lid 24 is forcibly opened (see FIGS. 2 and 3). Moreover, when the spiral blade 24c rotates around the vertical axis when the steel pipe pile 10 is buried, the spiral blade 24c bites into the ground G to generate a propulsive force into the ground, and the steel pipe pile 10 can be buried more easily. Let

  Further, the YATCO 20 is provided with a device for restricting relative rotation of the movable lid 24 with respect to the hopper 21 at a predetermined time, for example, a relative rotation restricting device comprising a combination of a recess and a protrusion fitted into the recess. It is preferable. For example, in this embodiment, for example, two relative rotation restricting protrusions (hereinafter also referred to as co-rotating protrusions) 21 b that protrude vertically downward are provided on the bottom of the hopper 21, and the flat plate portion 24 b of the movable lid 24 is provided on the flat plate portion 24 b. A co-rotation notch 24d into which the co-rotation protrusion 21b can be fitted is provided (see FIG. 3 and the like). When the internal piping 22 and the hopper 21 are rotated in a state in which the common rotation projection 21b is fitted in the rotation regulating notch 24b, the movable lid 24 is rotated together with these to restrict relative rotation with respect to the hopper 21 and the like. be able to. The common rotation projection 21b is in a state of being fitted into the common rotation notch 24d when the pile is embedded in the ground, while the common rotation notch 24d is automatically pulled from the common rotation notch 24d. It can come out and does not hinder the operation for opening the movable lid 24.

  Then, an example of the construction procedure at the time of embedding the steel pipe pile 10 is demonstrated below (refer FIG. 5 etc.).

  First, when the steel pipe pile 10 is built in the ground G, the open / close guide (not shown) of the steadying device 4 of the pile driving machine 1 is opened, the auger 3 is lowered along the leader 2, and the steel pipe pile 10 Is connected to the auger 3. Then, the auger 3 is raised and the steel pipe pile 10 is suspended, and the said steel pipe pile 10 is set according to a pile core (refer FIG. 1). When the tip of the steel pipe pile 10 is set on the pile core, the open / close guide is closed to keep the steady state, and the steel pipe pile 10 is gripped.

  Here, after confirming that the steel pipe pile 10 is vertically built, the auger 3 gives a positive rotation (right rotation) to the steel pipe pile 10, and the propulsive force generated by the spiral blades 12 of the steel pipe pile 10 It is embedded in the ground G (see FIGS. 5A and 5B). If the 1st steel pipe pile 10 (10A) is embed | buried, the steel pipe pile 10 (10B) after 2nd will be added by welding or a mechanical coupling as needed (refer FIG.5 (C)).

  Next, the Yatco 20 according to the present invention is installed at a predetermined position. Here, the Yatco 20 is lowered from the upper part of the second steel pipe pile 10 (10B), and the steel pipe pile 10 is passed through the inner steel pipe 22 (see FIG. 5D). In addition, like the Example mentioned later, you may make it insert the 2nd steel pipe pile 10 (10B) in the internal steel pipe 22 of the Yatco 20, and add both steel pipe piles, inserting. Next, the engaging protrusion 11 of the steel pipe pile 10 is engaged with a notch 22c (not shown in FIG. 5 of the notch cover 22d) of the pile engaging portion 22b of the internal steel pipe 22 (see FIG. 5E). ). At this time, since the steel pipe pile 10 is in a state of passing through the internal steel pipe 22 of the YATCO 20, the steel pipe pile 10 can be held in a state of being substantially coincident with the rotation center of the YATCO 20.

  Subsequently, the auger 3 rotates the Yatco 20 in the normal direction (right rotation), and further embeds the steel pipe pile 10 (see FIG. 5F). In the case of this embodiment, the driving force by the auger 3 is that the engagement protrusion 22a of the Yatco 20 → the internal steel pipe 22 → the pile engagement portion 22b → the engagement protrusion 11 → the first steel pipe pile 10A → the second steel pipe pile 10B. It is transmitted to the steel pipe pile 10 by a route, and the engagement protrusion 22a of the Yatco 20 → the inner steel pipe 22 → the spoke (connection member) 23 → the hopper 21 → the common rotation protrusion 21b → the common rotation notch 24d → the pipe portion 24a → It is transmitted to the movable lid 24 through a route called the movable lid 24. When the steel pipe pile 10 is embedded by rotating the Yatco 20 forward (rightward), the periphery of the steel pipe pile 10 (second steel pipe pile 10B in this embodiment) can be expanded and excavated by the hopper 21.

  Next, only the Yatco 20 is pulled up from the ground G (see FIG. 5G). When the Yatco 20 is pulled up, an enlarged excavation hole is built in the ground G according to the outer shape of the hopper 21 (see FIG. 5H). After that, ground improvement material is placed in this expanded excavation hole to improve the ground. At this time, it is possible to perform the next burying of the steel pipe pile 10 and the construction of the enlarged excavation hole by using the Yatco 20 pulled up from the ground G.

  As explained above, according to the construction method of the steel pipe pile 10 in this embodiment, various processes, such as the embedding process of the steel pipe pile 10, the expansion excavation process for ground improvement, can be implemented simultaneously. That is, according to this construction method, the process of embedding the steel pipe pile 10 in the ground G using the Yatco 20 and the process of constructing the enlarged excavation hole around the steel pipe pile 10 by the hopper 21 can be simultaneously performed. it can. According to this, since it is possible to perform different processes of embedding the steel pipe pile 10 and the process of constructing the enlarged excavation hole at a time, the number of processes required during construction can be reduced and construction efficiency can be improved. It becomes. In addition, the reduction in the number of processes is advantageous in terms of cost and quality control during construction of the steel pipe pile 10.

  Moreover, according to the construction method in this embodiment, the steel pipe pile 10 can be embed | buried in the ground G, without constructing the drilling hole of an enlarged diameter beforehand, and only the periphery of the upper part of the said steel pipe pile 10 can be expanded and excavated ( (See FIG. 5 etc.) According to this, until the ground improvement material 30 to be placed thereafter is solidified in the expanded excavation hole, the tip of the steel pipe pile 10 is buried in the ground, and the steel pipe pile 10 is expanded in the expanded excavation hole. It is possible to maintain a state that is difficult to move. For this reason, since the ground improvement material 30 can be solidified in a uniform state around the steel pipe pile 10, there is an advantage that the horizontal proof stress of the steel pipe pile 10 can be easily improved without going through an extra adjustment / management process. is there.

  Further, in this construction method, since the enlarged digging hole is constructed by propelling it into the ground while rotating the hopper (outer frame body) 21 without constructing the digging hole of the enlarged diameter in advance, It is also characteristic in that soil is not performed. That is, by eliminating (or reducing) the residual soil (construction by-product) generated during the construction of the steel pipe pile 10, it is possible to reduce the residual soil disposal cost (industrial waste handling). It is also desirable from the environmental aspect to suppress the generation of construction by-products in this way.

  Furthermore, according to this construction method, it is possible to embed the next steel pipe pile 10 in another place while placing the ground improvement material in the enlarged excavated portion after the Yatco 20 is pulled up from the ground. . That is, according to the construction method of the present embodiment, after finishing the process of burying one pile and constructing an expanded excavation hole, placing the ground improvement material on the expanded excavated part, Since it is possible to proceed in parallel with the process of building the buried / expanded excavation hole, it is possible to improve the construction speed and shorten the construction time required for the whole. In general pile construction, it is considered that a plurality of steel pipe piles 10 are sequentially constructed by a single machine (or a limited number) of pile drivers 1 within a predetermined range. As in the pile construction method of the embodiment, the process of embedding / expanding excavation hole of one steel pipe pile 10 and the process of placing and solidifying the ground improvement material in the expansion excavation hole can be carried out independently. If possible, it is preferable in that each process can be performed in parallel at different locations.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the above-described embodiment, the YATCO 20 in which the spiral blade 24c is formed around the pipe portion 24a of the movable lid 24 is illustrated, but another spiral blade is provided on the outer surface of the other portion, for example, the hopper 21. May be formed.

  Moreover, although the steel pipe pile was shown as a specific example of the pile used as construction object in embodiment mentioned above, this is only a suitable example, for example, applies this invention also to other types of piles, such as a concrete pile. It is possible.

  In the above-described embodiment, the mode in which the ground improvement material is filled after the hopper (outer frame body) 21 is completely pulled out from the ground is illustrated (see FIGS. 5H and 5I). It is only a suitable example. In addition to this, for example, the placement of the ground improvement material into the enlarged excavation hole may be started before the hopper 21 is completely pulled out from the ground. In short, in the construction method according to the present invention, it is possible to place the ground improvement material without using the Yatco 20 and to use the Yatco 20 regardless of the placement of the ground improvement material. Therefore, whether or not the hopper 21 is completely pulled out from the ground does not affect the placement timing of the ground improvement material.

  Furthermore, in embodiment mentioned above, after illustrating the construction method of the steel pipe pile 10, after illustrating the Yatco 20 provided with the outflow hole 21a, the movable cover 24, etc., such Yatco 20 is only a suitable example. More specifically, the Yatco 20 having the above-described structure is useful when the ground improvement material filled in the hopper 21 is caused to flow out of the outflow hole 21a to place the ground improvement material in the enlarged excavation hole. However, it is natural that the present invention can be implemented with the YATTCO 20 having a structure other than this. For example, the present invention can also be implemented by a simple container-like hopper (outer frame body) 21 that does not include the outflow hole 21a and the movable lid 24, as in the above-described embodiment. is there.

  The present invention is suitably applied to a case where a pile having spiral blades (for example, a steel pipe pile) is rotated while being steady and is used in a case where it is embedded in the ground.

DESCRIPTION OF SYMBOLS 10 ... Steel pipe pile (pile), 20 ... Yatco, 21 ... Hopper (outer frame), 22 ... Internal steel pipe (guide), 30 ... Ground improvement material, G ... Ground

Claims (2)

An outer frame member to expand excavated soil, a guide for holding the state of being substantially coincides with the rotation center of the pile core the Ya Ttoko piles, the forceps with a reference,
Connect another pile to the top of the pile to which rotational force is transmitted from the Yatco, and hold the other pile with the guide,
The pile is held in a state of being substantially coincident with the center of rotation of the yatco, the pile is embedded in the ground using the yatco, and the periphery of the pile is enlarged and excavated by the outer frame body. not through, the expanding ground improvement the periphery of the pile by pouring the land Release modifying material into excavated portion, the construction method of the pile using forceps. Wherein after the middle or pulled pulled from the ground the tongs and pouring the soil improvement material into the enlarged excavated portion, the construction method of the pile using forceps according to claim 1.

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