JP5474512B2 - 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 has an outer frame that functions as a hopper capable of expanding the ground and storing the ground improvement material, and a state in which the pile core of the pile is substantially matched with the rotation center of the yatco. And holding the pile in a state where it substantially coincides with the center of rotation of the yatco, rotating the yatco to embed the pile in the ground, and surrounding the pile with the outer frame. The ground improvement material stored in the outer frame body is expanded, and the surrounding area of the pile is improved by placing the Yatco in the expanded area while pulling it up from the ground.

  In such a construction method, if the pile is buried 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. Moreover, when pulling up the Yatco, it is possible to improve the ground by placing a ground improvement material on the expanded excavated portion. For example, in the conventional method, an enlarged excavation hole is built first, then the pile is buried, and then various steps are sequentially performed such as improving the ground around the pile. According to the method, ground improvement can also be performed in the step of burying piles.

  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. In addition, in this construction method, the ground improvement material stored in the outer frame body is driven into the enlarged excavation hole while lifting the Yatco, so the ground improvement material is not mixed with the ground sediment. Can be filled. For this reason, it is easier to exhibit the effect of the ground improvement material than in the conventional construction method. In addition, according to this construction method, the tip of the pile can be buried in the ground, so that the pile may move in the expanded excavation hole until the ground improvement material solidifies. Less is. For this reason, the state which aligned the center of the pile and the center of the ground improvement material can be maintained, and the ground improvement material can be solidified in an even state around the pile. By these, according to the construction method concerning this invention, the bending moment which may act on a pile can be reduced, and horizontal proof stress can be improved. In short, the construction method according to the present invention is characteristic in that the horizontal strength (strength against earthquake) in the vicinity of the pile head can be improved simultaneously with the construction (buried) of the pile.

  In such construction methods, use a Yatco provided with an open / close lid that opens and closes the outflow hole of the ground improvement material in response to resistance in the ground when the Yatco is propelled into the ground and pulled up from the ground. Is preferred. According to this, when the Yatco is pulled up from the ground, the opening / closing lid is automatically operated to open the outflow hole, and the ground improvement material can be placed in conjunction with the operation.

  In this construction method, it is more preferable to use a yatco in which a resistance increasing portion for increasing resistance in the ground with respect to the opening / closing lid at the time of lifting is provided on the opening / closing lid.

  Furthermore, in this construction method, the resistance increasing portion is a blade that generates a propulsive force to the ground when rotating, and it is preferable that the yatco is rotated when the pile is buried.

  Further, in this construction method, when the pile is held in a state substantially coincident with the center of rotation of the yatco, the pile head of the pile is held at a position substantially equal to the height of the upper edge of the outer frame body. It is also preferable.

  Moreover, in this construction method, it is also 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.

  Furthermore, in this construction method, it is preferable to use a tubular member arranged at the center of the outer frame as the guide.

  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). It is a side view which shows the structural example of the yatco in the 2nd Embodiment of this invention. It is a figure which shows the construction procedure of the steel pipe pile in the 2nd Embodiment of this invention in order of (A)-(E). It is a side view which shows the structural example of the yatco in the 3rd Embodiment of this invention. It is a figure which shows the construction procedure of the steel pipe pile in the 3rd Embodiment of this invention in order of (A)-(E). It is a side view which shows the structural example of the yatco in the 4th Embodiment of this invention. It is a figure which shows the construction procedure of the steel pipe pile in the 4th Embodiment of this invention in order of (A)-(D).

  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 the 1st-4th embodiment of this invention is described sequentially one after another.

  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.

<First Embodiment>
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). Since such a spoke-like connecting member 23 can secure a sufficient opening, it obstructs the work of filling the ground improvement material 30 in the hopper 21 or the work of checking how much the ground improvement material 30 is filled. Don't be. Further, 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.

  Moreover, the outflow hole 21a for making the ground improvement material 30 stored in the said hopper 21 flow out outside is provided in the bottom part of the hopper (outer frame body) 21, for example (refer FIG. 2, FIG. 3). . 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).

  Further, the YATCO 20 includes 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.

  Here, in this embodiment, a predetermined amount of ground improvement material (cement milk or the like) 30 is filled in the hopper 21 of the Yatco 20 (see FIG. 5G), and then only the Yatco 20 is pulled up from the ground G. (See FIG. 5H). When the Yatco 20 is pulled up, the movable lid 24 slides due to the weight of the earth and the ground improvement material 30 and the resistance acting on the spiral blade 24c, and the outflow hole 21a is automatically opened. Accordingly, the ground improvement material 30 flows out from the outflow hole 21a in conjunction with the lifting operation of the Yatco 20, and is sequentially driven from the bottom in the enlarged excavation hole, so that the periphery of the steel pipe pile 10 is improved (FIG. 5 ( I)).

  As explained above, according to the construction method of the steel pipe pile 10 in the present embodiment, various processes such as the embedding process of the steel pipe pile 10, the expanded excavation process for ground improvement, and the placement process of the ground improvement material 30 in some cases. Can be carried out simultaneously or in succession. 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. In addition, when the Yatco 20 is pulled up, the ground improvement material 30 can be placed on the enlarged excavated portion. According to this, since it becomes possible to perform different processes, such as the embedding process of the steel pipe pile 10 and the building process of the improved body, at the same time, the number of processes passed during construction can be reduced, and construction efficiency can be improved. Become. 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 solidifies 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 maintained in a state in which it is difficult to move in the expanded excavation hole. be able to. 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.

  Furthermore, in this construction method, the ground improvement material 30 stored in the hopper 21 is driven into the expanded excavation hole while being not mixed with the earth and sand of the ground G while pulling up the Yatco 20 ( In other words, it is possible to perform “replacement placement” instead of “mixed placement” as in the prior art. Therefore, since the boundary surface between the steel pipe pile 10 and the ground improvement material 30 does not contact the ground G, only the ground improvement material 30 can be solidified in the expanded excavation hole, so that the desired strength is achieved or obtained. There is an advantage that it is easy.

  Furthermore, this construction method can advantageously implement pile construction even when groundwater veins exist in the ground G. If explanation is added about this point, if an enlarged excavation hole is built beforehand in the ground G like the past, for example, it may break through a groundwater vein and groundwater may flow into an excavation hole, and a hole wall may collapse. In this regard, according to the construction method of the present embodiment, the hole wall of the excavation hole is pressed by the hopper 21 until immediately before the ground improvement material 30 is placed in the enlarged excavation hole (see FIG. 5G, etc.). Even if the enlarged excavation hole penetrates the groundwater vein, the groundwater can be prevented from flowing until immediately before the ground improvement material 30 is placed. Therefore, according to this construction method, the advantage that the quality at the time of pile construction can be improved than before, the improvement effect by the ground improvement material 30 than in the conventional construction method is exhibited, and the horizontal strength of the steel pipe pile 10 is improved. There is also an advantage that it is easy to improve.

  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.

  Moreover, according to the construction method of this embodiment which constructs the steel pipe pile 10 using the Yatco 20 provided with the internal steel pipe 22 as a guide of the steel pipe pile 10, there are also the following advantages. That is, the internal steel pipe 22 separates the ground improvement material 30 and the steel pipe pile 10 filled in the hopper 21, and until the ground improvement material 30 flows out from the outflow hole 21a, the ground improvement material 30 is a steel pipe. The state which does not adhere to the surface of the pile 10 is maintained (refer FIG. 5 (G), (H) etc.). Further, for example, when the Yatco 20 is installed at a predetermined position from the upper part of the second steel pipe pile 10 (10B) (see FIG. 5D), the steel pipe is used in the case of a discontinuous structure in which the guide is interrupted, for example. Although it is necessary to install the Yatco 20 while aligning the center of the Yatco 20 with the center of the pile 10, in this embodiment, it is easy to guide the steel pipe pile 10 along the inner peripheral surface of the inner steel pipe 22 and install it. There is no hassle to align many times in the middle.

  In addition, in this construction method, there is an advantage that the amount of the ground improvement material 30 can be easily grasped. That is, since the enlarged excavation hole is constructed according to the outer shape of the hopper 21, the amount of the ground improvement material 30 to be placed in the enlarged excavation hole can be easily calculated based on the capacity of the hopper 21. It is easy to grasp how much the ground improvement material 30 should be prepared. This is also advantageous in terms of cost and quality control during construction of the steel pipe pile 10. It should be noted that the depth to which the steel pipe pile 10 and the hopper 21 are propelled can be appropriately changed according to the design of the structure to be supported. It is always easy to grasp the amount of the ground improvement material 30 that should be.

  A specific example of this embodiment will be added below. In this embodiment, a steel pipe pile 10 having a diameter of about 165 mm is embedded 10 m (the first steel pipe pile 10 </ b> A is 5 m and the second steel pipe pile 10 </ b> B is 5 m) and at the same time a ground improvement body having a diameter of about 700 mm is about 5 m deep. Built. That is, first, the first steel pipe pile (lower pile) 10A is buried as usual (see FIG. 5 (B)), and then, conventionally, the second steel pipe pile (upper pile) 10B is added and buried as it is. However, here, the second steel pipe pile (upper pile) 10B was inserted into the internal steel pipe 22 of the integrated Yatco 20, and both piles (lower pile and upper pile) were joined together. Thereafter, the steel pipe pile 10 was buried in the ground G as it was to a predetermined depth (in this case, 10 m). At this point, the steel pipe pile 10 was buried to a depth of 10 m, and the Yatco 20 with the steel pipe pile 10 inserted therein was buried 5 m. In addition, the inside of the hopper 21 of the Yatco 20 at this time was a hollow because the outflow hole 21 a was covered with the movable lid 24. Subsequently, the ground improvement material 30 was put into the cavity in the hopper 21 and filled, and the Yatco 20 was lifted and collected without rotation (however, it may be rotated). When the Yatco 20 was pulled up, the movable lid 24 was relatively slid by the spiral blade 24c functioning as an anchor, the outflow hole 21a was opened, and the ground improvement material 30 flowed out. The improved material that flowed out became an improved body around the steel pipe pile 10 as it was, and was integrated with the steel pipe pile 10. At this time, since the steel pipe pile 10 did not touch the surrounding ground G, soil did not adhere to the surface of the steel pipe pile 10.

  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 ground improvement material 30 is placed in the enlarged excavation hole while lifting the Yatco 20 from the ground G (see FIG. 5 (H), etc.). If no pile is used, it is possible to build only the improved body. In such a case, a columnar improvement body is formed over the entire length of the enlarged excavation hole.

  In the embodiment described above, the YATCO 20 in which the spiral blade 24c is formed around the pipe portion 24a of the movable lid 24 is illustrated. However, another spiral blade is provided on the outer surface of the other portion, for example, the hopper 21. May be formed.

  Moreover, in embodiment mentioned above, although the positional relationship of the upper edge of the hopper 21 and the steel pipe pile 10 was not explained in full detail, as for the outer frame body as the hopper 21, the upper edge of the steel pipe pile 10 which is embedment object It is preferable to be formed so as to be located at a height substantially equal to the pile head. In such a case, for example, as shown in FIG. 5, only the upper periphery of the steel pipe pile 10 can be improved in the ground, and an improved body useful for improving the horizontal strength can be effectively 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.

<Second Embodiment>
A yatco 20 that employs a movable lid 24 having a structure different from that of the above-described embodiment and a method for constructing the steel pipe pile 10 using the yatco 20 will be described below as a second embodiment of the present invention (FIGS. 6 and 6). 7). In FIG. 6, only the hopper 21 is cut in half and the inside thereof is also shown.

  The Yatco 20 of this embodiment is such that a hopper (outer frame) 21 is provided with a hinged movable lid (opening / closing lid) 24. In this case, the number and arrangement of the movable lid 24 and the outflow holes 21a opened and closed by the movable lid 24 are not particularly limited. For example, in this embodiment, the outflow holes 21a are provided at two locations on the tapered portion of the hopper 21. A movable lid 24 is provided in each of the outflow holes 21a (see FIG. 6 and the like). Each movable lid 24 is an open lid that is connected to a fulcrum 24e near the lower edge of the outflow hole 21a with a hinge so as to be able to be opened and closed, and its movement is restricted by hitting a stopper 21f inside the outflow hole 21a. It can be opened outward from the closed position. For example, in this embodiment, it opens automatically by the pressure received by the ground improvement material 30 with which the inside of the hopper 21 was filled (refer FIG.7 (C) etc.).

  An example of the construction procedure when embedding the steel pipe pile 10 using the Yatco 20 described above will be described below (see FIG. 7). However, description is abbreviate | omitted about the process similar to a 1st actual form, such as the construction process to the ground G of the steel pipe pile 10. FIG.

  After the erection process (the description is omitted here), the steel pipe pile 10 is penetrated into the ground G to a predetermined depth and embedded (FIG. 7A). Thereafter, a predetermined amount of ground improvement material (cement milk or the like) 30 is filled in the hopper 21 of the Yatco 20 (see FIG. 7B), and then only the Yatco 20 is pulled up from the ground G (FIG. 7C). reference). When the Yatco 20 is pulled up, the movable lid 21 receiving pressure from the ground improvement material 30 automatically opens, and the ground improvement material 30 flows out from the outflow hole 21a and is placed in the enlarged excavation hole (FIG. 7 ( C) and (D)). When the Yatco 20 is completely pulled up, a predetermined amount of ground improvement material 30 is placed and the construction is completed (see FIG. 7E).

<Third Embodiment>
Hereinafter, a yatco 20 employing a passive movable lid 24 and a construction method of the steel pipe pile 10 using the yatco 20 will be described as a third embodiment of the present invention (see FIGS. 8 and 9). In addition, in FIG. 8, only the hopper 21 is cut in half and the inside is also shown.

  The Yatco 20 of this embodiment is such that a slidable movable lid (open / close lid) 24 is provided on a hopper (outer frame) 21. In this case, the number and arrangement of the movable lid 24 and the outflow holes 21a opened and closed by the movable lid 24 are not particularly limited. For example, in this embodiment, the outflow holes 21a are provided at two locations on the tapered portion of the hopper 21. A movable lid 24 is provided in each of the outflow holes 21a (see FIG. 8 and the like). Each movable lid 24 is guided by a guide 24h formed around the outflow hole 21a and can slide in the generatrix direction of the tapered portion. One end of a drawing line 24g is attached to the movable lid 24. The other end of the drawing line 24g is attached at a position where it can be operated from the ground, for example, by being hooked on the upper edge of the hopper 21 (see FIG. 8 and the like).

  An example of the construction procedure when embedding the steel pipe pile 10 using the Yatco 20 described above will be described below (see FIG. 9). However, description is abbreviate | omitted about the process similar to a 1st actual form, such as the construction process to the ground G of the steel pipe pile 10. FIG.

After the erection process (the description is omitted here), the steel pipe pile 10 is penetrated into the ground G to a predetermined depth and embedded (FIG. 9A). Thereafter, a predetermined amount of ground improvement material (cement milk or the like) 30 is filled in the hopper 21 of the Yatco 20 (see FIG. 9B), the pulling line 24g is pulled to remove the movable lid 21, and the outflow hole 21a. Is opened (see FIG. 9C). Thereafter, when only the Yatco 20 is lifted from the ground G, the ground improvement material 30 flows out from the outflow hole 21a and is placed in the enlarged excavation hole (see FIG. 9D). When the Yatco 20 is completely pulled up, a predetermined amount of ground improvement material 30 is placed, and the construction is completed (see FIG. 9E).
<Fourth Embodiment>
Hereinafter, a yatco 20 that employs a movable lid 24 of another form and a construction method of the steel pipe pile 10 using the yatco 20 will be described as a fourth embodiment of the present invention (see FIGS. 10 and 11). In addition, in FIG. 10, only the hopper 21 is cut in half and the inside is also shown.

  The Yatco 20 of the present embodiment is such that a hopper (outer frame body) 21 is provided with a movable lid (open / close lid) 24 made of a rubber valve. In this case, the number and arrangement of the movable lid 24 and the outflow holes 21a opened and closed by the movable lid 24 are not particularly limited. For example, in the present embodiment, the outflow holes 21a are provided in the tapered portion of the hopper 21, and the outflow holes 21a are provided. A rubber valve is provided to form a movable lid 24 (see FIG. 10 and the like). Moreover, the pumping pipe 24i for pumping the ground improvement material 30 is connected to the outflow hole 21a of the Yatco 20 (see FIG. 10 etc.).

  An example of the construction procedure when embedding the steel pipe pile 10 using the Yatco 20 described above will be described below (see FIG. 11). However, it is the same as the above-mentioned case that the description of the steps similar to the first actual form such as the step of building the steel pipe pile 10 in the ground G is omitted.

  After the erection process (the description is omitted here), the steel pipe pile 10 is penetrated into the ground G to a predetermined depth and embedded (FIG. 11 (A)). Then, the hose 24j whose one end is connected to the plant, for example, is connected to the pressure feeding pipe 24i (see FIG. 11B). Thereafter, only the Yatco 20 is pulled up from the ground G, and at the same time, the ground improvement material 30 is pumped through the hose 24j and the pumping pipe 24i. The ground improvement material 30 thus pumped flows out from the outflow hole 21a and is placed in the enlarged excavation hole (see FIG. 11C). The construction is completed when the Yatco 20 is completely pulled up and a predetermined amount of ground improvement material 30 is placed (see FIG. 11D).

  In the case of the present embodiment, the ground improvement material 30 is not stored in the hopper 21 but directly placed in the enlarged excavation hole via the pressure feed pipe 24i. Reference numeral 21 in this embodiment is a “hopper” as in the other embodiments, but it does not function as a storage device as in the other embodiments, and is exclusively used for expanding excavation and maintaining the shape of the excavation hole (hole wall). Functioning as a device having an outer frame for maintenance).

  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 ... Yatko, 21 ... Hopper (outer frame body), 21a ... Outflow hole, 22 ... Internal steel pipe (guide), 22b ... Pile engaging part, 24 ... Movable lid (open / close lid), 24c ... spiral blade (resistance increasing part), 30 ... ground improvement material, G ... ground

Claims (6)

An outer frame member which functions as a reservoir capable hopper soil improvement material while expanding drilling the ground, provided with a guide for holding the state of being substantially coincides with the rotation center of the pile core the Ya Ttoko pile, the Using a Yatco provided with an open / close lid that opens and closes the outflow hole of the ground improvement material in response to resistance in the ground at the time of propulsion to the ground and lifting from the ground ,
The pile is held in a state substantially coincident with the center of rotation of the yatco, the yatco is rotated to embed the pile in the ground, and the periphery of the pile is enlarged by the outer frame body. A pile construction method using a yatco that improves the ground around the pile by placing the ground improvement material stored in the body into the enlarged excavated portion while lifting the yatco from the ground. The pile construction method using a yatco according to claim 1 , wherein a resistance increasing portion that increases resistance in the ground with respect to the opening / closing lid at the time of pulling is used. The said resistance increase part is a blade | wing which produces the driving force to the ground at the time of rotation, The construction method of the pile using the yatco of Claim 2 which rotates the said yatco at the time of the embedding | buried of the said pile. When the pile is held in a state substantially coincident with the center of rotation of the yatco, the pile head of the pile is held at a position substantially equal to the height of the upper edge of the outer frame. A method for constructing a pile using the yatco according to any one of 3 above. The pile construction method using the yatco according to any one of claims 1 to 4 , wherein another pile is connected to the upper part of the pile to which the yatco transmits the rotational force and held by the guide. The pile construction method using the yatco according to any one of claims 1 to 5 , wherein a tubular member disposed in the center of the outer frame body is used as the guide.

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