JP6819443B2 - Construction method of rotary press-fit steel pipe pile - Google Patents

Description

The present invention relates to a method for constructing a rotary press-fit steel pipe pile.

Conventionally, as a method of placing steel pipe piles, there is a method of penetrating the steel pipe piles into the ground by hitting or vibro hammering, but there is a drawback that it is difficult to apply in urban areas due to large noise and vibration. Therefore, the rotary press-fitting method is generally known as a method for driving steel pipe piles with low noise and low vibration. In such a rotary press-fitting method, steel pipe piles can be penetrated into the ground due to low ground vibration and low noise, which is suitable for construction conditions in urban areas and the like. However, there is a conflicting relationship between workability and bearing capacity performance. When the penetration resistance is small, the bearing capacity is small, and when the penetration resistance is large, it is not possible to penetrate to the predetermined target depth. It stayed high, and a heavy machine with a higher output was needed.

Therefore, as a method of achieving both workability and bearing capacity as described above, for example, as shown in Patent Document 1, propulsive force is obtained by a spiral blade attached to the tip of a pile to improve workability. There is known a construction method using a steel pipe pile that makes it possible to obtain bearing capacity by enhancing the closing effect by means of protrusions for promoting clogging installed in the steel pipe. In this case, it is possible to obtain the same bearing capacity as the conventional one with a small amount of rooting.

Japanese Unexamined Patent Publication No. 2004-278306

However, in the method of constructing a rotary press-fit steel pipe pile provided with protrusions for promoting blockage as in Patent Document 1, for example, in the case of a ground with a thick soft intermediate layer, a large amount of earth and sand flows into the pipe before reaching the support layer. Then, it may be blocked by the protrusion. In that case, the tip surface of the pile is closed and the cross-sectional area is increased, so that the workability is lowered. In addition, the ground strength may vary even within the same site, and the blockage state may differ depending on the intrusion point.
Therefore, although the blockage can be promoted, the blockage state cannot be controlled according to the construction conditions, so that the range of application is limited, for example, it becomes difficult to apply the ground in a thick intermediate layer. There was room for improvement in that respect.

The present invention has been made in view of the above-mentioned problems, and it is possible to control the closed state of the steel pipe pile according to the construction conditions such as the ground, and to achieve the improvement of workability and bearing capacity in a well-balanced manner. It is an object of the present invention to provide a method of constructing a rotary press-fit steel pipe pile that can be performed.

In order to achieve the above object, the method of constructing a rotary press-fit steel pipe pile according to the present invention is a method of constructing a rotary press-fit steel pipe pile, in which the steel pipe body protrudes inward in the pipe radial direction at the tip and is orthogonal to the pile axis direction. It is a construction method of a rotary press-fit steel pipe pile in which a steel pipe pile having a closed plate for reducing the opening area of the steel pipe pile is rotationally press-fitted into the ground, and the tip of the vibrating rod is positioned below the closed plate inside the steel pipe pile. The steel pipe pile reaches a preset rod tip adjustment depth that forms a depth for changing the region where the tip of the vibrating rod is located in the first step of rotationally press-fitting the steel pipe pile while vibrating the vibrating rod. It is characterized by having a second step of pulling up the vibrating rod above the closing plate and rotationally press-fitting the steel pipe pile while vibrating it.

In the present invention, the rod tip of the vibrating rod is arranged in a region below the closing plate of the steel pipe pile, and the steel pipe pile can be rotationally press-fitted while loosening by vibrating the earth and sand in that region with the rod tip. Therefore, it is possible to suppress blockage due to earth and sand flowing into the pipe, reduce the penetration resistance of the steel pipe pile, and increase the press-fitting speed, so that workability can be improved. Furthermore, when the vibrating rod is vibrated and pulled above the closing plate, the earth and sand that has flowed in from the lower end opening of the steel pipe pile is not loosened by the vibrating rod in the area below the closing plate, so it is held down by the closing plate. It becomes a compacted state, and the bearing capacity of earth and sand in the steel pipe pile can be increased. In other words, by pulling up the vibrating rod after the steel pipe pile reaches the rod tip adjustment depth, the sediment in the range where the rod tip is pulled out becomes a consolidated region (closed state), and the steel pipe pile reaches the pile reach target depth. At that point, the earth and sand in the area of a predetermined height from the lower end of the steel pipe pile can be consolidated.
As described above, in the present invention, the closed state of the steel pipe pile can be controlled by using a vibrating rod at the time of rotational press-fitting of the steel pipe pile and changing the position of the rod tip with respect to the closing plate, and the construction is performed according to the conditions. Can be done.

Further, in the method for constructing a rotary press-fit steel pipe pile according to the present invention, the earth and sand in the lower region of the closing plate becomes loose due to the vibration of the vibrating rod, and the steel pipe pile is suppressed from being blocked. It can be kept small, the device for rotational press-fitting can be miniaturized, and the construction cost can be reduced. In addition, the construction space can be reduced by downsizing the device, and construction in a narrow space becomes possible.
Further, in the present invention, in addition to press-fitting the steel pipe pile, vibration is applied by the vibrating rod. However, since the vibrating vibrating rod is located in the steel pipe pile and gives vibration only to the ground inside the steel pipe pile. While maintaining the effects of low ground vibration and low noise that the rotary press-fitting method has in the past, the penetration resistance can be reduced to improve workability, and the same bearing capacity as the conventional method can be obtained.

Further, in the method of constructing the rotary press-fit steel pipe pile according to the present invention, the closing plates are provided in a plurality of stages at intervals in the pile axis direction, and in the first step, among the plurality of stages of the closing plates. The tip of the vibrating rod is positioned below the lowermost closing plate, the steel pipe pile is rotationally press-fitted while vibrating the vibrating rod, and the vibrating rod is directly above the vibrating rod in the second step. It is preferable that the second step is repeated by pulling up the closing plate and rotationally press-fitting the steel pipe pile while vibrating the vibrating rod.

In this case, by providing a plurality of stages of closing plates, the closed state of the steel pipe pile described above can be controlled step by step, and the construction by rotational press fitting of the steel pipe pile can be performed more accurately. That is, the rod tip is gradually pulled up from the lower region to the upper region among the regions between the obstructing plates adjacent to each other above and below the plurality of obstructing plates, and the steel pipe pile is penetrated. Can be done.

Further, the method for constructing a rotary press-fit steel pipe pile according to the present invention may be characterized in that the opening area of each of the plurality of stages of the closing plates becomes smaller from the pile tip side to the pile head side.

In this case, since the closing plate on the pile tip side has a larger opening area than the closing plate on the pile head side, the amount of earth and sand inside the steel pipe pile passes through the opening, and the closing plate on the pile head side has a larger opening area. Since it is small, the amount of sediment passing through is small. Therefore, in the region below the closing plate on the pile head side, the earth and sand can surely enter the region between the closing plates, and the earth and sand can be made dense.

Further, in the method for constructing a rotary press-fit steel pipe pile according to the present invention, it is preferable that the distance between the closing plates adjacent to each other in the pile axis direction is larger than the overhang length of the closing plates on the pile tip side.

In this case, by making the distance between the closing plates adjacent to each other in the pile axis direction longer than the overhang length of the closing plates on the pile tip side, the earth and sand reach the corners and are filled, and the filling rate is improved. be able to. Therefore, it is possible to prevent the earth and sand from reaching the corners and lowering the filling rate, as in the case where the distance between adjacent closing plates is shorter than the overhang length of the closing plates on the pile tip side. A dense solid part is formed inside the steel pipe pile to maintain the bearing capacity.

Further, in the method for constructing a rotary press-fit steel pipe pile according to the present invention, the inner peripheral end of the closed plate in the pipe radial direction is inclined toward the pile tip side or the pile head side from the outer outer peripheral end. Is preferable.

In the present invention, when the inner end of the closing plate on the inner side in the radial direction is inclined toward the pile tip side, the earth and sand located at the corners can be made more dense.
Further, when the inner end of the closing plate on the inner side in the radial direction is inclined toward the pile head side, the penetration resistance due to the closing plate can be reduced.

Further, the method of constructing a rotary press-fit steel pipe pile according to the present invention may be characterized in that the closing plate is formed by overlay welding of one or more layers.

In this case, regardless of the roundness of the steel pipe body, the closed plate can be manufactured relatively easily by adjusting the welding, and bending is required to follow the circumference of the steel pipe, which was necessary when using a steel plate. There is an advantage that work and management of welding leg length are not required. Further, in the case of the present invention, since overlay welding can be performed in a post-process after manufacturing the steel pipe main body, the work labor is reduced, and it is particularly efficient when the protruding length of the closing plate is short.
Further, when the closed plate is formed by inclining it with respect to the axial direction of the steel pipe body, it is necessary to perform a three-dimensionally complicated bending process for a steel plate or the like, but in overlay welding, the angle and shape of the backing plate It is only necessary to adjust the above, and it is possible to respond efficiently and easily.
Furthermore, since it is possible to change the build-up amount of welding by adjusting the welding speed and the number of layers, the length protruding inward in the pipe radial direction is changed in the circumferential direction of the steel pipe body. It has the advantage of making things easier.

Further, in the method of constructing a rotary press-fit steel pipe pile according to the present invention, the steel pipe pile has a peripheral surface of the steel pipe body and the closing plate within a range of a length twice the pile diameter from the tip of the pile upward. It is preferable that at least a part of the anti-vibration material is attached.

In this case, it is possible to suppress the vibration of the closing plate due to the vibration of the rod tip of the vibrating rod. As a result, it is possible to prevent the earth and sand flowing directly under the closing plate from becoming dense (liquefied) due to the vibration of the closing plate. In particular, since the in-pipe obstruction is predominant in the range of twice the pile diameter from the tip of the pile upward, it is effective to provide a vibration isolator on at least a part of the peripheral surface and the obstruction plate of the steel pipe pile in this range. Is the target.

Further, in the method for constructing a rotary press-fit steel pipe pile according to the present invention, it is preferable that the vibration isolator is provided on the closing plate.

In the present invention, the vibration generated in the closing plate itself can be suppressed by the vibration-proof material, and it is more certain that the earth and sand flowing directly under the closing plate due to the vibration of the closing plate described above becomes dense (liquefied). Can be prevented.

According to the construction method of the rotary press-fit steel pipe pile of the present invention, the closed state of the steel pipe pile can be controlled according to the construction conditions such as the ground, and the improvement of workability and bearing capacity can be achieved in a well-balanced manner.

It is a partially broken side view which shows the construction method of the steel pipe pile by 1st Embodiment of this invention. It is a breaking perspective view which shows the structure of the lower part of a steel pipe pile. It is a vertical cross-sectional view which shows the structure of the lower part of a steel pipe pile. It is a horizontal sectional view orthogonal to the pile axis direction of a steel pipe pile. It is a horizontal sectional view which shows the closing plate by a modification, and is the figure corresponding to FIG. (A) to (c) are diagrams showing the construction procedure of the steel pipe pile. (A) to (c) are diagrams showing the construction procedure of the steel pipe pile following FIG. 6 (c). (A) to (c) are diagrams showing the construction pattern of the steel pipe pile according to the modified example. (A) and (b) are vertical cross-sectional views showing the structure of the closing plate according to the second embodiment. It is a vertical sectional view which shows the structure of the closing plate according to 3rd Embodiment. It is a vertical cross-sectional view for demonstrating the operation of the closing plates according to the third embodiment, (a) is a view when the distance between the closing plates is long, and (b) is a case where the distance between the closing plates is short. It is a figure of. It is a vertical sectional view which shows the structure of the closing plate by 4th Embodiment. It is a vertical sectional view which shows the structure of the closing plate by 4th Embodiment. It is a vertical cross-sectional view which shows the structure of the steel pipe pile which has a vibration-proof material according to 5th Embodiment. (A) to (c) are diagrams showing the manufacturing process of the closing plate according to the sixth embodiment.

Hereinafter, a method of constructing a rotary press-fit steel pipe pile according to an embodiment of the present invention will be described with reference to the drawings.

(First Embodiment)
As shown in FIG. 1, the method of constructing a rotary press-fit steel pipe pile according to the present embodiment is a construction method in which a steel pipe pile 1 (rotary press-fit steel pipe pile) is press-fitted using a rotary press-fitting device 10 in the steel pipe pile 1 during this construction. This is a method in which the vibrating rod 2 is inserted into the pipe, and the steel pipe pile 1 is press-fitted into the support layer G1 while being vibrated by the vibrating device 20.
Here, reference numeral G0 in FIG. 1 indicates a soft layer in the ground, and reference numeral G1 indicates a support layer located below the intermediate layer G0. Further, in the steel pipe pile 1 and the vibrating rod 2, the lower ends thereof are referred to as a pile tip 1a and a rod tip 2a, respectively.

The rotary press-fitting device 10 includes a chuck portion (not shown) that grips the steel pipe pile 1 from the outer peripheral side, rotates the steel pipe pile 1 gripped by the chuck portion about the pile shaft O, and presses it downward. Has the function of

As the vibrating device 20, for example, a well-known vibro hammer or the like used for placing a steel sheet pile or the like can be adopted, and the vibration rod 20 is suspended by a crane (not shown) and grips the rod upper end 2b of the vibrating rod 2 in the vertical direction. It is possible to vibrate. The vibrating rod 2 has a rod tip 2a having a conical shape, and for example, a steel tubular one having an outer diameter of 100 mm is used. When the steel pipe pile 1 is press-fitted, the steel pipe pile 1 is viewed from the pile axis O direction of the steel pipe pile 1. It is located in the center of the building.

The steel pipe pile 1 is made of, for example, a steel pipe (steel pipe body) having a diameter of 1000 mm, is joined by welding, and is driven into the ground in a state where a plurality of steel pipe piles are added on a coaxial line.
As shown in FIGS. 2 to 4, the steel pipe pile 1 is a pair of closing plates 11 (11A, 11B) that project toward the tip of the pile 1a inward in the pipe radial direction and reduce the projected area of the opening 11a. Is provided. The closing plates 11A and 11B each have a ring shape extending over the entire circumference in the circumferential direction, and are provided at intervals in the pile axis O direction from each other.
As shown in FIG. 3, the upper limit of the positions where the closing plates 11A and 11B are provided is in the range from the pile tip 1a of the steel pipe pile 1 to the position separated by twice (2D) the outer diameter dimension D of the steel pipe pile 1. It is provided in L. In this case, since the in-pipe blockage is predominant in the range twice from the pile tip 1a, it is possible to effectively block the earth and sand in the region below the closing plate 11.

The overhang length r of the pair of closing plates 11A and 11B is perpendicular to the pile axis O direction, and the closing plates 11A and 11B have the same shape and the overhang length r in the pipe radial direction has the same length dimension. Is set to. The overhang length r of the closing plates 11A and 11B is set to a size that allows the closing plate 11 to have an opening 11a having a size through which the vibrating rod 2 can be inserted. Then, as shown in FIG. 3, the distance H between the closing plates 11A and 11B adjacent to each other in the pile axis O direction is larger than the overhang length r of the closing plates 11A and 11B.
The closing plates 11A and 11B are not limited to being one, and as shown in FIG. 5, they are divided into a plurality (four) in the circumferential direction, and the peripheral end portions 11c are joined by the welded portion W. It may have been done. The division may be 1/2 (semicircle). By dividing in the circumferential direction in this way, the work of welding the closing plate 11 to the inner peripheral surface of the steel pipe pile 1 can be easily performed.

Here, the pile arrival target depth P1 is set according to the depth of the support layer G1 and the soil condition, and means the depth at which the pile tip 1a of the steel pipe pile 1 is reached in the support layer G1. The rod deepest target depth P2 means the deepest depth reached by the vibrating rod 2 during press fitting of the steel pipe pile 1. Further, the rod tip adjustment depth P3 is set to the depth of the pile tip 1a that changes the region where the tip of the vibrating rod 2 (rod tip 2a) is located, and a predetermined depth is set in advance.
Inside the steel pipe pile 1 shown in FIGS. 1 to 3, the region below the first closing plate 11A located at the lowest stage is referred to as the first region T1, and the first closing plate 11A and the second closing plate The region between them is referred to as a second region T2, and a predetermined region above the second closing plate 11B is referred to as a third region T3.

Next, the construction method of the steel pipe pile 1 described above will be described in detail with reference to the drawings.
In the construction method according to the present embodiment, as shown in FIG. 1, the rotary press-fitting device 10 is first installed on the ground where the steel pipe pile 1 is to be driven, and the steel pipe pile 1 to be driven first is set. Subsequently, the vibration device 20 equipped with the vibrating rod 2 is suspended by a crane, and the rod tip 2a of the vibrating rod 2 is placed inside the steel pipe pile 1 so as to be at a predetermined position with respect to the pile tip 1a of the steel pipe pile 1. By inserting it, the press-fitting preparation is completed. Specifically, the rod tip 2a is positioned in the first region T1 between the pile tip 1a and the first closing plate 11A at the bottom.

Next, as shown in FIG. 6A, the rotary press-fitting of the steel pipe pile 1 is started, and at the same time, vibration is applied to the vibration rod 2 in the steel pipe pile 1 to penetrate the ground. At this time, the earth and sand (reference numeral Ga) taken into the steel pipe pile 1 is totally disturbed by the vibration of the vibrating rod 2 and becomes loose, so that the penetration resistance of the steel pipe pile 1 becomes small.

Next, as shown in FIG. 6 (b), when the pile tip 1a approaches the pile reach target depth P1 (FIG. 7 (c)), for example, the distance (from the pile reach target depth P1 to the pile tip 1a). When the distance L1) is 2 times (2D) the outer diameter dimension D of the steel pipe pile 1 shown in FIG. 3 (2 m if the pile diameter is 1 m) from the pile tip 1a, the vibrating rod 2 is pulled up to position the rod tip 2a in the second region T2 between the first-stage first closing plate 11A and the second-stage second closing plate 11B.
In this case, the rod tip adjustment depth P3a is the depth of the pile tip 1a when the tip position of the vibrating rod 2 is moved from the first region T1 to the second region T2, and the outer diameter dimension of the steel pipe pile 1 from the pile arrival target depth P1. The position is twice as high as D.

Here, in FIGS. 6 (a) to 6 (c) and 7 (a) to 7 (c), the solid line of reference numeral Q1 indicates the flow line at the center position of the pile tip 1a of the steel pipe pile 1, and the broken line of reference numeral Q2. Indicates the flow line of the rod tip 2a. That is, in FIG. 6B, a flow line in which the position of the rod tip 2a is pulled up from the first region T1 to the second region T2 is shown.

Subsequently, as shown in FIG. 6C, the steel pipe pile 1 is penetrated again in a state where the vibrating rod 2 is vibrated. At this time, since the earth and sand in the second region T2 becomes loose due to the vibration of the vibrating rod 2, the effect of reducing the penetration resistance due to the vibration of the vibrating rod 2 is particularly effective above the first closing plate 11A of the first stage. Become. On the other hand, in the portion directly below the first closing plate 11A (the dense region Ma showing the triangle in FIG. 6C), the first closing plate 11A plays a role of hindering the effect of vibration of the vibration rod 2, and the steel pipe pile 1 As new earth and sand are taken in along with the intrusion, it becomes dense and the strength increases.
Here, in FIG. 6C, the dark dot portion shows the dense region Ma with high sediment density, and the thin dot portion shows the loose sediment Ga. The dense region Ma is an region surrounded by a virtual inclined surface from the opening 11a forming the inner peripheral end of the first closing plate 11A to the pile tip 1a.

The penetration length of the steel pipe pile 1 at this time is longer than the length from the pile tip 1a to the first closing plate 11A. As a result, the filling rate of the earth and sand Ga taken into the first region T1 can be increased.
Then, although the penetration resistance is slightly increased, the earth and sand Ga flows upward through the opening 11a of the first closing plate 11A to maintain the turbulent state, so that the state of being completely closed is not reached, so that the state is completely closed. The penetration resistance is smaller than that of the conventional technology.

Next, as shown in FIG. 7A, the vibrating rod 2 was pulled up from the second region T2, and the rod tip 2a was located in the region above the second closing plate 11B in the second stage (third region T3). Put it in a state.
In this case, the rod tip adjustment depth P3b is the depth of the pile tip 1a when the tip position of the vibrating rod 2 is moved from the second region T2 to the third region T3, and is the depth from the pile arrival target depth P1 to the outer diameter of the steel pipe pile 1. From a position that is twice as shallow as the dimension D to a position that is deeper by the penetration length. The rod tip adjustment depth P3a shown in FIG. 6B and the rod tip adjustment depth P3b shown in FIG. 7A may be the same depth in some cases.

After that, as shown in FIG. 7B, the steel pipe pile 1 is penetrated into the support layer G1 in a state where the vibrating rod 2 is vibrated, and further reaches the pile reaching target depth P1 shown in FIG. 7C. At this time, since the earth and sand Ga in the third region T3 becomes loose due to the vibration of the vibrating rod 2, the effect of reducing the penetration resistance due to the vibration of the vibrating rod 2 is particularly effective above the second closing plate 11B of the second stage. become.
On the other hand, immediately below the second closing plate 11B in the second region T2, the second closing plate 11B plays a role of hindering the effect of the vibration of the vibrating rod 2, and new earth and sand are taken in as the steel pipe pile 1 penetrates. The dense region Ma becomes dense and the strength increases. The penetration length of the steel pipe pile 1 in this step is longer than the distance between the first closing plate 11A and the second closing plate 11B. As a result, the filling rate of the earth and sand Ga taken into the second region T2 can be increased.
Since the earth and sand flow upward from the opening 11b of the second closing plate 11B to maintain the turbulent state, it does not reach the state of being completely closed, so that it penetrates as compared with the conventional technique of completely closing. The resistance becomes smaller.

Next, as shown in FIG. 7 (c), after the steel pipe pile 1 reaches the pile reaching target depth P1, the vibrating rod 2 is vibrated while the vibrating rod 2 having reached the rod deepest target depth P2 is vibrated. By completely pulling it out, the construction of one steel pipe pile 1 is completed. After the construction is completed, the regions T1, T2, and T3 below the press-fitted steel pipe pile 1 become dense regions Ma, and other than that, loose earth and sand Ga exists. Since the earth and sand above the second closing plate 11B acts as an overload on this loose earth and sand Ga, it is in a restrained state. Since the strength of the soil in the restrained state is increased, the entire lower part of the steel pipe pile 1 is closed, and the bearing capacity equal to or higher than that of the conventional one can be exhibited.

Further, in the present embodiment, the vibrating rod 2 may be completely pulled out before reaching the pile reaching target depth P1 at the final stage, and the rotational press-fitting alone may penetrate to a certain depth. As a result, it is possible to newly take in the earth and sand into the above-mentioned loose earth and sand area to make it dense and block it, which is a more effective method.
It is known that the closing efficiency (easiness of closing) of the steel pipe pile 1 depends on the pile diameter. Here, since the opening 11a of the closing plate 11 corresponds to the pile diameter, there is no closing plate 11. It can be closed more efficiently than when a normal steel pipe pile is closed.

Further, in a normal steel pipe pile, the inside of the pipe is blocked by the frictional force of the earth and sand that comes into contact with the inner peripheral surface of the steel pipe pile. On the other hand, since the closing plates 11A and 11B of the present embodiment also have a bearing action (pressing the earth and sand in the depth direction), a stronger closing state can be formed. For example, the same effect as that of JP-A-2004-278306 can be obtained.

As a compaction construction management method, a method generally used in the field of ground compaction (for example, non-patent document "soil compaction", Japanese Geotechnical Society / Practical Series 30, ground) The Engineering Society) can be used to measure the response acceleration of the vibrating rod 2, and when the frequency distribution reaches a predetermined state, it can be determined that the predetermined compaction strength has been achieved.

According to the method of constructing the rotary press-fit steel pipe pile described above, as shown in FIGS. 1 and 2, the rod tip 2a of the vibrating rod 2 is arranged in the first region T1 below the closing plate 11 in the steel pipe pile 1. Then, the steel pipe pile 1 can be rotationally press-fitted while loosening by vibrating the earth and sand in that region with the rod tip 2a. Therefore, it is possible to suppress blockage due to earth and sand flowing into the pipe, reduce the penetration resistance of the steel pipe pile 1, and increase the press-fitting speed, so that workability can be improved.

Further, as shown in FIGS. 6 and 7, when the vibrating rod 2 is vibrated and pulled upward above the closing plates 11A and 11B, the earth and sand flowing in from the lower end opening of the steel pipe pile 1 is more than the closing plates 11A and 11B. Since it is not loosened by the vibrating rod 2 in the lower region, it is pressed by the closing plate 11 to be in a compacted state, and the bearing capacity of the earth and sand in the steel pipe pile 1 can be increased. That is, by pulling up the vibrating rod 2 at a predetermined position shallower than the pile reach target depth P1 of the steel pipe pile 1, the earth and sand Ga at the position where the rod tip 2a is pulled out becomes a dense region Ma, that is, a closed state, and the steel pipe is closed. When the pile 1 reaches the target depth P1 for reaching the pile, the earth and sand in the region of a predetermined height from the pile tip 1a of the steel pipe pile 1 can be made dense (see FIG. 7C).
As described above, in the present embodiment, the closed state of the steel pipe pile 1 can be controlled by using the vibrating rod 2 at the time of rotational press fitting of the steel pipe pile 1 and changing the position of the rod tip 2a with respect to the closing plate 11. It is possible to carry out the construction according to.

Further, in the method of constructing the rotary press-fit steel pipe pile according to the present embodiment, the earth and sand in the lower region of the closing plate 11 becomes loose due to the vibration of the vibrating rod 2, and the blocking of the steel pipe pile 1 is suppressed. The press-fitting of 1 can be suppressed to a small size, the device for performing rotary press-fitting can be miniaturized, and the construction cost can be reduced.
In addition, the construction space can be reduced by downsizing the device, and construction in a narrow space becomes possible.

Further, in the present embodiment, in addition to press-fitting the steel pipe pile 1, vibration is applied by the vibrating rod 2. However, the vibrating vibrating rod 2 is located in the steel pipe pile 1 and the ground inside the steel pipe pile 1 is provided. Since vibration is applied only to the pipe, the penetration resistance can be reduced to improve workability and the same bearing capacity as the conventional one can be obtained while maintaining the effects of low ground vibration and low noise that the rotary press-fitting method has conventionally. ..

Further, in the method of constructing the rotary press-fit steel pipe pile according to the present embodiment, the vibrating rod 2 is pulled out stepwise before reaching the pile reach target depth P1 of the steel pipe pile 1 in the support layer G1, so that the steel pipe pile 1 is constructed. In the range where the vibrating rod 2 is pulled out from the tip, there is no rod tip 2a, and it is not necessary to loosen the earth and sand that enters the inside of the steel pipe pile 1. Therefore, the ground of the hard support layer G1 effectively provides a solid state. Can be formed.

Further, in the present embodiment, by providing the two-stage closing plates 11A and 11B in the vertical direction, the closed state of the steel pipe pile 1 described above can be controlled stepwise, and the construction is performed by rotational press fitting of the steel pipe pile 1. Can be performed more accurately.
That is, the rod tip 2a is gradually pulled out from the lower region to the upper region of the region between the two-stage obstruction plates 11A and 11B adjacent to each other above and below, and the steel pipe is pulled out. The pile 1 can be penetrated.

The positional relationship between the rod tip 2a of the vibrating rod 2 and the support layer G1 and the target depth P1 to reach the pile, and the timing of pulling out the vibrating rod 2 are not limited to the above-mentioned construction method, for example, FIG. There are other construction patterns (first modification to third modification) as shown in a) to (c).
8 (a) to 8 (c) are diagrams schematically showing the relationship between the flow line Q1 indicating the center of the pile tip 1a of the steel pipe pile 1 and the flow line Q2 of the rod tip 2a.

The construction pattern according to the first modification shown in FIG. 8 (a) is once or a plurality of times (twice in FIG. 8 (a)) as shown in FIGS. 6 (b) to 7 (b) described above. It has a partial drawing step of partially pulling out the vibrating rod 2, and after such a partial pulling step, the vibrating rod 2 is completely pulled out before the pile tip 1a of the steel pipe pile 1 reaches the pile reaching target depth P1. This is a method of pulling out and press-fitting only the steel pipe pile 1 to reach the pile arrival target depth P1.
In this first modification, even after the steel pipe pile 1 reaches the support layer G1, the upper portion of the earth and sand of the hard support layer G1 that enters the steel pipe pile 1 can be partially loosened by the vibration of the vibrating rod 2. It is possible to prevent the steel pipe pile 1 from being blocked at the start of penetration of the support layer G1, and after the vibrating rod 2 is completely pulled out, it is blocked by the earth and sand flowing in from the pile tip 1a due to the press fitting of the steel pipe pile 1. A high bearing capacity can be obtained by reaching the pile arrival target depth P1.

Further, in the construction pattern according to the second deformation example shown in FIG. 8B, the pile tip 1a of the steel pipe pile 1 is the pile arrival target without carrying out the partial drawing step as in the construction pattern in the first deformation example described above. This is a construction method in which the vibrating rod 2 is completely pulled out from the inside of the steel pipe pile 1 after reaching the depth P1.
In this second modification, since the rod tip 2a of the vibrating rod 2 is located below the lowermost closing plate, the steel pipe pile 1 enters the steel pipe pile 1 even after it reaches the support layer G1. By loosening the entire earth and sand of the hard support layer G1 by the vibration of the vibration rod 2, the penetration resistance can be reduced and the steel pipe pile 1 can be reliably reached to the pile reach target depth P1.

Further, the construction pattern according to the third modification shown in FIG. 8C is the vibration rod in the construction pattern according to the second modification described above, before the pile tip 1a of the steel pipe pile 1 reaches the pile arrival target depth P1. This is a construction method in which 2 is completely pulled out from the inside of the steel pipe pile 1.
In the case of this third modification, since the rod tip 2a of the vibrating rod 2 is located below the lowermost closing plate, the inside of the steel pipe pile 1 even after the steel pipe pile 1 reaches the support layer G1. By loosening the entire earth and sand of the hard support layer G1 that enters the pile by the vibration of the vibrating rod 2, the penetration resistance is reduced, and after the vibrating rod 2 is completely pulled out, the pile tip 1a is press-fitted with the steel pipe pile 1. Blockage progresses due to the earth and sand flowing in from the pile, and high bearing capacity can be obtained by reaching the pile arrival target depth P1.

As described above, in the construction method of the rotary press-fit steel pipe pile according to the present embodiment, the closed state of the steel pipe pile 1 can be controlled according to the construction conditions such as the ground, and the workability and the bearing capacity performance are improved. It can be achieved in a well-balanced manner.

Next, another embodiment according to the method of constructing the rotary press-fit steel pipe pile of the present invention will be described with reference to the attached drawings, but the same or similar members and parts as those of the first embodiment described above will be the same. The description will be omitted by using reference numerals, and a configuration different from that of the first embodiment will be described.

(Second Embodiment)
In the first embodiment described above, the closing plates 11 (11A, 11B) are provided in two stages, but the quantity (number of stages) of the closing plates 11 can be appropriately set.
For example, the steel pipe pile 1A according to the second embodiment shown in FIG. 9A is configured to be provided with three-stage closing plates 11A, 11B, and 11C. Further, the steel pipe pile 1B shown in FIG. 9B has a configuration in which only the one-stage closing plate 11A is provided.
In short, it is sufficient that the tip portion of the steel pipe pile is provided with a closing plate 11 that projects inward in the pipe radial direction and reduces the projected area of the opening 11a. Preferably, the closing plate 11 may be provided in the range L from the pile tip 1a of the steel pipe pile 1 to a position separated by twice (2D) the outer diameter dimension D of the steel pipe pile 1.

(Third Embodiment)
Further, in the first embodiment described above, the overhang lengths r of the plurality of closing plates 11A and 11B are the same, and the opening area at the positions of the closing plates 11A and 11B is also the same, but the present invention is limited to this. There is no. That is, in the steel pipe pile 2D1C according to the third embodiment shown in FIG. 10, a plurality of (three steps) closing plates 11A, 11B, and 11C are provided from the first closing plate 11A on the pile tip 1a side to the third on the pile head side. The opening 11a becomes smaller toward the closing plate 11C, that is, the opening area becomes smaller toward the third closing plate 11C on the pile head side.

In the steel pipe pile 1C according to the third embodiment, since the first closing plate 11A on the pile tip 1a side has a larger opening area than the third closing plate 11C on the pile head side, the inside of the opening 11a is filled with the steel pipe pile 1. Since the amount of sediment passing through the inside is large and the opening area is as small as the third closing plate 11C on the pile head side, the amount of sediment passing is small. Therefore, in the region below the third closing plate 11C on the pile head side, the earth and sand can surely enter the region between the closing plates 11, and the earth and sand can be made dense. ..

In the steel pipe pile 1C of the third embodiment, as shown in FIG. 10, the distance H between the closing plates 11 adjacent to each other in the vertical direction is the closing plate 11 on the pile tip 1a side (here, the first closing plate 11A). ) Is larger than the overhang length r.
In this case, as shown in FIG. 11A, the earth and sand reach the corners and are filled, and the filling rate can be improved. Therefore, as in the case where the distance between the adjacent closing plates 11 is shorter than the overhang length of the closing plates 11 on the pile tip 1a side (see FIG. 11B), it is difficult for earth and sand to reach the corners and the filling rate. Can be prevented from decreasing, and a dense solid portion can be formed inside the steel pipe pile 1 to maintain the bearing capacity.

(Fourth Embodiment)
Next, in the steel pipe pile 1D according to the fourth embodiment, as shown in FIG. 12, the inner peripheral end (opening 11a) of the closing plate 11 in the pipe radial direction is the pile tip of the outer outer peripheral end 11d. It is configured to incline at a predetermined inclination angle toward the 1a side. In this case, the earth and sand (dense region Ma) located at the corners can be made more dense.
Further, as shown in FIG. 13, the steel pipe pile 1E has a configuration in which the inner peripheral end (opening 11a) of the closing plate 11 in the pipe radial direction is inclined at a predetermined inclination angle toward the pile head side. ing. In this case, the penetration resistance by the closing plate 11 can be reduced.
In the case of the steel pipe piles 1D and 1E, the inclination angle of the closing plate 11 can be arbitrarily set.

(Fifth Embodiment)
Next, in the steel pipe pile 1F of the fifth embodiment shown in FIG. 14, the anti-vibration material 12 is provided on the upper surfaces 11b of the closing plates 11A and 11B in a range of twice the pile diameter from the pile tip 1a upward. It has a pasted structure.
In this case, the vibration isolator 12 can suppress the vibration generated in the closing plate 11 itself due to the vibration of the rod tip 2a of the vibration rod 1. As a result, it is possible to more reliably prevent the earth and sand flowing directly under the closing plate 11 from liquefying due to the vibration of the closing plate 11.

The anti-vibration material 12 is not limited to being attached to the upper surface 11b of the closing plate 11, and is the circumference of the steel pipe pile 1 in a range of twice the pile diameter from the pile tip 1a upward. The anti-vibration material 12 may be attached to at least a part of the surface and the closing plate 11.
In particular, since the pipe blockage is predominant in the range of twice the pile diameter from the pile tip 1a upward, the vibration isolator 12 is applied to at least a part of the peripheral surface of the steel pipe pile 1 and the blockage plate 11 in this range. It is effective to provide it.

(Sixth Embodiment)
Next, in the sixth embodiment shown in FIGS. 15A to 15C, the closing plate 13 is formed by forming one or more overlay weld beads B. The build-up weld bead B has one or more layers (1 layer or more) so that the build-up weld bead B has a length equivalent to the protrusion length from the inner peripheral surface of the steel pipe body 1A of the close plate 13 at the installation position of the closing plate 13. In the figure, the overlay welding beads B1, B2, ... (2 layers) are projected inward in the pipe radial direction. As a specific construction method, first, as shown in FIG. 15A, removable backing plates 14 are arranged in parallel with each other on both sides of the inner peripheral surface of the steel pipe body 1A with the installation position of the closing plate 13 sandwiched between them. First, the first layer overlay welding bead B1 is provided by overlay welding in which the welding torch is moved along the backing plate 14. Next, as shown in FIG. 15B, the second layer overlay welding bead B2 is provided so as to be overlapped on the first layer overlay welding bead B1 (inner peripheral side) by performing overlay welding. .. After that, as shown in FIG. 15C, by removing the backing plate 14, a closing plate 13 composed of two layers of overlay welding beads B1 and B2 is formed.
The welding method at this time may be mechanically carried out using an automatic welding torch, or may be manually carried out by a welder (welding worker). Further, although a general water-cooled steel plate (water-cooled steel plate) is used as the backing plate 14, one made of ceramics can also be adopted.

In the sixth embodiment, in the production of the closing plate 13 by overlay welding, the closing plate 13 can be manufactured relatively easily by adjusting the welding regardless of the roundness of the steel pipe body 1A, and the steel plate can be manufactured. There is an advantage that the bending work and the control of the welding leg length to follow the circumference of the steel pipe, which are necessary when using the above, are not required.
Further, when the closing plate 13 is provided by overlay welding as in the sixth embodiment, overlay welding can be performed in a post-process after manufacturing the steel pipe main body 1A, so that the work labor is reduced and the closing plate 13 is closed. It is particularly efficient when the protruding length of the plate 13 is short.
Further, when the closing plate 13 is formed by inclining the steel pipe body 1A in the axial direction, it is necessary to perform a three-dimensionally complicated bending process on the steel plate or the like, but in overlay welding, the backing plate 14 is formed. All you have to do is adjust the angle and shape, and you can respond efficiently and easily.
Furthermore, since it is possible to change the build-up amount of welding by adjusting the welding speed and the number of layers, the length protruding inward in the pipe radial direction changes in the circumferential direction of the steel pipe body 1A. It has the advantage of being easy to make.

Although the embodiment of the method for constructing a rotary press-fit steel pipe pile according to the present invention has been described above, the present invention is not limited to the above embodiment and can be appropriately changed without departing from the spirit of the present invention.

For example, in the present embodiment, after the vibrating rod 2 reaches the rod deepest target depth P2, the vibrating rod 2 is vibrated in a stepwise manner in the order of the first region T1, the second region T2, and the third region T3. The steel pipe pile 1 is rotationally press-fitted while being pulled up, but the method is not limited to such stepwise pulling up. For example, a method of pulling up the vibrating rod 2 while repeatedly raising and lowering it may be used. The point is that after the vibrating rod 2 reaches the rod deepest target depth P2, the rod tip 2a of the vibrating rod 2 may be positioned above the position of the rod deepest target depth P2.

Further, the vibration exciter may be configured to be housed in the inner surface of the steel pipe pile head and pressed against the steel pipe pile by flood control or the like. In this case, since the vibration exciter fits inside the steel pipe pile, the steel pipe pile plays a role of soundproofing, and the noise generated from the vibration device can be reduced.

The configuration of the steel pipe pile 1 and the vibrating rod 2 such as length and diameter can be appropriately set.

In addition, it is possible to replace the components in the above-described embodiment with well-known components as appropriate without departing from the spirit of the present invention.

1 Steel pipe pile (rotary press-fit steel pipe pile)
1a Pile tip 2 Vibration rod 2a Rod tip 10 Rotational press-fitting device 11, 11A, 11B, 11C, 13 Closure plate 11a Opening 20 Vibration device P1 Pile reach target depth P2 Rod deepest target depth P3 Rod tip adjustment depth G0 Soft layer G1 Support layer Ga Sediment Ma Dense area T1 1st area T2 2nd area T3 3rd area

Claims (8)

A steel pipe pile having a steel pipe body and a closing plate that protrudes inward in the pipe radial direction at the tip and reduces the opening area of the steel pipe body in a steel pipe cross section orthogonal to the pile axis direction is rotationally press-fitted into the ground. It is a construction method of rotary press-fit steel pipe piles.
The first step of positioning the tip of the vibrating rod below the closing plate inside the steel pipe pile and rotationally press-fitting the steel pipe pile while vibrating the vibrating rod.
After the steel pipe pile reaches a preset rod tip adjustment depth that forms a depth for changing the region where the tip of the vibrating rod is located, the vibrating rod is pulled up above the closing plate and vibrated while the steel pipe pile is vibrated. The second step of rotary press fitting and
A method of constructing a rotary press-fit steel pipe pile, which is characterized by having. The closing plates are provided in a plurality of stages at intervals in the pile axis direction.
In the first step, the tip of the vibrating rod is positioned below the lowermost closing plate among the plurality of stages of the closing plate, and the steel pipe pile is rotationally press-fitted while vibrating the vibrating rod.
In the second step, the vibrating rod is pulled up above the closing plate directly above the vibrating rod, and the steel pipe pile is rotationally press-fitted while vibrating the vibrating rod.
The method for constructing a rotary press-fit steel pipe pile according to claim 1, wherein the second step is repeatedly performed. The method for constructing a rotary press-fit steel pipe pile according to claim 2, wherein the opening area of each of the plurality of stages of the closing plates decreases from the pile tip side toward the pile head side. The method for constructing a rotary press-fit steel pipe pile according to claim 2 and 3, wherein the distance between the closing plates adjacent to each other in the pile axis direction is larger than the overhang length of the closing plates on the pile tip side. Any one of claims 1 to 4, wherein the inner peripheral end on the inner side in the pipe radial direction is inclined toward the pile tip side or the pile head side from the outer outer peripheral end. Construction method of rotary press-fit steel pipe pile described in. The method for constructing a rotary press-fit steel pipe pile according to any one of claims 1 to 5, wherein the closing plate is formed by overlay welding of one or more layers. Anti-vibration material is attached to the steel pipe pile from the tip of the pile upward to at least a part of the peripheral surface of the steel pipe body and the closing plate within a range of twice the diameter of the pile. The method for constructing a rotary press-fit steel pipe pile according to any one of claims 1 to 6, characterized in that. The method for constructing a rotary press-fit steel pipe pile according to claim 7, wherein the anti-vibration material is provided on the closing plate.

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