KR20230112149A - Pile, pile construction method, structure, structure construction method, pile design method, and pile manufacturing method - Google Patents

Abstract

In the pile 1 according to the present invention, two or more plate-shaped pins 5 are installed on the outer circumferential surface of the pile body 3 at the lower end of the pile body 3, and the vertical length of the pile body 3 is 1 or more and 1.75 times or less of the outer diameter of the pile body 3, and the inclination angle is 0 degrees or more and 45 degrees or less with respect to the central axis of the pile body 3.

Description

Pile, pile construction method, structure, structure construction method, pile design method, and pile manufacturing method

The present invention relates to a pile, a pile construction method, a structure, a structure construction method, a pile design method, and a pile manufacturing method.

In harbor structures, steel pipe piles are commonly used frequently. Depending on structures and ground conditions, such as bracing piles for piers and quays, high pull-out support force is required for steel pipe piles. As a method of increasing the pulling capacity, there is a rotating pile method in which wings are attached to the tips of steel pipe piles. In the harbor field, in relation to the construction space, the pile driving method using an impact hammer or a vibro-hammer is the mainstream, and the rotary pile method requiring a relatively large rotary construction machine is not applied. As another method, there is a method of penetrating a steel pipe pile with a water jet combined vibro method, switching to cement milk spraying in the ground, and integrating the steel pipe pile and the ground. However, since this method requires a large substrate required for water jetting or cement milk spraying, it is not economical for marine construction requiring a ship. Furthermore, since the said construction method uses cement milk, it is also unpreferable also in the environmental aspect of a harbor.

On the other hand, piles that can be constructed by the pile driving method and the press-in method, which are mainstream in the field of ports without using water jet or cement milk spraying, and can exhibit high pull-out bearing capacity, have been proposed. For example, a steel pipe pile in which a plurality of spiral ribs forming a spiral are formed on the outer circumferential surface of the lower side of the steel pipe (see Patent Document 1), and a plate-shaped protrusion along the axial direction of the pile body made of steel pipe. A steel pipe pile in which a protrusion body is fixed (see Patent Document 2) has been proposed.

Japanese Unexamined Patent Publication No. 2017-95880 Japanese Laid-Open Utility Model Publication No. Hei 3-18238

The steel pipe pile described in Patent Literature 1 enhances the pulling-out holding force by the circumferential frictional force of the spiral rib. However, the steel pipe pile described in Patent Literature 1 is not economical because it is necessary to form spiral ribs on the outer peripheral surface of the steel pipe so as to form a spiral shape. On the other hand, the steel pipe pile described in Patent Literature 2 enhances the pulling-out holding force by the circumferential frictional force or the pressing force of the plate-shaped projection body. However, since the steel pipe pile described in Patent Literature 2 needs to form a relatively large protruding body in order to increase the circumferential frictional force, it is costly and not economical from the viewpoint of material cost and processing cost. In addition, in order to exert a sufficient pulling-out holding force, it is necessary to penetrate the tip of the pile into the support layer more than usual in order to penetrate the entire projection body into the support layer. Therefore, construction becomes large-scale, and there is a possibility that construction troubles such as restriction of construction space, noise and vibration, poor penetration, and breakage of piling bodies may occur.

The present invention has been made in view of the above problems, and its object is to provide a pile, a pile construction method, a structure, a structure construction method, a pile design method, and a pile manufacturing method that can exhibit high pull-out bearing capacity and high press-in support force even under conditions where construction does not require a large-scale base material for construction, is excellent in economics and environment, and has little penetration into the support layer, and can suppress the occurrence of construction troubles.

In the pile according to the present invention, two or more plate-shaped pins are installed on the outer circumferential surface of the pile body at the lower end of the pile body, and each pin has a vertical length of 0.5 times or more and 1.75 times or less of the outer diameter of the pile body. The angle of inclination is 0 degrees or more and 45 degrees or less with respect to the central axis of the pile body.

In the construction method of the pile according to the present invention, the pile according to the present invention is penetrated into the ground where the support layer exists, and the upper end of the pin installed in the pile is penetrated so that it is located in the support layer.

A structure according to the present invention is equipped with piles according to the present invention.

The method for constructing a structure according to the present invention includes a step of penetrating the pile according to the present invention into the ground.

The pile design method according to the present invention is the pile design method according to the present invention, wherein the inclination angle is set based on the pull-out bearing capacity and the press-in bearing capacity required for the pile, and then the lower limit of the vertical length is set according to the pull-out bearing capacity and the press-fit bearing capacity.

The pile design method according to the present invention is to design a pile in which two or more plate-shaped pins are installed on the outer circumferential surface of the pile body at the lower end of the pile body, and each pin has a vertical length of the pile body. It is set so that it is 0.5 times or more and 1.75 times or less of the outer diameter of the pile body, and the inclination angle is 0 degrees or more and 45 degrees or less with respect to the central axis of the pile body.

The pile manufacturing method according to the present invention manufactures a pile in which two or more plate-shaped pins are installed on the outer circumferential surface of the pile body at the lower end of the pile body, and each pin has a vertical length of the pile body. It is formed so that it is 0.5 times or more and 1.75 times or less of the outer diameter of the pile body, and the inclination angle is 0 degrees or more and 45 degrees or less with respect to the central axis of the pile body.

According to the pile, the pile construction method, the structure, the structure construction method, the pile design method, and the pile manufacturing method according to the present invention, a large-scale base material is not required for construction, economical and environmental aspects are excellent, and furthermore, high pull-out bearing capacity and high press-in bearing capacity can be exhibited even under conditions where penetration into the support layer is small, and the occurrence of construction trouble can be suppressed.

1 is a conceptual diagram illustrating a pile according to an embodiment of the present invention, where (a) is a case where the pin is attached substantially parallel to the central axis of the pile body, and (b) is a case where the pin is inclined with respect to the central axis of the pile body.
2 is a conceptual diagram illustrating the behavior of exerting a pulling-out bearing capacity when a pulling-out load acts on a pile according to an embodiment of the present invention.
3 is a diagram showing the relationship between the penetration position of the lower end of the pile and the support layer according to the embodiment of the present invention.
4 is a construction conceptual diagram in the case of rotationally penetrating a pile according to an embodiment of the present invention by a vertical load.
5 is a conceptual diagram showing a force acting on a pin when rotationally penetrating a pile according to an embodiment of the present invention by a vertical load.
6 is a diagram showing a three-dimensional FEM model used for verifying the pull-out bearing capacity of piles in the embodiment.
7 is a graph showing the relationship between the loading load and the pull-out amount calculated by analysis for piles pinned parallel to the central axis of the pile body.
8 is a graph showing the relationship between the applied load and the amount of withdrawal calculated by analysis for piles to which pins are attached with an inclination with respect to the central axis of the pile body.

(Mode for implementing the invention)

As illustrated in FIG. 1 , in the pile 1 according to the embodiment of the present invention, two or more plate-shaped pins 5 are installed on the outer peripheral surface of the pile body 3 at the lower end of the pile body 3. Each pin 5 has a vertical length lfv of 0.5 times or more and 1.75 times or less of the outer diameter D of the pile body 3, and an inclination angle β (see FIG. 1 (b)) of the pile body 3. It is 0 degrees or more and 45 degrees or less with respect to the central axis.

In addition, FIG. 1 (a) shows the case where the pin 5 is attached substantially parallel to the central axis of the pile main body 3, and FIG. 1 (b) shows the case where the pin 5 is attached obliquely with respect to the central axis of the pile main body 3. "Substantially parallel" here means that the angle with respect to the central axis of the pile main body 3 is 0 degree or more and less than 1 degree.

In addition, in the pile 1 according to the embodiment of the present invention, the distance between the pins 5 adjacent to each other is 1/16 or more of the outer circumferential length of the pile body 3, the distance between the adjacent pins 5 is 1/2 or less of the outer circumferential length of the pile main body 3, the lower end position of the pin 5 is 50 mm or less from the lower end of the pile main body 3, and the upper end position of the pin 5 is from the lower end of the pile main body 3 to the pile main body 3 One or more of the following conditions are satisfied.

1, lt represents the distance from the lower end of the pile body 3 to the lower end of the pin 5 (50 mm or less). α represents the tip angle of the pin 5. Here, the tip angle α of the pin 5 is a predetermined angle determined from the relationship between the workability required for the pile 1 and the bearing capacity. The tip angle α is preferably 60 degrees or less from the effect of reducing the shear force received by the pin welding portion due to the pressure resistance of the pin plate thickness portion at the time of pile insertion. In addition, the pin length lf is the distance when the lower end and the upper end of the pin 5 on the attachment side of the pile body 3 are connected in a straight line, and the pin horizontal length lfh is the lower end of the pin 5 and the upper end of the pile body 3. The length in the direction perpendicular to the central axis of the pile body 3, all of which are determined based on the plate thickness of the pin 5.

Prior to explaining the reason why the pin 5 is limited as described above in the pile 1 according to the present embodiment, the pulling out bearing capacity exertion behavior when a pulling load acts on the pile 1 in which the pin 5 is installed is explained.

In FIG. 2, a conceptual diagram of the pulling-out bearing capacity exertion behavior when a pulling-out load acts on the pile 1 shown in FIG. 1(a) is shown. In FIG. 2 , the ground 13 demonstrating the pulling-out bearing capacity represents the ground resisting to exert the pulling-out bearing capacity at the time of pulling out the pile 1. In addition, the ground 13 exhibiting a supporting force for pulling out expands due to the effect of the internal friction angle of the ground near the upper end of the pin, and the effect of the expansion weakens when it is separated from a certain distance to form a cylindrical sliding surface. In addition, the expansion effect by the internal friction angle of the ground increases as the ground becomes stronger.

The pull-out support capacity increases as the range of the pull-out support exerting ground 13 that resists when the pile 1 is pulled out is wider. Therefore, compared to the spiral ribs used for the steel pipe piles disclosed in the above-mentioned Patent Document 1, by using the pin 5 with a large protruding amount from the surface of the pile body 3 in the radial direction of the pile 1, the ground 13 for exerting the pulling-out bearing capacity is widened, and a high effect can be exhibited. In addition, by the presence of the pin 5, not only the pull-out bearing capacity is increased, but also when the pile 1 is press-in, near the lower end of the pin 5, the press-in bearing capacity exerts the effect of the internal friction angle of the ground. Since the ground (not shown) expands, the press-in bearing capacity is also improved.

Next, the reason for the limitation of the pin 5 in the pile 1 according to this embodiment is described with reference to FIGS. 1-5. First, "the number of pins (lower limit)", "vertical length" and "inclination angle", which are conditions necessary for obtaining the effect of the present invention, will be described.

(number of pins (lower limit))

The number of fins 5 is two or more. As shown in FIG. 2 described above, the pulling-out bearing capacity of the pile 1 is exerted as resistance by the ground 13 exhibiting the pulling-out bearing capacity. And, as the number of pins 5 increases, the force transmitted from the pins 5 to the ground increases, and the effect of the internal friction angle of the ground in the ground 13 exerting a pull-out support force near the upper end of the pin increases, and the pull-out support force increases. In addition, by the presence of the pin 5, not only the pull-out bearing capacity is increased, but also when the pile 1 is press-in, in the vicinity of the lower end of the pin 5, the press-in bearing capacity is exerted by the effect of the internal friction angle of the ground. Since the ground expands, the press-in bearing capacity is also improved. In addition, as described above, the existence of the pins 5 (that is, one or more pins 5) improves not only the pull-out support force but also the push-in support force as well. This is because, as described above, even when the pile 1 is press-in, the ground for exerting the press-in bearing capacity expands near the lower end of the pin 5 due to the effect of the internal friction angle of the ground. Therefore, the number of pins 5 is determined by the workability required for the pile 1, the pulling-out bearing capacity, and the press-fitting bearing capacity. In addition, in this embodiment, in order to penetrate the pile 1 stably in the axial direction, it is set as two or more sheets.

(vertical length)

The vertical length lfv is 0.5 times or more and 1.75 times or less with respect to the outer diameter D of the pile body 3 (see Fig. 1). Here, as shown in FIG. 1, vertical length lfv is the distance of the lower end and upper end of the pin plate thickness center in the central axis direction of the pile main body 3.

The reason why the vertical length lfv satisfies the above range will be explained based on FIG. 3 . 3 is a diagram schematically showing the relationship between the penetration position of the pile 1 in the vertical direction and the support layer 15 in the case of penetrating the pile 1 into the ground 11 in which the support layer 15 exists below. In FIG. 3 (a), the upper end of the pin 5 is located in the support layer 15, and in FIG. 3 (b), the upper end of the pin 5 is not located in the support layer 15.

In general, the ground for which piles are required to have improved pull-out bearing capacity and push-in bearing capacity is one in which a support layer (hard ground) exists under a soft ground having a thick layer thickness. This is because, in soft ground, the pull-out support force and press-in support force due to the circumferential friction between the pile body and the ground cannot be expected. In the pile 1 according to the present embodiment, the presence of the pin 5 not only enhances the pull-out bearing capacity, but also improves the press-in bearing capacity as well. This is because, as described above, even when the pile 1 is press-in, the ground for exerting the press-in bearing capacity expands near the lower end of the pin 5 due to the effect of the internal friction angle of the ground. On the other hand, in the pile 1 according to the present embodiment, the pull-out support force is exerted as resistance by the pull-out support force exerting ground 13. Therefore, it is preferable that the upper end of the pin 5 be located in the support layer 15, which is a strong ground having a large internal friction angle, in order to sufficiently widen the ground 13 exhibiting the pulling capacity. In addition, in order to reliably position the upper end of the fin 5 in the support layer 15, it is preferable that the fin length lf be short within a range not impairing performance.

However, when the pin length lf is too short, when welding the pin 5 to the pile body 3 made of steel pipe, temporary fixation of the pin 5 with a jig becomes difficult, and the workability at the time of attaching the pin 5 deteriorates. Since the size of the jig changes depending on the outer diameter of the pile main body 3, in the pile 1 according to the present embodiment, in order not to make the pin length lf too short, the vertical length lfv is 0.5 times or more than the outer diameter of the pile main body 3.

On the other hand, if the fin length lf is too long under the same construction conditions, as shown in Fig. 3(b), the upper end of the fin 5 does not penetrate the support layer 15, and sufficient pulling-out holding force cannot be exhibited.

In addition, depending on the condition of the support layer 15, it is possible to increase the amount of insertion of the pile 1 into the support layer 15. However, in many cases, the penetration of the pile 1 is stopped before reaching the depth assumed in practice, and if the pin length lf is unexpectedly long, the upper end of the pin 5 is not located in the support layer 15. The risk increases. In general, the criterion for the amount of penetration into the support layer in the pile driving method is considered to be about twice the outer diameter of the pile body in consideration of the strength of the construction machine and the pile body. Therefore, in the pile 1 according to the present embodiment, the pin 5 is stably penetrated into the support layer 15, the upper end of the pin 5 is positioned in the support layer 15, and the support layer 15 exhibits a sufficient pull-out support force In order to exert the pull-out support force with the resistance of the ground 13, the vertical length lfv is set to 1.75 times or less of the outer diameter D of the pile body 3.

(tilt angle)

The inclination angle β is 0 degrees or more and 45 degrees or less with respect to the central axis of the pile body 3 (see Fig. 1). Here, inclination-angle (beta) is set as the angle with respect to the central axis of the pile main body 3 when the point in 1/2 position of the pin length lf is made into a rotation center.

The reason why the inclination angle β is within the above range is as follows. In FIG. 4, the construction concept at the time of vertically penetrating the pile 1 of 1-45 degree|times into the ground 11 with an inclination angle (beta) is shown.

When the inclination angle β is 0 degrees or more and less than 1 degree (FIG. 1 (a)), since it becomes a pin 5 (vertical pin) substantially parallel to the central axis of the pile body 3, it becomes a vertical penetration similar to that of a general steel pipe pile. On the other hand, when the inclination angle β is 1 degree or more and 45 degrees or less (FIG. 1 (b)), since it becomes a pin 5 (inclined pin) inclined with respect to the central axis of the pile body 3, when a vertical load is applied to the pile 1, the soil passes between the pins 5 in the ground (black arrow in FIG. That is, when a vertical load is applied to the pile 1 to which the pin 5 is attached with respect to the central axis of the pile body 3, the penetration resistance by the pin 5 can be alleviated by rotating the pile body 3.

As shown in FIG. 2 described above, the pulling-out bearing capacity of the pile 1 is exerted as resistance by the ground 13 exhibiting the pulling-out bearing capacity. And, as the inclination angle β is larger, the force transmitted from the pin 5 to the ground increases, and the effect of the internal friction angle of the ground in the ground 13 exerting a pulling-out bearing force in the vicinity of the upper end of the pin increases, and the pull-out holding force increases. On the other hand, when the inclination angle β is large, the resistance at the time of penetration increases and construction efficiency deteriorates. Therefore, the inclination angle β needs to consider not only the pulling-out bearing capacity but also the penetration resistance. Hereinafter, the relationship between the inclination angle and penetration resistance will be described.

5, when the inclination angle β is 30 degrees (FIG. 5 (a)) and 60 degrees (FIG. 5 (b)), the pile 1 is rotated into the ground 11 by a vertical load. The force acting on the pin 5 when inserted is shown. In addition, in FIG. 5, illustration of the pile 1 and the pile main body 3 is abbreviate|omitted.

When a vertical load is applied to the pile to penetrate the ground 11, a normal drag force acts on the pin 5 from the ground 11, and as a result, a rotational force (referred to as “pin driving force”) acts to rotate the pile body 3 around the central axis. Specifically, the normal drag force with respect to the pin 5 is componentized in the vertical direction of the ground 11 and the direction orthogonal to this vertical direction. The component force in the direction orthogonal to this vertical direction corresponds to the "pin driving force". 5, the vertical direction of the ground 11 corresponds to the axial direction of the pile body 3, and the direction orthogonal to the vertical direction of the ground 11 corresponds to the tangential direction to the outer periphery of the pile body 3, respectively. Therefore, the pin driving force becomes the rotational force of the pile main body 3.

Here, comparing the case where the inclination angle β is 30 degrees (FIG. 5(a)) and the case where it is 60 degrees (FIG. 5(b)), in the case where the inclination angle β is 60 degrees, the pin driving force is small. In this way, when the inclination angle β is too large, the propulsive force decreases, and as a result, the penetration resistance increases.

Therefore, in this embodiment, the ratio of the pin driving force (rotational force of the pile body 3) to the vertical load does not decrease significantly, and the pile 1 can be penetrated without losing the rotational force of the pile body 3. In order to do so, the inclination angle β was set to 45 degrees or less.

In the present embodiment, the lower limit of the angle of inclination β is set to 0 degrees or more, but the inclination angle β is preferably set to 1 degree or more in order to penetrate while rotating the pile body 3 at the time of construction and to relieve the penetration resistance.

Next, the selection conditions "Pin lower end position", "Pin upper end position", "Pin width", "Number of pins (upper limit)", and "Pin spacing" will be described. These selection conditions can be set as needed depending on the use of piles, the purpose of construction of piles, the ground to be penetrated, and the support layer.

(located at the bottom of the pin)

It is preferable to set the lower end position of the pin 5 so that the distance lt from the lower end of the pile main body 3 to the lower end of the pin 5 may become 50 mm or less (refer FIG. 1). This is preferable as the attachment position of the pin 5 is closer to the lower end of the pile body 3, and the workability of the lower end of the pile body 3 and, for example, the pin 5 in the pile body 3 made of a steel pipe. Weldability at the time of attachment to the pile body 3 is considered.

(at the top of the pin)

It is preferable that the position of the upper end of the pin 5 is less than twice the outer diameter D of the pile body 3 from the lower end of the pile body 3 (see Fig. 1). Regarding the position of the upper end of the pin 5, as shown in FIG. 3 (a) described above, the pin 5 stably penetrates the support layer 15 to position the upper end of the pin 5 in the support layer 15. It is based on the viewpoint.

(pin width)

The fin width wf is preferably twice or more than the fin plate thickness tf. In addition, it is preferable to make pin width wf 1/2 or less of the outer diameter of the pile main body 3 (refer FIG. 1). Here, the pin width wf is the length in the circumferential direction of the pin at a position of 1/2 of the pin length lf, as shown in FIG. 1 . The pull-out support capacity increases as the range of the pull-out support exerting ground 13 that resists when the pile 1 is pulled out is wider. For this reason, the larger the amount of protrusion from the surface of the pile main body 3 is, the wider the ground 13 for exhibiting the pulling-out bearing capacity is, and a high effect can be exhibited.

The lower limit of the pin width wf takes into consideration the adhesion of the pin 5 to the pile body 3. The upper limit of the pin width wf is the pin outer diameter Df (see FIG. 1), when the outer diameter of the imaginary circle passing through the outermost edge of the pin 5 is the pin outer diameter Df (see FIG. 1). From the viewpoint of workability, the pin outer diameter Df is preferably up to about twice the outer diameter of the pile body 3.

(number of pins (upper limit) and spacing)

The number of sheets to which the pins 5 are attached is preferably 16 or less. In addition, it is preferable to make the space|interval of mutually adjacent pins 5 into 1/16 or more of the outer diameter D of the pile main body 3 as a lower limit. Moreover, as an upper limit, it is preferable to set it as 1/2 or less. Here, the space|interval of the mutually adjacent pin 5 is set as the distance of the plate thickness center of the pin 5 in the outer circumferential direction of the pile main body 3.

The reason why the number of pins 5 and the interval are within the above range is as follows. In order to stably penetrate the pile 1 in the axial direction, at least two pins are required, and when the two pins 5 are attached at equal intervals in the outer circumferential direction of the pile main body 3, the pin interval is 1/2 of the outer circumferential length of the pile main body 3. On the other hand, regarding the upper limit of the number of sheets to which the pins 5 are attached, when a steel pipe is used for the pile main body 3, since the pins 5 are generally added to the pile main body 3 by welding or the like, considering the required work space, it is preferable to set it to 16 or less. Then, when 16 pins 5 are attached at equal intervals in the outer circumferential direction of the pile main body 3, the interval between the pins 5 adjacent to each other is 1/16 of the outer circumferential length of the pile main body 3. In addition, the more the number of pins 5 is within the above range, the higher the cost, but the larger the pressure area of the upper end of the pin 5, the higher the load transmission force to the ground, and the higher the pull-out holding force.

As described above, according to the pile 1 according to the embodiment of the present invention, it is possible to exhibit high pull-out bearing capacity and high press-in bearing capacity even under the condition of little penetration into the support layer. Therefore, the force for penetrating much into the support layer may be smaller, and the machine used for construction can be miniaturized. As a result, it is possible to suppress the occurrence of construction troubles such as restriction of construction space, noise, vibration, poor penetration, and damage to the pile body, and it is possible to provide piles with excellent workability, economy, and environmental aspects.

In addition, the pile 1 according to the embodiment of the present invention is particularly preferably applicable to harbor structures requiring high pull-out bearing capacity and press-fitting bearing capacity. A harbor structure here refers to a pier, an auxiliary pile of a quay, and the like. In addition to harbor structures, it is possible to apply similarly to offshore wind power foundations, building foundations, pier foundations, or rock anchors. This is because there are cases in which these structures also require high pull-out bearing capacity and press-fitting bearing capacity.

In addition, as shown in FIG. 3 above, the pile 1 according to the present embodiment is most preferably penetrated into a support layer that exerts the maximum effect of the bearing capacity. Not limited to such a usage form, the present invention can also be applied to friction piles that do not penetrate the support layer or to matters. In addition, with respect to general steel pipe piles (also called corrugated pipes), it is possible to improve the pull-out bearing capacity and press-in bearing capacity.

Further, the fins 5 may be attached at unequal intervals as long as they are within the range of the above fin intervals. In addition, the pin 5 does not necessarily need to be attached axially symmetrically with respect to the central axis of the pile main body 3, and may be attached asymmetrically by performing appropriate design and construction management. Moreover, although the pin 5 shown in FIG. 1 is attached so that it may rotate clockwise with respect to the central axis of the pile main body 3, it may be attached so that it may rotate counterclockwise. In addition, although a pin may be attached to the pile head, it is preferable not to attach a pin to the pile head because it inhibits the rotation of the pile generated during construction and becomes a factor of disturbing the ground. In addition, even when the pins are substantially parallel, rotation of the pile may occur depending on the state of the ground or how a load is applied.

In addition, the pile 1 according to this embodiment is not limited to a steel pipe pile in which a steel plate pin is attached to a steel pipe pile body, but can also be applied to a concrete pile. In the case of concrete piles, the pins may also be made of concrete using molds.

In the above description, the pile has been described as the invention of the object, but the pile 1 according to the embodiment of the present invention penetrates so that the upper end of the pin 5 installed at the lower end of the pile body 3 is located in the support layer. It can be used in a construction method. With this construction method, the pile 1 according to the present embodiment can be penetrated into the ground where the support layer exists. In addition, the construction method for penetrating the pile 1 used in this case into the ground is not specifically limited. It is possible to use a known, known, or unknown pile construction method.

In addition, for the pile 1 according to the embodiment of the present invention, a construction method of penetrating into the ground by a pile driving method or a press-in method is applicable. In addition, the pile 1 according to the present embodiment is very suitable as a pile used in these construction methods. It is due to the following reason.

In general, the smaller the resistive force generated when a load is applied to the pile during construction, the higher the workability. Since the pile 1 according to the present embodiment has a relatively small inclination angle β (see FIG. 1 (b)), the resistance to the vertical load is small, and it can be said that it is suitable for the pile driving method or the press-in method, which is construction by vertical load. However, in order to minimize the resistance at the time of penetration, it is necessary to take care not to cause restraint in the rotational direction during construction.

Next, an example of constructing the pile 1 according to the present embodiment by the pile driving method and an example of constructing by the press-in method will be described. First, in the case of the pile driving method, a hammer such as a weight is dropped to apply a hitting load to the pile head, or the pile is vibrated to temporarily lower the strength of the ground and relatively increase the vertical load due to its own weight to penetrate the pile. On the other hand, in the case of the press-in method, the pile is penetrated by applying a static press-in load to the pile head in the vertical direction. Even in the case of using these construction methods, it is a more preferable construction method to penetrate the pile into the ground so that the upper end of the pin 5 provided at the lower end of the pile body 3 is located in the support layer.

In addition, the pile 1 according to the present embodiment may be used for a structure provided with the pile 1 according to the present embodiment.

Here, as described above, the pile according to the present invention is particularly suitable for a harbor structure, an offshore wind power foundation, a building foundation, a pier foundation, or a rock anchor among structures.

In addition, the pile 1 according to the present embodiment can be used in a method for constructing a structure including a step of penetrating the pile 1 into the ground.

In addition, the pile 1 according to the present embodiment can be used also in a method for constructing a structure having the construction method for the pile 1 described above.

In addition, in the above description, although piles have been described as the invention of the product, the pile 1 according to the present embodiment is designed by the following design method. As a pile design method for designing a pile in which two or more plate-shaped pins are installed on the outer circumferential surface of the pile body at the lower end of the pile body, each pin has a vertical length of 0.5 times or more and 1.75 times or less of the outer diameter of the pile body. Set the inclination angle to be 0 degrees or more and 45 degrees or less with respect to the central axis of the pile body.

In addition, the order of each constituent element of the pile design method in the present invention is not limited to the order described above. In addition, the suitable range of each selection condition, such as the distance between adjacent pins, the position of the lower end and the upper end of the pin, and the pin width, is the same as that described for the pile 1 according to the present embodiment as described above. Therefore, it is preferable to set each of these selection conditions to the suitable range described for the pile 1 as needed.

In addition, the pile 1 according to this embodiment is also designed by the following design method. First, the target pull-out bearing capacity of the pile 1 according to the present embodiment is set. Next, the upper limit of the inclination angle β and the number of pins is set according to the pulling-out support force required of the pile 1. This is because the upper limit of the inclination angle β and the number of pins has a large influence on the pulling-out holding force. In setting these conditions, when priority is given to workability, the inclination angle β is reduced and the number of pins is increased within an allowable range. On the other hand, when economic efficiency is given priority, the inclination angle β is increased within an allowable range and the number of pins is reduced within an allowable range.

Then, after determining the inclination angle β and the number of pins, the lower limit of the vertical length lfv is set according to the pulling-out bearing capacity required of the pile 1. In determining the vertical length (lfv), when workability is given priority, the vertical length (lfv) is increased within an allowable range, and when economy is given priority, the vertical length (lfv) is reduced within an allowable range.

In addition, in the design method of the pile 1 according to the present embodiment, in addition to the vertical length lfv, it is preferable to set the pin width wf according to the pulling-out bearing capacity required of the pile 1. In determining the fin width wf, when priority is given to the workability of the pile 1, the fin width wf is reduced within an allowable range and the vertical length lfv is increased within an allowable range. On the other hand, when economy is given priority, the pin width (wf) is increased and the vertical length (lfv) is reduced within an allowable range.

In addition, in the design method of the pile 1 according to the present embodiment, the “allowance range” may be a range set according to the pulling-out bearing capacity required of the pile 1, or it may be within the range of each condition of the pin 5 described in the pile 1 according to the present embodiment.

In addition, the pile 1 according to this embodiment is manufactured by the following manufacturing method. A pile manufacturing method for manufacturing a pile in which two or more plate-shaped pins are installed on the outer circumferential surface of the pile body at the lower end of the pile body, wherein each pin has a vertical length of 0.5 times or more and 1.75 times or less of the outer diameter of the pile body. It is formed so that the angle of inclination is 0 degrees or more and 45 degrees or less with respect to the central axis of the pile body.

In addition, the order of each constituent element of the pile manufacturing method in the present invention is not limited to the order described above. In addition, in the manufacturing method of the pile 1 according to the present embodiment, the suitable range of each selection condition of the spacing of the pins 5 adjacent to each other, the position of the lower end and the upper end of the pin 5, and the pin width is the same as that described for the pile 1 according to the present embodiment. Therefore, it is preferable to form each of these selection conditions in the suitable range described for the pile 1 as needed.

[Example]

Since analysis was performed to verify the operation and effect of the present invention, this will be described below. In the said analysis, the pull-out bearing capacity of the pile 23 was calculated|required using the 3-dimensional FEM model 21 shown in FIG.

In the three-dimensional FEM model 21 for verification, a pile 23 (outer diameter D of the pile body 25 609.6 mm, plate thickness 12 mm, length 9.34 m) equipped with a steel pipe pile body 25 and a steel plate pin 27 is arranged in the center of the ground 31, and the lower end side of the pile 23 is 1.22 m (twice the outer diameter of the pile body 25). ) as purchased. The ground 31 has a cylindrical shape with an outer diameter of 12 m and a height of 12 m, and a stratum boundary dividing the upper layer 33 (N value 20) and the lower layer 35 (N value 50) is formed at a depth of 8.12 m. The support layer in the actual ground was simulated. The material data of the pile 23 and the ground 31 is a bilinear type elasto-plastic model in which the secondary gradient changes at the yield point, and between the pile 23 and the ground 31, elements capable of considering interaction behavior such as contact and friction are introduced.

Then, the relationship between the applied load and the pulling amount when a pull-out load was applied vertically upward to the pile 23 was calculated, and the pull-out holding capacity of the pile 23 was determined. In addition, the pulling capacity of a general steel pipe pile is regarded as the load load at the time of the standard pulling amount, and the standard pulling amount is 0.1 times the outer diameter of the steel pipe or 0.1 times the outer diameter of the pin. So, in this Example, the standard pulling amount was set to 0.1 times the outer diameter of the pile main body 25, and the applied load at the time of the said standard drawing amount was made into the pulling load.

Further, in this embodiment, the pull-out holding force when the shape of the pin 27 in the pile 23 was changed was determined. The specifications, such as the shape of the pin 27 in the pile 23, are shown below (refer FIG. 1). Eight pins 27 were formed on the outer circumferential surface of the pile body 25 at equal intervals. The vertical length (lfv) was 1 time, 1.75 times, and 2.5 times (1D, 1.75D, and 2.5D) the outer diameter D of the pile main body 25. The distance lt from the lower end of the pile body 25 to the lower end of the pin 27 was 50 mm. The fin width wf was 0.25 times the outer diameter of the pile body 25. At this time, the outer diameter Df of the pin was 1.5 times the outer diameter D of the pile body 25. The inclination angle (β) was 0 degrees or 9.46 degrees. The tip angle α of the pin 27 was 60 degrees. In addition, the fin plate thickness tf was 25 mm. In addition, the said specification is within the range of this invention except the case where the vertical length (lfv) was made into 2.5 times the outer diameter of the pile main body 25.

In FIG. 7, the relationship between the applied load and the amount of drawing when the vertical length lfv is changed in the pile 23 with the inclination angle β of 0 degree is shown. Here, FIG. 7 also shows the reference amount of drawing.

In general, the criterion for the amount of penetration into the support layer in the pile driving method is considered to be about twice the outer diameter of the pile body, taking into account the strength of the construction machine and the pile body. Then, in this embodiment, taking this point into consideration, the amount of penetration of the pile into the support layer was set to twice the outer diameter of the pile main body 3 (ie, 2D). From FIG. 7, it was confirmed that when the vertical length (lfv) was as short as 1 time (1D) of the outer diameter of the pile body 25 within the scope of the present invention, the highest pulling-out capacity was confirmed. This is because when the vertical length lfv is short, the upper end of the pin 27 is located deep in the lower layer 35 (support layer), and the ground for exerting the pulling force is wider, so that the pulling force is maximized. Also, even when the vertical length lfv is 1.75D, which is within the scope of the present invention, since the upper end of the pin 27 is located in the lower layer 35, a pull-out holding force close to that when the vertical length lfv is 1D is obtained. Since the pull-out support force is exhibited as resistance by the pull-out support force exerting ground 13, it became clear that the longer the distance between the upper end of the pin and the support layer surface, the more effective it can be. On the other hand, when the vertical length (lfv) is 2.5 times (2.5D) the outer diameter of the pile body 25, which is out of the scope of the present invention, the upper end of the pin 27 is not located in the lower layer 35 (support layer). Since the resistance by the ground 13 is insufficient, the pulling capacity is not sufficiently exhibited.

In FIG. 8, the relationship between the applied load and the amount of pulling out when the vertical length lfv is changed in the pile 23 with the inclination angle β of 9.46 degrees is shown. Similar to Fig. 7 described above, Fig. 8 also shows a reference amount of drawing based on 0.1 times the outer diameter of the steel pipe.

From FIG. 8, even when the pin 27 is inclined with respect to the central axis of the pile body 25, as in the case where the inclination angle β is set to 0 degrees, the vertical length lfv is within the scope of the present invention. When it is 1 times the outer diameter (1D) of the pile body 25, it has been confirmed that the pulling-out capacity is the highest. Also, even when the vertical length lfv is 1.75D, which is within the scope of the present invention, since the upper end of the pin 27 is located in the lower layer 35, a pull-out holding force close to that when the vertical length lfv is 1D is obtained. In other words, in order to sufficiently widen the ground 13 exhibiting a pulling bearing capacity due to the effect of the internal friction angle of the ground in the vicinity of the upper end of the pin to exert the pulling bearing capacity, according to this embodiment, the distance between the upper end of the pin and the surface of the support layer is 0.25D or more. It can be confirmed that it is sufficient. On the other hand, when the vertical length (lfv) is 2.5 times (2.5D) the outer diameter of the pile body 25, which is outside the scope of the present invention, the upper end of the pin 27 is lower layer 35 (support layer). In addition, comparing the results of FIG. 7 and FIG. 8, when the pin 27 is inclined with respect to the central axis of the pile body 25, the pressure resistance by the ground 13 exhibiting the pulling-out bearing capacity increases, and the pulling-out bearing capacity is higher. It was also confirmed that it was higher. Further, it can be expected to increase the press-in holding force, which shows the same tendency as the pulling-out holding force.

According to the present invention, it is possible to provide a pile, a pile construction method, a structure, a structure construction method, a pile design method, and a pile manufacturing method that can exhibit high pull-out bearing capacity and high press-in bearing capacity even under conditions where construction does not require a large-scale base material for construction, is excellent in economics and environment, and has little penetration into the support layer.

1 : stake
3: pile body
5 : pin
11: ground
13: Ground for drawing support
15: support layer
21: 3D FEM model
23 : stake
25: pile body
27: pin
31: ground
33: upper layer
35: lower layer

Claims (7)

A pile in which two or more plate-shaped pins are installed on the outer circumferential surface of the pile body at the lower end of the pile body,
Each of the above pins,
The vertical length is 0.5 times or more and 1.75 times or less of the outer diameter of the pile body,
A pile having an inclination angle of 0 degrees or more and 45 degrees or less with respect to the central axis of the pile body. A method for constructing a pile in which the pile according to claim 1 is penetrated into the ground in which a support layer exists,
A method of constructing a pile, wherein the upper end of the pin installed in the pile penetrates so as to be located in the support layer. A structure provided with the pile according to claim 1. A method for constructing a structure provided with piles according to claim 1,
A method of constructing a structure comprising the step of penetrating the pile into the ground. As a method of designing the pile according to claim 1,
Based on the pull-out support force required for the pile, the inclination angle is set,
Then, the pile design method of setting the lower limit of the vertical length according to the pulling-out bearing capacity. As a pile design method for designing a pile in which two or more plate-shaped pins are installed on the outer circumferential surface of the pile body at the lower end of the pile body,
Each of the above pins,
The vertical length is 0.5 times or more and 1.75 times or less of the outer diameter of the pile body,
A pile design method in which the inclination angle is set to be 0 degrees or more and 45 degrees or less with respect to the central axis of the pile body. A pile manufacturing method for manufacturing a pile in which two or more plate-shaped pins are installed on the outer circumferential surface of the pile body at the lower end of the pile body,
Each of the above pins,
The vertical length is 0.5 times or more and 1.75 times or less of the outer diameter of the pile body,
A method for manufacturing a pile, wherein the inclination angle is formed to be 0 degrees or more and 45 degrees or less with respect to the central axis of the pile body.