JPH1143936A - Pile coupling part structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pile coupling part structure in which a coupling part provided with high bending yield strength and rigidity can be obtained by simple connection work. SOLUTION: In a pile coupling part structure, a pair of an outer engagement end part 4 and an inner engagement end part 6 to be freely engaged with each other are respectively formed on a first pile 1 and a second pile 2 to be adjacent to each other in an axial line direction, and an engagement protrusion 7 and a counter engagement protrusion 8 to be engaged with each other by rotation around an axial center in the condition as the outer engagement end part 4 and the inner engagement end part 6 are engaged with each other are respectively provided on an inner wall part 11 of the outer engagement end part 4 and an outer wall part 12 of the inner engagement end part 6. The engagement protrusions 7 and the counter engagement protrusions 8 are respectively provided in parallel in an axial center direction of the first pile 1 and the second pile 2, and in the outer engagement end part 4, the engagement protrusion 7 provided on the tip end part 10 side are formed in a larger diameter than the engagement proturision 7 provided on the base end part 9 side, while in the inner engagement end part 6, the couter engagement protrusion 8 on the tip end part 10 side is formed in a smaller diameter than the counter engagement protrusion 8 on the base end part 9 side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a pair of outer fitting ends and inner fitting ends which can be freely fitted to each other are formed on a first pile and a second pile adjacent to each other in the axial direction, respectively. In a state where the outer fitting end and the inner fitting end are fitted, an engaging projection and an engaged projection are engaged with each other so as to be prevented from being detached from each other by a relative rotation operation around the axis. The present invention relates to a joint structure of a pile provided separately on an inner wall portion of the outer fitting end portion and an outer wall portion of the inner fitting end portion.

[0002]

2. Description of the Related Art Conventionally, as a joint portion structure of this kind of pile, there has been a screw type as shown in FIGS. That is, the male threaded portion 30 is formed at the end of one of the connected piles, and the female threaded portion 31 is formed at the end of the other pile. For example, the pile formed with the female screw portion 31 is first buried in the ground, and the pile formed with the male screw portion 30 is screwed into the buried pile and connected. This screwing work,
It is performed in a state where the axes Z1 and Z2 of both piles are matched. If the joint structure of the pile is a screw type, a large number of threads along the longitudinal direction of the pile are engaged. Therefore, after the connection is completed, the pile has high strength against bending force and the like acting on the pile.

[0003]

However, according to the conventional joint structure of a pile, there are the following problems. That is, in the screw type configuration, as shown in FIG. 7 (a), it is necessary that the axis Z2 of the pile to be screwed in exactly coincides with the axis Z1 of the pile already embedded. In particular, it is important to align the axes at the time when the screwing of the male screw part 30 and the female screw part 31 is started. In other words, if the axes do not match, the distal end of the male thread 30 and the distal end of the female thread 31 may excessively collide with each other at the beginning of screwing, and the thread may be damaged. Even if the screwing is started, not only do the threads compete with each other and an excessive rotational force is required, but also there is a possibility that the screw threads may be damaged or the two piles may bite and the screwing may not be released. In addition, the rotation of the pile to be added later is usually performed manually, but when the number of rotations required until screwing is completed is large, the operation becomes very complicated. During the screwing operation, the pile is suspended by a crane or the like, but in order to enable the pile to be rotated manually, the vertical position of the pile must be adjusted so that the threads are not pressed. Moreover,
The vertical position of the pile descends with the screwing. Adjusting the vertical position of the pile for this purpose requires a very delicate operation. Further, the completion of screwing is usually determined by the size of the gap between the distal end of the male screw 30 and the step provided at the base of the female screw 31. However, since the pile is rotated manually, the force required for rotation differs depending on the processing accuracy of the threaded portion. Therefore, the degree of screwing is not constant, and the gap varies, resulting in insufficient construction management. The purpose of the present invention is
An object of the present invention is to provide a pile joint structure in which the disadvantages of the prior art are eliminated and a joint having high bending strength and rigidity can be obtained by a simple connecting operation.

[0004]

[Means for Solving the Problems]

(Structure 1) In the joint structure of a pile according to the present invention, as described in claim 1, a plurality of engaging projections and engaged projections are provided in the axial direction of the first pile and the second pile, respectively. Side by side, at the outside fitting end,
The formation portion of the engagement protrusion provided on the distal end portion is formed to have a larger diameter than the formation portion of the engagement protrusion provided on the base end portion, and the inner fitting end portion has It is characterized in that the formed location of the engaged projection is smaller in diameter than the location of the engaged projection provided on the base end side. (Operation / Effect) As in the present configuration, the engagement protrusions of the outer fitting end are provided at a plurality of locations along the axial direction of the first pile with respect to the first pile, and the inner fitting end is also provided. Is provided at a plurality of locations along the axial direction of the second pile with respect to the second pile, so that the outer fitting end and the inner fitting end are the first pile or the second pile. Engagement is performed at a plurality of locations along the axis of the pile. This can be a joint that can effectively withstand particularly when a bending external force acts on the joint between the first pile and the second pile. In addition, in the outer fitting end portion, the forming portion of the engaging convex portion provided on the distal end portion side is formed in the outer fitting end portion and the inner fitting end portion. The diameter of one of the inner fitting ends is smaller at the portion where the engaged convex portion provided on the tip end side is formed.
In other words, of the locations where the engaging projection and the engaged projection are formed,
On the side close to the first pile or the second pile, the thickness of the member is set to be large, and the cross-sectional defect at the portion is made small.
Normally, when a bending external force is applied to the joint, the stress is most concentrated on the boundary between the pile main body and the joint, where the cross-sectional shape changes. In this regard, in this configuration, since the cross-sectional defect of the portion is small as described above, higher bending strength and rigidity can be exhibited with respect to the bending external force. Further, in this configuration, the inner fitting end of the second pile, the diameter of which is reduced toward the end, is connected to the outer fitting end of the first pile, the diameter of which is increased toward the end. Therefore, when the first pile is inserted into the second pile, the first pile can be easily inserted even if the axes of both piles do not exactly match. As described above, with this configuration, a joint having high bending strength and rigidity can be obtained by a simple connecting operation.

(Structure 2) In the joint structure of a pile according to the present invention, the engaging projection and the engaged projection are respectively connected to the first and second piles. A plurality can be provided at intervals in the circumferential direction. (Operation / Effect) In this configuration, in addition to providing a plurality of engaging protrusions and engaged protrusions in the axial direction of the first pile and the second pile, the present invention is also arranged so as to be dispersed in the circumferential direction of the axial center. Is what you do. With this configuration, it is possible to withstand the bending force acting on the pile from any direction, so that the bending strength and rigidity of the joint portion are improved.

(Structure 3) In the joint structure of a pile according to the present invention, as described in claim 3, the inner wall of the outer fitting end is formed on a tapered surface that increases in diameter toward the distal end, and the inner wall is formed with a tapered surface. The outer wall portion of the fitting end can be formed in a tapered surface whose diameter decreases toward the distal end. (Operation / Effect) With this configuration, when the inner fitting end is inserted into the outer fitting end, both tapered surfaces function as mutual guide surfaces, and the axial center of the first pile and the second pile are This has the effect of automatically matching the axis with the axis. Since the inner fitting end is inserted while sliding on the inner surface of the outer fitting end, the operation of inserting the inner fitting end becomes very easy. Also, in view of the state in which the connection has been completed, the outer peripheral surface of the engaged convex portion provided at the inner fitting end and the inner peripheral surface of the outer fitting end, and the engaging projection provided at the outer fitting end are provided. It is conceivable that the outer peripheral surface of the portion and the outer peripheral surface of the inner fitting end come into contact with each other in a state where a predetermined pressing force is generated by the weight of the second pile or the like. In this case, there is no backlash between the first pile and the second pile, the displacement between the axis of the first pile and the axis of the second pile is effectively prevented, and high bending rigidity is achieved. It is possible to obtain a joint portion having Furthermore, according to this configuration, it is possible to obtain a joint having high bending strength and rigidity for the same reason as described in the operation and effect of Configuration 1 above.

(Structure 4) In the joint structure of a pile according to the present invention, the contact surfaces of the engaging projection and the engaged projection that are in contact with each other are formed by a spiral. The first pile and the second pile can be formed obliquely with respect to the circumferential direction so as to form a portion. (Operation / Effect) With this configuration, for example, by rotating the second stake relative to the first stake, the contact force between the engagement projection and the engaged projection is increased. Of course. There is no play between the engaging projection and the engaged projection. Therefore, in this case,
The bending rigidity of the joint is improved. In addition, according to this configuration, for example, when the second pile is rotated, the engagement projection and the engaged projection always come into contact with each other, so that the second pile is not excessively rotated. That is, it has a stopper function when rotating the second pile, so that the connection work of the piles can be simplified.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

(Outline) The joint structure of a pile according to the present invention is shown in FIG.
As shown in FIG. 2, for example, a first pile 1 buried first in a burial hole and a second pile 2 connected to the first pile 1
And provided between them. Specifically, the first pile 1 is composed of a first pile main body 3 and an outer fitting end 4, and the second pile 2 is
It comprises a second pile main body 5 and an inner fitting end 6. In a normal case, the inner fitting end 6 is inserted into the outer fitting end 4 so that the progress of the work can be easily visually recognized.
The stake 2 is connected. The joint structure of the pile according to the present invention is such that the inner fitting end 6 having the engaged projection 8 formed therein is inserted into the outer fitting end 4 having the engaging projection 7 formed therein. The part 6 is rotated by a predetermined angle around its own axis Z2 to thereby
And the engaged convex portion 8 are engaged with each other, and both are fixed in a state where the inner fitting end portion 6 is prevented from falling out of the outer fitting end portion 4.

(First Pile and Second Pile) The first pile 1 and the second pile 2 have, for example, the appearance shown in FIG. The outer fitting end 4 includes a base end 9 and a distal end 10. The base end portion 9 refers to a portion of the outer fitting end portion 4 on the first pile main body 3 side, and the tip end portion 10 literally refers to a portion near the distal end portion 10 of the first pile 1. The inner wall portion of the outer fitting end portion 4 extending from the distal end portion 10 to the base end portion 9 is formed in a step shape. Here, an example of a four-stage configuration is shown. On each inner wall portion 11 of the step-like portion, an engaging projection 7 projecting in the radial direction of the axis Z1 of the first pile 1 is provided. The engagement projection 7 is a portion that engages with the engagement projection 8 of the second pile 2 as described later. A plurality of the engagement protrusions 7 are provided on the inner wall portion 11 of the specific step portion at intervals in the circumferential direction X thereof. Here, four points are provided along the circumferential direction X. The individual engagement projections 7 are dispersedly arranged in a direction of about 90 degrees about the axis Z1, and the individual engagement projections 7 extend over a range of about 45 degrees. Also, a plurality of engaging projections 7 are provided for the stepped portions arranged in parallel in the direction of the axis Z1. It is assumed that the positional relationship between the respective engaging projections 7 substantially coincides with the direction of the axis Z1 as shown in FIG. In this way, the engagement projections 7 are formed at a total of 16 locations.

The inner fitting end 6 of the second pile 2 also includes a base end 9 and a tip end 10. In the second pile 2, the outer surface of the inner fitting end 6 is formed in a four-step shape. Each outer wall 12
Is provided with an engaged convex portion 8. The engaged projections 8 are dispersed and arranged in a direction of about 90 degrees around the axis Z2 of the second pile 2 as in the case of the first pile 1 and extend over a range of about 45 degrees along the circumferential direction. It has been extended. The engaged convex portions 8 provided on the respective step portions are also substantially aligned in the axis Z2 direction. In this way, the engaged projections 8 are also formed at a total of 16 locations.

As a result of the above configuration, in the outer fitting end portion 4, the closer the engaging convex portion 7 provided on the distal end portion 10 is formed, the more the engaging convex portion provided on the base end portion 9 is located. The diameter is larger than the portion where the portion 7 is formed. On the other hand, in the inner fitting end portion 6, the formation position of the engaged protrusion 8 provided on the side of the distal end portion 10 is larger than the formation position of the engaged protrusion 8 provided on the base end portion 9. Also has a small diameter. In the case of this configuration, the outer fitting end 4 can be regarded as having an opening that is widened toward the distal end 10, and the one inner fitting end 6 can be regarded as having the tapered distal end 10. Since it is possible, the inner fitting end 6 of the second pile 2
Can be easily inserted into the outer fitting end 4 of the first pile 1.

The insertion of the second pile 2 is performed in a state where the arrangement of the engagement projections 7 in the direction of the axis Z1 and the arrangement of the engagement projections 8 in the direction of the axis Z2 are different in the circumferential direction X. Do. Thereby, the second pile 2 can be inserted to a predetermined position with respect to the first pile 1. 2A shows a state before the second pile 2 is inserted into the first pile 1, and FIG. 2B shows a state where the insertion of the second pile 2 is completed. However, the second pile 2 has not been rotated yet. If the axis Z1 of the first pile 1 and the axis Z2 of the second pile 2 do not match, the step of the outer fitting end 4 and the step of the inner fitting end 6 during the insertion of the second pile 2. In some cases, the second pile 2 can be inserted to a predetermined depth by adjusting the position of the axis Z2 of the second pile 2 with respect to the axis Z1 of the first pile 1 as appropriate. it can. When the second pile 2 is inserted to a predetermined depth, the engaging projections 7 and the engaged projections 8 to be engaged with each other are located at different positions in the directions of the axes Z1 and Z2. If the second pile 2 is rotated around the axis Z2 in this state, the engaging projection 7 and the engaged projection 8 are engaged, and the second pile 2 is Can be linked. This state is shown in FIG. In order to reliably perform the rotation operation of the second pile 2, for example, the outer peripheral surface 10 a of the tip 10 of the outer fitting end 4 of the first pile 1 and the second pile main body 5 of the second pile 2 It is preferable to provide alignment marks 13 on the outer peripheral surface 5a near the base end portion 9, respectively. That is, if the second pile 2 is rotated until the alignment marks 13 match, the engaging projection 7 and the engaged projection 8 are securely engaged.

In order to smoothly rotate the second pile 2, for example, as shown in FIGS. 3 (a) and (b), the outer periphery of the second pile main body 5 and the vicinity of the base end 9 are disposed. It is convenient to attach a handle 14 for rotating work. The handle 14 is configured to be detachable. For this purpose, a bolt hole 15 is provided in the outer peripheral portion, and a handle 14 having a male screw portion at an end portion is provided.
May be screwed. FIG. 3A shows a state in which the second pile 2 has been inserted and has not yet been rotated.
(B) rotating the second pile 2 to obtain the alignment mark 1;
3 indicates a state of coincidence.

As shown in FIG. 1 and FIG.
For example, a step-like annular convex portion 16 is formed along the entire periphery of the distal end portion 10 of the external fitting end portion 4 and the distal end portion 10 of the external fitting end portion 4. The annular convex portion 16 of the inner fitting end 6 is provided on the outer peripheral side of the distal end portion 10, and the annular convex portion 16 of the outer fitting end portion 4 is provided on the inner peripheral side of the distal end portion 10. On the other hand, a base groove 17 is formed along the entire circumference of the base end 9 of the inner fitting end 6 and the base end 9 of the outer fitting end 4, as shown in FIG. Both proximal grooves 17 are
It protrudes in the axis Z1, Z2 directions. With this configuration,
When the second pile 2 is inserted into the first pile 1, or when the connection between the second pile 2 and the first pile 1 is completed, FIG.
As shown in (1), the annular projection 16 and the base groove 17 are coaxially engaged. In particular, the annular convex portion 16 and the base end groove portion 17 come into contact with each other in the radial direction Y of the shaft centers Z1 and Z2. In other words, according to the present configuration, when a bending force is applied to the joint, or when an excessive compressive or tensile force is applied along the axial direction, the distal end portion 10 and the proximal end portion 9 are separated from each other. To prevent For example, when a bending force is applied to the joint, the outer fitting end 4 and the inner fitting end 6 are deformed as shown in FIG. 4 and the degree of engagement between the engaging projection 7 and the engaged projection 8 is reduced. Therefore, there is a risk that the second pile 2 may fall out. Further, even if the second pile 2 can be prevented from coming off, the outer fitting end 4 or the inner fitting end 6 may be deformed, and in this case, the strength of the joint portion is reduced. However, if the annular convex portion 16 and the base groove portion 17 are provided as in this configuration, the distal end portion 1 when a bending force is applied to the joint portion is provided.
The displacement between 0 and the base end 9 can be suppressed. In particular, the tip 1 of the inner fitting end 6 and the outer fitting end 4, which tend to be thinner.
The cross-sectional shape of 0 is maintained in a circular cross-section, so that a joint portion having high proof stress can be obtained.

When the second pile 2 is rotated around the axis Z2 by a predetermined angle as in the present invention, the engaging projection 7 and the engaged projection 8 are connected so that the rotation operation can be performed. As a result, there is a case where play is present in the connection part in a state where the connection of the piles is completed. When such play is present, the rigidity of the connecting portion is reduced. In order to prevent this, in the joint structure of the pile according to the present invention, as shown in FIG.
The contact surface 18 between the and the engaged convex portion 8 is formed obliquely with respect to the circumferential direction X of the axis cores Z1 and Z2 so as to form a part of a spiral. In the case of FIG. 5, the individual engaging projections 7 or
Opposite slopes are provided on the upper and lower surfaces of each of the engaged projections 8.
With this configuration, when the second pile 2 is rotated, the engagement protrusion 7
The contact force between the engaging convex portion 8 and the engaged convex portion 8 can be increased, and there is no play between the engaging convex portion 7 and the engaged convex portion 8, and a strong joint portion can be obtained. In this case, the second
A stopper function when rotating the pile 2 is generated, and the second pile 2
Is not rotated too much, and the connection work of the piles can be simplified.

(Others) The first pile main body 3 and the second pile main body 3
The pile main body 5 can be usually formed of a steel pipe such as a rolled steel pipe or a cast pipe because of its high strength and excellent workability. However, it is not limited to this.
It may be a concrete pile. In the case of a concrete pile, the outer fitting end 4 or the inner fitting end 6 formed in advance is used by being embedded in the end of the pile.

(Effect) As described above, in the joint structure of the pile according to the present invention, the plurality of engaging projections 7 and the engaged projections 8 along the axes Z1 and Z2 are engaged. Therefore, a high-strength joint portion that effectively opposes bending force and the like can be obtained. In addition, the connection work can be performed without using a special lifting machine, and the connection operation of the piles is very simple because it is sufficient to rotate only a predetermined angle around the axis Z2. Further, the end of the connection work can be determined based on the rotation angle of the pile, so that the quality control of the joint portion becomes easy. In addition, with the pile joint structure of the present invention, since the progress of the work is not hindered by the weather, advantages such as shortening of the construction period and cost reduction are obtained.

[Other Embodiments] <1> In the above embodiment, the inner wall 11 of the outer fitting end 4 and the outer wall 12 of the inner fitting end 6 are formed in a stepped manner. However, as shown in FIGS. 6A and 6B, the inner wall 11 of the outer fitting end 4 and the outer wall 12 of the inner fitting end 6 can be formed into a substantially conical tapered surface. FIG. 6 (a) shows the second pile 2
6 has not been rotated yet after the
(B) shows a state in which the connection of the second pile 2 has been completed by rotating the second pile 2. With this configuration, the inner fitting end 6
When the tape is inserted into the outer fitting end 4, the two tapered surfaces function as mutual guide surfaces, and the axis Z1 of the first pile 1 and the axis Z2 of the second pile 2 are automatically matched. To play. Then, since the inner fitting end 6 is inserted while sliding on the inner wall portion 11 of the outer fitting end 4, the work of inserting the inner fitting end 6 becomes very easy. When the connection is completed, the outer peripheral surface 8a of the engaged projection 8 provided on the inner fitting end 6 and the inner wall 11 of the outer fitting end 4 are connected.
The outer peripheral surface 7a of the engaging projection 7 provided on the outer fitting end 4 and the outer wall 12 of the inner fitting end 6 generate a predetermined pressing force due to the weight of the second pile 2 or the like. It is conceivable that they come into contact with each other. In this case, there is no play between the first pile 1 and the second pile 2, and the displacement between the axis Z1 of the first pile 1 and the axis Z2 of the second pile 2 is effectively prevented. Therefore, a joint having high bending rigidity can be obtained. In FIG. 6, when the cross section of the contact portion between the engaging projection 7 and the engaged projection 8 is viewed, the contact surface 18 is formed perpendicular to the axis Z1, Z2. In this case, no component force is generated at the contact portion regardless of whether a compressive force or a tensile force acts between the first pile 1 and the second pile 2. Therefore, deformation of the cross-sectional shape of the outer fitting end 4 and the inner fitting end 6 can be prevented, and the second pile 2
Escape can be effectively prevented. However, the inclination of the contact surface 18 can be arbitrarily configured depending on the convenience of processing.

<2> In the above embodiment, the first pile main body 3
The outer fitting end 4 is formed integrally with the second pile main body 5 and the inner fitting end 6
Is shown as an example. However, it is not limited to this embodiment. That is, although not shown, only the outer fitting end 4 and only the inner fitting end 6 are formed independently, and these outer fitting end 4 or inner fitting end 6 are attached to the end of the pile main body. The connection may be made by welding or the like. As in the other embodiment, if only the outer fitting end 4 and the inner fitting end 6 are manufactured, various manufacturing methods such as forging and cutting can be easily applied at the time of manufacturing. Handling is also easy. As a result, processing accuracy is improved, and manufacturing efficiency is improved. In addition, these external fitting end portions 4
Alternatively, since the inner fitting end 6 can be attached to a member other than the pile, it is also possible to configure a joint structure relating to various members.

In the description of the appended claims, reference is made to the drawings, and in order to facilitate comparison with the drawings, reference numerals are used. However, the present invention is not limited to the configuration shown in the accompanying drawings. Absent.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a joint structure of a pile according to the present invention.

FIG. 2 is a longitudinal sectional view showing a connecting process of piles.

FIG. 3 is a cross-sectional view showing a connecting process of the piles.

FIG. 4 is an explanatory view showing a joint structure of a pile when a bending force is applied.

FIG. 5 is an explanatory view showing an engagement mode between an engaging projection and an engaged projection.

FIG. 6 is a longitudinal sectional view showing a connecting process of a pile according to another embodiment.

FIG. 7 is a longitudinal sectional view showing a joint structure of a pile according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st pile 2 2nd pile 4 Outer fitting end part 6 Inner fitting end part 7 Engagement convex part 8 Engagement convex part 9 Base end part 10 Tip part 11 Inner wall part of outer fitting end part 12 Inner fitting end part Outer wall 18 Contact surface X Peripheral direction of pile

Claims (4)

[Claims] A pair of outer fitting ends (4) that can be fitted to each other.
And an inner fitting end (6) are formed separately on a first pile (1) and a second pile (2) adjacent in the axial direction, and the outer fitting end (4) and the inner fitting end are formed. With the part (6) fitted, the engaging convex part (7) and the engaged convex part (8) that engage with each other so as to prevent them from being detached from each other by a relative rotation operation about the axis are formed. An inner wall portion (11) of the outer fitting end (4) and the inner fitting end (6);
A joint portion structure of a pile separately provided on an outer wall portion (12) of the first pile (7) and the engaged convex portion (8), respectively. 1) A plurality of the second piles (2) are arranged side by side in the axial direction, and in the outer fitting end portion (4), as the engagement protrusion (7) provided on the tip (10) side, The engagement protrusion (7) provided on the base end (9) side is formed to have a diameter larger than that of the formation part, and the inner fitting end (6) is provided on the tip end (10) side. The closer the engagement convex portion (8) is formed, the more the base end portion (9)
The joint structure of a pile formed smaller in diameter than the formation location of the engaged protrusion (8) provided on the side. 2. The engaging projection (7) and the engaged projection (8) are spaced from each other in the circumferential direction (X) of the first pile (1) and the second pile (2). The joint structure for a pile according to claim 1, wherein a plurality of the joints are provided. 3. The inner wall (11) of the outer fitting end (4).
Is formed on a tapered surface that increases in diameter toward the tip end,
The joint structure of a pile according to claim 1 or 2, wherein the outer wall (12) of the inner fitting end (6) is formed in a tapered surface whose diameter decreases toward the distal end. 4. The first pile (1) such that a contact surface (18) where the engaging projection (7) and the engaged projection (8) contact each other forms a part of a spiral. 1) The joint structure for a pile according to any one of claims 1 to 3, wherein the joint is formed obliquely with respect to a circumferential direction (X) of the second pile (2).