JP2009024436A - Mechanical joint of steel pipe pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mechanical joint of a steel pipe pile manufacturable at low cost and having high reliability. <P>SOLUTION: This joint comprises an outer joint member 3 and an inner joint member 4. In the inner joint member 4, a thick-wall ring-shaped flange part 13 is formed integrally with the end edge of a thick-wall tubular base 8. The outer diameter of the flange part is generally equal to the outer diameter of a steel pipe pile to be joined thereto. The outer diameter of the base 8 is slightly smaller than the inner diameter of the outer joint member 3. The end surface of one steel pipe pile is aligned with each other and welded to the end surface of the flange part 13. A plurality of pin insertion holes 10 are circumferentially formed in the peripheral wall 16 of the base 8. The outer joint member 3 has an outer diameter generally equal to the outer diameter of the steel pipe pile and an inner diameter slightly larger than the outer diameter of the base 8, and axially aligned with the end surface of the other steel pipe pile and welded thereto. Pin insertion holes 12 of the same diameter are so formed as to correspond to the pin insertion holes 10 drilled in the base 8, and pins 18 are inserted into and connected to the pin insertion holes 10, 12. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a mechanical joint for steel pipe piles, and more particularly to a mechanical joint for steel pipe piles which is easy to manufacture and can be provided at a low cost and has a sufficient strength for practical use.

  There are steel pipe piles and concrete piles as ready-made piles used in various civil engineering works, both of which may be joined as necessary. Generally, welding is often used for joining piles in the field, but it is difficult to ensure the welding quality, the work is subject to the weather, and the welding work takes a long time. In concrete piles, joints using mechanical joints that do not require on-site welding have recently been implemented frequently.

  Also, in the field of concrete piles, the background of the spread of mechanical joints is that steel materials that are several times stronger than concrete can be used as joint materials, and generally there are steel end plates at both ends of concrete piles. Since this can be used as a part of the joint material, there are reasons that the overall cost can be kept low.

On the other hand, in the case of steel pipe piles, steel is used as a joint material, as is the case with steel pipe piles, but in order to make the joint part strength equal to or higher than that of the steel pipe pile body, the use of high-quality, high-strength steel materials and complex structures are adopted. As a result, it is inevitable that the manufacturing cost of the joint will increase with this, and the spread is hindered.
JP 2006-28913 A JP 2001-11850 A JP 2006-207117 A None

  Patent Documents 1 to 3 all relate to mechanical joints for steel pipe piles. In Patent Document 1, circular protrusions are alternately provided in the circumferential direction on the outer surface of the male cylinder and the inner surface of the female cylinder, respectively. A joint is disclosed in which a cylinder is inserted into a female cylinder and then rotated and joined. In this joint, the tensile force is transmitted by contact between the arc-shaped protrusions (gears), and the transmission capability of the tensile force is large and the bending moment is also strong. However, it is unrealistic to fix the arc-shaped projections to the joint body by welding. Normally, a thick cylindrical body is cut with a lathe to form arc-shaped projections. It is clear that the cutting of the cylindrical body in the axial direction is extremely inefficient and is the biggest factor of the high cost.

  In this joint, the rotational torque is transmitted by a key provided between the male and female cylinders. However, since the key in this case is not a simple cylindrical pin, the manufacturing cost of the key and its insertion hole is high. Inevitably, this also increases the overall cost. Taking these points into consideration, the mechanical joint disclosed in Patent Document 1 is difficult in cost.

  On the other hand, in Patent Document 2, an inner joint pipe having a pin insertion hole or a plurality of strip-shaped flat plates are inserted into an outer joint pipe having the same pin insertion hole, and then a pin is inserted into both pin insertion holes to be coupled. A mechanical joint of structure is disclosed. In this joint, the axial force (tensile force and compressive force) of the steel pipe pile is transmitted through the shearing force of the pin member, but a large compressive force or tensile force can be generated only by the pin member. It was impossible in terms of strength to be transmitted as will be described later.

  In this joint, the inner joint pipe is structured to be fixed to the inner surface of the steel pipe end, and in the drawing, both ends are fillet welded, and a notch is provided at the lower part of the inner joint pipe to weld. An example of increasing the length of the part is shown, but in the former case, the welding work inside the steel pipe is difficult unless the pipe diameter is sufficiently large, and because the fillet weld is used, the welding strength is There is a problem that it is difficult to secure, but the latter is shown as a supplement to this, but as the weld length becomes longer, it is natural that workability deteriorates, and as a result, there is a disadvantage that costs increase. It was.

  On the other hand, when a strip-shaped flat plate is used as an alternative to the inner joint pipe, the same problem as in the case of the welding of the notch described above occurs, and the torsional strength and rigidity of the strip-shaped section are significantly higher than those of the annular section. Inferiority, there was a drawback that the steel pipe body could not have the same strength unless the thickness was made very large. Furthermore, in order to remedy this drawback, a technique for joining an inner joint pipe and a steel pipe via a thick short pipe is also disclosed, but the procurement cost and welding cost of the thick short pipe are excessive. As a result, there is a drawback that the joint becomes expensive. From these points, the joint disclosed in Patent Document 2 cannot be said to have sufficient practicality.

  Furthermore, Patent Document 3 discloses a hole provided at the boundary of the concavo-convex part after fitting the concavo-convex part of the first joint (upper joint) and the second joint (lower joint) provided with concavo-convex at the end part. A mechanical joint having a structure in which a pin is inserted is disclosed, and although it differs greatly in form from the mechanical joint disclosed in Patent Document 2, not only the axial direction but also the bending moment depends on the pin. The point of trying to transmit is uniform, and in that sense, it has the same problems as the mechanical joint disclosed in Patent Document 2 described above.

  In addition, in this joint, the pin facing the shear direction cannot exhibit shear resistance, and the cross-sectional area of the concavo-convex portion is only half that of the upper and lower portions, so that sufficient shear strength cannot be ensured. There was a problem. Therefore, the joint disclosed in Patent Document 3 is not sufficient in strength, and must be said to have a practical problem.

  By the way, the force acting on the foundation pile is usually compressive force, tensile force, bending moment, shearing force, rotational torque (torsional shearing force). Except for special cases, it is the compressive force in the direction of the pile axis, and large pulling force, bending moment, and shearing force are applied to the foundation pile only for a short period of time such as an earthquake or strong wind. Further, the pulling force is usually as small as a fraction of the compression force, and the frequency of occurrence is low. Furthermore, even when a bending moment is applied, it is normal that the bending moment does not act on the pile alone but acts simultaneously with the compressive force. In other words, when the foundation pile is viewed as an annular cross section, the portion where the tensile stress is generated is only a small portion of the circumference, and the value is small, and the compressive stress is generated mostly. It will be.

  On the other hand, when a rotary penetrating pile is constructed, a rotational torque of the same magnitude as the torsional strength of steel pipe piles is frequently generated, so when using a joint for this rotary penetrating pile, it is necessary to withstand this torque. When trying to counter this rotational torque with only the horizontal shear resistance of the pin, the shearing force of the pin against the rotational torque equivalent to the torsional strength of the steel pipe resists the tensile force equivalent to the tensile strength of the steel pipe. It has hitherto been known that it is theoretically only 1/3 compared to the shearing force of the pin.

  From the consideration of the general acting force of the foundation pile described above, the present inventor is more rational that the compressive force is transmitted by contacting the member directly rather than via a pin, as will be described later. It has been found that a pulling force with a low occurrence frequency and a small force is rational in terms of mechanism when transmitted through a pin. Based on the above findings, the present inventor has conducted research to solve the problems inherent in mechanical joints used for joining steel pipe piles. In addition, the present inventors have succeeded in developing a mechanical joint with high practical value that can be manufactured at low cost, and propose it as the present invention.

  Thick-cylindrical cylindrical portion with a thick annular ring (13) integrally extending perpendicularly outward from one end of the thick cylindrical base (8) The outer diameter of the collar portion (13) is substantially the same as the outer diameter of the pair of steel pipe piles to be joined, and the outer diameter of the base portion (8) is slightly smaller than the inner diameter of the outer joint material (3). And the end face of one of the steel pipe piles is welded and fixed to the end face of the collar part (13) in a state in which its axis is aligned, and the shaft (1) is attached to the peripheral wall (16) of the base part (8). An inner joint material (4) in which a plurality of pin insertion holes (10) are drilled at intervals from each other in a direction perpendicular to the center; an outer diameter substantially the same as the outer diameter of the steel pipe pile to be joined; Each has an inner diameter slightly larger than the outer diameter of the base (8) of the inner joint material (4), and the end face of the other steel pipe pile is Of the inner diameter of the inner joint material (4) and the pin insertion hole (10) having the same diameter at a position corresponding to the pin insertion hole (10) formed in the base (8). 12) A steel-walled cylindrical outer joint material (3) having a perforation formed therein. The base (8) of the inner joint material (4) is inserted into the inner diameter side of the outer joint material (3). When the pin (18) is inserted into each of the pin insertion holes (10) and (12) and a compressive force is applied to the pair of steel pipe piles, the end face of the flange portion (13) of the inner joint material (4) and the outer joint The inner joint material (4) and the outer joint material (3) were combined so that the end surface of the material (3) was in contact with each other, thereby solving the above problem.

  The upper surface of the flange portion 13 of the inner joint material 4 is welded to the lower end of the upper steel pipe pile 1 in a state where the axis is aligned, and the lower end surface of the outer joint material 3 is aligned with the upper surface of the lower steel pipe pile 2 The base 8 of the inner joint material 4 is inserted into the inner diameter side of the outer joint material 3 fixed to the upper surface of the lower steel pipe pile 2 and the positions of the respective pin insertion holes 10 and 12 are aligned. The pin 18 is inserted into the lower steel pipe pile 2 and the upper steel pipe pile 1 is connected. In this state, when a compressive force is applied downward from the upper steel pipe pile 1, the compressive force is transmitted straight to the outer joint material 3 via the collar portion 13. That is, the compressive force is directly transmitted from the flange portion 13 of the inner joint material 4 to the end face of the outer joint material 3, and basically no force is transmitted to the pin 18, and a very simple force transmission path is obtained. Therefore, bearing stress is generated in the abutting portions, but the distribution is uniform in the thickness direction, and the abutting area is equal to the cross-sectional area of the outer joint material 3 and is sufficiently wide, so that a large bearing stress difference occurs. No compression occurs, and the compressive force is transmitted to the lower steel pipe pile 2 without difficulty.

  On the other hand, when a tensile force is applied from the upper steel pipe pile 1, the tensile force is transmitted from the collar portion 13 of the inner joint material 4 to the base portion 8, and then is transmitted to the pin 18 as a vertical shear force, and further to the outer joint material 3. It will be transmitted as a pulling force. In this case, the degree of bearing stress generated in each contact portion is much larger than the above-described compressive force when compared per unit area. 12 shows the deformation state of each member when a tensile force is transmitted from the base 8 of the inner joint material 4 to the outer joint material 3 via the pin 18, and FIG. 13 shows the pins of the outer joint material 3 and the inner joint material 4. 18 schematically shows the distribution state of the bearing stress generated in the 18 contact portions, and the area (contact area) that receives the bearing pressure of the base 8 of the inner joint material 4 and the outer joint material 3 is the above-described compression. Since it is much smaller than the case, the average value of the bearing stress generated in the contact portion is considerably large. However, the tensile force acts on the foundation pile only for a short time in the event of an abnormality such as an earthquake or strong wind, and the tensile force is usually less than a fraction of the compressive force, and its frequency of occurrence is low. The pin 18 and its contact portion can sufficiently withstand this bearing stress and reliably transmit the tensile force.

  Further, when a bending moment is applied, a compression force is applied to approximately half of the joint and a tensile force is generated to approximately the other half when viewed from the annular cross section. The transmission of these forces is the same transmission mechanism as that when the aforementioned compressive force is applied and when the tensile force is applied. However, the bending moment does not act on the pile alone, and usually acts simultaneously with the compressive force as described above. For this reason, when viewed as a cylindrical thick section, compressive stress is generated mostly, and the region where the tensile force is generated is extremely limited. As a result, the bearing stress around the pin is small and can be designed without difficulty even when a bending moment is applied. On the other hand, when a shearing force acts, the shearing force from the upper steel pipe pile 1 is transmitted to the base 8 of the inner joint material 4 via the collar portion 13 of the inner joint material 4, and this base 8 presses the outer joint material 3. Is transmitted to this. Further, when rotational torque (torsional shearing force) acts, it is transmitted as a torsional shearing force from the collar portion 13 of the inner joint material 4 to the base portion 8, and then as a horizontal shearing force to the pin 18, from which the outer jointing material 3 It is transmitted as torsional shear force. In addition, during the construction of the rotational penetration pile, a rotational torque with a value similar to the torsional strength of the steel pipe pile is frequently generated, but the shearing force of the pin 18 against the rotational torque equivalent to the torsional strength of the steel pipe is Compared to the shearing force of the pin 18 that opposes the tensile force equivalent to the tensile strength, the theoretical value is only about 1/3, so that the pin 18 can sufficiently resist this rotational torque.

  As described above, the mechanical joint for joining steel pipe piles according to the present invention skillfully utilizes the contact characteristics between a pair of joints and the transmission characteristics when using a pin, respectively, and compressive force (compressive force due to bending moment). If a tensile force (including a tensile force due to a bending moment) is applied due to contact between the flange of the inner joint material and the upper end surface of the outer joint material, the force is transmitted by the pin. It has a simple structure with no waste considering the load conditions of the actual foundation pile, can be manufactured at low cost while having sufficient reliability, and installation and connection work on site can be performed very easily. It has an effect and has high practicality.

  The greatest feature lies in that the form of the pair of joint members is devised so that the compressive force is transmitted directly and the tensile force is transmitted via the pins.

  1 is a perspective view of Embodiment 1 of a mechanical joint for joining steel pipe piles according to the present invention, FIG. 2 is a perspective view in a state of being fixed to the steel pipe pile, and FIG. 3 is a perspective view of a state in which the steel pipe piles are similarly joined. 4 is a sectional view taken along line AA in FIG. 3, FIG. 5 is a sectional view taken along line BB in FIG. 4, and FIG. 6 is a sectional view taken along line CC in FIG.

  In the figure, 1 is an upper steel pipe pile to be joined, and 2 is a lower steel pipe pile. The mechanical joint for joining steel pipe piles according to the present invention is used to join the lower end of the upper steel pipe pile 1 and the upper end of the lower steel pipe pile 2 in series, and is made of a steel inner joint material 4, The outer joint material 3 and the plurality of pins 18 are configured.

  The inner joint member 4 is a cylindrical member with a flange made of steel, in which a thick annular collar 13 is integrally extended perpendicularly from the upper edge of the base 8 having a thick cylindrical shape toward the outside. The outer diameter of the collar portion 13 is substantially the same as the outer diameter of the upper steel pipe pile 1, and the outer diameter of the base portion 8 is formed to be slightly smaller than the inner diameter of the lower steel pipe pile 2, respectively. The lower end surface of the upper steel pipe pile 1 is fixed to the upper surface 5 of 13 by welding in a state where the axes are aligned. Further, a plurality of pin insertion holes 10 are formed in the peripheral wall 16 of the base portion 8 at intervals from each other in a direction perpendicular to the axis.

  On the other hand, the outer joint material 3 is a steel thick cylindrical member having an outer diameter substantially the same as the outer diameter of the lower steel pipe pile 2 and an inner diameter slightly larger than the outer diameter of the base 8 of the inner joint material 4. When the base portion 8 of the inner joint material 4 is inserted into the inner diameter side of the outer joint material 3, a pin having the same diameter is provided at a position corresponding to the pin insertion hole 10 formed in the base portion 8 of the inner joint material 4. Insertion holes 12 are formed, and the outer joint material 3 and the inner joint material 4 are connected by inserting pins 18 into the pin insertion holes 10 and 12. And the lower end of this outer joint material 3 is fixed to the upper end surface 6 of the lower steel pipe pile 2 by welding in a state in which its axial center coincides. In this embodiment, the inner joint material 4 is welded and fixed to the upper steel pipe pile 1 and the outer joint material 3 is welded and fixed to the lower steel pipe pile 2. The joint material 3 may be fixed to the lower steel pipe pile 2 by welding.

  The outer joint material 3 may be a short cut of a suitable ready-made steel pipe, or may be manufactured by forging or cast steel. If the roundness and dimensions on the inner diameter side are inappropriate, the inner diameter side is cut with a lathe. You may do it. On the other hand, the inner joint material 4 is obtained by cutting a thin steel pipe such as a seamless steel pipe or a centrifugal cast steel pipe into a short length or by cutting the lower part of the outer peripheral surface of a cylindrical body manufactured by forging with a numerically controlled lathe. You may use what gave the shape process.

  These cutting processes are different from the case where gears are formed in the tube axis direction, etc., and since they have a constant shape in the circumferential direction, if the blade of the numerically controlled lathe is applied while the material is rotated, it is easy in a short time. Can be implemented. Further, since the pin insertion holes 10 and 12 have a circular cross section, they can be accurately formed in a short time by using a horizontal drilling machine capable of numerical control operation. Further, the pin 18 may be manufactured by cutting a high-strength steel bar such as a PC steel bar into a short length or by die forging.

  Further, as described above, the inner joint material 4 is fixed to the lower end of the upper steel pipe pile 1 and the outer joint material 3 is fixed to the upper end of the lower steel pipe pile 2 by welding, but as shown in FIG. By chamfering the outer edge upper portion of the flange portion 13 of the joint material 4 and the outer edge lower portion of the outer joint material 3 to form the slopes 19 and 20 for groove welding, the welding operation can be performed more easily, reliably and firmly. More convenient. The slopes 19 and 20 for groove welding can be easily formed by a lathe.

  In addition, it is necessary that the pin 18 does not fall off or move from the pin insertion holes 10 and 12 during the construction. For this purpose, a backing metal strip is placed on the inner diameter side of the base 8 of the inner joint material 4. It is sufficient if it is attached in advance. However, as shown in FIG. 8, the pin insertion hole 10 is not completely penetrated to the inner diameter side, but is stopped halfway to form a non-penetrating portion 21, or as shown in FIG. If a retaining means is provided, for example, by forming the penetrating portion 22, it is possible to prevent the pins 18 from moving off at a much lower cost than attaching a backing metal strip. Normally, the cutting edge of the drill blade has a conical shape, so the formation of the incomplete penetrating portion 22 shown in FIG. 9 is extremely easy.

  On the other hand, in order to prevent the pin 18 from moving and falling off, a gum tape or the like is wound around the outer joint material 3, or a steel outer band 23 is wound as shown in FIG. Fix it. Also, depending on the construction method and ground conditions, an unexpected force may be applied from the earth and sand around the steel pipe pile, and the outer band 23 for preventing the pin 18 from moving off may be displaced or fall off. In this case, as shown in FIG. 11, the formation surface of the pin insertion hole 12 is slightly dented from the outer periphery of the outer joint material 3, and the length of the pin 18 is shortened by the amount of depression, and the outer band 23 Is wound around the outer periphery of the outer joint material 3 in advance, and when the outer joint material 3 and the inner joint material 4 are joined, the outer band 23 is shifted, and after inserting the pin 18, the outer band 23 is covered with the end face of the pin 18, and the outer The outer periphery of the band 23 and the outer periphery of the lower steel pipe pile 2 may be flush with each other.

  In this way, the steel pipe pile joint-like mechanical joint according to the present invention skillfully utilizes the contact characteristics between a pair of joints and the transmission characteristics when the pins are interposed, and includes a compressive force (including a compressive force due to a bending moment). ) Acts, the pulling force (including the pulling force due to the bending moment) is transmitted by the pin due to the contact between the flange of the inner joint material and the upper end surface of the outer joint material. It has a simple structure with no waste in consideration of the load conditions, and can be manufactured at low cost while having sufficient reliability. It has practicality.

  It can be used in various civil engineering works using foundation piles.

The perspective view of Example 1 of the mechanical coupling for joining of the steel pipe pile which concerns on this invention. Similarly, the perspective view of the state which adhered to the steel pipe pile, respectively. Similarly, the perspective view of the state which joined the steel pipe pile. FIG. 4 is a cross-sectional view taken along line AA in FIG. 3. FIG. 5 is a sectional view taken along line BB in FIG. 4. CC sectional view taken on the line CC in FIG. The fragmentary sectional view of the Example which provided the slope for groove welding. The fragmentary sectional view of the Example which provided the movement drop-off prevention means of the pin 18. FIG. The fragmentary sectional view of another Example which provided the movement drop-off prevention means of the pin 18. FIG. Similarly, the fragmentary sectional view of the Example which provided the means which prevents the movement drop-out of the pin 18 outside. Similarly, the fragmentary sectional view of another Example which provided the means which prevents the movement loss of the pin 18 to the outer side. Explanatory drawing which drew typically the deformation | transformation state of the pin 18 periphery at the time of tensile force being added. Similarly, an explanatory view schematically showing the distribution of the bearing stress generated in the contact portion of the pin 18.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper steel pipe pile 2 Lower steel pipe pile 3 Outer joint material 4 Inner joint material 5 Upper surface 6 Upper end surface 8 Base part 10 Pin insertion hole 12 Pin insertion hole 13 Collar part 16 Perimeter wall 18 Pin 19 Slope 20 for groove welding For groove welding Slope 21 non-penetrating part 22 imperfect penetrating part 23 outer band

Claims (4)

Thick-cylindrical cylindrical portion with a thick annular ring (13) integrally extending perpendicularly outward from one end of the thick cylindrical base (8) The outer diameter of the collar portion (13) is substantially the same as the outer diameter of the pair of steel pipe piles to be joined, and the outer diameter of the base portion (8) is slightly smaller than the inner diameter of the outer joint material (3). And the end face of one of the steel pipe piles is welded and fixed to the end face of the collar part (13) in a state in which its axis is aligned, and the shaft (1) is attached to the peripheral wall (16) of the base part (8). An inner joint material (4) in which a plurality of pin insertion holes (10) are drilled at intervals from each other in a direction perpendicular to the center; an outer diameter substantially the same as the outer diameter of the steel pipe pile to be joined; Each has an inner diameter slightly larger than the outer diameter of the base (8) of the inner joint material (4), and the end face of the other steel pipe pile is Of the inner diameter of the inner joint material (4) and the pin insertion hole (10) having the same diameter at a position corresponding to the pin insertion hole (10) formed in the base (8). 12) A steel-walled cylindrical outer joint material (3) having a perforation formed therein. The base (8) of the inner joint material (4) is inserted into the inner diameter side of the outer joint material (3). When the pin (18) is inserted into each of the pin insertion holes (10) and (12) and a compressive force is applied to the pair of steel pipe piles, the end face of the flange portion (13) of the inner joint material (4) and the outer joint A mechanical joint for steel pipe piles, wherein the inner joint material (4) and the outer joint material (3) are combined so that the end face of the material (3) contacts. The upper edge upper part of the flange part (13) of the inner joint material (4) and the outer edge lower part of the outer joint material (3) are chamfered to form slopes (19) and (20) for groove welding, respectively. A mechanical joint for steel pipe piles according to claim 1. 2. A mechanical joint for steel pipe piles according to claim 1, wherein means for preventing the pin (18) from coming off is provided at the inner end of the pin insertion hole (10). The portion of the outer peripheral wall surface of the outer joint material (3) where the pin insertion hole (12) is formed is recessed from its periphery, and a steel outer band (23) is turned around the outer peripheral wall of the outer joint material (3). The mechanical joint for a steel pipe pile according to claim 1, wherein when wound, the outer periphery of the outer band (23) and the outer periphery of the steel pipe pile are flush with each other.

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