JP6465395B2 - Steel pipe joint structure and steel pipe pile embedding method using the same - Google Patents

Description

  The present invention relates to a steel pipe joint structure mainly applied when embedding a steel pipe pile having a small pile diameter in the ground, and a steel pipe pile embedding method using the same.

  From the standpoint of the support mechanism, the pile foundation for supporting the structure consists of a support pile that secures the support force by penetrating the lower end into a good quality support layer, and the surrounding ground when there is no good quality support layer. Friction piles that secure supporting force by friction are broadly classified, but from the viewpoint of construction method, they are classified as driven piles, embedded piles, cast-in-place piles, etc., and from the viewpoint of pile diameter, φ300 mm or less A pile method called a micropile method using embedded piles or driven piles is known.

  Since the micropile method can be implemented with relatively small construction machines, it has proven itself as an effective method when it is not possible to secure sufficient construction space in confined areas, places with limited heads, mountains, slopes, etc. is there.

  In the case of using a steel pipe pile as an embedded pile in the micropile construction method, first, a drilling hole is first formed in the ground, and then a steel pipe pile is built in the drilling hole, and a grout material is provided below and around the steel pipe pile. Fill.

  In this case, the filled grout material is solidified around the steel pipe pile and transmits a horizontal force and a frictional force along the peripheral surface of the steel pipe pile between the steel pipe pile and the surrounding ground. It solidifies below, transmits the axial force of the steel pipe pile to the ground in a dispersed state, and plays a role of increasing the tip support force of the steel pipe pile.

JP-A-10-252060 Japanese Patent No. 3747594

  Here, when the excavation hole is formed, cutting scraps may remain near the bottom surface. However, if the grout material solidifies in a state where the cutting scraps are unevenly distributed, the strength of the solidified body becomes insufficient, and the lower end of the steel pipe pile Therefore, it is difficult to expect a sufficiently large tip support force.

  After forming the excavation hole, the present applicant disturbs the bottom of the excavation hole at the lower end of the steel pipe pile by pushing down and rotating the steel pipe pile built in the excavation hole and Then, the ground improvement region is formed below the bottom by stirring and mixing together with the cutting waste and grout material remaining on the bottom surface of the excavation hole, and then the lower end of the steel pipe pile becomes the height near the top of the ground improvement region. Thus, a new method for retreating the steel pipe pile was developed.

  In this way, in the ground improvement region, the cutting waste generated at the time of forming the excavation hole is in a state of being agitated and mixed together with the disturbing soil and the grout material, so that the ground improvement region has a good quality with excellent strength. It will be consolidated as a ground improvement body, thus greatly improving the tip bearing capacity of the steel pipe pile.

  However, since the micropile construction method is premised on construction in a narrow space or where there is a space limitation, steel pipe piles are joined by screw joints instead of welding. When the plate is moved up and down or rotated in both directions, there has been a problem that the joint portion is loosened and the compressive strength, tensile strength or bending strength at the joint portion may be impaired.

  By the way, one side of the two piles to be joined is provided with a male thread part and the other with a female thread part, and they are screwed together, and a reverse rotation prevention pin is screwed into the screw hole of the female thread part. Patent Documents 1 and 2 disclose a configuration in which the tip is fitted into a locking hole or a locking groove provided on the peripheral surface of the male screw portion to prevent loosening at the joint location. At the time, due to variations in the tightening force at the site, the relative rotational positions of the two piles in the tightening completed state also vary, so the screw hole of the female screw portion and the locking hole or locking of the male screw portion Although it is necessary to provide play between the groove, in that case, there is a possibility that the two pieces of the pile piles are not sufficiently prevented from loosening as a result of reverse rotation by the amount of play.

  The present invention has been made in consideration of the above-described circumstances. When two pile bodies are joined in place by screw joints, even if the tightening force varies, the two pile bodies can be reliably rotated in reverse. It is an object of the present invention to provide a steel pipe joint structure that can be prevented and a method for embedding a steel pipe pile using the same.

In order to achieve the above object, a steel pipe joint structure according to the present invention is provided in one of the two pile bodies joined together along the material axis direction as described in claim 1. The male screw portion is screwed into the female screw portion provided on the other pile body, and the locking pin is inserted into the screw hole formed through the female screw portion along the thickness direction of the female screw portion. Then, the tip of the locking pin is inserted into a circular groove formed in an annular shape or a spiral shape on the peripheral surface of the male screw portion, whereby the locking pin engages with the circular groove by the locking action of the locking pin. In the steel pipe joint structure in which relative rotation of the pile body is prevented ,
Of the opposing groove wall surfaces of the circumferential groove, the groove wall surface located on the front end side of the male screw portion is inclined so that the top surface of the wall surface is retracted toward the front end side of the male screw portion from the bottom surface of the wall surface, and the wall surface of the groove And the tip of the locking pin is brought into contact.

  In the steel pipe joint structure according to the present invention, the locking pin includes a shaft portion screwed into the screw hole and a truncated cone portion provided at a tip of the shaft portion. The peripheral surface of the portion is configured to contact the groove wall surface along the generatrix.

  In the steel pipe joint structure according to the present invention, the thread groove of the male thread portion is the circumferential groove.

  Moreover, the joint structure of the steel pipe which concerns on this invention makes the outer diameter of the said pile body 300 mm or less.

Further, according to the method for embedding a steel pipe pile according to the present invention, as described in claim 5, the grout material is put into the excavation hole at the same time as or after the steel pipe pile is built in the excavation hole formed in the ground. Throw in,
The steel pipe pile is rotated while being pushed down to disturb the bottom bottom of the excavation hole at the lower end of the steel pipe pile, and the disturbed soil is removed from the bottom of the excavation hole before the start of the disturbance. By stirring and mixing with the grout material, a ground improvement region is formed below the bottom surface,
The steel pipe pile is retracted so that the lower end of the steel pipe pile is at a height near the top of the ground improvement region,
A steel pipe pile embedding method for solidifying the ground improvement region by solidifying a grout material filled around the steel pipe pile and solidifying the grout material contained in the ground improvement region, the steel pipe pile The two adjacent pile bodies are joined mutually using the joint structure of the steel pipe as described in any one of Claim 1 thru | or 4.

[First invention]
In the joint structure of the steel pipe according to the first invention, the male screw portion provided on one of the two pile bodies is screwed to the female screw portion provided on the other, and they are joined to each other. Then, the locking pin is inserted into the screw hole of the female screw portion, and the tip of the locking pin is inserted into the circumferential groove formed on the peripheral surface of the male screw portion. The groove wall surface located on the front end side of the male screw portion (hereinafter, this is particularly referred to as a groove wall surface for locking) is inclined so that the top of the wall surface is retracted to the front end side of the male screw portion from the bottom of the wall surface. The tip of the locking pin is brought into contact with the groove wall surface.

  In this way, even if there is a variation in the relative positional relationship between the screw hole provided in the female screw portion and the circumferential groove provided in the male screw portion, if the variation is within a certain range, By appropriately moving the pin back and forth along the screw hole, the tip of the locking pin can be brought into contact with the locking groove wall surface.

  Therefore, when joining two pile bodies with threaded joints, the two pile bodies are aligned along the rotational direction and eventually along the axis of the material after tightening is completed due to variations in tightening force at the site. Even when the relative positions vary, it is possible to prevent the two piles from rotating backward.

  As described above, the wall surface of the locking groove needs to be inclined so that the top surface of the wall surface recedes toward the front end side of the male screw portion rather than the bottom surface of the wall surface. For example, it may be an upright wall surface.

  The locking pin may be composed only of a shaft portion screwed into the screw hole, and the peripheral edge of the shaft portion may be brought into contact with the locking groove wall surface. The pin is composed of a shaft portion screwed into the screw hole and a truncated cone portion provided at the tip of the shaft portion, and the peripheral surface of the truncated cone portion is in contact with the groove wall surface along the generatrix. If it is configured as described above, it is possible to sufficiently increase the locking strength due to the line contact compared to the former configuration in which the locking strength may be insufficient due to the point contact.

  The circumferential groove of the male thread portion can be arbitrarily configured and may be configured separately from the thread groove of the male thread portion. However, the thread groove of the male thread portion is the circumferential groove of the present invention. As a result, it is possible to save the trouble of separately forming a circumferential groove different from the thread groove in the male thread portion.

  When the thread groove of the male thread is used as the circular groove of the present invention, the thread groove can be a thread groove of a triangular screw or a trapezoidal screw or a thread groove of a sawtooth screw. The locking groove wall surface and the opposite wall surface are both inclined surfaces and are symmetrically arranged in the cross section. In the latter case, the locking groove wall surface is inclined and the opposite wall surface is upright. It becomes a surface.

  Pile bodies that make up steel pipe piles are mainly targeted for those with an outer diameter of approximately 300 mm or less, which are adopted in the micropile method, but when a pulling force is applied to a steel pipe pile, A pile body having an outer diameter exceeding 300 mm may be used as long as the pulling strength by engagement can be sufficiently ensured even if the groove wall on the female screw portion side to be in contact is not upright.

[Second invention]
In the steel pipe pile embedding method according to the second aspect of the invention, first, an excavation hole for building the steel pipe pile is formed in the ground. In forming the excavation hole, a known construction method such as a double pipe drilling hole or an earth auger may be employed as appropriate.

  At the stage where the excavation hole is formed, cutting scraps remain on the bottom surface of the excavation hole. In this state, a steel pipe pile is built in the excavation hole and a grout material is introduced into the excavation hole. The timing of input may be simultaneous with the construction of the steel pipe pile, or may be before or after the construction. The grout material can be composed of a hydraulic material such as cement or lime.

  In constructing steel pipe piles, a plurality of pile bodies are sequentially joined along their material axis directions using the steel pipe joint structure according to the first invention.

  In addition, conventionally, when two pile bodies are joined by screw joints, the two pile bodies are rotated along the direction of rotation after the completion of the tightening due to variations in the tightening force at the site. Since the relative position varies along the axial direction, even if a locking pin is used, the occurrence of reverse rotation is inevitably caused by the amount of play considering variation, and there is a concern about the strength reduction at the joint, According to the steel pipe joint structure according to the first invention, even if the relative position of the two pile bodies varies along the material axis direction, the locking pin can be set without providing play. The construction accuracy during tightening at the site is greatly eased.

  Next, by rotating the steel pipe pile while pushing it down, the bottom of the drilling hole is disturbed at the lower end of the steel pipe pile, and the disturbed soil remains on the bottom surface of the drilling hole before the start of the disturbance. And a ground improvement area | region is formed under this bottom face by stirring and mixing with grout material. The steel pipe pile may be pushed down and rotated using, for example, a boring machine.

  It is arbitrary how the bottom surface of the excavation hole is disturbed at the lower end of the steel pipe pile, but the steel pipe pile has a range corresponding to at least the cross section thereof by rotating around the pile main body and the material axis of the pile main body, for example. It can be composed of a disturbance means provided at the tip of the pile body so that it can be disturbed.

    If the ground improvement area | region is formed, this steel pipe pile will be evacuated so that the lower end of a steel pipe pile may become the top edge vicinity height of a ground improvement area | region.

  Next, the grout material filled around the steel pipe pile is solidified, and the ground improvement region is consolidated by solidifying the grout material included in the ground improvement region.

  In this way, the cutting waste generated at the time of forming the excavation hole and remaining on the bottom surface of the excavation hole is uniformly mixed with the disturbed soil and the grout material to become a ground improvement region, so that the grout material is solidified. When this is done, the ground improvement region is consolidated in a state where the cutting waste is not unevenly distributed.

  Therefore, the ground improvement region is consolidated as a high-quality ground improvement body excellent in strength, and thus it is possible to avoid a situation where the grout material solidifies in a form in which cutting waste is unevenly distributed, for example, It becomes possible to greatly enhance the tip support force of the pile.

  Moreover, by pushing down and rotating the steel pipe pile and performing a retreat operation, there may be a load that causes a relative rotation in the opposite direction at the joint portion of the two adjacent pile bodies. Even if it occurs, the reverse rotation is reliably prevented by the first invention.

It is the figure which showed the joint structure of the steel pipe which concerns on 1st Embodiment, (a) is a longitudinal cross-sectional view along a material-axis direction, (b) is a cross-sectional view, (c) is the detail which follows an AA line Sectional drawing. The figure which showed the assembly start condition in the joint structure of the steel pipe which concerns on 1st Embodiment. The figure which showed the assembly completion situation in the joint structure of the steel pipe which concerns on 1st Embodiment. It is explanatory drawing which showed the effect | action of the joint structure of the steel pipe which concerns on 1st Embodiment, (a), (c), (e) is the contact state of the locking pin 105 and the groove | channel wall surface 109 for locking. FIGS. 4A and 4B are views showing the relative positional relationship between the screw hole 104 of the female screw portion 103b and the screw groove 106 of the male screw portion 103a, and FIGS. The arrow view from the BB line, CC line, and DD line direction in (c). The detailed figure which concerns on a modification. The detail figure which concerns on another modification. The side view which showed the steel pipe pile 1 which concerns on 2nd Embodiment. It is the figure which showed the cutting cutter 7, (a) is the figure looked up from the downward | lower direction, (b) is a perspective view. The construction drawing which showed the implementation procedure of the embedding method of the steel pipe pile which concerns on 2nd Embodiment. The construction drawing which showed the implementation procedure of the embedding method of the steel pipe pile concerning a 2nd embodiment continuously. The construction drawing which showed the implementation procedure of the embedding method of the steel pipe pile concerning a 2nd embodiment continuously.

  Hereinafter, embodiments of a steel pipe joint structure according to the present invention and a steel pipe pile embedding method using the same will be described with reference to the accompanying drawings.

[First embodiment]
FIG. 1 is a cross-sectional view and a detailed view showing a joint structure of a steel pipe according to the present embodiment. As can be seen in the figure, the joint structure 101 of the steel pipe according to the present embodiment is a male provided on one pile body 102a out of the two pile bodies 102a and 102b joined together along the material axis direction. A screw pin 103a is screwed into a female screw portion 103b provided in the other pile body 102b, and a locking pin is inserted into a screw hole 104 formed through the female screw portion along the thickness direction of the female screw portion 103b. The leading end of the locking pin is inserted into a screw groove 106 as a circular groove formed in a spiral shape on the peripheral surface of the male screw portion 103a.

  The male threaded portion 103a may be welded to the end of the steel pipe constituting the pile body 102a in advance at a factory or the like before being brought into the site, and the female threaded part 103b is similarly a steel pipe constituting the pile body 102b. What is necessary is just to weld to the edge part.

  The locking pin 105 includes a shaft portion 107 screwed into the screw hole 104 and a truncated cone portion 108 provided at the tip of the shaft portion.

  The screw holes 104 are provided at two rotation angle positions orthogonal to each other, as can be seen in FIG.

  The male screw portion 103a is configured as a trapezoidal screw, and the screw groove 106 of the male screw portion is a groove located on the tip side of the male screw portion 103a in the opposing groove wall surface as shown in FIG. A wall surface (upper side in the figure, hereinafter referred to as a locking groove wall surface) 109 is inclined so that the top surface of the wall surface is retracted to the front end side of the male screw portion 103a from the bottom surface of the wall surface.

  In addition, because of the trapezoidal screw, the top of the wall surface of the groove wall surface (lower side in the figure) located on the base end side of the male screw portion 103a is retracted to the base end side of the male screw portion 103a rather than the bottom surface of the wall surface. It is inclined like this.

  Here, the locking pin 105 is arranged so that the peripheral surface of the truncated cone part 108 contacts the locking groove wall surface 109 along the generatrix, that is, the peripheral surface of the truncated cone part 108 is in line contact with the locking groove. It is configured to contact the wall surface 109.

  In order to assemble the steel pipe joint structure 101 according to the present embodiment, first, one pile body 102a is stably embedded by being embedded or driven into the ground. The male threaded portion 103a of the pile body 102a is previously cleaned as necessary.

  Next, as shown in FIG. 2, the other pile body 102b is lifted, and the lower end opening of the female screw portion 103b provided at the lower end is fitted into the tip of the male screw portion 103a to rotate the pile body 102b. The female thread portion 103b of the pile body 102b is screwed into the male thread portion 103a of the pile body 102a.

  Next, the locking pin 105 is inserted into the screw hole 104 so that the shaft portion 107 of the locking pin 105 is screwed into the screw hole 104 of the female screw portion 103b, and the tip thereof is inserted into the screw groove 106 of the male screw portion 103a. While being inserted, the locking pin 105 is screwed into the screw hole 104 until the peripheral surface of the truncated cone portion 108 provided at the tip of the locking pin 105 contacts the locking groove wall surface 109 along the generatrix.

  In this way, as shown in FIG. 3, the locking pin 105 has the peripheral surface of the truncated cone portion 108 with the locking groove wall surface in a state where the shaft portion 107 is screwed into the screw hole 104 of the female screw portion 103 b. Even if the pile body 102a and the pile body 102b try to rotate relative to each other, the relative rotation of the two is prevented by the locking action of the locking pin 105.

  FIG. 4 shows the contact state between the locking pin 105 and the locking groove wall surface 109 for each relative positional relationship between the screw hole 104 of the female screw portion 103b and the screw groove 106 of the male screw portion 103a. is there.

  First, FIG. 4 (a) is a reproduction of what has already been described in FIG. 1 (c) or FIG. 3 (b). In this case, the truncated cone portion 10 is shown in FIG. 4 (b). In this way, the locking groove wall surface 109 abuts over the entire length of the busbar on the peripheral surface.

  Next, FIGS. 4C and 4D show a case where the screw hole 104 of the female screw portion 103b is shifted downward from the screw groove 106 of the male screw portion 103a. In this case, Similar to the case (a), the truncated cone portion 108 abuts against the locking groove wall surface 109 over the entire length of the peripheral surface of the peripheral surface, and the distal end surface of the truncated cone portion 108 abuts against the bottom surface of the screw groove 106.

  Next, FIGS. 4E and 4F show a case in which the screw hole 104 of the female screw portion 103b is displaced upward from the screw groove 106 of the male screw portion 103a. In this case, Although the front end surface of the truncated cone part 108 is largely separated from the bottom surface of the screw groove 106, the truncated cone part 108 contacts the locking groove wall surface 109 within a limited range of the generatrix of the peripheral surface.

  As described above, even if there is some variation in the relative position along the material axis direction between the screw hole 104 of the female screw portion 103b and the screw groove 106 of the male screw portion 103a, the shaft portion 107 becomes the female screw portion. The circumferential surface of the truncated cone portion 108 is securely in contact with the locking groove wall surface 109 in a state of being screwed into the screw hole 104 of 103b.

  As described above, according to the steel pipe joint structure 101 according to the present embodiment, the relative positional relationship between the screw hole 104 provided in the female screw portion 103b and the screw groove 106 provided in the male screw portion 103a varies. If the variation is within a certain range, the locking pin 105 is appropriately advanced and retracted along the screw hole 104 to engage the truncated cone portion 108 provided at the tip of the locking pin 105. It can be brought into contact with the stop groove wall 109 without fail.

  Therefore, when the pile body 102a and the pile body 102b are joined with a threaded joint, the two pile bodies 102a and 102b are extended along the rotation direction after the completion of tightening due to variations in the tightening force at the site. Even when the relative position varies along the material axis direction, it is possible to prevent the two pile bodies 102a and 102b from rotating in reverse.

  In the present embodiment, the male screw portion 103a and the female screw portion 103b are single-threaded screws, but it goes without saying that the present invention is not limited to such single-threaded screws but can be applied to double-threaded or triple-threaded screws.

  Further, in the present embodiment, the male screw portion 103a and the female screw portion 103b are right-hand screws, but may be left-hand screws (reverse screws) instead.

  In this embodiment, two screw holes 104 are provided at rotational angle positions orthogonal to each other. However, as long as the locking action is exerted, the screw holes 104 may be installed alone, or conversely, a total of 4 every 90 °. A configuration in which one set is also acceptable.

  Further, in the present embodiment, the male screw portion 103a and the female screw portion 103b are constituted by trapezoidal screws, but instead of this, a triangular screw may be used, or a sawtooth screw as shown in FIG. 5 may be used.

  In the case of a sawtooth screw, the male threaded portion of one pile according to the present invention is replaced with a male threaded portion 103a 'instead of the male threaded portion 103a and the other pile according to the present invention. Instead of the female screw portion 103b, the female screw portion of the body is a female screw portion 103b 'of the sawtooth screw, and the groove on the side where the inclined surface is formed in the opposing groove wall of the screw groove 106' of the sawtooth screw. The wall is the locking groove wall surface 109 of the present invention, and the peripheral surface of the truncated cone portion 108 of the locking pin 105 is brought into contact with the locking groove wall surface.

  In the present embodiment, the circular groove of the present invention formed in an annular shape or a spiral shape is configured by the screw groove 106 of the male screw portion 103a. Instead, the circular groove is provided in the male screw portion 103a. You may comprise an annular groove.

  FIG. 6 shows a joint structure of a steel pipe according to the above modification, and as shown in FIG. 6 (a), in the vicinity of the distal end of the male screw portion 113a provided on one pile body 112a, While the annular groove 116 formed in an annular shape is provided on the peripheral surface, the screw hole 104 is formed through the female screw portion 113b provided in the other pile body 112b along the thickness direction, and the annular groove 116 of the opposing groove walls of 116, the groove wall surface located on the front end side of the male screw portion 113a is inclined so that the top surface of the wall surface recedes toward the front end side of the male screw portion rather than the bottom surface of the wall surface. In the state where 112b is joined, as shown in FIG. 4B, the locking pin 105 is screwed into the screw hole 104 and the tip thereof is inserted into the annular groove 116, and the truncated cone part 108 of the locking pin is inserted. The circumferential surface of the groove is the above-mentioned groove wall surface, that is, a locking groove wall 109 are brought into contact with.

  Even in this modified example, the same effects as those of the above-described embodiment are obtained, but the description thereof is omitted here.

[Second Embodiment]
Next, a second embodiment will be described. Note that components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 7 is a side view showing a steel pipe pile according to the present embodiment. As shown in the figure, the steel pipe pile 1 according to the present embodiment is built in the excavation hole 3 formed in the ground 2 and the grout material 9 filled between the excavation hole wall 5 is provided. The steel pipe pile embedding structure in which the ground improvement body 8 is formed below the bottom surface 4 is constructed after the completion of the embedding.

  The steel pipe pile 1 is composed of a pile main body 6 and a cutting cutter 7 as a disturbance means provided at the tip of the pile main body, and the cutting cutter rotates the pile main body 6 around the material axis, The range corresponding to the cross section of the pile body can be disturbed.

  The pile main body 6 can be comprised by the cylindrical steel pipe below about 300 mm employ | adopted, for example with a micropile construction method.

  Here, the pile body 6 is formed by mutually joining a plurality of pile bodies with threaded joints along their material axis directions, and each pile body is provided with a female thread portion 103b at the lower end thereof. And two threaded bodies adjacent to each other at any position are the pile body 102a and the pile body 102b described in the first embodiment, and By screwing the female thread portion 103b provided in the pile body 102b to the male thread portion 103a provided in one pile body 102a, the two pile bodies can be joined to each other. In addition, about the structure of the external thread part 103a and the internal thread part 103b, the description is abbreviate | omitted here.

  As can be clearly seen in FIG. 8, the cutting cutter 7 has a pair of fan-like flat plates 11, 11 whose central angles are substantially perpendicular to each other, at the position where they are rotationally symmetric around the material axis of the pile body 6. The cutting teeth 12 are erected on one of the edges along the radial direction among the peripheral edges of the fan-shaped flat plates 11 and 11 and arranged so as to close the side openings.

  On the other hand, two openings sandwiched between the fan-shaped flat plates 11, 11 among the openings on the front end side of the pile body 6 function as discharge ports 13, 13 from which the grout material that has been pumped through the internal space of the pile body 6 is discharged. To do.

  In order to embed the steel pipe pile 1 in the ground 2 using the steel pipe pile embedding method according to the present embodiment, first, as shown in FIG. 9 (a), while protecting the hole wall 5 with the outer casing 41, the inner casing 42 The excavation hole 3 for constructing the steel pipe pile 1 is formed in the ground 2 by so-called double pipe drilling. It is desirable to form the excavation hole 3 so that the bottom surface 4 reaches the support layer of the ground 2.

  If the excavation hole 3 is formed, as shown in FIG. 9 (b), the inner casing 42 is removed, while the outer casing 41 is left as it is, and the hole wall 5 is continuously protected.

  Here, at the stage where the excavation hole 3 is formed, as shown in the figure, the cutting waste 43 remains on the bottom surface 4 of the excavation hole, but no special measures are required to discharge it.

  Next, as shown in FIG. 10 (a), the steel pipe pile 1 is built in the excavation hole 3, and the casing 41 is provided with a sufficient amount of grout material 51 necessary to form a ground improvement region to be described later. In the state of being left behind, it is first introduced into the excavation hole 3.

  The grouting material 51 may be input simultaneously with the construction of the steel pipe pile 1 or may be introduced before or after the construction. The grout material 51 may be pumped using the internal space, and the grout material may be discharged from the discharge ports 13 and 13 formed at the lower end of the pile body 6.

  In constructing the steel pipe pile 1, a plurality of pile bodies are sequentially joined along their material axis directions using the steel pipe joint structure according to the first embodiment, but the steel pipe pile according to the first embodiment According to the joint structure, even if the relative positions of the two adjacent pile bodies 102a and the pile bodies 102b vary along the material axis direction, the locking pin 105 penetrates the female screw portion 103b without providing play. Since it can arrange | position and the front-end | tip can be made to contact | abut to the locking groove wall surface 109 of the external thread part 103a, the construction precision at the time of the clamping | tightening in a field is eased significantly.

  Next, as shown in FIG. 10 (b), the steel pipe pile 1 is rotated while being pushed down by using, for example, a boring machine, and the cutting cutter 7 provided at the tip of the steel pipe pile is disturbed below the bottom surface 4 of the excavation hole 3. At the same time, the disturbed soil is agitated and mixed with the cutting waste 43 and the grout material 51 remaining on the bottom surface 4 of the excavation hole 3, and the ground improvement region 52 composed of the disturbed soil, the cutting waste 43 and the grout material 51 is excavated. It is formed below the bottom surface 4 of the hole 3.

  If vibration is applied to the lower end of the pile main body 6 or the cutting cutter 7 during the stirring and mixing, the stirring and mixing of the disturbing soil, the cutting waste 43 and the grout material 51 can be performed uniformly and efficiently.

  When the ground improvement region 52 is formed, the steel pipe pile is retracted so that the lower end of the steel pipe pile 1 becomes a height near the top end of the ground improvement region 52 as shown in FIG. Retraction of the steel pipe pile 1 is performed before the ground improvement region 52 is consolidated.

  Next, as shown in FIG. 11 (b), the remaining amount of grout material 61 necessary for embedding the steel pipe pile 1 is secondarily introduced into the excavation hole 3 while the outer casing 41 is pulled out.

  The grout material 61 is preferably introduced into the excavation hole 3 after the ground improvement region is substantially solidified so that disturbed soil and cutting waste 43 contained in the ground improvement region 52 are not mixed into the grout material 61. If there is no risk of contamination, the grout material 61 may be introduced before the ground improvement region 52 is consolidated.

  Next, the grout material 61 filled around the steel pipe pile 1 is solidified, and when the grout material 51 included in the ground improvement region 52 is not yet solidified, the ground improvement region is solidified. Is consolidated as a ground improvement body 8.

  As described above, according to the steel pipe pile 1 and the embedding method thereof according to the present embodiment, the cutting waste 43 generated at the time of forming the excavation hole 3 and remaining on the bottom surface 4 of the excavation hole is disturbed soil or grout. Since the ground improvement region 52 is agitated and mixed with the material 51 evenly, when the grout material 51 is solidified, the ground improvement region 52 is consolidated in a state where the cutting waste 43 is not unevenly distributed.

  Therefore, the ground improvement region 52 is consolidated as a high-quality ground improvement body 8 having excellent strength, and thus it is possible to avoid a situation in which the grout material is solidified in such a manner that the cutting waste 43 is unevenly distributed downward, for example. As a result, the tip bearing capacity of the steel pipe pile 1 can be greatly increased, and as a result, the number of steel pipe piles can be reduced, the diameter of the steel pipe pile can be reduced, or the pile length of the steel pipe pile can be reduced. Become.

  In addition, according to the method for embedding a steel pipe pile according to the present embodiment, the grout material 51 necessary and sufficient for forming the ground improvement region 52 is primarily charged in a state where the outer casing 41 remains, Since the ground improvement region 52 is formed and the outer casing 41 is pulled out, the remaining amount of the grout material 61 necessary for embedding the steel pipe pile 1 is secondarily introduced. There is no possibility of mixing into the grout material 61 filled around the pile 1.

  Therefore, it becomes possible to comprise the solidified body formed around the steel pipe pile 1 only by the grout material 61 that does not include the disturbing soil and the cutting waste 43, and the reliability of the load transfer function of the steel pipe pile 1 is improved. .

  Moreover, according to the embedding method of the steel pipe pile concerning this embodiment, in assembling the pile main body 6 of the steel pipe pile 1 by sequentially joining a plurality of pile bodies along their material axis directions, Since the screw joint has the steel pipe joint structure according to the first embodiment, the relative positional relationship between the screw hole 104 provided in the female screw portion 103b and the screw groove 106 provided in the male screw portion 103a varies. If the variation is within a certain range, the locking pin 105 is appropriately advanced and retracted along the screw hole 104 to engage the truncated cone portion 108 provided at the tip of the locking pin 105. It can be brought into contact with the stop groove wall 109 without fail.

  Therefore, when the pile body 102a and the pile body 102b are joined with a threaded joint, the two pile bodies 102a and 102b are extended along the rotation direction after the completion of tightening due to variations in the tightening force at the site. Even when the relative position varies along the material axis direction, it is possible to prevent the two pile bodies 102a and 102b from rotating in reverse.

  Therefore, when the above-mentioned steel pipe pile 1 is pushed down, rotated, and retracted, even if a load that causes relative rotation in the opposite direction occurs at each joint location, each pile body rotates reversely to the joint location. The loosening can be surely prevented.

DESCRIPTION OF SYMBOLS 1 Steel pipe pile 2 Ground 3 Excavation hole 4 Bottom face 5 Hole wall 6 Pile main body 7 Cutting cutter (disturbance means)
8 Ground improvement body 41 Outer casing (casing)
43 Cutting waste 51 Grout material (Grout material to be introduced primarily)
52 Ground improvement area 61 Grout material (secondary grout material)
102a, 112a Pile body (one pile body)
102b, 112b Pile body (the other pile body)
103a, 103a ', 113a Male thread part 103b, 103b', 113b Female thread part 104 Screw hole 105 Locking pin 106, 106 'Screw groove (circular groove)
107 Shaft portion 108 Frustum portion 109 Locking groove wall surface 116 Screw groove (circular groove)

Claims (5)

Of the two pile bodies joined together along the material axis direction, the male screw portion provided in one pile body is screwed into the female screw portion provided in the other pile body, and the female screw A locking pin is inserted through a screw hole formed through the female screw portion along the thickness direction of the portion, and the tip of the locking pin is formed in an annular shape or a spiral shape on the peripheral surface of the male screw portion. In the steel pipe joint structure in which relative rotation of the two pile bodies is prevented by the locking action of the locking pin with respect to the circular groove,
Of the opposing groove wall surfaces of the circumferential groove, the groove wall surface located on the front end side of the male screw portion is inclined so that the top surface of the wall surface is retracted toward the front end side of the male screw portion from the bottom surface of the wall surface, and the wall surface of the groove A steel pipe joint structure characterized in that a tip of the locking pin is brought into contact with the steel pipe. The locking pin includes a shaft portion screwed into the screw hole and a truncated cone portion provided at a tip of the shaft portion, and a circumferential surface of the truncated cone portion is formed along the generatrix with the groove. The steel pipe joint structure according to claim 1, wherein the steel pipe joint structure is configured to abut against a wall surface. The steel pipe joint structure according to claim 1 or 2, wherein the thread groove of the male thread portion is the circumferential groove. The steel pipe joint structure according to any one of claims 1 to 3, wherein an outer diameter of the pile body is 300 mm or less. At the same time as or after the steel pipe pile is built in the excavation hole formed in the ground, grout material is thrown into the excavation hole,
The steel pipe pile is rotated while being pushed down to disturb the bottom bottom of the excavation hole at the lower end of the steel pipe pile, and the disturbed soil is removed from the bottom of the excavation hole before the start of the disturbance. By stirring and mixing with the grout material, a ground improvement region is formed below the bottom surface,
The steel pipe pile is retracted so that the lower end of the steel pipe pile is at a height near the top of the ground improvement region,
A steel pipe pile embedding method for solidifying the ground improvement region by solidifying a grout material filled around the steel pipe pile and solidifying the grout material contained in the ground improvement region, the steel pipe pile A pile of steel pipe piles, wherein two adjacent pile bodies are joined to each other using the steel pipe joint structure according to any one of claims 1 to 4. Embedding method.

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