JP7277726B2 - Steel pipe piles and construction methods for steel pipe piles - Google Patents

Description

The present invention relates to a steel pipe pile and a steel pipe pile construction method.

Excavation bits attached to the ends of steel pipe piles are expected not only to have the conventional effect of excavating the ground, but also to control the movement of the excavated soil according to the rotation direction of the pile, and to suppress or promote clogging with soil inside the pipe. be. For example, in Patent Document 1, the tangential direction at the intersection of the longitudinal center axis of the drilling bit and the outer circumference of the steel pipe pile forms an angle, and this angle causes the cutting edge of the drilling bit to move toward the inside of the steel pipe pile. The technology provided is described. As a result, for example, before the pile tip reaches the bearing layer, the earth and sand are pushed out of the pile to suppress clogging of the soil inside the pipe, thereby improving excavability, and after the pile tip reaches the bearing layer, the pile By reversing the direction of rotation of the pile, the earth and sand are taken into the inside of the pile, and a high bearing capacity can be obtained by promoting the clogging of the soil inside the pipe.

Japanese Patent No. 5053154

However, when penetrating the tip of the steel pipe pile into the ground, a large earth pressure acts on the excavation bit attached to the tip of the pile. In addition, large construction resistance (rotational torque and vertical press force) also acts on the drilling bit in a support layer with high ground strength. As a result, it is assumed that the drilling bit is deformed. Therefore, in order to maximize the effect of the excavation bit described in Patent Document 1, for example, it is desirable to have a structure that can maintain the function of the excavation bit against deformation due to earth pressure and construction resistance.

Accordingly, an object of the present invention is to provide a new and improved steel pipe pile and a steel pipe pile construction method capable of maintaining the function of an excavation bit against deformation during excavation.

According to one aspect of the present invention, in a steel pipe pile including a steel pipe body and a plate-like drilling bit attached to an end surface of the steel pipe body at an angle with respect to a circumferential tangent line of the steel pipe body, the drilling bit is attached to the steel pipe body. At least one set of inner and outer bits having at least partial circumferential overlap is included.

In the above steel pipe pile, the excavated area by the inner bit may be the same as or larger than the excavated area by the outer bit. In addition, the inner bit and the outer bit, which overlap each other in the circumferential direction of the steel pipe body, may be parallel to each other in the planar arrangement. The drill bit may further include a bit that does not overlap other bits in the circumferential direction of the steel pipe body.

In the steel pipe pile described above, the tip end face of at least one of the inner bit and the outer bit in the pile axial direction may be formed with an inclination in which the protruding height increases from the inner side to the outer side in the radial direction of the steel pipe body. At least one of the inner bit and the outer bit may be formed with a tapered cross-section that becomes thicker from the inside to the outside in the radial direction of the steel pipe body. Further, the excavation bit may have a plate shape that is curved so as to form a C-shape or an S-shape when the steel pipe pile is viewed from the tip side.

According to another aspect of the present invention, in the steel pipe pile construction method described above, the excavation bit pushes earth and sand to the outside of the steel pipe body until the tip of the steel pipe pile reaches a predetermined depth in the first rotation direction. and excavating while rotating the steel pipe pile in a second rotation direction in which the excavation bit takes the earth and sand inside the steel pipe body until the tip of the steel pipe pile reaches the stop depth. A steel pipe pile construction method is provided, including the steps of:

In the steel pipe pile construction method described above, the steel pipe pile may be rotated in the second rotation direction after the tip end of the steel pipe pile reaches the support layer during the anchoring. Alternatively, at the time of stopping, excavation is performed while rotating the steel pipe pile in the second rotation direction immediately before the tip of the steel pipe pile reaches the supporting layer, and the tip of the steel pipe pile reaches the supporting layer. good. Moreover, the step of excavating while rotating the steel pipe pile in the first direction of rotation and the step of excavating while rotating the steel pipe pile in the second direction of rotation may be alternately performed.

According to the above configuration, by arranging the inner bit and the outer bit so as to overlap each other in the circumferential direction of the steel pipe body, even if, for example, earth pressure or construction resistance acts on one of the bits, the other bit will not move. It can support it and restrain the deformation of the drilling bit. Therefore, the function of the drilling bit can be maintained against deformation during drilling.

It is the figure which looked at the steel pipe pile concerning one embodiment of the present invention from the side and the tip side. It is a figure for demonstrating the relationship between the inside bit and outside bit in the steel pipe pile shown by FIG. It is a figure which shows the other example of the steel pipe pile which concerns on embodiment of this invention. It is a figure which shows the other example of the steel pipe pile which concerns on embodiment of this invention. It is a figure which shows the other example of the steel pipe pile which concerns on embodiment of this invention. It is a figure which shows another example of the steel pipe pile which concerns on embodiment of this invention. It is a figure which shows another example of the steel pipe pile which concerns on embodiment of this invention. It is a figure which shows another example of the steel pipe pile which concerns on embodiment of this invention. It is a figure which shows another example of the steel pipe pile which concerns on embodiment of this invention. It is a figure which shows another example of the steel pipe pile which concerns on embodiment of this invention.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the present specification and drawings, constituent elements having substantially the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description.

Drawing 1 is a figure which looked at the steel pipe pile concerning one embodiment of the present invention from the side and the tip side. As shown in FIG. 1 , the steel pipe pile 10 includes a steel pipe body 11 and an excavation bit 12 attached to an end surface 11E of the steel pipe body 11 . Drill bit 12 includes an inner bit 121 and an outer bit 122 . In this embodiment, both the inner bit 121 and the outer bit 122 are attached at angles θ1, θ2 (0<θ1, θ2<90°) with respect to the circumferential tangent line of the steel pipe body 11, respectively. Here, the angles θ1 and θ2 are determined at positions where the thickness center lines of the plate-shaped inner bit 121 and the plate-shaped outer bit 122 intersect the thickness center line _LC11 of the steel pipe body 11, respectively. It is the angle formed by the thickness center line L _C11 and the tangent line L _T11 (the circumferential tangent line of the steel pipe body 11). The angles θ1 and θ2 are hereinafter also referred to as attachment angles of the inner bit 121 and the outer bit 122 .

As described above, the inner bit 121 and the outer bit 122 are attached at the attachment angles θ1 and θ2, respectively. is rotated counterclockwise (CCW) shown in FIG. In addition, until the tip of the pile reaches the slamming depth, excavate while rotating the steel pipe pile 10 clockwise (CW) shown in FIG. By doing so, high bearing capacity can be obtained. The drilling bit 12 has edges on both the inner and outer sides in the radial direction of the steel pipe body 11, which makes it possible to drill while reversing the direction of rotation of the steel pipe body 11 as described above.

The method of attaching the drilling bit 12 to the steel pipe body 11 may be, for example, welding or mechanical joining means such as screwing. In the example shown in FIG. 1, the end surface 11E of the steel pipe body 11 and the upper end surface of the drilling bit 12 are aligned, but the drilling bit 12 may be fitted into a groove or notch formed in the end surface 11E. , the end including the end surface 11E of the steel pipe body 11 is fitted into the groove or notch formed in the upper end surface of the drilling bit 12, and the end surface 11E and the upper end surface of the drilling bit 12 are joined together. It is also possible to form grooves or cuts in both of them and to join these grooves or cuts after fitting them together. In this case, the end face 11E of the steel pipe body 11 and the upper end face of the drill bit 12 do not necessarily match.

2 is a diagram for explaining the relationship between the inner bit and the outer bit in the steel pipe pile shown in FIG. 1. FIG. As shown in FIG. 2 , the paired inner bit 121 and outer bit 122 have at least partial overlap in the circumferential direction of the steel pipe body 11 . That is, when the viewpoint is placed on the center C of the steel pipe body 11, the inner bit 121 and the outer bit 122 that form a pair are at least partially overlapped. In the example shown in FIG. 2, the mounting angle of the inner bit 121 and the mounting angle of the outer bit 122 are equal. The mounting angles may differ between the bit 121 and the outer bit 122 .

As described above, when the tip of the steel pipe pile 10 is penetrated into the ground, a large earth pressure acts on the excavation bit 12, and a large construction resistance acts on the excavation bit 12 in the support layer with high ground strength. As a result, it is assumed that the drilling bit 12 is deformed. On the other hand, by arranging the inner bit 121 and the outer bit 122 so as to overlap in the circumferential direction of the steel pipe body 11, for example, the outer bit 122 that receives the earth pressure from the outside of the steel pipe pile 10 is placed in the inner bit 121. In addition, the inner bit 121 that receives construction resistance in the tangential direction of the steel pipe body 11 can be supported by the outer bit 122 . In this manner, deformation of the drilling bit 12 can be suppressed in this embodiment. When one of the inner bit 121 and the outer bit 122 supports the other, for example, one deformed bit may contact the other bit, or the bits may be sandwiched between them even if they do not contact each other. The bit may be supported through earth and sand.

In addition, in the present embodiment, in the step of excavating while rotating the steel pipe pile 10 counterclockwise (CCW) shown in FIG. The wear of the inner bit 121 is minimized in the excavation process before reaching, and then in the process of excavating the bearing layer while rotating the steel pipe pile 10 clockwise (CW) shown in FIG. It is possible to fully demonstrate the function of taking in. Thus, in this embodiment, by suppressing the deformation and wear of the excavation bit 12, it is possible to maintain the function of suppressing or promoting clogging of the pipe interior soil by the excavation bit 12 against the earth pressure and construction resistance. can.

Although the excavation area R1 by the inner bit 121 is larger than the excavation area R2 by the outer bit 122 in the example shown in FIG. 1, the excavation areas R1 and R2 may have the same size. From the viewpoint of suppressing deformation of the outer bit 122 due to construction resistance in the process of excavating while rotating the steel pipe pile 10 clockwise (CW) shown in FIG. Desirably equal to or greater than R2.

In addition, in the example shown in FIG. 2 , the inner bit 121 and the outer bit 122 protrude both inside and outside the steel pipe body 11 when viewed from the tip side of the steel pipe pile 10 . In this way, even if the drill bit protrudes only to the outside of the steel pipe body 11 in the examples shown in the other figures, the drill bit projects to both the inside and the outside of the steel pipe body 11 as a modification. Alternatively, a configuration is possible in which the drilling bit protrudes only inside the steel pipe body 11 . The direction in which the drilling bit protrudes from the steel pipe body 11 may differ between the inner bit 121 and the outer bit 122 .

3 to 5 are diagrams showing other examples of steel pipe piles according to embodiments of the present invention. In the examples shown in FIGS. 3 to 5, the inner bit 121 and the outer bit 122, which overlap each other in the circumferential direction of the steel pipe body 11, are parallel to each other in the planar arrangement. In this case, the mounting angle θ1 of the inner bit 121 is larger than the mounting angle θ2 of the outer bit 122 (θ1>θ2). By arranging the inner bit 121 and the outer bit 122 parallel to each other in a plane arrangement, the inner bit 121 can effectively support the outer bit 122 which is about to be deformed by earth pressure. In addition, since the inner bit 121 and the outer bit 122 are parallel in the planar arrangement, the drilling bit 12 can be easily attached to the steel pipe body 11 .

In the example shown in FIG. 3, the length D1 of the inner bit 121 and the length D2 of the outer bit 122 are equal (D1=D2). In the example shown in FIG. 4, by extending the outer bit 122 to the outside of the steel pipe body 11, the excavation regions R of the inner bit 121 and the outer bit 122 are substantially aligned with the example of FIG. At this time, the length D2 of the outer bit 122 is longer than the length D1 of the inner bit 121 (D1<D2). In the example shown in FIG. 5, the portion of the outer bit 122 corresponding to the inner side of the steel pipe body 11 is shortened from the example of FIG. is shorter (D1>D2). In this manner, various configurations are possible with respect to the length of the inner bit 121 and the outer bit 122, the attachment position, and the size of overlap.

FIG. 6 is a diagram showing still another example of the steel pipe pile according to the embodiment of the present invention. A steel pipe pile 20 shown in FIG. 6 includes a steel pipe body 11 and an excavation bit 22 . The drill bit 22 has an inner bit 121 and an outer bit 122 similar to the example shown in FIG. including. In the example shown in FIG. 6, bit 222 is mounted at a similar mounting angle and length as outer bit 122 . Thus, drilling bit 22 need not consist solely of a set of inner bit 121 and outer bit 122, but may include other, singly mounted bit 222 as well.

FIGS. 7-10 is a figure which shows another example of the steel pipe pile which concerns on embodiment of this invention. In the example shown in FIG. 7, the drilling bit 32 of the steel pipe pile 30 is attached at an angle to the circumferential tangent of the steel pipe body 11, similar to the example described above with reference to FIG. It includes an inner bit 321 and an outer bit 322 with at least partial overlap about 11 circumferential directions. In addition, in the illustrated example, the end surfaces 321E and 322E of the inner bit 321 and the outer bit 322, that is, the end surfaces opposite to the end surface 11E of the steel pipe body 11, are provided with a thread extending from the inside to the outside in the radial direction of the steel pipe body 11. An inclination is formed in which the height of the protrusion increases.

When the tip surfaces 321E and 322E of the inner bit 321 and the outer bit 322 are inclined as described above, excavation can be performed efficiently by concentrating the stress on the tips of the inner bit 321 and the outer bit 322 formed by the inclination. can do. As a result, the earth pressure acting on the bit can be reduced, and as a result, deformation of the bit can be suppressed. In the illustrated example, both tip surfaces 321E and 322E of the inner bit 321 and the outer bit 322 are inclined, but only one of the tip surfaces may be inclined.

In the example shown in FIG. 8, the drilling bit 32 of the steel pipe pile 30 is attached at an angle to the circumferential tangent of the steel pipe body 11, similar to the example described above with reference to FIG. It includes an inner bit 321A and an outer bit 322 with at least partial overlap about 11 circumferential directions. In addition, in the illustrated example, the inner bit 321A is formed with a tapered cross section that becomes thicker from the inside to the outside in the radial direction of the steel pipe body 11 . Specifically, the inner bit 321A has a thickness t ₁ on the radially inner side of the steel pipe body 11 and a thickness t ₂ on the outer side, and the thickness t ₂ is greater than the thickness t ₁ (t ₁ <t ₂ ). .

When the inner bit 122B is formed with a tapered cross-section as described above, efficient excavation can be achieved by concentrating stress on the tip of the inner bit 321A thickened by the tapered cross-section. As a result, the earth pressure acting on the bit can be reduced, and as a result, deformation of the bit can be suppressed. In the illustrated example, only the inner bit 321A is formed with a tapered cross section, but both the inner bit 321A and the outer bit 322 may be formed with a tapered cross section, and only the outer bit 322 is formed with a tapered cross section. may Further, by combining the example of FIG. 8 and the example of FIG. 7, the tip surface of the inner bit 321 or the outer bit 322 may be inclined and the inner bit 321 or the outer bit 322 may be formed with a tapered cross section.

In the example shown in FIG. 9, the excavation bit 42 of the steel pipe pile 40 includes plate-shaped inner and outer bits 421 and 422 that are curved to form a C shape when the steel pipe pile 40 is viewed from the tip side. . In this _{case , the} mounting angle _? and the tangent line _LT11 to the pipe thickness center line _LC11 . The mounting angles of the inner bit 421 and the outer bit 422 (angles θ1 and θ2 in the example shown in FIG. 1) can be similarly defined. In the example of FIG. 9, the curved drilling bit 42 tends to produce a flow of earth and sand away from the steel pipe body 11 and the drilling bit 42 when the steel pipe pile 40 rotates counterclockwise (CCW). When the steel pipe pile 40 rotates clockwise (CW), it is easy to generate a flow of earth and sand toward the inside of the steel pipe body 11 . Excavation using the steel pipe pile 40 becomes smoother due to the smooth flow of earth and sand.

In the example shown in FIG. 10 , the excavation bit 52 of the steel pipe pile 50 includes plate-shaped inner and outer bits 521 and 522 that are curved to form an S shape when the steel pipe pile 50 is viewed from the tip side. . In this case, the mounting angle θ of the drilling bit 52 is set so that the thickness center of both ends of the drilling bit 52 is at the position where the curved plate thickness centerline _LC32 of the drilling bit 52 intersects the pipe thickness centerline _LC11 of the steel pipe body 11. This is the angle formed by the connecting straight line _LE32 and the tangent line _LT11 to the tube thickness center line _LC11 . The attachment angles of the inner bit 521 and the outer bit 522 (angles θ1 and θ2 in the example shown in FIG. 1) can be similarly defined. In the example of FIG. 10, in addition to making it easier to generate a flow of earth and sand similar to the example of FIG. It becomes easier to create a flow of earth and sand away from the excavation bit 52 . As in the example of FIG. 9 , excavation using the steel pipe pile 50 becomes smoother due to the smooth flow of earth and sand.

(Construction method for steel pipe piles)
For example, the following construction methods can be implemented using the steel pipe piles according to the embodiments and modifications of the present invention as described above. In addition, below, although the construction method using the steel pipe pile 10 of the example shown by FIG. 1 is demonstrated, the steel pipe pile 20,30,40,50 which concerns on another example can implement the same construction method.

First, until the tip of the steel pipe pile 10 (the tip of the drilling bit 12 or the end surface 11E of the steel pipe body 11) reaches a predetermined depth, the drilling bit 12 pushes out the earth and sand to the outside of the steel pipe body 11 in the first rotation direction ( The step of excavating while rotating the steel pipe pile 10 counterclockwise (CCW) shown in FIG. 1 is performed. After that, until the tip of the steel pipe pile 10 reaches the ramming depth, the drill bit 12 takes the earth and sand inside the steel pipe body 11 in the second rotation direction (clockwise (CW) shown in FIG. 1). A step of excavating while rotating is performed. Here, the predetermined depth is, for example, a distance of about 1 to 5 times the diameter of the steel pipe body 11 above the stop depth. As a result, when the steel pipe pile 10 is driven down, the lower end of the steel pipe pile 10 is blocked with the sediment that has been taken in, and a high bearing capacity can be obtained.

The relationship between the predetermined depth and the depth of the support layer in the ground is arbitrary. That is, the predetermined depth may be deeper than the depth of the support layer. In this case, in the construction method, the steel pipe pile 10 is rotated in the second rotation direction after the tip of the steel pipe pile 10 reaches the support layer during the anchoring. Alternatively, the predetermined depth may be shallower than the depth of the support layer. In this case, in the construction method, immediately before the tip of the steel pipe pile 10 reaches the support layer, excavation is performed while rotating the steel pipe pile 10 in the second rotation direction when the tip of the steel pipe pile 10 reaches the support layer. will be stopped after reaching

In the construction method, the step of excavating while rotating the steel pipe pile 10 in the first rotation direction and the step of excavating while rotating the steel pipe pile 10 in the second rotation direction may be alternately performed. . That is, even before the tip of the steel pipe pile 10 reaches a predetermined depth, it is possible to excavate while rotating the steel pipe pile 10 in the second rotation direction. Specifically, for example, when the embedding of the steel pipe pile 10 is not smooth, the steel pipe pile 10 is embedded while alternately switching the rotation direction, and finally the steel pipe pile 10 is rotated in the second rotation direction. It is conceivable to stop it by rotating it. In this case, the predetermined depth is the depth at which the steel pipe pile 10 was last rotated in the first direction of rotation, and can be, for example, the same depth as the stop depth. For example, in the above case, not only the direction of rotation of the steel pipe pile 10 but also excavation (lowering of the tip) and retreating (rising of the tip) of the steel pipe pile 10 may be performed alternately.

Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention belongs can conceive of various modifications or modifications within the scope of the technical idea described in the claims. It is understood that these also naturally belong to the technical scope of the present invention.

10,20,30,40,50 Steel pipe pile 11 Steel pipe body 11E End face 12,22,32,42,52 Excavation bit 121,321,421,521 Inside bit 122,322, 422, 522... outside bit, 222... singly mounted bit.

Claims (11)

A steel pipe pile comprising a steel pipe body and a plate-shaped excavation bit attached to an end surface of the steel pipe body at an angle with respect to a circumferential tangent line of the steel pipe body,
wherein the drilling bit includes at least one set of inner and outer bits that at least partially overlap when viewed at the center of the steel pipe body;
The steel pipe pile, wherein the inner bit and the outer bit cross the steel pipe body in the pipe thickness direction of the steel pipe body . The steel pipe pile according to claim 1, wherein an excavated area by the inner bit is the same as or larger than an excavated area by the outer bit. 3. The steel pipe pile according to claim 1 or 2, wherein said at least one set of said inner bit and said outer bit are parallel to each other in a planar arrangement. The steel pipe pile according to any one of claims 1 to 3, wherein the drill bit further includes a bit that does not overlap other bits when viewed at the center of the steel pipe body. At least one of the inner bit and the outer bit has a tip end surface in the pile axis direction formed with an inclination in which the protruding height increases from the inside to the outside in the radial direction of the steel pipe body. 5. The steel pipe pile according to any one of 4. 6. The steel pipe body according to any one of claims 1 to 5, wherein at least one of the inner bit and the outer bit is formed with a tapered cross section that becomes thicker from the inside to the outside in the radial direction of the steel pipe body. Steel pipe pile. The steel pipe according to any one of claims 1 to 6, wherein the excavation bit has a plate shape that is curved into a C-shape or an S-shape when the steel pipe pile is viewed from the tip side. pile. A steel pipe pile construction method according to any one of claims 1 to 7,
a step of excavating while rotating the steel pipe pile in a first rotation direction in which the excavation bit pushes earth and sand out of the steel pipe body until the tip of the steel pipe pile reaches a predetermined depth;
a step of excavating while rotating the steel pipe pile in a second rotation direction in which the excavation bit takes earth and sand into the inside of the steel pipe body until the tip of the steel pipe pile reaches a slamming depth. Method. The construction method of the steel pipe pile according to claim 8, wherein, in the stopping, the tip of the steel pipe pile reaches the support layer, and then the steel pipe pile is rotated in the second rotation direction. During the driving, excavation is performed while rotating the steel pipe pile in the second rotation direction immediately before the tip of the steel pipe pile reaches the support layer, and the tip of the steel pipe pile reaches the support layer. The construction method of the steel pipe pile according to claim 8, wherein the steel pipe pile is stopped from. The step of excavating while rotating the steel pipe pile in the first direction of rotation and the step of excavating while rotating the steel pipe pile in the second direction of rotation are alternately performed. 11. The steel pipe pile construction method according to any one of 10.

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