WO2022050133A1 - Screw joint, steel pipe with screw joint, structure, method for building structure, landslide prevention pile, method for constructing landslide prevention pile, method for designing screw joint, method for producing screw joint, and method for producing steel pipe with screw joint - Google Patents

Abstract

A screw joint 1 according to the present invention is located at ends of steel pipes 3 and joins the steel pipes 3 to each other. The screw joint 1 comprises a male-side cylindrical body 7 having a male screw 5 comprising a taper screw, and a female-side cylindrical body 11 having a female screw 9 comprising a taper screw. The inclination angle of stabbing flanks 5a, 9a of screw threads of the male screw 5 and the female screw 9 with respect to a direction at right angles to a steel pipe axis is within a range from 0 degree to +8 degrees.

Description

ねじ継手、ねじ継手付き鋼管、構造体、構造体の構築方法、地すべり抑止杭、地すべり抑止杭の施工方法、ねじ継手の設計方法、ねじ継手の製造方法、ねじ継手付き鋼管の製造方法Threaded joints, steel pipes with threaded joints, structures, construction methods of structures, landslide suppression piles, landslide suppression pile construction methods, threaded joint design methods, threaded joint manufacturing methods, threaded jointed steel pipe manufacturing methods

　本発明は、例えば地すべり地帯に設置される地すべり抑止用鋼管杭(略して「地すべり抑止杭」)に用いられるねじ継手、ねじ継手付き鋼管、構造体、構造体の構築方法、地すべり抑止杭、地すべり抑止杭の施工方法、ねじ継手の設計方法、ねじ継手の製造方法、ねじ継手付き鋼管の製造方法に関する。 INDUSTRIAL APPLICABILITY The present invention provides, for example, a threaded joint, a steel pipe with a threaded joint, a structure, a method for constructing a structure, a landslide suppressing pile, and a landslide used for a landslide suppressing steel pipe pile (abbreviated as "ground slip suppressing pile") installed in a landslide zone. Regarding the construction method of restraint piles, the design method of threaded joints, the manufacturing method of threaded joints, and the manufacturing method of steel pipes with threaded joints.

　地すべり抑止用鋼管杭(以下、省略して「地すべり抑止杭」とする)は、地すべり地帯に設置されるもので、その施工場所は重機等の搬入が困難な急傾斜地であることが多い。そのため、打撃により杭を打ち込むことができず、オーガーなどによりプレボーリングした孔に杭を建て込むことが行われている。ところで、地すべり抑止杭の全長は、現地の状況によって相違するが、一般に２０～３０ｍに達する場合が多い。しかし、輸送等の制限があるため、５～８ｍ程度の鋼管杭を現場で継杭しながら施工するのが通常である。 Landslide deterrent steel pipe piles (hereinafter abbreviated as "landslide deterrent piles") are installed in landslide areas, and their construction sites are often steep slopes where it is difficult to carry heavy machinery. Therefore, it is not possible to drive the pile due to the impact, and the pile is built in the hole pre-bored by an auger or the like. By the way, the total length of the landslide deterrent pile varies depending on the local situation, but generally reaches 20 to 30 m in many cases. However, due to restrictions on transportation, etc., it is usual to construct steel pipe piles of about 5 to 8 m while connecting them at the site.

　この継杭作業は不安定な環境下で行われるため、迅速かつ確実な作業が強く求められる。また、地すべり崩壊面は、どの地層面で起こるかを予測することが難しいため、地すべり抑止杭は、継杭のための継手部を含むほぼ全長にわたって、どの部分でも設計上必要な強度以上の断面諸性能を有していなければならないことが多い。 Since this joint pile work is performed in an unstable environment, quick and reliable work is strongly required. In addition, since it is difficult to predict on which landslide surface the landslide collapse surface will occur, the landslide deterrent pile has a cross section that is stronger than the design required for any part over almost the entire length including the joint for the joint pile. It often has to have various performances.

　このため、従来、地すべり抑止杭の継杭は、現場での溶接作業によって行われている。しかしながら、このような作業環境が悪い場所での現場溶接には、次のような問題がある。
（１）現在の慣用サイズの鋼管は肉厚が厚いため、１か所の溶接に時間がかかる。
（２）作業環境が悪いため溶接品質が落ち易く、継手強度の確保が容易でない。
（３）労働条件が悪いため、優れた溶接技能者を確保しにくい。
（４）現場溶接では溶接品質を確保することが困難なため、高張力鋼を使用しにくい。 For this reason, conventionally, the joint pile of the landslide prevention pile is performed by welding work at the site. However, on-site welding in such a place where the working environment is bad has the following problems.
(1) Since the current conventional size steel pipe is thick, it takes time to weld at one place.
(2) Since the working environment is bad, the welding quality tends to deteriorate, and it is not easy to secure the joint strength.
(3) Due to poor working conditions, it is difficult to secure excellent welding technicians.
(4) Since it is difficult to ensure welding quality in on-site welding, it is difficult to use high-strength steel.

　このようなことから、現場継杭作業を前提とする地すべり抑止杭については、次のような要件をすべて満すことが要求される。
（１）継杭作業が容易で、かつ作業時間が短いこと。
（２）鋼管杭どうしの継手部の品質が作業環境及び技量に影響されることなく、良好に確保されること。
（３）継手部の強度が鋼管杭本体（以下、杭本体という）と同等以上であること。
（４）継手部の外径が杭本体より大きくならないこと。
（５）杭本体が高張力鋼の場合でも適用できること。 For these reasons, it is required that all of the following requirements be satisfied for landslide prevention piles that are premised on on-site joint pile work.
(1) Easy pile work and short work time.
(2) The quality of the joints between steel pipe piles should be ensured well without being affected by the working environment and skill.
(3) The strength of the joint is equal to or higher than that of the steel pipe pile body (hereinafter referred to as the pile body).
(4) The outer diameter of the joint should not be larger than the pile body.
(5) Applicable even when the pile body is made of high-strength steel.

　上記のような要件に対応する、地すべり抑止杭の継手として、端部に雌ねじ継手部を有する杭本体と、端部にこの雌ねじ継手部の外径と実質的に同じ外径の雄ねじ継手部を有する杭本体とを備え、雌ねじ継手部及び雄ねじ継手部は数回転でねじ込みが完了するように設定された傾斜及びねじ山高さとねじ山間隔を有するテーパ状のねじ継手からなり、雌ねじ継手部及び雄ねじ継手部のねじ終点部における断面係数と材料強度の積が杭本体の断面係数と材料強度の積より大きくなるように構成したものがある（例えば、特許文献１参照）。また、雄ねじ及び雌ねじはテーパねじであり、ねじ山形状が台形状で、かつ２条～３条の多条ねじとした地すべり抑止鋼管杭継手が開示されている（例えば、特許文献２参照）。 As a joint for a landslide prevention pile that meets the above requirements, a pile body having a female thread joint at the end and a male thread joint with an outer diameter substantially the same as the outer diameter of the female thread joint at the end. The female threaded joint and the male threaded joint consist of a tapered threaded joint with an inclination and thread height and thread spacing set so that screwing can be completed in a few turns, and the female threaded joint and the male threaded joint. Some are configured so that the product of the cross-sectional coefficient and the material strength at the thread end point of the joint portion is larger than the product of the cross-sectional coefficient and the material strength of the pile body (see, for example, Patent Document 1). Further, a male thread and a female thread are tapered threads, and a landslide-preventing steel pipe pile joint having a trapezoidal thread shape and a multi-threaded thread having 2 to 3 threads is disclosed (see, for example, Patent Document 2).

特開平７－８２７３８号公報Japanese Unexamined Patent Publication No. 7-82738 特開平１０－２５２０５６号公報Japanese Unexamined Patent Publication No. 10-252056

　地すべり抑止杭のねじ継手には高い耐力が求められる一方で足場の悪い施工現場において人力での回転接合を行う必要がある。そして、ねじ継手はショルダー部がタッチするまでねじ込むことを基本としているが、上記のような施工現場での接合のため、完全にねじを締め切れずショルダー部がタッチせずに隙間が２ｍｍ程度生じてしまうことがある。 While high yield strength is required for the threaded joints of landslide prevention piles, it is necessary to perform rotary joining manually at construction sites where scaffolding is poor. The screw joint is basically screwed in until the shoulder part touches, but due to the joining at the construction site as described above, the screw cannot be completely tightened and the shoulder part does not touch, resulting in a gap of about 2 mm. It may end up.

　この場合、牽引工具等を用いて完全接合状態とすることで隙間が生じないようにすることもできるが、非常に手間がかかる。そのため、牽引工具等を用いて完全接合状態にすることを前提とするなら一般的な現場溶接接合に対するねじ継手の優位性が減殺されてしまう。 In this case, it is possible to prevent a gap from forming by using a towing tool or the like to make a perfect joint, but it is very time-consuming. Therefore, if it is premised that the complete joint state is achieved by using a traction tool or the like, the superiority of the threaded joint over the general on-site welded joint is diminished.

　また、一般的にねじ継手は圧縮荷重に対してショルダー部とねじ部で抵抗し、引張荷重に対してねじ部で抵抗するよう設計される。このため、完全にねじを締め切っていない不完全接合状態で曲げ荷重による圧縮荷重がねじ継手に作用すると、ショルダー部が圧縮荷重を伝達せず、ねじ部のみで荷重に抵抗することとなる。この結果、継手鋼材の全塑性荷重を十分に活かせないまま、圧縮側のねじ部が外れてしまいねじ継手の破壊に至ることがある。 Also, in general, threaded joints are designed to resist compressive loads at the shoulders and threads, and to resist tensile loads at the threads. Therefore, if a compressive load due to a bending load acts on the threaded joint in an incompletely joined state in which the screws are not completely closed, the shoulder portion does not transmit the compressive load, and only the threaded portion resists the load. As a result, the threaded portion on the compression side may come off and the threaded joint may be destroyed without fully utilizing the total plastic load of the joint steel material.

　本発明は、上記課題に鑑みてなされたものであって、その目的は、ショルダー部がタッチしない不完全接合状態であっても圧縮側のねじ部が外れることなく継手鋼材の全塑性荷重を十分に活かすことができるねじ継手を提供することにある。また、本発明の他の目的は、このようなねじ継手を前提としたねじ継手付き鋼管、構造体、構造体の構築方法、地すべり抑止杭、地すべり抑止杭の施工方法、ねじ継手の設計方法、ねじ継手の製造方法、ねじ継手付き鋼管の製造方法を提供することにある。 The present invention has been made in view of the above problems, and an object of the present invention is to sufficiently apply the total plastic load of the joint steel material without the threaded portion on the compression side coming off even in an incompletely joined state where the shoulder portion does not touch. It is to provide a threaded joint that can be utilized in. Further, another object of the present invention is a steel pipe with a threaded joint, a structure, a method of constructing a structure, a method of constructing a landslide restraining pile, a method of constructing a landslide suppressing pile, a method of designing a threaded joint, on the premise of such a threaded joint. It is an object of the present invention to provide a method for manufacturing a threaded joint and a method for manufacturing a steel pipe with a threaded joint.

　本発明に係るねじ継手は、鋼管の端部にあって前記鋼管同士を接合するねじ継手であって、テーパねじからなる雄ねじを有する雄側筒体と、テーパねじからなる雌ねじを有する雌側筒体と、を備え、前記雄ねじと前記雌ねじにおけるねじ山のスタビング面の鋼管軸直角方向に対する傾斜角度が0度～＋8度の範囲内にある。 The threaded joint according to the present invention is a threaded joint at the end of a steel pipe that joins the steel pipes to each other, and has a male side cylinder having a male screw made of a tapered screw and a female side cylinder having a female screw made of a tapered screw. The body is provided, and the inclination angle of the stubing surface of the thread in the male thread and the female thread with respect to the direction perpendicular to the steel pipe axis is in the range of 0 degrees to +8 degrees.

　前記雄側筒体と前記雌側筒体における全てのねじ山及びこれに対応するねじ底のピッチが同じであるとよい。 It is preferable that the pitches of all the threads and the corresponding screw bottoms in the male-side cylinder and the female-side cylinder are the same.

　本発明に係るねじ継手付き鋼管は、本発明に係るねじ継手における雄側筒体と雌側筒体を、次の（１）から（３）のいずれか１つの態様で備える。
（１）前記雄側筒体を、前記鋼管の少なくとも一端に設ける態様
（２）前記雌側筒体を、前記鋼管の少なくとも一端に設ける態様
（３）前記雄側筒体と前記雌側筒体を、前記鋼管の一端と他端に設ける態様 The steel pipe with a screw joint according to the present invention comprises a male side cylinder and a female side cylinder in the screw joint according to the present invention in any one of the following (1) to (3).
(1) A mode in which the male side cylinder is provided at at least one end of the steel pipe (2) A mode in which the female side cylinder is provided at at least one end of the steel pipe (3) The male side cylinder and the female side cylinder Is provided at one end and the other end of the steel pipe.

　本発明に係る構造体は、本発明に係るねじ継手と、該ねじ継手で連結された複数の鋼管とを備える。 The structure according to the present invention includes a threaded joint according to the present invention and a plurality of steel pipes connected by the threaded joint.

　本発明に係る構造体の構築方法は、本発明に係る構造体の構築方法であって、連結対象となるねじ継手付き鋼管の一方の回転を拘束した状態で、他方のねじ継手付き鋼管のねじ継手を、一方のねじ継手付き鋼管のねじ継手に位置合わせして回転嵌合する。 The method for constructing the structure according to the present invention is the method for constructing the structure according to the present invention, in which the rotation of one of the steel pipes with a threaded joint to be connected is restrained, and the screw of the steel pipe with a threaded joint of the other is restrained. The joint is aligned and rotationally fitted to the threaded joint of one of the threaded steel pipes.

　本発明に係る地すべり抑止杭は、本発明に係るねじ継手と、該ねじ継手で連結された複数の鋼管とを備える。 The landslide restraining pile according to the present invention includes a threaded joint according to the present invention and a plurality of steel pipes connected by the threaded joint.

　本発明に係る地すべり抑止杭の施工方法は、本発明に係るねじ継手を端部に取り付けた鋼管を用いた地すべり抑止杭の施工方法であって、次の（１）から（３）のいずれか１つの態様で施工する。
（１）地盤に杭を挿入する孔を必要な長さの全長に亘って掘削する孔掘削工程と、掘削した孔に前記鋼管の頭が突出するように吊下げて、前記ねじ継手により順次回転接合して自重挿入し、所定の本数の継杭が完了した後、前記鋼管の周面と地盤との隙間に充填材を充填して地盤に密着させる工程とを含む態様
（２）地盤に杭を挿入する孔を必要な長さの全長に亘って掘削する孔掘削工程と、前記鋼管を前記ねじ継手により必要長さ接合する鋼管接合工程と、接合された鋼管を孔に挿入し、前記鋼管の周面と地盤との隙間に充填材を充填して地盤に密着させる工程とを含む態様
（３）既に施工済みの杭あるいは反力部材によって反力を取りながら、前記鋼管を回転圧入により地中に貫入する工程と、地中に貫入した鋼管の頭部に前記鋼管を回転接合する工程と、回転接合した鋼管を回転圧入により地中に貫入する工程とを含む態様 The method for constructing a landslide restraining pile according to the present invention is a method for constructing a landslide restraining pile using a steel pipe having a screw joint attached to an end thereof according to the present invention, and is any of the following (1) to (3). It is constructed in one mode.
(1) A hole excavation process in which a hole for inserting a pile in the ground is excavated over the entire length required, and the steel pipe is suspended from the excavated hole so that the head of the steel pipe protrudes, and is sequentially rotated by the screw joint. Aspects including a step of joining and inserting by its own weight, and after completing a predetermined number of joint piles, filling the gap between the peripheral surface of the steel pipe and the ground with a filler and bringing it into close contact with the ground (2) Pile on the ground. A hole drilling step of drilling a hole to be inserted over the entire length of a required length, a steel pipe joining step of joining the steel pipe to the required length by the screw joint, and a steel pipe joining step of inserting the joined steel pipe into the hole and inserting the steel pipe into the hole. Aspects including a step of filling a gap between the peripheral surface and the ground with a filler and bringing it into close contact with the ground (3) While taking a reaction force with a pile or a reaction force member that has already been constructed, the steel pipe is rotationally press-fitted into the ground. A mode including a step of penetrating into the ground, a step of rotationally joining the steel pipe to the head of the steel pipe penetrating into the ground, and a step of penetrating the rotary-bonded steel pipe into the ground by rotational press-fitting.

　本発明の第１の態様に係るねじ継手の設計方法は、テーパねじからなる雄ねじを有する雄側筒体と、テーパねじからなる雌ねじを有する雌側筒体と、を有し、鋼管の端部にあって前記鋼管同士を接合するねじ継手の設計方法であって、前記雄ねじと前記雌ねじにおけるねじ山のスタビング面の鋼管軸直角方向に対する傾斜角度を、0度～＋8度の範囲内で設定する。 The method for designing a threaded joint according to the first aspect of the present invention includes a male side cylinder having a male screw made of a tapered screw and a female side cylinder having a female screw made of a tapered screw, and has an end portion of a steel pipe. In this method of designing a threaded joint for joining steel pipes to each other, the inclination angle of the stubing surface of the thread of the male thread and the female thread with respect to the direction perpendicular to the steel pipe axis is set within the range of 0 degrees to +8 degrees. ..

　本発明の第２の態様に係るねじ継手の設計方法は、テーパねじからなる雄ねじを有する雄側筒体と、テーパねじからなる雌ねじを有する雌側筒体と、を有し、鋼管の端部にあって前記鋼管同士を接合するねじ継手の設計方法であって、鋼材全塑性荷重に対する載荷荷重の比と、設定ねじ鉛直角度との関係を、摩擦係数ごとに予め求めておき、設計に際して設定した摩擦係数において前記比が1.0以上になる設定ねじ鉛直角度を、前記雄側筒体と前記雌側筒体におけるねじ山のスタビング面の鋼管軸直角方向に対する傾斜角度として設定する。 The method for designing a threaded joint according to a second aspect of the present invention includes a male side cylinder having a male screw made of a tapered screw and a female side cylinder having a female screw made of a tapered screw, and has an end portion of a steel pipe. This is a method for designing a threaded joint that joins steel pipes to each other. The relationship between the ratio of the loaded load to the total plastic load of the steel material and the vertical angle of the set screw is obtained in advance for each friction coefficient and set at the time of design. The set screw vertical angle at which the ratio is 1.0 or more in the friction coefficient is set as the inclination angle of the stubing surface of the thread in the male side cylinder and the female side cylinder in the direction perpendicular to the steel pipe axis.

　本発明の第１の態様に係るねじ継手の製造方法は、テーパねじからなる雄ねじを有する雄側筒体と、テーパねじからなる雌ねじを有する雌側筒体と、を有し、鋼管の端部にあって前記鋼管同士を接合するねじ継手の製造方法であって、前記雄ねじと前記雌ねじにおけるねじ山のスタビング面の鋼管軸直角方向に対する傾斜角度を、0度～＋8度の範囲内で形成する。 The method for manufacturing a threaded joint according to the first aspect of the present invention includes a male side cylinder having a male screw made of a tapered screw and a female side cylinder having a female screw made of a tapered screw, and has an end portion of a steel pipe. It is a method of manufacturing a threaded joint for joining the steel pipes to each other, and forms an inclination angle of the stubing surface of the thread of the male thread and the female thread in the direction perpendicular to the steel pipe axis within a range of 0 degrees to +8 degrees. ..

　本発明の第２の態様に係るねじ継手の製造方法は、テーパねじからなる雄ねじを有する雄側筒体と、テーパねじからなる雌ねじを有する雌側筒体と、を有し、鋼管の端部にあって前記鋼管同士を接合するねじ継手の製造方法であって、鋼材全塑性荷重に対する載荷荷重の比と、設定ねじ鉛直角度との関係を、摩擦係数ごとに予め求めておき、予め設定された摩擦係数において前記比が1.0以上になる設定ねじ鉛直角度を、前記雄側筒体と前記雌側筒体におけるねじ山のスタビング面の鋼管軸直角方向に対する傾斜角度として形成する。 The method for manufacturing a threaded joint according to a second aspect of the present invention includes a male side cylinder having a male screw made of a tapered screw and a female side cylinder having a female screw made of a tapered screw, and has an end portion of a steel pipe. In this method of manufacturing a threaded joint for joining steel pipes to each other, the relationship between the ratio of the loaded load to the total plastic load of the steel material and the set screw vertical angle is obtained in advance for each friction coefficient and set in advance. A set screw vertical angle at which the ratio is 1.0 or more in the friction coefficient is formed as an inclination angle of the stubing surface of the thread in the male side cylinder and the female side cylinder in the direction perpendicular to the steel pipe axis.

　前記雄側筒体と前記雌側筒体を、次の（１）から（３）のいずれか１つの態様で取り付けるとよい。
（１）前記雄側筒体を、前記鋼管の少なくとも一端に取り付ける態様
（２）前記雌側筒体を、前記鋼管の少なくとも一端に取り付ける態様
（３）前記雄側筒体と前記雌側筒体を、前記鋼管の一端と他端に取り付ける態様 The male-side cylinder and the female-side cylinder may be attached in any one of the following (1) to (3).
(1) A mode in which the male side cylinder is attached to at least one end of the steel pipe (2) A mode in which the female side cylinder is attached to at least one end of the steel pipe (3) The male side cylinder and the female side cylinder Is attached to one end and the other end of the steel pipe.

　本発明によれば、曲げによる圧縮荷重がねじ継手に作用した場合に、ショルダー部の隙間が２ｍｍ程度あるような完全に締め切っていない不完全接合状態であっても、圧縮側のねじ部のみで十分な荷重伝達ができ、圧縮側のねじ部が外れることなくねじ継手鋼材の全塑性荷重を十分に活かすことができる。そのため足場の悪い施工現場において人力での回転接合を行う必要がある地すべり抑止杭に用いられるねじ継手において、労力のかかる牽引工具による締め切りや厳密な施工管理を省略することができる。 According to the present invention, when a compressive load due to bending acts on a threaded joint, even in an incompletely joined state where the shoulder portion has a gap of about 2 mm and is not completely closed, only the threaded portion on the compression side is used. Sufficient load transmission is possible, and the total plastic load of the threaded joint steel material can be fully utilized without the threaded portion on the compression side coming off. Therefore, in a threaded joint used for a landslide prevention pile that requires manual rotary joining at a construction site with poor scaffolding, it is possible to omit the labor-intensive deadline and strict construction management.

図１は、本発明の一実施の形態に係るねじ継手の説明図である。FIG. 1 is an explanatory diagram of a threaded joint according to an embodiment of the present invention. 図２は、図１のねじ継手を用いた地すべり抑止杭に曲げ荷重が作用した際の、ねじ継手を含む全体の挙動を説明する説明図である。FIG. 2 is an explanatory diagram illustrating the overall behavior including the threaded joint when a bending load is applied to the landslide restraining pile using the threaded joint of FIG. 1. 図３は、図２の状態におけるねじ継手の挙動を説明する説明図である。FIG. 3 is an explanatory diagram illustrating the behavior of the threaded joint in the state of FIG. 図４は、スタビング面もしくはロード面における鋼管軸直角方向に対する傾斜角度（設定ねじ鉛直角度）とスタビング面間もしくはロード面間の摩擦係数との関係を示す図である。FIG. 4 is a diagram showing the relationship between the inclination angle (set screw vertical angle) of the stubing surface or the load surface in the direction perpendicular to the steel pipe axis and the friction coefficient between the stubing surfaces or the load surface. 図５は、従来例におけるねじ継手の挙動を説明する説明図である。FIG. 5 is an explanatory diagram illustrating the behavior of the threaded joint in the conventional example. 図６は、傾斜角度の検討における鋼材全塑性荷重を説明する説明図である。FIG. 6 is an explanatory diagram illustrating the total plastic load of the steel material in the examination of the inclination angle. 図７は、傾斜角度の検討における解析結果を示す図である（その１）。FIG. 7 is a diagram showing the analysis results in the examination of the inclination angle (No. 1). 図８は、傾斜角度の検討における解析結果を示す図である（その２）。FIG. 8 is a diagram showing the analysis results in the examination of the inclination angle (No. 2). 図９は、傾斜角度の検討における解析結果を示す図である（その３）。FIG. 9 is a diagram showing the analysis results in the examination of the inclination angle (No. 3).

　本実施の形態に係るねじ継手１は、図１（ａ）に示すように、鋼管３の（軸方向）端部にあって鋼管３同士を接合するものであって、テーパねじ（taper　thread）からなる雄ねじ５を有する雄側筒体７と、テーパねじ（taper　thread）からなる雌ねじ９を有する雌側筒体１１とを備えている。以下、各構成を詳細に説明する。 As shown in FIG. 1A, the threaded joint 1 according to the present embodiment is located at the (axial) end of the steel pipe 3 and joins the steel pipes 3 to each other, and is a taper thread. It includes a male-side cylinder 7 having a male screw 5 made of, and a female-side cylinder 11 having a female screw 9 made of a taper thread. Hereinafter, each configuration will be described in detail.

　本実施の形態のねじ継手１は、複数の鋼管３を連結することで構成される構造体の一例として地すべり抑止用鋼管杭(以下、省略して「地すべり抑止杭」とする)を例示し、この鋼管３の接合手段として適用したものである。地すべり抑止杭の場合、杭本体となる鋼管３の直径φは216mm以上である。上限は特に規定はないが、近年の傾向を踏まえると、鋼管の直径φは2500mm以下である。図１（ａ）に示す状態は、非締め切り状態、すなわち雌側筒体１１の先端１１ａが雄側筒体７のショルダー部７ａに接触していない（ショルダータッチしていないともいう）状態を示している。 The threaded joint 1 of the present embodiment exemplifies a steel pipe pile for landslide prevention (hereinafter, abbreviated as "landslide prevention pile") as an example of a structure composed of connecting a plurality of steel pipes 3. It is applied as a joining means for the steel pipe 3. In the case of a landslide restraining pile, the diameter φ of the steel pipe 3 serving as the pile body is 216 mm or more. There is no particular upper limit, but based on recent trends, the diameter φ of steel pipes is 2500 mm or less. The state shown in FIG. 1A indicates a non-deadline state, that is, a state in which the tip end 11a of the female side cylinder 11 is not in contact with the shoulder portion 7a of the male side cylinder 7 (also referred to as not touching the shoulder). ing.

　雄側筒体７と雌側筒体１１は、図１（ａ）に示すように、下杭及び上杭となる鋼管３の外径と実質的に等しい外径を有するリング体にねじ加工したものであり、雄側筒体７が上杭の下端に雌側筒体１１が下杭の上端にそれぞれ取り付けられている。本実施の形態の場合、鋼管端部への雄側筒体または雌側筒体の取り付けは、溶接により接合されることで行われている。 As shown in FIG. 1A, the male side cylinder 7 and the female side cylinder 11 are threaded into a ring body having an outer diameter substantially equal to the outer diameter of the steel pipe 3 to be the lower pile and the upper pile. The male side cylinder 7 is attached to the lower end of the upper pile, and the female side cylinder 11 is attached to the upper end of the lower pile. In the case of the present embodiment, the male-side cylinder or the female-side cylinder is attached to the end of the steel pipe by joining them by welding.

　ここで、雄側筒体７と雌側筒体１１は、鋼管３と同じ鋼種としても良い。ただし、同じ鋼種を用いて雄側筒体７と雌側筒体１１の強度を高くしたい場合には厚さが必要となり、鋼管３に対する張り出し幅が大きくなる。その結果、施工性や荷重伝達性能を落とす場合がある。そこで、厚さをあまり厚くしたくない場合には、雄側筒体７と雌側筒体１１の鋼種として、鋼管３の鋼種の降伏強度を上回る鋼種を選択することで張り出し幅を減らすことができる。例えば、一般的な地すべり抑止杭においては、鋼管３の鋼種としては、SKK490材相当（規格降伏強度が315N/mm²）またはSM570材相当（規格降伏強度が板厚16mm以下で460N/mm²、板厚16mm越え40mm以下で450N/mm²、板厚40mm越え75mm以下で430N/mm²）の鋼種が用いられる。そこで、雄側筒体７の鋼種及び／又は雌側筒体１１の鋼種にHITEN780材相当（規格降伏強度が685N/mm²）の鋼種を用いれば、強度を高くしつつ雄側筒体７と雌側筒体１１の厚さを減らすことができ、鋼管３に対する張り出し幅を抑えることができる。 Here, the male side cylinder 7 and the female side cylinder 11 may have the same steel type as the steel pipe 3. However, if it is desired to increase the strength of the male side cylinder 7 and the female side cylinder 11 using the same steel type, a thickness is required, and the overhang width with respect to the steel pipe 3 becomes large. As a result, workability and load transmission performance may be reduced. Therefore, if you do not want to make the thickness too thick, you can reduce the overhang width by selecting a steel grade that exceeds the yield strength of the steel grade of the steel pipe 3 as the steel grade of the male side cylinder 7 and the female side cylinder 11. can. For example, in a general landslide restraint pile, the steel type of steel pipe 3 is equivalent to SKK490 material (standard yield strength is 315N / mm ² ) or SM570 material (standard yield strength is 460N / mm ² when the plate thickness is 16mm or less). Steel grades of 450 N / mm ² when the plate thickness exceeds 16 mm and 40 mm or less, and 430 N / mm ² ) when the plate thickness exceeds 40 mm and 75 mm or less are used. Therefore, if a steel grade equivalent to HITEN 780 material (standard yield strength of 685 N / mm ² ) is used for the steel grade of the male side cylinder 7 and / or the steel grade of the female side cylinder 11, the male side cylinder 7 can be used while increasing the strength. The thickness of the female side cylinder 11 can be reduced, and the overhang width with respect to the steel pipe 3 can be suppressed.

　雄側筒体７に形成された雄ねじ５と雌側筒体１１に形成された雌ねじ９は、どちらもテーパねじである。雄ねじ５と雌ねじ９は、雄側筒体７と雌側筒体１１を近づける方向に回転することで接合する。図１（ａ）では雄側筒体７を上側とし、雌側筒体１１を下側としているが、上下を反対にしても良い。前述のショルダー部７ａは、雄側筒体７のテーパねじの終端に雌側筒体１１の先端１１ａが接触できるよう、段状となっている。 The male screw 5 formed on the male side cylinder 7 and the female screw 9 formed on the female side cylinder 11 are both tapered screws. The male screw 5 and the female screw 9 are joined by rotating the male-side cylinder 7 and the female-side cylinder 11 in a direction to bring them closer to each other. In FIG. 1A, the male side cylinder 7 is on the upper side and the female side cylinder 11 is on the lower side, but the top and bottom may be reversed. The shoulder portion 7a described above is stepped so that the tip 11a of the female cylinder 11 can come into contact with the end of the tapered screw of the male cylinder 7.

　図１（ａ）における点線の丸部分の拡大図を図１（ｂ）に示す。図１（ｂ）においては、雄ねじ５と雌ねじ９は台形ねじ（trapezoidal　thread）、角ねじ（square　thread）またはのこ歯ねじ（buttress　thread）のいずれかであることが好ましい。また、雄ねじ５のねじ山は頂部５１と、それに繋がる２つの側面５ａ（後述のスタビング面５ａ），５ｂ（後述のロード面５ｂ）とを備えている。さらに、雄ねじ５のねじ山の側面５ａと一方の隣のねじ山の側面５ｂとはねじ底５２でつながっている。雄ねじ５ねじ山の側面５ｂと他方の隣の側面５ａとは、ねじ底５２でつながっている。同様に、雌ねじ９は、ねじ山に頭頂９１とそれに繋がる２つの側面９ｂ（後述のロード面９ｂ），９ａ（後述のスタビング面９ａ）とを備えている。さらに、雌ねじ９のねじ山の側面９ａと一方の隣のねじ山の側面９ｂとはねじ底９２でつながっている。雌ねじ９のねじ山の側面９ｂと他方の隣の側面９ａとは、ねじ底９２でつながっている。 FIG. 1 (b) shows an enlarged view of the dotted circle portion in FIG. 1 (a). In FIG. 1 (b), the male thread 5 and the female thread 9 are preferably either trapezoidal threads, square threads, or sawtooth threads. Further, the thread of the male screw 5 includes a top portion 51 and two side surfaces 5a (stabbed surface 5a described later) and 5b (load surface 5b described later) connected to the top portion 51. Further, the side surface 5a of the thread of the male screw 5 and the side surface 5b of the thread adjacent to one side are connected by a thread bottom 52. The side surface 5b of the male thread 5 thread and the side surface 5a adjacent to the other side are connected by a screw bottom 52. Similarly, the female screw 9 is provided with a crown 91 and two side surfaces 9b (load surface 9b described later) and 9a (stubing surface 9a described later) connected to the crown 91 on the screw thread. Further, the side surface 9a of the thread of the female thread 9 and the side surface 9b of the thread adjacent to one side are connected by a thread bottom 92. The side surface 9b of the thread of the female thread 9 and the side surface 9a adjacent to the other side are connected by a thread bottom 92.

　また、図１（ａ）に示したＰはねじ山のピッチを示している。このねじ山のピッチＰとは、ある１条における雄ねじ５のねじ山頂部５１の端から次の１条の雄ねじ５のねじ山頂部５１の始まる位置までの鋼管軸方向の距離、あるいは、ある１条の雌ねじ９のねじ山頂部９１の端から次の１条のねじ山頂部９１の始まる位置までの鋼管軸方向の距離である。同様に、ねじ底のピッチとは、ある１条における雄ねじ５のねじ山頂部５１に対応するねじ底９２の端から、次の１条の雄ねじ５のねじ山頂部５１に対応するねじ底９２の始まる位置までの、鋼管軸方向の距離である。または、ある１条の雌ねじ９のねじ山頂部９１に対応するねじ底５２の端から、次の１条のねじ山頂部９１に対応するねじ底５２の始まる位置までの、鋼管軸方向の距離である。１条ねじの場合には、ピッチは、１回転したときにねじが進む距離を意味する。これに対して、多条ねじにおいては、ねじの条数によって１回転したときの進む距離が異なることから、一定の距離としてのピッチを定義できない。このため、本明細書では上記のように定義している。 Further, P shown in FIG. 1 (a) indicates the pitch of the screw thread. The pitch P of this thread is the distance in the steel pipe axial direction from the end of the thread top 51 of the male thread 5 in one thread to the starting position of the thread top 51 of the next male thread 5 in one thread, or 1 It is the distance in the steel pipe axial direction from the end of the thread top 91 of the female thread 9 of the thread to the starting position of the thread top 91 of the next thread 1. Similarly, the pitch of the thread bottom is the pitch of the thread bottom 92 corresponding to the thread top 51 of the next male thread 5 from the end of the thread bottom 92 corresponding to the thread top 51 of the male screw 5 in one thread. The distance along the steel pipe axis to the starting position. Alternatively, at the distance in the steel pipe axial direction from the end of the thread bottom 52 corresponding to the thread top 91 of one female thread 9 to the starting position of the thread bottom 52 corresponding to the next thread top 91 of one thread. be. In the case of a single thread, the pitch means the distance that the screw travels when it makes one revolution. On the other hand, in the case of a multi-threaded screw, the pitch as a constant distance cannot be defined because the distance traveled when one rotation is performed differs depending on the number of threads of the screw. Therefore, it is defined as described above in this specification.

　また、図１（ａ）に示したｈはねじ高さを示している。ここで、ねじ高さｈとは、雄ねじ５のねじ山頂部５１からねじ底５２までの距離（テーパの勾配軸２１に直交する勾配軸直交軸２３方向の距離）、または、雌ねじ９のねじ山頂部９１からねじ底９２までの距離（テーパの勾配軸２１に直交する勾配軸直交軸２３方向の距離）である。 Further, h shown in FIG. 1 (a) indicates the screw height. Here, the thread height h is the distance from the thread top 51 of the male thread 5 to the thread bottom 52 (distance in the direction of the gradient axis orthogonal axis 23 orthogonal to the gradient axis 21 of the taper), or the thread top of the female thread 9. The distance from the portion 91 to the screw bottom 92 (distance in the direction of the gradient axis orthogonal axis 23 orthogonal to the gradient axis 21 of the taper).

　本実施の形態に係るねじ継手１においては、雄側筒体７に形成された雄ねじ５と雌側筒体１１に形成された雌ねじ９におけるねじ山のスタビング面５ａ、９ａの鋼管軸直角方向に対する傾斜角度αが0度～＋8度に設定されている。ここで、傾斜角度αについて説明する。図１（ｂ）に示すように、鋼管軸２５に直交方向の軸を鋼管直交軸２７とすれば、傾斜角度αは、ねじ継手１を鋼管軸方向の断面にした状態（図１（ａ）の状態）において、雄ねじ５と雌ねじ９におけるねじ山のスタビング面５ａ、９ａが、同断面上にある鋼管直交軸２７と成す角度である。ここで、図示はしていないが、ねじ山のロード面５ｂ、９ｂの傾斜角度も同様に定義することができる。すなわち、鋼管軸２５に直交方向の軸を鋼管直交軸２７とすれば、ねじ山のロード面５ｂ、９ｂの傾斜角度は、ねじ継手１を鋼管軸方向の断面にした状態（図１（ａ）の状態）において、雄ねじ５と雌ねじ９におけるねじ山のロード面５ｂ、９ｂが、同断面上にある鋼管直交軸２７と成す角度である。 In the screw joint 1 according to the present embodiment, the stubing surfaces 5a and 9a of the threads of the male screw 5 formed on the male side cylinder 7 and the female screw 9 formed on the female side cylinder 11 with respect to the direction perpendicular to the steel pipe axis. The tilt angle α is set to 0 to +8 degrees. Here, the inclination angle α will be described. As shown in FIG. 1 (b), if the axis in the direction orthogonal to the steel pipe shaft 25 is the steel pipe orthogonal axis 27, the inclination angle α is a state in which the threaded joint 1 has a cross section in the steel pipe axial direction (FIG. 1 (a)). In the state of), the stubing surfaces 5a and 9a of the threads of the male thread 5 and the female thread 9 are at an angle formed with the steel pipe orthogonal axis 27 on the same cross section. Although not shown here, the inclination angles of the load surfaces 5b and 9b of the thread can be similarly defined. That is, if the axis orthogonal to the steel pipe shaft 25 is the steel pipe orthogonal axis 27, the inclination angles of the load surfaces 5b and 9b of the thread are in a state where the threaded joint 1 has a cross section in the steel pipe axial direction (FIG. 1A). The load surface 5b, 9b of the thread on the male thread 5 and the female thread 9 is an angle formed with the steel pipe orthogonal axis 27 on the same cross section.

　以下、ねじ山のスタビング面５ａ、９ａの鋼管軸直角方向に対する傾斜角度αをこのように設定している理由を、図２～図４に基づいて説明する。なお、本明細書において、ねじ山のスタビング面５ａ、９ａ及びロード面５ｂ、９ｂに設定された鋼管軸直角方向６６に対する傾斜角度αを、設定ねじ鉛直角度という場合がある。 Hereinafter, the reason why the inclination angle α of the stubing surfaces 5a and 9a of the screw thread with respect to the direction perpendicular to the steel pipe axis is set in this way will be described with reference to FIGS. 2 to 4. In the present specification, the inclination angle α with respect to the steel pipe axis perpendicular direction 66 set on the stubing surfaces 5a and 9a and the load surfaces 5b and 9b of the thread may be referred to as a set screw vertical angle.

　図２は、非締め切り状態の地すべり抑止杭に曲げ荷重が作用した際の、ねじ継手１を含む鋼管杭全体の挙動を示し、図３は図２の状態におけるねじ継手１の挙動を示している。まず、ねじ山のロード面５ｂ、９ｂとスタビング面５ａ、９ａについて、雄ねじ山を例に挙げて説明する。雄ねじ５のねじ山のロード面５ｂとは、雄ねじ５のねじ山における両側面（フランク）のうち、雄側筒体７の基端側（鋼管３が接合される側）にある面である。同様に、雌ねじ９のねじ山のロード面９ｂとは、雌ねじ９のねじ山における両側面（フランク）のうち、雌側筒体１１の基端側（鋼管３が接合される側）にある面である。雄ねじ５と雌ねじ９とを回転嵌合して接続した後に、ねじ継手１が引張荷重を受けたとき、雄ねじ５のねじ山のロード面５ｂと雌ねじ９のねじ山のロード面９ｂとが接触する。 FIG. 2 shows the behavior of the entire steel pipe pile including the threaded joint 1 when a bending load is applied to the landslide restraining pile in the non-deadline state, and FIG. 3 shows the behavior of the threaded joint 1 in the state of FIG. .. First, the load surfaces 5b and 9b of the screw thread and the stubing surfaces 5a and 9a will be described by taking a male thread as an example. The load surface 5b of the thread of the male thread 5 is a surface on both side surfaces (franks) of the thread of the male thread 5 on the base end side (the side to which the steel pipe 3 is joined) of the male side cylinder 7. Similarly, the load surface 9b of the thread of the female thread 9 is the surface on both side surfaces (franks) of the thread of the female thread 9 on the base end side (the side to which the steel pipe 3 is joined) of the female side cylinder 11. Is. After the male thread 5 and the female thread 9 are rotationally fitted and connected, when the threaded joint 1 receives a tensile load, the load surface 5b of the thread of the male thread 5 and the load surface 9b of the thread of the female thread 9 come into contact with each other. ..

　また、雄ねじ５のねじ山のスタビング面５ａとは、雄ねじ５のねじ山における両側面（フランク）のうち、雄側筒体７の先端１１ａ側にある面である。同様に、雌ねじ９のねじ山のスタビング面９ａとは、雌ねじ９のねじ山における両側面（フランク）のうち、雌側筒体１１の先端１１ａ側にある面である。雄側筒体７を雌側筒体１１に預けて回転嵌合する際には、雄ねじ５のねじ山のスタビング面５ａは、雌ねじ９のスタビング面９ａと接触する。つまり、端的に言うと、ねじ継手１はスタビング面５ａ、９ａで圧縮力を伝達し、ロード面５ｂ、９ｂで引張力を伝達するような構造となる。なお、ねじ山のスタビング面５ａ、９ａの鋼管軸直角方向に対する傾斜角度αに対し、ねじ山の頂部５１、９１に対して根元の幅が広がる方向の角度を＋（プラス）の角度とし、狭まる方向の角度を－（マイナス）の角度と表記する。 Further, the stubing surface 5a of the thread of the male screw 5 is a surface on both side surfaces (franks) of the thread of the male screw 5 on the tip 11a side of the male side cylinder 7. Similarly, the stubbing surface 9a of the thread of the female thread 9 is a surface on both side surfaces (franks) of the thread of the female thread 9 on the tip 11a side of the female side cylinder 11. When the male-side cylinder 7 is deposited in the female-side cylinder 11 and rotationally fitted, the stubbing surface 5a of the thread of the male screw 5 comes into contact with the stubing surface 9a of the female screw 9. That is, in short, the threaded joint 1 has a structure in which the compressive force is transmitted on the stubing surfaces 5a and 9a and the tensile force is transmitted on the load surfaces 5b and 9b. The angle of inclination α of the stubing surfaces 5a and 9a of the thread in the direction perpendicular to the steel pipe axis is narrowed by setting the angle in the direction in which the width of the root widens with respect to the tops 51 and 91 of the thread as a + (plus) angle. The angle in the direction is expressed as a- (minus) angle.

　前述したように本実施の形態では、ねじ山のスタビング面５ａ、９ａの鋼管軸直角方向に対する傾斜角度が0度～＋8度に設定されている（図３の一部拡大図参照）。ねじ山のスタビング面５ａ、９ａの設定ねじ鉛直角度を上記のように設定することで、ねじ継手１において曲げ荷重が作用した際に圧縮力が働く側（図３において上側が圧縮、下側が引張）で、ねじ山の接触面が滑り出しにくくなる。これにより、図３に示すように、雄ねじ５のスタビング面５ａが滑って外れることなく、十分な荷重伝達ができる状態になる。 As described above, in the present embodiment, the inclination angles of the stubing surfaces 5a and 9a of the threads with respect to the direction perpendicular to the steel pipe axis are set to 0 to +8 degrees (see a partially enlarged view of FIG. 3). Setting the stubing surfaces 5a and 9a of the thread thread By setting the vertical angle of the screw as described above, the side where the compressive force acts when a bending load is applied to the threaded joint 1 (in FIG. 3, the upper side is compression and the lower side is tension). ) Makes it difficult for the contact surface of the thread to slip out. As a result, as shown in FIG. 3, the stubing surface 5a of the male screw 5 does not slip off, and a sufficient load can be transmitted.

　ここで、スタビング面５ａ、９ａの設定ねじ鉛直角度とねじの滑り難さとの関係について、図４に基づいて説明する。図４は、クーロンの摩擦法則（F=μN：Fは摩擦力、μは固体間の摩擦係数、Nは垂直力）と、スタビング面５ａ、９ａもしくはロード面５ｂ、９ｂの設定ねじ鉛直角度と摩擦係数との関係を示したものである。縦軸は設定ねじ鉛直角度（°）を、横軸は、接触したスタビング面５ａとスタビング面９ａとの間（略して、「スタビング面間」と呼ぶこともある）、もしくは接触したロード面５ｂとロード面９ｂとの間（略して、「ロード面間」と呼ぶこともある）の摩擦係数（無次元量）を示している。図４中の直線は、上記のクーロンの摩擦法則から導き出した式で、設定ねじ鉛直角度をαとし静止摩擦係数をμとした場合の関係を示しており、下記の式（１）となる。 Here, the relationship between the vertical angle of the set screw of the stubing surfaces 5a and 9a and the slip resistance of the screw will be described with reference to FIG. FIG. 4 shows Coulomb's friction law (F = μN: F is the friction force, μ is the coefficient of friction between solids, N is the normal force) and the set screw vertical angles of the stubing surfaces 5a and 9a or the load surfaces 5b and 9b. It shows the relationship with the coefficient of friction. The vertical axis represents the vertical angle (°) of the set screw, and the horizontal axis represents the contact between the stubing surface 5a and the stubing surface 9a (sometimes referred to as “stubbing surface” for short) or the contacted load surface 5b. The coefficient of friction (dimensionless quantity) between the load surface 9b and the load surface 9b (sometimes referred to as “load surface interval” for short) is shown. The straight line in FIG. 4 is an equation derived from the above-mentioned Coulomb's friction law, and shows the relationship when the set screw vertical angle is α and the static friction coefficient is μ, and is the following equation (1).

α=tan^-1(μ)・・・（１） α = tan ^-1 (μ) ・ ・ ・ (1)

　なお、αは接触したスタビング面５ａ、９ａもしくは接触したロード面５ｂ、９ｂの鋼管軸直角方向に対する角度で、正負は前述した定義の通りである。式（１）によれば、特定の設定ねじ鉛直角度αにおけるスタビング面間もしくはロード面間の摩擦係数が静止摩擦係数μよりも小さくなると、スタビング面同士もしくはロード面同士が滑り出す。つまり、設定ねじ鉛直角度αが式（１）以下となる領域の条件であれば滑り出さない。言い換えると、スタビング面５ａ、９ａまたはロード面５ｂ、９ｂにおいて、図４中で設定ねじ鉛直角度αが式（１）以下となるハッチング領域はねじが「滑らない範囲」を示している。また、図中において設定ねじ鉛直角度αが式（１）より上となるハッチングされていない領域は、ねじが「滑る範囲」を示している。 Note that α is the angle of the contacted stubing surfaces 5a and 9a or the contacted load surfaces 5b and 9b with respect to the direction perpendicular to the steel pipe axis, and the positive and negative are as defined above. According to the equation (1), when the friction coefficient between the stubing surfaces or the load surfaces at a specific set screw vertical angle α becomes smaller than the static friction coefficient μ, the stubing surfaces or the load surfaces start to slide from each other. That is, if the condition is in the region where the vertical angle α of the set screw is equal to or less than the equation (1), the screw does not start to slide. In other words, on the stubing surfaces 5a and 9a or the load surfaces 5b and 9b, the hatched region where the set screw vertical angle α is equal to or less than the equation (1) in FIG. 4 indicates a “range in which the screw does not slip”. Further, in the figure, the unhatched region where the set screw vertical angle α is higher than the equation (1) indicates the “sliding range” of the screw.

　図４から分かる通り、スタビング面間もしくはロード面間の摩擦係数が同じであれば、設定ねじ鉛直角度αが小さいほど、すなわちスタビング面５ａ、９ａの鋼管軸直角方向に対する傾斜角度が小さいほど、スタビング面５ａ、９ａが滑りにくくなることが分かる。そして、後述の［傾斜角度の検討］で示す発明者の検討により、スタビング面５ａ、９ａの鋼管軸直角方向に対する傾斜角度を0度～＋8度に設定することで、鋼材の全塑性荷重に至るまで滑りが発生しないことが分かった。本発明はかかる知見に基づいて設定ねじ鉛直角度を0度～＋8度に設定している。 As can be seen from FIG. 4, if the friction coefficient between the stubing surfaces or the load surface is the same, the smaller the vertical angle α of the set screw, that is, the smaller the inclination angle of the stubing surfaces 5a and 9a with respect to the steel pipe axis perpendicular direction, the more stubing. It can be seen that the surfaces 5a and 9a are less slippery. Then, according to the inventor's examination shown in [Examination of inclination angle] described later, by setting the inclination angle of the stubing surfaces 5a and 9a with respect to the direction perpendicular to the steel pipe axis to 0 degree to +8 degree, the total plastic load of the steel material is reached. It turned out that slipping did not occur until. In the present invention, the vertical angle of the set screw is set to 0 to +8 degrees based on such findings.

　図５は、特許文献２に記載のねじ継手１３におけるスタビング面１５ａ、１７ａ（特許文献２では、ねじ挿入面１３、２３が該当する。）の角度が鋼管軸直角方向に対する傾斜角度が＋20度～＋45度である従来のねじ継手１３に、図２に示した曲げ荷重が作用したときの挙動を示している。特許文献２のねじ継手１３では、曲げ荷重が作用した際に圧縮力が働く図中上側のねじ部において、ねじ部の摩擦力を越える力が働くことで、図５に示すように、雄ねじ１５のスタビング面１５ａに滑りが生じてねじが外れてしまう。 In FIG. 5, the angle of the stubing surfaces 15a and 17a (corresponding to the screw insertion surfaces 13 and 23 in Patent Document 2) of the threaded joint 13 described in Patent Document 2 is an inclination angle of +20 degrees with respect to the direction perpendicular to the steel pipe axis. The behavior when the bending load shown in FIG. 2 is applied to the conventional threaded joint 13 having a temperature of +45 degrees is shown. In the threaded joint 13 of Patent Document 2, a force exceeding the frictional force of the threaded portion acts on the upper threaded portion in the figure in which a compressive force acts when a bending load is applied, so that the male screw 15 acts as shown in FIG. The stubing surface 15a of the above slips and the screw comes off.

　以上のように、本実施の形態のねじ継手１においては、スタビング面５ａ、９ａの鋼管軸直角方向に対する傾斜角度（設定ねじ鉛直角度）を0度～＋8度に設定した。これにより、鋼管３の曲げによる圧縮荷重が継手に作用した場合に、ショルダー部７ａの隙間が２ｍｍ程度あるような完全に締め切っていない不完全接合状態であるねじ継手１であっても、圧縮側のねじ部のみで十分な荷重伝達ができる。その結果、圧縮側のねじ部が外れることなく継手鋼材の全塑性荷重を十分に活かすことができる。そのため、地すべり抑止杭に用いられるねじ継手１において、特に好適である。その理由は、地すべり抑止杭に用いられるねじ継手１では、足場の悪い施工現場において人力での回転接合を行う場合が多く、その場合、労力のかかる牽引工具による締め切りや厳密な施工管理を省略することができるからである。 As described above, in the threaded joint 1 of the present embodiment, the inclination angle (set screw vertical angle) of the stubing surfaces 5a and 9a with respect to the direction perpendicular to the steel pipe axis is set to 0 degree to +8 degree. As a result, when the compressive load due to the bending of the steel pipe 3 acts on the joint, even if the threaded joint 1 is in an incompletely joined state where the gap between the shoulder portions 7a is about 2 mm and is not completely closed, the compression side Sufficient load transmission is possible only with the threaded part of. As a result, the total plastic load of the joint steel material can be fully utilized without the threaded portion on the compression side coming off. Therefore, it is particularly suitable for the threaded joint 1 used for the landslide restraining pile. The reason is that in the threaded joint 1 used for the landslide prevention pile, the rotary joint is often performed manually at the construction site where the scaffolding is poor, and in that case, the deadline by the labor-intensive traction tool and the strict construction management are omitted. Because it can be done.

　本実施の形態のねじ継手１を地すべり抑止杭に適用した際の具体的な施工方法として、以下３つが考えられる。
（ａ）地盤に杭を挿入する孔を必要な長さの全長に亘って掘削する孔掘削工程と、掘削した孔に本発明のねじ継手１を取り付けた鋼管の頭が突出するように吊下げて、ねじ継手１により順次回転接合して自重挿入し、所定の本数の継杭が完了した後、鋼管周面と地盤との隙間に充填材（例えば、グラウト、モルタル等）を充填して地盤に密着させる。
（ｂ）地盤に杭を挿入する孔を必要な長さの全長に亘って掘削する孔掘削工程と、本発明のねじ継手１を取り付けた鋼管をねじ継手１により必要長さ接合する鋼管接合工程と、接合された鋼管を孔にクレーン等で挿入し、鋼管周面と地盤との隙間に充填材（例えば、グラウト、モルタル等）を充填して地盤に密着させる。
（ｃ）既に施工済みの杭あるいは反力部材によって反力を取りながら、本発明のねじ継手１を取り付けた鋼管を回転圧入により地中に貫入する工程と、地中に貫入した杭頭部に本発明のねじ継手１を取り付けた鋼管を回転接合する工程と、回転接合した鋼管を回転圧入により地中に貫入する工程とを含むもの。 The following three can be considered as specific construction methods when the threaded joint 1 of the present embodiment is applied to a landslide restraining pile.
(A) A hole excavation step of excavating a hole for inserting a pile in the ground over the entire length required, and suspending the excavated hole so that the head of a steel pipe to which the threaded joint 1 of the present invention is attached protrudes. After the predetermined number of piles are completed, the gap between the peripheral surface of the steel pipe and the ground is filled with a filler (for example, grout, mortar, etc.) and the ground is inserted. Adhere to.
(B) A hole excavation step of excavating a hole for inserting a pile in the ground over the entire length required, and a steel pipe joining step of joining a steel pipe to which the threaded joint 1 of the present invention is attached by the threaded joint 1 to the required length. Then, the joined steel pipe is inserted into the hole by a crane or the like, and the gap between the peripheral surface of the steel pipe and the ground is filled with a filler (for example, grout, mortar, etc.) and brought into close contact with the ground.
(C) The process of penetrating the steel pipe to which the threaded joint 1 of the present invention is attached into the ground by rotary press-fitting while taking the reaction force with a pile or reaction force member that has already been constructed, and the pile head that has penetrated into the ground. It includes a step of rotationally joining a steel pipe to which a screw joint 1 of the present invention is attached and a step of penetrating the rotary-joined steel pipe into the ground by rotary press-fitting.

　もちろん、本発明は地すべり抑止杭以外の杭または鋼管に対しても利用できる。より具体的には、支持杭、摩擦杭、鋼管矢板、斜杭または構造物の一部である鋼管などにも利用できる。これらの用途に使用した場合でも、既に説明した効果、すなわち、鋼管３の曲げによる圧縮荷重が継手に作用した場合に、ショルダー部７ａの隙間が２ｍｍ程度あるような完全に締め切っていない不完全接合状態であるねじ継手１であっても、圧縮側のねじ部のみで十分な荷重伝達ができるという効果を得ることができる。 Of course, the present invention can also be used for piles or steel pipes other than landslide prevention piles. More specifically, it can also be used for support piles, friction piles, steel pipe sheet piles, slanted piles, steel pipes that are part of structures, and the like. Even when used for these purposes, the effect already explained, that is, when the compression load due to bending of the steel pipe 3 acts on the joint, the gap between the shoulder portions 7a is about 2 mm and the incomplete joint is not completely closed. Even in the threaded joint 1 in the state, it is possible to obtain the effect that sufficient load can be transmitted only by the threaded portion on the compression side.

　ここで一般的にテーパねじ継手が用いられる油井管用のねじ継手について説明する。油井管の場合、最大径が240mmと小さいので、少ないトルクで回転し接合させることができる。また、管内の内容物を漏れなく輸送する目的のため、シール性への要求が高い。その結果、ねじを締めきった状態、すなわち雌側筒体１１の先端１１ａが雄側筒体７のショルダー部７ａに接触している（ショルダータッチしているともいう）状態で使用される。そのため、接続された油井管に曲げ荷重が作用した際には、圧縮力をショルダー部で伝達が可能である。さらに、外部から何らかの荷重がかかる構造部材でないことから、高い強度が求められるわけでもない。以上の事情と、シール性を高める観点から、小さなトルクで回転するようスタビング面の鋼管軸直角方向に対する傾斜角度は+30°～+60°とされる。一方で、構造部材として用いられるねじ継手では、想定される最大径は2500mm程度のため、回転させるのに非常の大きなトルクを必要とし、接合難易度が高い。また、構造部材であるため、ねじ山にも高い強度が求められ、スタビング面の鋼管軸直角方向に対する傾斜角度は大きい方が望ましい。そして、油井管程のシール性は求められていない。そこで、従来のテーパねじ継手（特に油井管の技術）をそのまま構造部材用途に適用した場合、雌側筒体１１の先端１１ａが雄側筒体７のショルダー部７ａに完全に接触していない非締め切り状態での使用が要求される。言い換えれば、構造部材としてのねじ山の強度を確保しつつ、非締め切り状態でも圧縮側のねじ部が外れることのないねじ継手であることが、本発明にかかるねじ継手の非常に顕著な効果である。 Here, a threaded joint for oil country tubular goods, in which a tapered threaded joint is generally used, will be described. In the case of oil country tubular goods, the maximum diameter is as small as 240 mm, so it can be rotated and joined with a small torque. In addition, there is a high demand for sealing performance for the purpose of transporting the contents in the pipe without leakage. As a result, the screw is tightened, that is, the tip 11a of the female cylinder 11 is in contact with the shoulder portion 7a of the male cylinder 7 (also referred to as shoulder touch). Therefore, when a bending load acts on the connected well pipe, the compressive force can be transmitted by the shoulder portion. Further, since it is not a structural member to which some load is applied from the outside, high strength is not required. From the above circumstances and the viewpoint of improving the sealing performance, the inclination angle of the stubing surface with respect to the direction perpendicular to the steel pipe axis is set to + 30 ° to + 60 ° so as to rotate with a small torque. On the other hand, since the maximum diameter of a threaded joint used as a structural member is about 2500 mm, a very large torque is required to rotate it, and the difficulty of joining is high. Further, since it is a structural member, high strength is required for the thread, and it is desirable that the inclination angle of the stubing surface with respect to the direction perpendicular to the steel pipe axis is large. And, the sealing property of the oil well pipe is not required. Therefore, when the conventional tapered threaded joint (particularly the oil well pipe technology) is applied as it is to the structural member application, the tip 11a of the female side cylinder 11 does not completely contact the shoulder portion 7a of the male side cylinder 7. It is required to be used in the deadline state. In other words, it is a very remarkable effect of the threaded joint according to the present invention that it is a threaded joint in which the threaded portion on the compression side does not come off even in a non-deadline state while ensuring the strength of the threaded thread as a structural member. be.

　なお、特許文献２において、ねじ挿入面角度（設定ねじ鉛直角度）を＋20度より小さくすると、ねじ切り加工時の切削抵抗が大きくなるため、１パスでの切削量を減少させなければならず、加工効率が低下すると記載されている。しかしながら、本発明を適用することでねじ部の荷重伝達効率が上がり、ねじ山数やねじ山高さを減らすことが可能になり、１パスでの切削量の減少が大きな問題となることはない。また、特許文献２には、継ぎ杭作業の際に上杭と下杭の芯合わせが容易でなくなり、ねじ締結性が低下するとも記載されているが、対象構造物は上杭と下杭の外径が同じである場合には、４方向で位置を確認することができるので芯合わせが大きな問題となることはない。 In Patent Document 2, if the screw insertion surface angle (set screw vertical angle) is made smaller than +20 degrees, the cutting resistance during thread cutting increases, so the cutting amount in one pass must be reduced. It is stated that the efficiency will decrease. However, by applying the present invention, the load transmission efficiency of the threaded portion is increased, the number of threads and the height of threads can be reduced, and the reduction of the cutting amount in one pass does not become a big problem. Further, Patent Document 2 also describes that the alignment of the upper pile and the lower pile becomes difficult during the joint pile work, and the screw fastening property is deteriorated. However, the target structure is the upper pile and the lower pile. When the outer diameters are the same, the positions can be confirmed in four directions, so that the alignment does not become a big problem.

　本発明は、テーパねじを対象としているが、テーパねじならば１条ねじのみならず多条ねじの場合も同様に適用可能である。 The present invention is intended for tapered screws, but if it is a tapered screw, it can be applied not only to a single-threaded screw but also to a multi-threaded screw.

　なお、雄側筒体７と雌側筒体１１における全てのねじ山及びこれに対応するねじ底のピッチを同じに設定することが好ましい。このように設定することで、ねじ継手１に荷重が作用した際に、軸方向で全てのねじ山が均等に当接して荷重伝達できる。 It is preferable to set the pitches of all the threads in the male-side cylinder 7 and the female-side cylinder 11 and the corresponding screw bottoms to be the same. By setting in this way, when a load is applied to the threaded joint 1, all the threads are evenly contacted in the axial direction and the load can be transmitted.

　なお、ねじ継手１を有する構造体として、例えば地すべり抑止杭を構築するには、連結対象となるねじ継手付き鋼管の一方の回転を拘束した状態で、他方のねじ継手鋼管のねじ継手１を、一方のねじ継手付き鋼管のねじ継手１に位置合わせして回転嵌合するようにすればよい。 As a structure having a threaded joint 1, for example, in order to construct a landslide prevention pile, the threaded joint 1 of the other threaded joint steel pipe is connected while the rotation of one of the threaded steel pipes to be connected is restrained. It may be aligned with the threaded joint 1 of one of the steel pipes with a threaded joint so as to be rotationally fitted.

　また、ねじ継手１を設計するには、以下のような設計方法となる。テーパねじからなる雄ねじを有する雄側筒体と、テーパねじからなる雌ねじを有する雌側筒体と、を有し、鋼管の端部にあって鋼管同士を接合するねじ継手の設計方法であって、雄ねじと雌ねじにおけるねじ山のスタビング面の鋼管軸直角方向に対する傾斜角度を、0度～＋8度の範囲内で設定するねじ継手の設計方法。 In addition, the following design method is used to design the threaded joint 1. It is a method of designing a threaded joint that has a male side cylinder having a male screw made of a tapered screw and a female side cylinder having a female screw made of a tapered screw, and is located at the end of a steel pipe to join the steel pipes to each other. , A method for designing threaded joints in which the inclination angle of the stubing surface of the thread for male and female threads with respect to the direction perpendicular to the steel pipe axis is set within the range of 0 degrees to +8 degrees.

　また、ねじ継手１を製造するには、以下のような製造方法となる。テーパねじからなる雄ねじを有する雄側筒体と、テーパねじからなる雌ねじを有する雌側筒体と、を有し、鋼管の端部にあって鋼管同士を接合するねじ継手の製造方法であって、雄ねじと雌ねじにおけるねじ山のスタビング面の鋼管軸直角方向に対する傾斜角度を、0度～＋8度の範囲内で形成するねじ継手の製造方法。 Further, in order to manufacture the threaded joint 1, the manufacturing method is as follows. A method for manufacturing a threaded joint having a male-side cylinder having a male screw made of a tapered screw and a female-side cylinder having a female screw made of a tapered screw, which are located at the end of a steel pipe and join the steel pipes to each other. , A method for manufacturing a threaded joint in which the inclination angle of the stubing surface of the thread for male and female threads with respect to the direction perpendicular to the steel pipe axis is within the range of 0 degrees to +8 degrees.

　また、ねじ継手１における雄側筒体７と雌側筒体１１を備えるねじ継手付き鋼管を製造するには、本発明に係るねじ継手における雄側筒体と雌側筒体を、鋼管の一端と他端に取り付けるようにすればよい。 Further, in order to manufacture a steel pipe with a screw joint including the male side cylinder 7 and the female side cylinder 11 in the screw joint 1, the male side cylinder and the female side cylinder in the screw joint according to the present invention are used at one end of the steel pipe. It may be attached to the other end.

［傾斜角度の検討］
　本発明では、上述したように、ねじ山のスタビング面５ａ、９ａの鋼管軸直角方向に対する傾斜角度の最適範囲として、0度～＋8度としているが、これはFEM解析結果に基づくものであり、以下このFEM解析について説明する。解析モデルは、鋼管外径508mmで板厚23mm、筒体外径508mm、載荷点間距離は1200mmとした3次元4点曲げ（図２参照）モデルで、鋼管３に取り付けられた雄側筒体７ともう一方の鋼管３に取り付けられた雌側筒体１１が接合された状態で等曲げ区間となる中央部にねじ継手１を配置し、曲げ荷重による耐力を確認するモデルとなっている。 [Examination of tilt angle]
In the present invention, as described above, the optimum range of the inclination angle of the stubing surfaces 5a and 9a of the thread with respect to the direction perpendicular to the steel pipe axis is set to 0 to +8 degrees, but this is based on the FEM analysis result. This FEM analysis will be described below. The analysis model is a three-dimensional four-point bending (see Fig. 2) model with a steel pipe outer diameter of 508 mm, a plate thickness of 23 mm, a cylinder outer diameter of 508 mm, and a distance between loading points of 1200 mm. In a state where the female side cylinder 11 attached to the other steel pipe 3 is joined, the threaded joint 1 is arranged in the central portion which is an equal bending section, and the model is to confirm the yield strength due to the bending load.

　また非締め切り状態を考慮するため、雄側筒体７と雌側筒体１１の初期配置をショルダー部７ａと雌側筒体１１の先端１１ａとの隙間が２ｍｍとなる状態とした。さらに接触状態を考慮するため、雄側筒体７と雌側筒体１１には接触判定が可能となる接触条件を与え、接触部となるスタビング面５ａと９ａ、ロード面５ｂと９ｂには下記で設定したスタビング面間およびロード面間の摩擦係数を用いた。鋼材の弾塑性挙動を考慮した接触解析弾塑性モデルとなっている。 In order to consider the non-deadline state, the initial arrangement of the male side cylinder 7 and the female side cylinder 11 is set so that the gap between the shoulder portion 7a and the tip end 11a of the female side cylinder 11 is 2 mm. Further, in order to consider the contact state, the male side cylinder 7 and the female side cylinder 11 are given contact conditions that enable contact determination, and the stubing surfaces 5a and 9a and the load surfaces 5b and 9b, which are the contact portions, are described below. The coefficient of friction between the stubing surface and the load surface set in step 1 was used. It is a contact analysis elasto-plastic model that considers the elasto-plastic behavior of steel materials.

　解析に用いたスタビング面間およびロード面間の摩擦係数は、滑る条件下（例えば潤滑油を塗布した条件下）における鋼材間の一般的な摩擦係数である0.1とした。 The coefficient of friction between the stubing surfaces and the load surface used in the analysis was 0.1, which is a general friction coefficient between steel materials under slipping conditions (for example, under conditions where lubricating oil was applied).

　また、ロード面５ｂ、９ｂの設定ねじ鉛直角度は0度とした。一般的にロード面の設定ねじ鉛直角度は0度の場合が、荷重伝達力が高いと言われている。設定ねじ鉛直角度がマイナスの場合には一般的にフックねじと呼ばれる形状で、ねじ部の滑りを抑制できるが、ねじ山の根元幅(ねじ山の側面５ａ，９ａと側面５ｂ，９ｂの根根元の幅)が小さくなることからねじ部の剛性が下がり、変形しやすい。このため、高耐力が要求される構造部材（特に、地すべり抑止杭、地すべり抑止用壁、土留め壁、基礎用鋼管杭、鋼管矢板、および鋼管柱）には適用が難しい。一方でプラスの場合には一般的に台形ねじと呼ばれる形状で、ねじ部の剛性が高く変形しにくいが、ねじ部の滑りが生じやすくなる。 The vertical angle of the set screws on the load surfaces 5b and 9b was set to 0 degrees. Generally, it is said that the load transmission force is high when the vertical angle of the set screw on the load surface is 0 degrees. When the vertical angle of the set screw is negative, a shape generally called a hook screw can suppress the slip of the threaded portion, but the root width of the thread (the root widths of the side surfaces 5a and 9a and the side surfaces 5b and 9b of the thread). Since the width) becomes smaller, the rigidity of the threaded portion decreases and it is easy to deform. Therefore, it is difficult to apply it to structural members that require high yield strength (particularly, landslide deterrent piles, landslide deterrent walls, earth retaining walls, foundation steel pipe piles, steel pipe sheet piles, and steel pipe columns). On the other hand, in the case of a plus, the shape is generally called a trapezoidal thread, and the rigidity of the threaded portion is high and it is difficult to deform, but the threaded portion tends to slip.

　すなわち、ロード面５ｂ、９ｂの設定ねじ鉛直角度を0度としたのは、ロード面５ｂ、９ｂの設定ねじ鉛直角度が+10度等であれば引張側で外れやすい条件となるが、ロード面５ｂ、９ｂの設定ねじ鉛直角度を0度とすることで、構造体としてのねじ継手１において最も引張荷重伝達力が高く、相対的に圧縮側で外れやすい条件となるからである。 That is, the setting screw vertical angle of the load surfaces 5b and 9b is set to 0 degrees, which is a condition that the load surface 5b and 9b can easily come off on the pulling side if the set screw vertical angle is +10 degrees or the like. This is because by setting the set screw vertical angle of 5b and 9b to 0 degrees, the tensile load transmission force is the highest in the threaded joint 1 as a structure, and the condition is relatively easy to come off on the compression side.

　このような条件下で圧縮側のねじ部の外れが生じず、鋼材全塑性荷重を発揮できるスタビング面５ａ、９ａの設定ねじ鉛直角度を規定することで、ロード面５ｂ、９ｂの設定ねじ鉛直角度に関係なく圧縮側のねじ外れを抑制できるスタビング面５ａ、９ａの設定ねじ鉛直角度を規定することができる。なお、鋼材全塑性荷重とは、図６に示すように、継手の弱点部となる雄ねじ５における最も根元側のねじ底中央部における断面（図６の破線の四角で囲んだ部分参照）を等価した仮想鋼管１９を想定した場合の塑性断面係数と鋼材降伏応力を基に計算した値である。 By defining the set screw vertical angles of the stubing surfaces 5a and 9a that can exert the total plastic load of the steel material without causing the screw portion on the compression side to come off under such conditions, the set screw vertical angles of the load surfaces 5b and 9b can be exerted. Regardless of the above, it is possible to specify the set screw vertical angle of the stubing surfaces 5a and 9a that can suppress the screw disengagement on the compression side. As shown in FIG. 6, the total plastic load of the steel material is equivalent to the cross section at the center of the screw bottom on the root side of the male screw 5 which is the weak point of the joint (see the part surrounded by the broken line in FIG. 6). It is a value calculated based on the plastic moment of inertia and the yield stress of the steel material when the virtual steel pipe 19 is assumed.

　本検討では、ロード面５ｂ、９ｂの設定ねじ鉛直角度は鋼管軸直角方向６６に対し0度とし、スタビング面５ａ、９ａの設定ねじ鉛直角度を0度、+5度、+6度、+8度、+10度の５ケースとして実施した。なお、ロード面の設定ねじ鉛直角度の場合と同様に、スタビング面の設定ねじ鉛直角度がマイナスの場合には一般的にフックねじと呼ばれる形状で、ねじ部の滑りを抑制できる。しかし、ねじ山の根元幅が小さくなることからねじ部の剛性が下がり、変形しやすいため、高耐力が要求される構造部材には適用が難しい。故に、検討からは除外した。 In this study, the set screw vertical angles of the load surfaces 5b and 9b are set to 0 degrees with respect to the steel pipe axis perpendicular direction 66, and the set screw vertical angles of the stubing surfaces 5a and 9a are set to 0 degrees, +5 degrees, +6 degrees and +8. It was carried out as 5 cases of +10 degrees. As in the case of the vertical angle of the set screw on the load surface, when the vertical angle of the set screw on the stubing surface is negative, the shape generally called a hook screw can suppress the slip of the screw portion. However, since the root width of the thread is reduced, the rigidity of the threaded portion is reduced and the thread is easily deformed, so that it is difficult to apply it to a structural member that requires high yield strength. Therefore, it was excluded from consideration.

　図７にロード面５ｂ、９ｂの設定ねじ鉛直角度が0度で、スタビング面５ａ、９ａの設定ねじ鉛直角度が0度の場合の解析結果を示す。図７の縦軸は鋼材の全塑性荷重で解析により求められた荷重を割ることで無次元化した荷重比（載荷荷重/鋼材全塑性荷重）であり、横軸が支間中央部変位(mm)である。 FIG. 7 shows the analysis results when the set screw vertical angles of the load surfaces 5b and 9b are 0 degrees and the set screw vertical angles of the stubing surfaces 5a and 9a are 0 degrees. The vertical axis of FIG. 7 is the load ratio (loaded load / total plastic load of steel material) made dimensionless by dividing the load obtained by analysis by the total plastic load of steel material, and the horizontal axis is the displacement at the center of the strut (mm). Is.

　図７より、スタビング面５ａ、９ａの設定ねじ鉛直角度が0度の場合には、荷重比が1.12を超えたところで、低下していることが読み取れる。すなわち、スタビング面５ａ、９ａの設定ねじ鉛直角度が0度の場合には、鋼材全塑性荷重ではねじ部が外れることがないことを示しており、鋼材全塑性荷重を発揮できることがわかる。ここで、荷重比が低下する直前の最大値（図７中の逆黒色三角印の箇所）を最大荷重比と呼んでおく。図７から、設定ねじ鉛直角度が0度の場合の最大荷重比は1.12となる。 From FIG. 7, it can be read that when the vertical angle of the set screw of the stubing surfaces 5a and 9a is 0 degrees, the load ratio decreases when the load ratio exceeds 1.12. That is, when the set screw vertical angle of the stubing surfaces 5a and 9a is 0 degrees, it is shown that the screw portion does not come off under the total plastic load of the steel material, and it can be seen that the total plastic load of the steel material can be exhibited. Here, the maximum value immediately before the load ratio decreases (the part marked with the inverted black triangle in FIG. 7) is referred to as the maximum load ratio. From FIG. 7, the maximum load ratio is 1.12 when the vertical angle of the set screw is 0 degrees.

　同様の解析をスタビング面５ａ、９ａの設定ねじ鉛直角度が+5度、+6度、+8度、+10度の場合についても実施し、図７と同様の解析結果を得て、設定ねじ鉛直角度毎の最大荷重比を求めた。スタビング面５ａ、９ａの設定ねじ鉛直角度が0度の場合を含め、設定ねじ鉛直角度毎の最大荷重比の結果をまとめて図８のグラフに示す。図８の縦軸は、図７の縦軸と同じ荷重比（載荷荷重/鋼材全塑性荷重）であり、横軸は設定ねじ鉛直角度(°)である。 The same analysis was performed when the vertical angles of the set screws of the stubing surfaces 5a and 9a were +5 degrees, +6 degrees, +8 degrees, and +10 degrees, and the same analysis results as in FIG. 7 were obtained. The maximum load ratio for each vertical angle was calculated. The graph of FIG. 8 summarizes the results of the maximum load ratio for each set screw vertical angle, including the case where the set screw vertical angle of the stubing surfaces 5a and 9a is 0 degrees. The vertical axis of FIG. 8 has the same load ratio (loaded load / total plastic load of steel material) as the vertical axis of FIG. 7, and the horizontal axis is the set screw vertical angle (°).

　図８のグラフには、解析結果を回帰分析した結果である点線を付している。この回帰分析の結果から、設定ねじ鉛直角度が8度以下であれば荷重比（載荷荷重/鋼材全塑性荷重）が1以上、つまり圧縮側のねじ部が外れることなく、鋼材全塑性荷重を活かすことができることが読み取れる。一方で8度超の場合は、鋼荷重比が1未満となり、鋼材全塑性荷重に達する前に圧縮側のねじ部が外れ、鋼材全塑性荷重を活かすことができないことが読み取れる。 The graph in FIG. 8 is marked with a dotted line, which is the result of regression analysis of the analysis results. From the results of this regression analysis, if the set screw vertical angle is 8 degrees or less, the load ratio (loaded load / total plastic load of steel material) is 1 or more, that is, the total plastic load of steel material is utilized without the threaded part on the compression side coming off. It can be read that it can be done. On the other hand, when the temperature exceeds 8 degrees, the steel load ratio becomes less than 1, and it can be read that the threaded portion on the compression side comes off before the total plastic load of the steel material is reached, and the total plastic load of the steel material cannot be utilized.

　以上の解析結果から、本発明において規定する設定ねじ鉛直角度として8度以下が妥当であることが実証されている。 From the above analysis results, it has been proved that 8 degrees or less is appropriate as the vertical angle of the set screw specified in the present invention.

　上記の検討は、スタビング面間およびロード面間の摩擦係数を0.1とした場合である。これは、継手を形成する鋼材間の摩擦係数が約0.45であり、これに潤滑油を塗布して滑る条件下では0.1～0.2となることから、最も厳しい条件として0.1を用いたものである。したがって、一般的なねじ継手においては、上記の結果が妥当する。 The above examination is based on the case where the coefficient of friction between the stubing surface and the load surface is 0.1. This is because the coefficient of friction between the steel materials forming the joint is about 0.45, and it is 0.1 to 0.2 under the condition of slipping by applying lubricating oil to it, so 0.1 is used as the strictest condition. Therefore, the above results are valid for general threaded joints.

　もっとも、図４に示されるように、スタビング面間もしくはロード面間の摩擦係数が小さくなるにしたがって、滑り出す設定ねじ鉛直角度は小さくなる。このため、発明者は念のためにスタビング面間およびロード面間の摩擦係数を0.06とした場合について、ロード面５ｂ、９ｂの設定ねじ鉛直角度を0度、スタビング面５ａ、９ａの設定ねじ鉛直角度を0度、+3度、+4度、+8度、+10度とした５ケースについて解析を実施した。解析結果を図９に示す。図９には、上述したスタビング面間およびロード面間の摩擦係数を0.1とした場合も併せて記載している。 However, as shown in FIG. 4, as the coefficient of friction between the stubing surfaces or the load surfaces decreases, the vertical angle of the set screw that starts to slide decreases. Therefore, the inventor set the friction coefficient between the stubing surfaces and the load surfaces to 0.06, and set the vertical angles of the set screws of the load surfaces 5b and 9b to 0 degrees, and set the vertical threads of the stubing surfaces 5a and 9a. Analysis was performed on 5 cases with angles of 0 degrees, +3 degrees, +4 degrees, +8 degrees, and +10 degrees. The analysis result is shown in FIG. FIG. 9 also shows the case where the above-mentioned friction coefficient between the stubing surface and the load surface is 0.1.

　図９のグラフから、スタビング面間およびロード面間の摩擦係数を0.06とした場合には、圧縮側のねじ部が外れることなく、鋼材全塑性荷重を活かすことができるためには、設定ねじ鉛直角度を3度以下に設定することになることが分かる。 From the graph of FIG. 9, when the friction coefficient between the stubing surface and the load surface is 0.06, the set screw vertical can be utilized in order to utilize the total plastic load of the steel material without the threaded portion on the compression side coming off. It can be seen that the angle will be set to 3 degrees or less.

　このことから、スタビング面間の摩擦係数が特殊な場合においてねじ継手１を設計するには、スタビング面間の摩擦係数を考慮して設計することがより好ましく、この場合の設計方法としては、以下のような設計方法となる。テーパねじからなる雄ねじ５を有する雄側筒体７と、テーパねじからなる雌ねじ９を有する雌側筒体１１と、を有し、鋼管３の端部にあって鋼管３同士を接合するねじ継手の設計方法であって、鋼材全塑性荷重に対する載荷荷重の比と、設定ねじ鉛直角度との関係を、スタビング面間の摩擦係数ごとに予め求めておき、設計に際して設定したスタビング面間の摩擦係数において比が1.0以上になる設定ねじ鉛直角度を、雄側筒体７と雌側筒体１１におけるねじ山のスタビング面５ａ、９ａの鋼管軸直角方向に対する傾斜角度として設定するねじ継手の設計方法。 From this, in order to design the threaded joint 1 when the friction coefficient between the stubing surfaces is special, it is more preferable to design in consideration of the friction coefficient between the stubing surfaces. In this case, the design method is as follows. It becomes a design method like. A threaded joint having a male-side cylinder 7 having a male screw 5 made of a tapered screw and a female-side cylinder 11 having a female screw 9 made of a tapered screw at the end of a steel pipe 3 to join the steel pipes 3 to each other. In this design method, the relationship between the ratio of the loaded load to the total plastic load of the steel material and the vertical angle of the set screw is obtained in advance for each friction coefficient between the stubing surfaces, and the friction coefficient between the stubing surfaces set at the time of designing. A method for designing a threaded joint in which a set screw vertical angle at which the ratio is 1.0 or more is set as an inclination angle of the stubing surfaces 5a and 9a of the threads of the male side cylinder 7 and the female side cylinder 11 with respect to the direction perpendicular to the steel pipe axis.

　また、スタビング面間の摩擦係数が特殊な場合において、ねじ継手１を製造するには、スタビング面間の摩擦係数を考慮してねじ継手を形成することがより好ましく、この場合の製造方法としては、以下のような製造方法となる。テーパねじからなる雄ねじを有する雄側筒体と、テーパねじからなる雌ねじを有する雌側筒体と、を有し、鋼管の端部にあって鋼管同士を接合するねじ継手の製造方法であって、載荷荷重と鋼材全塑性荷重との比と、設定ねじ鉛直角度との関係を、スタビング面間の摩擦係数ごとに予め求めておき、予め設定されたスタビング面間の摩擦係数において比が1.0以上になる設定ねじ鉛直角度を、雄側筒体と雌側筒体におけるねじ山のスタビング面の鋼管軸直角方向に対する傾斜角度として形成するねじ継手の製造方法。 Further, in the case where the friction coefficient between the stubing surfaces is special, in order to manufacture the threaded joint 1, it is more preferable to form the threaded joint in consideration of the friction coefficient between the stubing surfaces, and the manufacturing method in this case is as follows. , The manufacturing method is as follows. A method for manufacturing a threaded joint having a male-side cylinder having a male screw made of a tapered screw and a female-side cylinder having a female screw made of a tapered screw, which are located at the end of a steel pipe and join the steel pipes to each other. , The relationship between the ratio of the loaded load and the total plastic load of the steel material and the set screw vertical angle is obtained in advance for each friction coefficient between the stubing surfaces, and the ratio is 1.0 or more in the preset friction coefficient between the stubing surfaces. A method for manufacturing a threaded joint in which the vertical angle of the set screw is formed as the inclination angle of the stubing surface of the thread in the male side cylinder and the female side cylinder in the direction perpendicular to the steel pipe axis.

　本発明によれば、ショルダー部がタッチしない不完全接合状態であっても圧縮側のねじ部が外れることなく継手鋼材の全塑性荷重を十分に活かすことができるねじ継手を提供することができる。また、本発明によれば、このようなねじ継手を前提としたねじ継手付き鋼管、構造体、構造体の構築方法、地すべり抑止杭、地すべり抑止杭の施工方法、ねじ継手の設計方法、ねじ継手の製造方法、ねじ継手付き鋼管の製造方法を提供することができる。 According to the present invention, it is possible to provide a threaded joint capable of fully utilizing the total plastic load of the joint steel material without the threaded portion on the compression side coming off even in an incompletely joined state where the shoulder portion does not touch. Further, according to the present invention, a steel pipe with a threaded joint, a structure, a method for constructing a structure, a method for constructing a landslide suppressing pile, a method for constructing a landslide suppressing pile, a method for designing a threaded joint, and a threaded joint on the premise of such a threaded joint. A method for manufacturing a steel pipe with a threaded joint can be provided.

　１　ねじ継手
　３　鋼管
　５　雄ねじ
　５ａ　スタビング面
　５ｂ　ロード面
　５１　頂部
　５２　ねじ底
　７　雄側筒体
　７ａ　ショルダー部
　９　雌ねじ
　９ａ　スタビング面
　９ｂ　ロード面
　９１　頂部
　９２　ねじ底
　１１　雌側筒体
　１１ａ　先端
　１３　ねじ継手（特許文献２）
　１５　雄ねじ
　１５ａ　スタビング面
　１５ｂ　ロード面
　１７　雌ねじ
　１７ａ　スタビング面
　１７ｂ　ロード面
　１９　仮想鋼管
　２１　テーパの勾配軸
　２３　勾配軸直交軸
　２５　鋼管軸
　２７　鋼管直交軸
　Ｐ　ねじ山のピッチ
　ｈ　ねじ高さ
　α　傾斜角度、設定ねじ鉛直角度（スタビング面に対するまたはロード面に対する） 1 Threaded joint 3 Steel pipe 5 Male thread 5a Stubbing surface 5b Load surface 51 Top 52 Thread bottom 7 Male side cylinder 7a Shoulder part 9 Female thread 9a Stubbing surface 9b Road surface 91 Top 92 Thread bottom 11 Female side cylinder 11a Tip 13 Patent Document 2)
15 Male thread 15a Stubbing surface 15b Load surface 17 Female thread 17a Stubbing surface 17b Load surface 19 Virtual steel pipe 21 Tapered slope axis 23 Slope axis orthogonal axis 25 Steel pipe axis 27 Steel pipe orthogonal axis P Thread pitch h Thread height α Inclination angle, setting Thread vertical angle (relative to stubing surface or relative to load surface)

Claims (12)

1. 　鋼管の端部にあって前記鋼管同士を接合するねじ継手であって、
   　テーパねじからなる雄ねじを有する雄側筒体と、
   　テーパねじからなる雌ねじを有する雌側筒体と、を備え、
   　前記雄ねじと前記雌ねじにおけるねじ山のスタビング面の鋼管軸直角方向に対する傾斜角度が0度～＋8度の範囲内にあるねじ継手。 A threaded joint at the end of a steel pipe that joins the steel pipes together.
   A male side cylinder with a male thread consisting of tapered threads,
   With a female side cylinder having a female thread consisting of a tapered thread,
   A threaded joint in which the inclination angle of the stubing surface of the thread of the male thread and the female thread with respect to the direction perpendicular to the steel pipe axis is in the range of 0 degrees to +8 degrees.
2. 　前記雄側筒体と前記雌側筒体における全てのねじ山及びこれに対応するねじ底のピッチが同じである請求項１に記載のねじ継手。 The threaded joint according to claim 1, wherein all the threads in the male-side cylinder and the female-side cylinder and the corresponding thread bottoms have the same pitch.
3. 　請求項１又は２に記載のねじ継手における雄側筒体と雌側筒体を、次の（１）から（３）のいずれか１つの態様で備えるねじ継手付き鋼管。
   （１）前記雄側筒体を、前記鋼管の少なくとも一端に設ける態様
   （２）前記雌側筒体を、前記鋼管の少なくとも一端に設ける態様
   （３）前記雄側筒体と前記雌側筒体を、前記鋼管の一端と他端に設ける態様 A steel pipe with a threaded joint comprising the male-side cylinder and the female-side cylinder in the threaded joint according to claim 1 or 2 in any one of the following (1) to (3).
   (1) A mode in which the male side cylinder is provided at at least one end of the steel pipe (2) A mode in which the female side cylinder is provided at at least one end of the steel pipe (3) The male side cylinder and the female side cylinder Is provided at one end and the other end of the steel pipe.
4. 　請求項１又は２に記載のねじ継手と、該ねじ継手で連結された複数の鋼管とを備える構造体。 A structure including the threaded joint according to claim 1 or 2 and a plurality of steel pipes connected by the threaded joint.
5. 　請求項４に記載の構造体の構築方法であって、連結対象となるねじ継手付き鋼管の一方の回転を拘束した状態で、他方のねじ継手付き鋼管のねじ継手を、一方のねじ継手付き鋼管のねじ継手に位置合わせして回転嵌合する構造体の構築方法。 The method for constructing a structure according to claim 4, wherein a threaded joint of a steel pipe with a threaded joint is connected to a steel pipe with a threaded joint while the rotation of one of the steel pipes with a threaded joint to be connected is restrained. How to build a structure that is aligned and rotationally fitted to a threaded joint.
6. 　請求項１又は２に記載のねじ継手と、該ねじ継手で連結された複数の鋼管とを備える地すべり抑止杭。 A landslide restraining pile including the threaded joint according to claim 1 or 2 and a plurality of steel pipes connected by the threaded joint.
7. 　請求項１又は２に記載のねじ継手を端部に取り付けた鋼管を用いた地すべり抑止杭の施工方法であって、次の（１）から（３）のいずれか１つの態様で施工する地すべり抑止杭の施工方法。
   （１）地盤に杭を挿入する孔を必要な長さの全長に亘って掘削する孔掘削工程と、掘削した孔に前記鋼管の頭が突出するように吊下げて、前記ねじ継手により順次回転接合して自重挿入し、所定の本数の継杭が完了した後、前記鋼管の周面と地盤との隙間に充填材を充填して地盤に密着させる工程とを備えた態様
   （２）地盤に杭を挿入する孔を必要な長さの全長に亘って掘削する孔掘削工程と、前記鋼管を前記ねじ継手により必要長さ接合する鋼管接合工程と、接合された鋼管を孔に挿入し、前記鋼管の周面と地盤との隙間に充填材を充填して地盤に密着させる工程とを備えた態様
   （３）既に施工済みの杭あるいは反力部材によって反力を取りながら、前記鋼管を回転圧入により地中に貫入する工程と、地中に貫入した鋼管の頭部に前記鋼管を回転接合する工程と、回転接合した鋼管を回転圧入により地中に貫入する工程とを備えた態様 A method for constructing a landslide prevention pile using a steel pipe having a threaded joint attached to an end according to claim 1 or 2, wherein the landslide is suppressed by any one of the following (1) to (3). Pile construction method.
   (1) A hole excavation process in which a hole for inserting a pile in the ground is excavated over the entire length required, and the steel pipe is suspended from the excavated hole so that the head of the steel pipe protrudes, and is sequentially rotated by the screw joint. After joining and inserting by its own weight and completing a predetermined number of joint piles, a step of filling the gap between the peripheral surface of the steel pipe and the ground with a filler and bringing it into close contact with the ground is provided. A hole drilling step of drilling a hole for inserting a pile over the entire length required, a steel pipe joining step of joining the steel pipe to the required length by the screw joint, and a steel pipe joining step of inserting the joined steel pipe into the hole and described above. An embodiment including a step of filling a gap between the peripheral surface of the steel pipe and the ground with a filler and bringing it into close contact with the ground (3) Rotatingly press-fitting the steel pipe while taking reaction force with a pile or reaction force member already constructed. An embodiment including a step of penetrating into the ground by means of a steel pipe, a step of rotationally joining the steel pipe to the head of the steel pipe that has penetrated into the ground, and a step of penetrating the rotary-bonded steel pipe into the ground by rotational press-fitting.
8. 　テーパねじからなる雄ねじを有する雄側筒体と、テーパねじからなる雌ねじを有する雌側筒体と、を有し、鋼管の端部にあって前記鋼管同士を接合するねじ継手の設計方法であって、
   　前記雄ねじと前記雌ねじにおけるねじ山のスタビング面の鋼管軸直角方向に対する傾斜角度を、0度～＋8度の範囲内で設定するねじ継手の設計方法。 It is a method of designing a threaded joint having a male-side cylinder having a male screw made of a tapered screw and a female-side cylinder having a female screw made of a tapered screw at the end of a steel pipe to join the steel pipes to each other. hand,
   A method for designing a threaded joint in which the inclination angle of the stubing surface of the thread of the male thread and the female thread with respect to the direction perpendicular to the steel pipe axis is set within the range of 0 degrees to +8 degrees.
9. 　テーパねじからなる雄ねじを有する雄側筒体と、テーパねじからなる雌ねじを有する雌側筒体と、を有し、鋼管の端部にあって前記鋼管同士を接合するねじ継手の設計方法であって、
   　鋼材全塑性荷重に対する載荷荷重の比と、設定ねじ鉛直角度との関係を、摩擦係数ごとに予め求めておき、設計に際して設定した摩擦係数において前記比が1.0以上になる設定ねじ鉛直角度を、前記雄側筒体と前記雌側筒体におけるねじ山のスタビング面の鋼管軸直角方向に対する傾斜角度として設定するねじ継手の設計方法。 It is a method of designing a threaded joint having a male-side cylinder having a male screw made of a tapered screw and a female-side cylinder having a female screw made of a tapered screw at the end of a steel pipe to join the steel pipes to each other. hand,
   The relationship between the ratio of the loaded load to the total plastic load of the steel material and the set screw vertical angle is obtained in advance for each friction coefficient, and the set screw vertical angle at which the ratio is 1.0 or more at the friction coefficient set at the time of design is described above. A method for designing a threaded joint in which the stubing surface of the threads of the male-side cylinder and the female-side cylinder is set as an inclination angle with respect to the direction perpendicular to the steel pipe axis.
10. 　テーパねじからなる雄ねじを有する雄側筒体と、テーパねじからなる雌ねじを有する雌側筒体と、を有し、鋼管の端部にあって前記鋼管同士を接合するねじ継手の製造方法であって、
    　前記雄ねじと前記雌ねじにおけるねじ山のスタビング面の鋼管軸直角方向に対する傾斜角度を、0度～＋8度の範囲内で形成するねじ継手の製造方法。 A method for manufacturing a threaded joint having a male-side cylinder having a male screw made of a tapered screw and a female-side cylinder having a female screw made of a tapered screw, which are located at the end of a steel pipe and join the steel pipes to each other. hand,
    A method for manufacturing a threaded joint in which the inclination angle of the stubing surface of the thread of the male thread and the female thread with respect to the direction perpendicular to the steel pipe axis is in the range of 0 degrees to +8 degrees.
11. 　テーパねじからなる雄ねじを有する雄側筒体と、テーパねじからなる雌ねじを有する雌側筒体と、を有し、鋼管の端部にあって前記鋼管同士を接合するねじ継手の製造方法であって、
    　鋼材全塑性荷重に対する載荷荷重の比と、設定ねじ鉛直角度との関係を、摩擦係数ごとに予め求めておき、予め設定された摩擦係数において前記比が1.0以上になる設定ねじ鉛直角度を、前記雄側筒体と前記雌側筒体におけるねじ山のスタビング面の鋼管軸直角方向に対する傾斜角度として形成するねじ継手の製造方法。 A method for manufacturing a threaded joint having a male-side cylinder having a male screw made of a tapered screw and a female-side cylinder having a female screw made of a tapered screw, which are located at the end of a steel pipe and join the steel pipes to each other. hand,
    The relationship between the ratio of the loaded load to the total plastic load of the steel material and the set screw vertical angle is obtained in advance for each friction coefficient, and the set screw vertical angle at which the ratio is 1.0 or more at the preset friction coefficient is determined. A method for manufacturing a threaded joint formed as an inclination angle of a stubing surface of a thread in a male-side cylinder and a female-side cylinder with respect to a direction perpendicular to the steel pipe axis.
12. 　請求項１又は２に記載のねじ継手における雄側筒体と雌側筒体を、次の（１）から（３）のいずれか１つの態様で取り付けるねじ継手付き鋼管の製造方法。
    （１）前記雄側筒体を、前記鋼管の少なくとも一端に取り付ける態様
    （２）前記雌側筒体を、前記鋼管の少なくとも一端に取り付ける態様
    （３）前記雄側筒体と前記雌側筒体を、前記鋼管の一端と他端に取り付ける態様 A method for manufacturing a steel pipe with a threaded joint, wherein the male-side cylinder and the female-side cylinder in the threaded joint according to claim 1 or 2 are attached by any one of the following (1) to (3).
    (1) A mode in which the male side cylinder is attached to at least one end of the steel pipe (2) A mode in which the female side cylinder is attached to at least one end of the steel pipe (3) The male side cylinder and the female side cylinder Is attached to one end and the other end of the steel pipe.

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