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  4. Vol.21 No.82 1997.4

本四技報 HONSHI TECHNICAL REPORT

Vol.21 No.82 1997.4

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【巻頭言】Prefatory note

  • 125年前

    125 years ago

    菊地徳彌

    Tokuya Kikuchi

【技術論文】Technical report

  • 舞子トンネル明かり巻部におけるプレキャスト化工法の設計・施工

    Design and Construction by Precast Work Method Over Open-Cut Section of Maiko Tunnel

    岩垣富春・浜村吉昭

    Tomiharu Iwagaki, Yoshiaki Hamamura

    神戸・鳴門ルートの神戸側陸上部に位置する舞子トンネルは、延長約3.3km、片側3車線の上下線併設トンネルである。その南坑口から232mの区間については、良好な住環境を保全するため明り巻トンネル構造とし、上部を盛土した後、神戸市による公園整備を行う計画とした。

    この区間の施工にあたり、トンネルのアーチ部にプレキャスト部材を活用したPre-Cast Arch Tunnel(PAT)工法を開発し、施工の省力化、工期短縮、工事に伴う騒音・振動の低減、施工の安全性の向上を図った。

    大断面のトンネルにプレキャスト部材を用いた施工は初めての試みであったが、当初の目的が達成できたのでその設計施工概要および実績について報告する。

    The Maiko Tunnel with a length of 3.3 kilometers is located on the on-land portion of Kobe-Naruto Route at the Kobe side, consisting of parallel tunnels with a width to 3-lane highway each. The portion over a length of 232 meters from the south portal of the tunnels was constructed by the open-cut method whose top was resurfaced by the earthwork to prepare a site for a park by the Kobe City to preserve a good environment for residential area. For the construction of this portion, the precast arch tunneling (PAT) method was developed that would be expected to cut down man-power, construction period, and construction noise and vibration, but raise the safety. Although the use of precast segment was rare in such a tunnel with a wide cross section, enough performance was achieved as it was expected. This paper reports the outline of design and construction work of the tunnel.

  • 撫養橋(上下線並列橋)の耐風応答特性

    Aerodynamic Responses of Muya Bridge in Parallel Arrangement

    帆足博明・谷口貴成・貴志友基

    Hiroaki Hoashi, Takashige Taniguch, Yuuki Kishi

    上下線並列構造となる撫養橋の耐風安定性に関しては、これまでにニ次元模型および一径間弾性模型を用いた風洞試験を実施しており、その結果、単独橋および並列橋ともにギャロッピング抑制のための制振プレートを兼ねた外部管理路を設置することとし、既に上り線は外部管理路を設置し、架設供用している。本文では、下り線に外部管理路を設置しない場合の並列橋の耐風安定性を、一径間弾性模型を用いた風洞試験により検討した。その結果、上下線の固有振動数比により耐風性が大きく影響を受けることおよび乱流中では、ギャロッピングは緩和され、乱れ強さの増加とともにバフェッティングに移行する傾向が分かった。

    The Muya Bridge has two separate decks: one for the north- and the other for the south-bound lanes, and the decks are arranged alongside each other. In the aerodynamic study on the bridge, wind tunnel tests were carried out using two dimensional and three-dimensional elastic models.

    As a result, it was required that a side maintenance deck, which would play a role as a damping plate, installed alongside of the decks to suppress galloping with the deck in both cases of single and parallel arrangement, and the deck for the north-bound lanes has been already completed and opened to public.

    This paper introduces the further study on the aerodynamic stability of the bridge by elastic model wind tunnel test, which was carried out to investigate feasibility of stabilization without the side maintenance deck.

    As a result, it was found that the aerodynamic responses would be greatly affected by the difference between natural frequencies of both decks, and the galloping would be reduced in a turbulent flow and transformed into the buffeting with increment of turbulent intensity.

  • 北備讃瀬戸大橋ケーブル送気試験

    Cable inside dry up test on Kitabisanseto Bridge

    奥田基・山下五月・伊香賀信文

    Motoi Okuda, Satsuki Yamashita, Nobufumi Ikoga

    ケーブルの防錆方法は、ラッピングワイヤーを使い表面をカバーして防水性を高める方法が従来使用されてきた。しかし、水分の侵入を防ぐことを主眼とするラッピングは、既に侵入した水分及び防水層を突破した水分に対しては、効果がないため、内部水の除去を目的にケーブル内に乾燥空気を挿入するシステムを考案し、北備讃瀬戸大橋の東ケーブル2Pで試験を行い、経過時間毎の湿度測定を中心として、乾燥範囲の到達を考察した報告である。

    For the purpose of anti-corrosion of the cable for the suspension bridge, the Cable wrapping systems have ordinarily been employed to cover the peripheral of the cable for waterproofing. However, this system was found to be insufficient to prevent corrosion of the cable in a corrosive environment such as one around the Honshu-shikoku Bridges, which is oceanic and with quite a few rainfalls throughout the year. A new system was worked out to dry up the moisture inside the cable that was produced by the residual water inside the cable. The system consists of air dryer, blower, desalinate filter, and air injection piping, as well as a watertight cable seethe. The measurements were made on the following items:

    1. Air humidity inside the Cable

    2. Air pressure inside the Cable

    As a result, it was found that the dehumidified area in the cable corresponded to the lapse of time for air injection and the quality of air-tightness of the cable cover. Also found was that the pressure change was observed over a length of 100 meters from the point of air injection, although the length of dehumidfied area along the cable far exceeded that. The system has still been under experiments, and this paper reports the outline of the system as an interim one.

  • 吊橋主塔の引張接合継手の製作架設

    Fabrication and Erection of Towers with Bolted-Flange joints on a Suspension Bridge

    佐々木雅敏・宮口典博・山口和範

    Masatoshi Sasaki, Norihiro Miyaguchi, Kazunori Yamaguchi

    来島第一大橋の2P・3P主塔の道路水平材より上の水平継手では、架設作業の省力化、安全性向上および工程短縮、また維持管理省力化や景観への配慮という観点から長締め形式の引張接合用高力ボルトを用いたフランジ接合(引張接合継手)を採用している。

    本文では、国内では実績のない接合方式の採用にあたっての各種検討結果、製作、架設について報告する。

    A bolted-flange joint system was designed for a part of towers, from a horizontal member at the roadway-height to the topmost part, of 2P and 3P of Kurushima Bridge, in order to reduce man power and construction period and raise safety with the site work, as well as to achieve easy maintenance and good aesthetics on the bridge. This paper introduces a course of design, fabrication, and erection on the joint system, which had been unprecedented in Japan.

  • 長大トラス吊橋のハンガーピン定着部補強構造の力の伝達機構と疲労挙動

    Force Transfer Mechanism and Fatigue Behavior of a Pin-Connection Anchor of Hanger for a Long-Span Suspension Bridge

    大橋治一・大川宗男

    Harukazu Ohashi, Muneo Okawa

    吊橋のハンガーロープと補剛桁連結部をピンで結合したピン定着部では、補剛桁からの力はピンとピン孔の支圧によりハンガーロープへと伝達される。暴風時などでは主ケーブルと補剛桁に相対な変位が生じるためハンガーロープのピン定着部には面外の力が作用する。このとき定着ピンは片当たりの状態となることや、繰り返しの力が定着構造に作用するとなどが予想されるが、このような場合の応力挙動や疲労挙動は明確でない。そこで本文は、補剛トラスを有する長大吊橋を対象に検討された二種類の定着構造について静的載荷試験および疲労試験を実施し、構造上の弱点部の把握並びに疲労強度と疲労挙動の確認を行った結果を報告する。

    Through pin-connection parts of suspender ropes attached to chord members of stiffening truss on a suspension bridge, all loads are transmitted by bearing of the pin and the pin plate. With a strong wind condition, the out-of-plane force acts repeatedly on the connection, which would be produced by the horizontal component of a tension in the suspender rope that would occur from a relative movement between the stiffening truss and the cable. This recurrent action creates a non-uniform condition of the bearing stress in the pin connection. This report presents results of static loading test and fatigue test that were carried out to verify weak points and the fatigue strength, using full-scale specimens representing two types of pin-connection structure for a long-span, truss-stiffened suspension bridge.

【海外報告】Overseas report

  • 鋼橋の耐震設計、評価、補修に関する米国の最近の情報(セミナー報告)

    Seismic Design,Evaluation and Retrofit of Steel Bridges,(2nd US seminar,San Francisco)

    秋山晴樹

    Haruki Akiyama

  • タンザニア動物保護区における道路及び橋梁の建設・補修工事の現状報告

    Report on Construction and Repair Works of Roads in Tanzania

    藤田太

    Futoshi Fujita

【技術ニュース】Technical news