JP7605715B2

JP7605715B2 - Vibration reduction mechanism and vibration reduction method

Info

Publication number: JP7605715B2
Application number: JP2021128453A
Authority: JP
Inventors: 和彦磯田
Original assignee: Shimizu Corp
Current assignee: Shimizu Corp
Priority date: 2021-08-04
Filing date: 2021-08-04
Publication date: 2024-12-24
Anticipated expiration: 2041-08-04
Also published as: JP2023023178A

Description

本発明は、振動低減機構および振動低減方法に関する。 The present invention relates to a vibration reduction mechanism and a vibration reduction method.

建設作業に伴って発生する作業音の振動数は主として４～１６Ｈｚの範囲とされており、振動数域が広範囲にわたるため、現場周辺での振動障害の発生と工事現場に対する周辺からの苦情等の要因となっている。解体工事や杭工事等においては、４～８Ｈｚの低振動数による大きな振動が生じ、建設重機や工事用車両等の通行においては、８～１６Ｈｚの高振動数による振動が長時間に渡って生じる。
上記の振動の対策方法として、工事現場において建設重機等の走行路上に古タイヤや防振マットや鉄板等を敷く方法や、振動波の伝播経路上の地表に防振溝や鋼矢板（防振壁）等を設置する方法や、工事現場の周縁に盛土や土嚢等を積み上げる方法がとられている。 The vibration frequencies of work noise generated by construction work are mainly in the range of 4 to 16 Hz, and because this frequency range is so wide, it is a cause of vibration disorders in the vicinity of the work site and complaints about the work site from the surrounding area. During demolition work and piling work, large vibrations with low frequencies of 4 to 8 Hz are generated, while the passage of heavy construction machinery and construction vehicles generates vibrations with high frequencies of 8 to 16 Hz for long periods of time.
Countermeasures against the above-mentioned vibrations include laying old tires, vibration-proof mats, steel plates, etc. on the roads on which heavy construction machinery runs at construction sites, installing vibration-proof trenches or steel sheet piles (vibration-proof walls) on the ground surface along the propagation path of the vibration waves, and piling up embankments and sandbags around the perimeter of construction sites.

しかしながら、古タイヤや防振マットや鉄板等を敷く方法は、移動する建設重機や工事用車両等による振動しか対応できず、工事等の作業による振動には対応できないという問題がある。また、防振溝を設置する方法は、１０ｍ程度の大規模な深さの防護溝を設けても高振動数域で平均５ｄＢ程度しか振動を低減できないという問題がある。鋼矢板を設置する方法は、鋼矢板の設置費用が高額であるため、工事が不経済となるという問題がある。また、盛土や土嚢等を積み上げる方法についても工費や設置スペースの問題がある。 However, the method of laying old tires, anti-vibration mats, steel plates, etc., has the problem that it can only deal with vibrations caused by moving heavy construction machinery and construction vehicles, etc., and cannot deal with vibrations caused by construction work, etc. The method of installing anti-vibration trenches has the problem that even if a large protective trench with a depth of about 10 m is installed, it can only reduce vibrations by an average of about 5 dB in the high frequency range. The method of installing steel sheet piles has the problem that the installation costs of steel sheet piles are high, making the construction uneconomical. Furthermore, the method of piling up embankments and sandbags has problems with the construction costs and installation space.

特開２０１７－１１５４７６号公報JP 2017-115476 A 特許６７８５５３５号公報Patent No. 6785535 特開２０１６－２３５１６号公報JP 2016-23516 A

一方で、上記の従来の振動に対する対策方法における諸問題に対し、対策の実施に要するコストを抑え所望の振動低減効果を確保する方法として、振動発生源と振動を低減する対象物との間の所定の位置に錘や土嚢等を敷設する方法がある（例えば、特許文献１および２参照）。しかし、上記の方法は、１１Ｈｚ以上の高振動数域で振動低減効果を発揮するものの、４～８Ｈｚの低振動数域では振動低減効果がほとんど得られないという課題がある。 On the other hand, in order to address the various problems associated with the above-mentioned conventional vibration countermeasures, there is a method of laying weights, sandbags, etc. at predetermined positions between the vibration source and the object for which vibration is to be reduced, as a method of reducing the costs required to implement the countermeasures and ensuring the desired vibration reduction effect (see, for example, Patent Documents 1 and 2). However, while the above-mentioned method is effective in reducing vibration in the high frequency range of 11 Hz and above, it has the problem that it provides almost no vibration reduction effect in the low frequency range of 4 to 8 Hz.

また、上記課題で挙げられた低振動数域の振動を低減できる方法として、振動伝達経路上に杭支持された基礎を設け、その上にばね支持された錘を設置しＴＭＤ（Tuned Mass Damper）動吸振器とした装置を設ける方法がある（特許文献３参照）。この方法では、ＴＭＤ動吸振器において固有振動数（ばねと錘の諸元）を低減対象の振動波の振動数と共振するように調整することで、任意の振動数で振動波の伝播をブロックする効果を発揮できる。しかし、上記の方法では、振動低減効果を大きくするためには錘の質量を大きくする必要があるという課題がある。また、１個の錘とそれを支持する複数のばねからなるＴＭＤ動吸振器により振動を低減できる対象振動数は１つしかないため、複数の振動数を低減するためには複数のＴＭＤ動吸振器を設置できる広い設置場所が必要になるという課題もある。また、錘の質量の調整やＴＭＤ動吸振器の設置場所を確保するためのコストが嵩み不経済な方法となるという課題もある。 As a method for reducing vibrations in the low frequency range mentioned in the above problem, there is a method of providing a foundation supported by piles on the vibration transmission path, and a spring-supported weight is placed on the foundation to provide a TMD (Tuned Mass Damper) dynamic vibration absorber (see Patent Document 3). In this method, the natural frequency (the specifications of the spring and weight) of the TMD dynamic vibration absorber is adjusted so that it resonates with the frequency of the vibration wave to be reduced, thereby achieving the effect of blocking the propagation of vibration waves at any frequency. However, the above method has the problem that the mass of the weight needs to be increased to increase the vibration reduction effect. In addition, since a TMD dynamic vibration absorber consisting of one weight and multiple springs supporting it can reduce vibrations at only one target frequency, there is also the problem that a large installation space is required to install multiple TMD dynamic vibration absorbers in order to reduce multiple frequencies. There is also the problem that the cost of adjusting the mass of the weight and securing the installation space for the TMD dynamic vibration absorber increases, making this method uneconomical.

また、近年、制振装置として直動変位（軸方向変位）をボールねじにより回転に変換し錘を回転させて慣性抵抗力を得る回転慣性質量ダンパーが適用されている。回転慣性質量ダンパーは上記の機構により、コンパクトな構成ながら回転させる錘質量の数百倍～数千倍もの大きな慣性質量を付与することができるという特徴を有する。 In recent years, rotary inertia mass dampers have been used as vibration control devices, which convert linear displacement (axial displacement) into rotation using a ball screw to rotate a weight and obtain inertial resistance. Thanks to the above mechanism, rotary inertia mass dampers have the advantage of being compact in configuration but capable of imparting a large inertial mass that is hundreds to thousands of times the mass of the weight being rotated.

本発明は、上記の事情に鑑みてなされたもので巨大な機構や多大なコストを要することなく、建設作業に伴い発生する振動を低減することができる振動低減機構および振動低減方法を提供することを目的とする。 The present invention was made in consideration of the above circumstances, and aims to provide a vibration reduction mechanism and vibration reduction method that can reduce vibrations generated during construction work without requiring a huge mechanism or significant costs.

上記目的を達成するため、本発明に係る振動低減機構は、振動発生箇所と振動障害予防箇所との間に設けられ、支持地盤まで根入れされ周面部の周面摩擦力を低減した根入れ部と、地表上に位置する杭頭部と、を備える杭体と、地表面において前記杭体の正面視両側に近接して配置され、鋼材で形成された第一架台部材と、前記第一架台部材の上部に配置され、鋼材で形成された第二架台部材と、を備える架台と、前記第一架台部材の間において前記杭体と前記第二架台部材との間に配置され、上端が前記第二架台部材に連結され、下端が前記杭頭部に連結された回転慣性質量ダンパーと、を備える。 In order to achieve the above object, the vibration reduction mechanism of the present invention comprises a pile body provided between a vibration generating point and a vibration damage prevention point, the pile body having an embedded portion that is embedded into the supporting ground to reduce the peripheral friction of the peripheral portion, and a pile head portion located on the ground surface, a stand provided with a first stand member made of steel that is disposed adjacent to both sides of the pile body when viewed from the front on the ground surface, a second stand member that is disposed on top of the first stand member and is also made of steel, and a rotary inertia mass damper that is disposed between the pile body and the second stand member between the first stand members, the upper end of which is connected to the second stand member, and the lower end of which is connected to the pile head portion.

上記の構成とすることで、架台と杭体と回転慣性質量ダンパーとからなり、巨大な錘や複数の振動数に対応するための機構を必要としない振動低減機構とすることができる。そのため、巨大な機構や多大なコストを要することなく、回転慣性質量ダンパーによる慣性質量と杭や架台による鉛直剛性とからなる振動系がＴＭＤ動吸振器と同様に機能するため、振動発生箇所から発生する振動に対する所望の振動低減効果を得ることが可能となる。 The above configuration makes it possible to create a vibration reduction mechanism consisting of a base, pile body, and rotary inertial mass damper, which does not require a huge weight or a mechanism to handle multiple vibration frequencies. Therefore, the vibration system consisting of the inertial mass of the rotary inertial mass damper and the vertical stiffness of the pile and base functions in the same way as a TMD dynamic vibration absorber, without requiring a huge mechanism or significant costs, making it possible to obtain the desired vibration reduction effect against vibrations generated from the vibration generation point.

また、本発明に係る振動低減機構において、前記第二架台部材の上部に設けられ、上載荷重を載荷する錘を備えてもよい。 The vibration reduction mechanism according to the present invention may also include a weight that is provided on the upper part of the second mounting member and that applies an upper load.

上記の構成とすることにより、従来技術にある地表に土嚢や錘を載荷する方法と同じ効果を発揮できる。そのため、振動低減機構は高振動数域の振動数に対する振動低減効果をより高めることができる。 The above configuration provides the same effect as the conventional method of loading sandbags or weights on the ground. As a result, the vibration reduction mechanism can further improve the vibration reduction effect for high-frequency range vibrations.

また、本発明に係る振動低減機構において、前記杭体と前記回転慣性質量ダンパーとは、直列されて伝播経路直交方向に複数設けられ、前記第二架台部材は、それぞれの前記回転慣性質量ダンパーの上部に設けられ、前記第一架台部材と前記第二架台部材とは、平面視井桁状に配設されてもよい。 In addition, in the vibration reduction mechanism according to the present invention, the pile body and the rotary inertia mass damper may be arranged in series in a direction perpendicular to the propagation path, the second mounting member may be provided above each rotary inertia mass damper, and the first mounting member and the second mounting member may be arranged in a grid pattern in a plan view.

上記の構成とすることにより、振動低減機構は、帯状に複数の振動低減機構を設ける構成となり、隣接する杭体の軸剛性または慣性質量を調整することで、複数の異なる振動数に対して振動低減機構を同調させることができる。そのため、振動発生要因となる多くの建設機械や工事用車両を有し、広範な箇所で複数の作業が行われる工事現場等の大規模な振動発生箇所に対しても所望の振動低減効果を発揮することが可能となる。
また、振動低減機構は、１つの架台に複数の回転慣性質量ダンパーおよび杭体を設ける構成にすることで、従来のＴＭＤ動吸振器のように同調振動数毎に大きな錘やばね等を設ける必要がなくなる。そのため、軽量かつ大きな設置スペースが不要なコンパクトな構成とすることが可能となる。また、多大なコストを要することなく複数の振動数に対応した振動低減対策を実施することが可能となる。 With the above configuration, the vibration reduction mechanism is configured to have multiple vibration reduction mechanisms arranged in a band, and the vibration reduction mechanisms can be tuned to multiple different vibration frequencies by adjusting the axial stiffness or inertial mass of adjacent pile bodies. Therefore, it is possible to achieve the desired vibration reduction effect even in large-scale vibration-generating locations such as construction sites where there are many construction machines and construction vehicles that generate vibration, and where multiple tasks are performed over a wide area.
In addition, by configuring the vibration reduction mechanism so that multiple rotary inertia mass dampers and pile bodies are provided on one frame, it is no longer necessary to provide large weights, springs, etc. for each tuned vibration frequency as in the conventional TMD dynamic vibration absorber. This makes it possible to have a lightweight, compact configuration that does not require a large installation space. It also makes it possible to implement vibration reduction measures that are compatible with multiple vibration frequencies without incurring large costs.

また、本発明に係る振動低減機構において、前記第一架台部材と前記第二架台部材とは、Ｈ形鋼で形成され、前記第一架台部材の下側フランジは、地表面に接し、前記第二架台部材の下側フランジは、前記第一架台部材の上側フランジと前記回転慣性質量ダンパーとにそれぞれ連結され、前記第一架台部材と前記第二架台部材とは、それぞれのＨ形の形成方向が平面視で直交するように配設されてもよい。 In addition, in the vibration reduction mechanism according to the present invention, the first and second mounting members may be formed of H-shaped steel, the lower flange of the first mounting member may be in contact with the ground surface, the lower flange of the second mounting member may be connected to the upper flange of the first mounting member and the rotary inertia mass damper, and the first and second mounting members may be arranged such that the directions of their respective H-shapes are perpendicular to each other in a plan view.

上記の構成とすることで、第一架台部材および第二架台部材は、曲げ剛性や曲げ強度に対する断面効率を向上させることができる。そのため、錘による上載荷重や架台の上部に配置されている第二架台部材の重量による振動低減機構の破損を防止し、所望の振動低減効果を発揮することが可能となる。 The above configuration allows the first and second mounting members to have improved cross-sectional efficiency with respect to bending rigidity and bending strength. This prevents damage to the vibration reduction mechanism caused by the weight of the weight of the second mounting member placed on top of the mounting frame or the weight of ...

また、本発明に係る振動低減機構において、前記杭体の周囲に土間コンクリートやモルタル等による地盤面補強層が形成され、前記地盤面補強層の上部に前記第一架台部材が設けられてもよい。 In addition, in the vibration reduction mechanism according to the present invention, a ground surface reinforcement layer made of concrete or mortar may be formed around the pile body, and the first mounting member may be provided on top of the ground surface reinforcement layer.

上記の構成とすることで、錘による上載荷重や振動低減機構の重量による振動低減機構が設置されている地盤の沈下を抑制することができ、振動低減機構の各部の配設位置のずれの発生等による振動低減効果の低下を防ぐことができる。 The above configuration makes it possible to suppress subsidence of the ground on which the vibration reduction mechanism is installed due to the load from the weight of the vibration reduction mechanism or the weight of the vibration reduction mechanism itself, and to prevent a decrease in the vibration reduction effect due to misalignment of the positions of the various parts of the vibration reduction mechanism.

また、本発明に係る振動低減方法は、上記のいずれかの振動低減機構が振動発生箇所と前記振動発生箇所から発生する振動波の伝播経路上にある振動障害予防箇所との間に設けられていることを特徴とする。 The vibration reduction method according to the present invention is characterized in that any one of the vibration reduction mechanisms described above is provided between a vibration generation location and a vibration disorder prevention location on the propagation path of the vibration wave generated from the vibration generation location.

上記の構成とすることにより、巨大な機構や多大なコストを要することのなく、所望の振動低減効果を得ることができる振動低減方法とすることが可能となる。 The above configuration makes it possible to provide a vibration reduction method that can achieve the desired vibration reduction effect without requiring a large mechanism or significant costs.

本発明によれば、巨大な機構や多大なコストを要することなく、建設作業に伴い発生する振動を低減することができる振動低減機構および振動低減方法を提供することができる。 The present invention provides a vibration reduction mechanism and a vibration reduction method that can reduce vibrations that occur during construction work without requiring large mechanisms or significant costs.

本発明の実施形態による振動低減機構の一例における設置位置を示す説明図である。5A and 5B are explanatory diagrams showing an installation position of an example of a vibration reduction mechanism according to an embodiment of the present invention. 本発明の実施形態による振動低減機構の一例における斜視図である。FIG. 2 is a perspective view of an example of a vibration reduction mechanism according to an embodiment of the present invention. 本発明の実施形態による振動低減機構の一例における回転慣性質量ダンパーの正面視断面図である。FIG. 2 is a cross-sectional front view of a rotary inertia mass damper in an example of a vibration reduction mechanism in accordance with an embodiment of the present invention. 本発明の実施形態による振動低減機構の一例を用いた振動低減モデルの説明図である。1 is an explanatory diagram of a vibration reduction model using an example of a vibration reduction mechanism according to an embodiment of the present invention. FIG. 本発明の実施形態による振動低減機構の一例を用いた振動低減モデルによる第１の比較ケースの検討結果（加振振動数と応答倍率との関係）を示すグラフである。11 is a graph showing the results of a study (relationship between excitation frequency and response magnification) of a first comparative case using a vibration reduction model that uses an example of a vibration reduction mechanism according to an embodiment of the present invention. 本発明の実施形態による振動低減機構の一例を用いた振動低減モデルによる第２の比較ケースの検討結果（加振振動数と応答倍率との関係）を示すグラフである。13 is a graph showing the results of a study (relationship between excitation frequency and response magnification) of a second comparative case using a vibration reduction model that uses an example of a vibration reduction mechanism according to an embodiment of the present invention. 本発明の実施形態による振動低減機構の一例を用いた振動低減モデルによる第３の比較ケースの検討結果（加振振動数と応答倍率との関係）を示すグラフである。13 is a graph showing the results of a study (relationship between excitation frequency and response magnification) of a third comparative case using a vibration reduction model that uses an example of the vibration reduction mechanism according to an embodiment of the present invention. 本発明の実施形態による振動低減機構の一例を用いた振動低減モデルによる第４の比較ケースの検討結果（加振振動数と応答倍率との関係）を示すグラフである。13 is a graph showing the results of a study (relationship between excitation frequency and response magnification) of a fourth comparative case using a vibration reduction model that uses an example of the vibration reduction mechanism according to an embodiment of the present invention. 本発明の実施形態による振動低減機構の一例を用いた振動低減モデルによる第５の比較ケースの検討結果（加振振動数と応答倍率との関係）を示すグラフである。13 is a graph showing the results of a study (relationship between excitation frequency and response magnification) of a fifth comparative case using a vibration reduction model that uses an example of the vibration reduction mechanism according to an embodiment of the present invention. 本発明の実施形態による振動低減機構の一例を用いた振動低減モデルによる第６の比較ケースの検討結果（加振振動数と応答倍率との関係）を示すグラフである。13 is a graph showing the results of a study (relationship between excitation frequency and response magnification) of a sixth comparative case using a vibration reduction model that uses an example of the vibration reduction mechanism according to an embodiment of the present invention. 本発明の実施形態による振動低減機構の一例を用いた振動低減モデルによる各比較ケースの検討結果（加振振動数と振動低減レベルとの関係）を示すグラフである。11 is a graph showing the results of examination of each comparison case (relationship between excitation frequency and vibration reduction level) using a vibration reduction model that uses an example of a vibration reduction mechanism according to an embodiment of the present invention.

以下、本発明の実施形態による振動低減機構および振動低減方法について、図１乃至図１１に基づいて説明する。 The vibration reduction mechanism and vibration reduction method according to an embodiment of the present invention will be described below with reference to Figures 1 to 11.

図１に示すように、本実施形態による振動低減機構１は、建設機械や工事用車両等の走行や工事作業が実施されている工事現場である振動発生箇所２における加振により発生する振動波２１の伝播方向上に設けられる。また、振動低減機構１は、振動発生箇所２と振動発生箇所２の近隣にある振動障害予防箇所１１（以下、「住居１１」とする）との間に設けられる。 As shown in FIG. 1, the vibration reduction mechanism 1 according to this embodiment is provided in the propagation direction of vibration waves 21 generated by excitation at a vibration generation location 2, which is a construction site where construction machinery, construction vehicles, etc. are traveling and construction work is being carried out. The vibration reduction mechanism 1 is also provided between the vibration generation location 2 and a vibration disorder prevention location 11 (hereinafter referred to as "residence 11") located near the vibration generation location 2.

図２に示すように、振動低減機構１は、杭体３と、第一架台部材４と第二架台部材５とから構成される架台６と、回転慣性質量ダンパー７と、錘８と、地盤面補強層９とから構成される。
また、以下の説明において特に断りがない限り、本実施形態では図１乃至図３において複数の杭体３と回転慣性質量ダンパー７の配設方向を「Ｘ方向」、Ｘ方向に対して水平に直交する方向を「Ｙ方向」、Ｘ方向およびＹ方向に直交する鉛直方向を「Ｚ方向」とする。 As shown in FIG. 2 , the vibration reduction mechanism 1 is composed of a pile body 3, a stand 6 composed of a first stand member 4 and a second stand member 5, a rotational inertia mass damper 7, a weight 8, and a ground surface reinforcement layer 9.
In addition, unless otherwise specified in the following description, in this embodiment, the arrangement direction of the multiple pile bodies 3 and the rotational inertia mass dampers 7 in Figures 1 to 3 is referred to as the "X direction", the direction horizontally perpendicular to the X direction is referred to as the "Y direction", and the vertical direction perpendicular to the X direction and Y direction is referred to as the "Z direction".

杭体３は、表層地盤９１を貫通し支持地盤９２に根入れされる根入れ部３１と、地盤Ｇより上方の地表に位置する杭頭部３２とを有する。そのため、杭体３は、振動低減機構１を設ける箇所において地表から支持地盤９２に達する長さを有する。杭体３は鋼管杭やＳＣ杭（鋼管巻き既製コンクリート杭）である。
根入れ部３１は、外周部に周面摩擦力を低減する構成を有する。例えば、根入れ部３１の外周面にアスファルトを塗布する構成や根入れ部３１の外周部にさらに鋼管を設けた二重鋼管とする構成が挙げられる。 The pile body 3 has an embedded portion 31 that penetrates the surface ground 91 and is embedded in the supporting ground 92, and a pile head portion 32 that is located on the ground surface above the ground G. Therefore, the pile body 3 has a length that reaches from the ground surface to the supporting ground 92 at the location where the vibration reduction mechanism 1 is provided. The pile body 3 is a steel pipe pile or an SC pile (a precast concrete pile wrapped in a steel pipe).
The embedment portion 31 has a structure for reducing the peripheral friction force at its outer periphery. For example, the structure may be such that asphalt is applied to the outer periphery of the embedment portion 31, or a double steel pipe may be provided on the outer periphery of the embedment portion 31.

第一架台部材４および第二架台部材５は、それぞれＨ形鋼により形成される。Ｈ形鋼の規格は、所望の振動低減機構１を形成することができれば限定されない。第一架台部材４は、下側フランジ４１が地表面に接地し、ウェブ４２はＸ－Ｚ平面内に配置される。第一架台部材４，４は、杭体３に対してＸ方向両側に均等間隔で設けられる。 The first mounting member 4 and the second mounting member 5 are each formed from an H-shaped steel. There are no limitations on the standard of the H-shaped steel as long as the desired vibration reduction mechanism 1 can be formed. The lower flange 41 of the first mounting member 4 is in contact with the ground surface, and the web 42 is disposed within the X-Z plane. The first mounting members 4, 4 are provided at equal intervals on both sides of the pile body 3 in the X direction.

第二架台部材５は、第一架台部材４のＺ方向上部に設けられ、下側フランジ５１が第一架台部材４，４の上側フランジ４３に接地し、ウェブ５２はＹ－Ｚ平面内に配置される。そのため、第二架台部材５は、第一架台部材４，４間をＹ方向に架設され配置される。 The second mounting member 5 is provided above the first mounting member 4 in the Z direction, with the lower flange 51 in contact with the upper flange 43 of the first mounting members 4, 4, and the web 52 disposed within the Y-Z plane. Therefore, the second mounting member 5 is disposed between the first mounting members 4, 4 in the Y direction.

上記の構成により、第一架台部材４と第二架台部材５とは、平面視で直交するように配設される。
架台６は、上記の向きでＺ方向に積載配置された第一架台部材４と第二架台部材５において、上側フランジ４３と下側フランジ５１とをボルト等の固定金具によって連結することにより形成される。 With the above-described configuration, the first mounting member 4 and the second mounting member 5 are disposed so as to be perpendicular to each other in a plan view.
The frame 6 is formed by connecting the upper flange 43 and the lower flange 51 of the first frame member 4 and the second frame member 5 which are stacked and arranged in the Z direction in the above-mentioned orientation, with fixing metal fittings such as bolts.

回転慣性質量ダンパー７は、上端が下側フランジ５１のＺ方向下面にボルト等の固定金具によって連結され、下端が杭頭部３２の上端にボルト等の固定金具によって連結されることにより、杭頭部３２と下側フランジ５１との間に配置される。 The rotational inertia mass damper 7 is positioned between the pile head 32 and the lower flange 51, with its upper end connected to the Z-direction underside of the lower flange 51 by a fixing metal fitting such as a bolt, and its lower end connected to the upper end of the pile head 32 by a fixing metal fitting such as a bolt.

図３に示すように、回転慣性質量ダンパー７は、平面視（回転軸方向）円形形状のボールねじ７１とボールナット７２と回転錘７３とを備える。回転慣性質量ダンパー７は、直動変位（ダンパー両端の鉛直相対変位）をボールねじ７１により回転に変換し、ボールナット７２が回転軸を一定に保ちながら回転錘７３を回転させる。回転慣性質量ダンパー７において、慣性質量をψとし、回転錘７３の直径をＤ、質量をｍ、密度をρ、Ｚ方向厚さをｔとし、ボールねじ７１のリード（ねじ山間隔）をＬ_ｄ、相対変位をｘ、錘回転角をθ、回転慣性モーメントＩ_θとすると、相対変位ｘを時間に対し２回微分した相対加速度（次式ではｘの上に‥で示す）に対する装置負担力Ｐは次式となる。また、慣性質量ψは次式となる。 As shown in Fig. 3, the rotary inertia mass damper 7 includes a ball screw 71, a ball nut 72, and a rotary weight 73, which are circular in plan view (in the direction of the rotation axis). The rotary inertia mass damper 7 converts linear displacement (vertical relative displacement between both ends of the damper) into rotation by the ball screw 71, and the ball nut 72 rotates the rotary weight 73 while keeping the rotation axis constant. In the rotary inertia mass damper 7, if the inertial mass is ψ, the diameter of the rotary weight 73 is D, the mass is m, the density is ρ, the thickness in the Z direction is t, the lead (thread interval) of the ball screw 71 is _Ld , the relative displacement is x, the weight rotation angle is θ, and the rotary inertia moment _Iθ , the load force P of the device against the relative acceleration (indicated by ... above x in the following equation) obtained by differentiating the relative displacement x twice with respect to time is expressed by the following equation. The inertial mass ψ is expressed by the following equation.

上式において、回転錘７３の直径Ｄはボールねじ７１のリードＬ_ｄに対して十分大きく、慣性質量ψは回転錘７３の直径Ｄの４乗に比例する。以上より、慣性質量ψは回転錘７３の質量ｍに対して数百倍から数千倍もの大きな慣性質量を付与でき、杭の鉛直ばねと直列することで、小型でも大きな質量を有するＴＭＤ動吸振器として機能する。 In the above equation, the diameter D of the rotating weight 73 is sufficiently large compared to the lead _Ld of the ball screw 71, and the inertial mass ψ is proportional to the fourth power of the diameter D of the rotating weight 73. From the above, the inertial mass ψ can impart an inertial mass several hundred to several thousand times larger than the mass m of the rotating weight 73, and by being connected in series with the vertical spring of the pile, it functions as a TMD dynamic vibration absorber that is small but has a large mass.

上記の杭体３と第二架台部材５と回転慣性質量ダンパー７は、第一架台部材４，４の間において同様の構成および配置でＸ方向に複数並列して設けられる。
本実施形態では、Ｘ方向に所定の間隔Ｘ_１で杭体３が複数打設され、第二架台部材５が第一架台部材４，４間にＹ方向に複数架設され、それぞれの杭体３と第二架台部材５との間に回転慣性質量ダンパー７が配置される構成がＸ方向に連続して設けられる。上記の構成により、振動低減機構１はＸ方向に帯状の防振帯１２を備える。また、第一架台部材４と第二架台部材５とは、平面視で直交するため、架台６はＸ方向に連続する平面視井桁状に形成される。 The pile body 3, the second frame member 5, and the rotary inertia mass damper 7 are provided in parallel in the X direction between the first frame members 4, 4 with the same configuration and arrangement.
In this embodiment, a plurality of pile bodies 3 are driven into the ground at a predetermined interval _X1 in the X direction, a plurality of second frame members 5 are installed between the first frame members 4, 4 in the Y direction, and a rotational inertia mass damper 7 is disposed between each of the pile bodies 3 and the second frame member 5, and this configuration is provided continuously in the X direction. With the above configuration, the vibration reduction mechanism 1 is provided with a belt-shaped vibration isolation belt 12 in the X direction. In addition, since the first frame member 4 and the second frame member 5 are orthogonal in a plan view, the frame 6 is formed in a grid shape in a plan view that is continuous in the X direction.

錘８は、複数の土嚢８１により構成される。土嚢８１は、第二架台部材５の上側フランジ５３上に積載される。錘８は、所望の振動低減機構１が形成されれば土嚢８１による構成に限定されず、例えば上側フランジ５３上に鋼板を積層した構成としてもよいし、コンクリートによる塊状体を載置した構成としてもよい。 The weight 8 is composed of multiple sandbags 81. The sandbags 81 are loaded on the upper flange 53 of the second mounting member 5. The weight 8 is not limited to being composed of sandbags 81 as long as the desired vibration reduction mechanism 1 is formed, and may be composed of, for example, steel plates stacked on the upper flange 53, or a concrete block placed on top.

地盤面補強層９は、第一架台部材４と地盤Ｇとの間に数ｃｍ程度の厚さで形成される。そのため、振動低減機構１は地盤面補強層９上に設けられる。地盤面補強層９の材質は、振動低減機構１の自重により破壊されない圧縮強度を備える捨てコンクリートや均しモルタル等の公知のセメント系材料とする。 The ground surface reinforcement layer 9 is formed with a thickness of about several centimeters between the first mounting member 4 and the ground G. Therefore, the vibration reduction mechanism 1 is provided on the ground surface reinforcement layer 9. The material of the ground surface reinforcement layer 9 is a known cement-based material such as sacrificial concrete or leveling mortar that has a compressive strength that will not be destroyed by the weight of the vibration reduction mechanism 1.

第一架台部材４は、アンカーボルト等の打ち込み型の固定金具を下側フランジ４１上から地盤面補強層９に打ち込むことで地盤面補強層９上に固定される。該固定金具は、地盤面補強層９を貫通し、地盤Ｇまで打設されてもよい。なお、第一架台部材４と地盤Ｇとの間に地盤面補強層９を形成しない構成の場合は、第一架台部材４は下側フランジ４１上から地盤Ｇに該固定金具を打ち込むことによって地表面に固定されてもよい。 The first mounting member 4 is fixed onto the ground surface reinforcement layer 9 by driving anchor bolts or other drive-in type fixing metal fittings into the ground surface reinforcement layer 9 from above the lower flange 41. The fixing metal fittings may be driven through the ground surface reinforcement layer 9 and into the ground G. In the case of a configuration in which the ground surface reinforcement layer 9 is not formed between the first mounting member 4 and the ground G, the first mounting member 4 may be fixed to the ground surface by driving the fixing metal fittings into the ground G from above the lower flange 41.

次に、上述した実施形態による振動低減機構および振動低減方法の作用・効果について図１乃至図１１に基づいて説明する。 Next, the operation and effects of the vibration reduction mechanism and vibration reduction method according to the above-mentioned embodiment will be described with reference to Figures 1 to 11.

図１乃至図３に示すように、振動低減機構１は、杭体３と、第一架台部材４と第二架台部材５とから構成される架台６と、回転慣性質量ダンパー７と、錘８と、地盤面補強層９とを備える。杭体３と第二架台部材５と回転慣性質量ダンパー７は、第一架台部材４，４の間において同様の構成および配置によりＸ方向に所定の間隔Ｘ_１で複数設けられ、振動低減機構１はＸ方向に帯状の防振帯１２を備える。上記の構成を備える振動低減機構１を振動発生箇所２と振動波２１の伝播方向上に位置する住居１１との間に設ける。 1 to 3, the vibration reduction mechanism 1 includes a pile body 3, a mount 6 composed of a first mount member 4 and a second mount member 5, a rotational inertia mass damper 7, a weight 8, and a ground surface reinforcing layer 9. The pile body 3, the second mount member 5, and the rotational inertia mass damper 7 are provided in a plurality of units with the same configuration and arrangement between the first mount members 4, 4 at a predetermined interval _X1 in the X direction, and the vibration reduction mechanism 1 includes a band-shaped vibration isolation belt 12 in the X direction. The vibration reduction mechanism 1 having the above configuration is provided between a vibration generation location 2 and a residence 11 located in the propagation direction of vibration waves 21.

上記の実施形態による振動低減機構１について、図４に示す地盤Ｇを複数の質点に分解して単純化した振動低減モデル１３を仮定し、振動波２１に対する振動低減効果について検討する。 For the vibration reduction mechanism 1 according to the above embodiment, we assume a simplified vibration reduction model 13 in which the ground G shown in Figure 4 is decomposed into multiple mass points, and examine the vibration reduction effect against vibration waves 21.

図４において、１つの質点を１０ｍ×１０ｍ×１０ｍの土塊Ｇと仮定する。質点はＧ_１からＧ_４までの４点仮定し、質点Ｇ_１からＧ_４は水平方向に同一延長線上に位置する。質点Ｇ_１は振動発生箇所２の位置であり、工事の作業や工事車両の通行等の外力の作用によって加振され、該加振によって生じた振動波２１が振動低減モデル１３上を伝播する。質点Ｇ_２は振動低減機構１が設けられ、質点Ｇ_１から水平方向に離隔Ｌだけ離れた位置とする。質点Ｇ_３は質点Ｇ_２から水平方向に離隔Ｌだけ離れた位置とする。質点Ｇ_４は質点Ｇ_３から水平方向に離隔Ｌだけ離れた位置とする。質点Ｇ_３および質点Ｇ_４は、振動低減機構１による振動低減効果の評価位置とする。土塊Ｇの質量Ｇ_ｍは２，０００ｔｏｎとする。また、離隔Ｌは１０ｍとする。 In FIG. 4, one mass point is assumed to be a lump of soil G of 10m×10m×10m. Four mass points, _G1 to _G4, are assumed, and mass points _G1 to _G4 are located on the same horizontal extension line. Mass point _G1 is the position of vibration generation point 2, and is excited by the action of external forces such as construction work and the passage of construction vehicles, and vibration waves 21 generated by the excitation propagate on the vibration reduction model 13. Mass point _G2 is a position where the vibration reduction mechanism 1 is provided, and is separated horizontally from mass point _G1 by a distance L. Mass point _G3 is a position separated horizontally from mass point _G2 by a distance L. Mass point _G4 is a position separated horizontally from mass point _G3 by a distance L. Mass points _G3 and _G4 are positions for evaluating the vibration reduction effect of the vibration reduction mechanism 1. The mass _Gm of the lump of soil G is 2,000 tons. The distance L is set to 10 m.

各質点は、鉛直方向にばね定数ｋ_１＝１０００ｋＮ／ｍｍの地盤軸ばね９３が仮定される。また、隣接する各質点間において水平方向にばね定数ｋ_２＝４００ｋＮ／ｍｍのせん断ばね９４が仮定される。地盤軸ばね９３は各質点が仮定される位置における軸剛性を示し、せん断ばね９４は地盤Ｇにおけるせん断剛性を示す。 A ground axial spring 93 with a spring constant _k1 = 1000 kN/mm is assumed for each mass point in the vertical direction. A shear spring 94 with a spring constant _k2 = 400 kN/mm is assumed between adjacent mass points in the horizontal direction. The ground axial spring 93 indicates the axial stiffness at the position where each mass point is assumed, and the shear spring 94 indicates the shear stiffness in the ground G.

質点Ｇ_２は、質点Ｇ_２に設けられる地盤軸ばね９３に並列配置される振動低減機構モデル１４が設けられる。振動低減機構モデル１４は、錘質点８２と、慣性質量ψ（ｔｏｎ）、減衰定数ｃ（ｋＮ／ｋｉｎｅ）の回転慣性質量ダンパーモデル７４と、軸剛性ｋ_３を有する架台軸ばね６１と、軸剛性ｋ_４を有する杭体軸ばね３３とを備える。回転慣性質量ダンパーモデル７４および錘質点８２と、架台軸ばね６１とは並列配置される。また、杭体軸ばね３３の軸剛性（ばね定数）は、杭体軸ばね３３の杭頭に荷重を載荷させた際の該荷重を該荷重による沈下量で除した値とする。 The mass point _G2 is provided with a vibration reduction mechanism model 14 arranged in parallel to the ground axial spring 93 provided at the mass point _G2 . The vibration reduction mechanism model 14 includes a weight mass point 82, a rotational inertia mass damper model 74 with an inertial mass ψ (ton) and a damping constant c (kN/kine), a base axial spring 61 having an axial stiffness _k3 , and a pile body axial spring 33 having an axial stiffness _k4 . The rotational inertia mass damper model 74, the weight mass point 82, and the base axial spring 61 are arranged in parallel. The axial stiffness (spring constant) of the pile body axial spring 33 is a value obtained by dividing a load applied to the pile head of the pile body axial spring 33 by the amount of settlement caused by the load.

本実施形態の慣性質量を用いた振動低減機構の検討において、錘質点８２の質量と架台軸ばね６１の架台剛性は無視する。つまり、質点Ｇ_２の質量をＧ_ｍ、ばね定数ｋ_３を∞とおく。そのため、振動低減モデル１３は、錘質点８２と回転慣性質量ダンパーモデル７４と杭体軸ばね３３とが鉛直方向に直列したＴＭＤ動吸振器機構を形成する。杭体軸ばね３３は、支持地盤９２に仮定される固定端９５まで延び、振動波２１による地盤変位も含めて評価する。なお、複数の振動低減機構を組み合わせたケースの検討においては、従来技術の地表に土嚢の錘を設置した場合についても併せて評価する。 In examining the vibration reduction mechanism using the inertial mass of this embodiment, the mass of the weight mass point 82 and the frame rigidity of the frame axle spring 61 are ignored. In other words, the mass of the mass point _G2 is set to _Gm , and the spring constant _k3 is set to ∞. Therefore, the vibration reduction model 13 forms a TMD dynamic vibration absorber mechanism in which the weight mass point 82, the rotational inertial mass damper model 74, and the pile axle spring 33 are vertically connected in series. The pile axle spring 33 extends to a fixed end 95 assumed to be in the supporting ground 92, and the evaluation also includes the ground displacement due to the vibration wave 21. Note that in examining a case in which multiple vibration reduction mechanisms are combined, the case in which sandbag weights are placed on the ground surface as in the conventional technology is also evaluated.

振動低減モデル１３では、質点Ｇ_２における慣性質量ψ（ｔｏｎ）、減衰定数ｃ（ｋＮ／ｋｉｎｅ）、軸剛性ｋ_４（ｋＮ／ｍｍ）を次表とした実施例１から４について振動低減機構モデル１４の振動低減効果を検討する。 In the vibration reduction model 13, the vibration reduction effect of the vibration reduction mechanism model ₁₄ is examined for Examples 1 to 4 in which the inertial mass ψ (ton), damping constant c (kN/kine), and axial stiffness _k4 (kN/mm) at mass point G2 are as shown in the following table.

振動低減モデル１３による検討では、質点Ｇ_１を直動方向に加速度加振したときの質点Ｇ_２、Ｇ_３、Ｇ_４の応答を振動発生箇所２における振動障害の原因となり得る振動数範囲と仮定する加振振動数１５Ｈｚまでの振動数域で評価する。質点Ｇ_１における加振振幅に対する質点Ｇ_ｉ（ｉ＝２～４）の加速度振幅の比を質点ｉにおける伝達関数の応答倍率Ｍ_ｉ（ｉ＝２～４）として次式で算出し、質点Ｇ_２に設けた振動低減機構モデル１４を通過し、質点Ｇ_３、Ｇ_４に伝達される振動波２１について検討する。 In the study using vibration reduction model 13, the responses of mass points _G2 , _G3 , and _G4 when mass point _G1 is accelerated in the linear direction are evaluated in a frequency range up to 15 Hz, which is assumed to be a frequency range that can cause vibration disorders at vibration generation location 2. The ratio of the acceleration amplitude of mass point G _i (i = 2 to 4) to the excitation amplitude at mass point _G1 is calculated using the following equation as the response magnification M _i (i = 2 to 4) of the transfer function at mass point i, and the vibration wave 21 that passes through vibration reduction mechanism model 14 provided at mass point _G2 and is transmitted to mass points _G3 and _G4 is studied.

また、振動低減モデル１３による検討では、質点Ｇ_２おける振動低減機構モデル１４の構成が異なる６種類のケースにおいて振動波２１による加振振動数ｆとケース１からケース６における質点ｉの応答倍率Ｍ_ｉ（ｉ＝２～４）との関係を図５乃至図１０に示し、各ケースの構成による振動低減効果について検討する。 In addition, in the study using the vibration reduction model 13, the relationship between the excitation frequency f due to the vibration wave 21 and the response magnification M _i (i = 2 to ₄ ) of mass point i in cases 1 to 6 for six different cases in which the vibration reduction mechanism model 14 at mass point G 2 is configured differently is shown in Figures 5 to 10, and the vibration reduction effect due to the configuration of each case is studied.

図５に示すように、振動低減機構がないケース１では全ての質点で振動波２１による地盤Ｇの卓越振動数となる４Ｈｚ近傍において振動波２１との共振により応答倍率（振幅）Ｍ_ｉが増大しているため、低振動数域における振動障害が生じる可能性が高い。 As shown in FIG. 5, in Case 1 without a vibration reduction mechanism, the response magnification (amplitude) _Mi increases at all mass points due to resonance with the vibration wave 21 in the vicinity of 4 Hz, which is the predominant frequency of the ground G due to the vibration wave 21, and therefore there is a high possibility that vibration disturbance will occur in the low frequency range.

図６に示すように、ケース２では、実施例１の構成を備えた振動低減機構モデル１４を設けることにより、全ての質点の応答倍率Ｍ_ｉにおいてケース１における地盤Ｇの卓越振動数である４Ｈｚ近傍の共振特性がケース１と比較して改善される。そのため、ケース２の振動低減機構モデル１４を設けることにより、振動波２１による低振動数域の振動を低減することが可能となる。 6, in Case 2, by providing the vibration reduction mechanism model 14 having the configuration of Example 1, the resonance characteristics near 4 Hz which is the predominant frequency of the ground G in Case 1 at the response magnifications _Mi of all mass points are improved compared to Case 1. Therefore, by providing the vibration reduction mechanism model 14 in Case 2, it becomes possible to reduce vibrations in the low frequency range caused by the vibration waves 21.

図７に示すように、ケース３では、実施例１、２の構成を備えた振動低減機構モデル１４を設けることにより、全ての質点の応答倍率Ｍ_ｉにおいて５Ｈｚ以上の振動はほぼ伝達されなくなる。そのため、ケース２の振動低減機構モデル１４のように杭体３と回転慣性質量ダンパー７が複数設けられる構成により、広範囲の振動数域の振動に対して振動低減効果を発揮することが可能となる。 As shown in Fig. 7, in Case 3, vibrations of 5 Hz or more are almost not transmitted at the response magnifications _Mi of all mass points by providing a vibration reduction mechanism model 14 having the configurations of Examples 1 and 2. Therefore, by providing a configuration in which multiple pile bodies 3 and rotational inertia mass dampers 7 are provided as in the vibration reduction mechanism model 14 of Case 2, it becomes possible to exert a vibration reduction effect against vibrations in a wide range of frequencies.

ケース４では、振動低減機構モデル１４を設けず、従来技術と同様に質点Ｇ_２に土塊Ｇの質量Ｇ_ｍの半分の質量である１０００ｔｏｎの錘（土嚢）を追加する。図８に示すように、上記の構成により、全ての質点の応答倍率Ｍ_ｉにおいて、３．５Ｈｚおよび５Ｈｚ近傍の共振特性は改善されないが、５．５Ｈｚ以上の振動はほぼ伝達されなくなる。以上より、振動低減機構１を設けない錘のみによる振動低減機構についても高振動数域においては一定の振動低減効果を有するといえる。 In Case 4, the vibration reduction mechanism model 14 is not provided, and a weight (sandbag) of 1000 tons, which is half the mass _Gm of the soil lump _G , is added to mass point G2 as in the prior art. As shown in Fig. 8, with the above configuration, the resonance characteristics near 3.5 Hz and 5 Hz are not improved at the response magnifications _Mi of all mass points, but vibrations of 5.5 Hz or higher are almost not transmitted. From the above, it can be said that a vibration reduction mechanism using only a weight without a vibration reduction mechanism 1 also has a certain vibration reduction effect in the high frequency range.

ケース５では、実施例１の振動低減機構モデル１４とケース４に適用した土塊Ｇの質量Ｇ_ｍの半分の質量である１０００ｔｏｎの錘（土嚢）とを質点Ｇ_２に設ける。図９に示すように、上記の構成により、全ての質点の応答倍率Ｍ_ｉにおいて、５．５Ｈｚ以上の振動はほぼ伝達されなくなる。以上より、振動低減機構モデル１４と簡易な構成の錘とを併用する構成によっても広範囲の振動数域の振動に対して振動低減低減効果を発揮することが可能となる。 In case 5, the vibration reduction mechanism model 14 of Example 1 and a weight (sandbag) of 1000 tons, which is half the mass _Gm of the lump of soil G applied in case 4, are attached to mass point _G2 . As shown in Fig. 9, with the above configuration, vibrations of 5.5 Hz or more are almost not transmitted at the response magnifications _Mi of all mass points. From the above, it is possible to achieve a vibration reduction effect against vibrations in a wide range of frequencies even with a configuration that uses the vibration reduction mechanism model 14 in combination with a weight of a simple configuration.

ケース６では、実施例２－４の振動低減機構モデル１４を振動波２１に対して帯状に対向するように設ける。図１０に示すように、上記の構成により、全ての質点の応答倍率Ｍ_ｉにおいて５Ｈｚ以上の振動はほぼ伝達されなくなる。また、６種類の検討ケースの中で最も応答倍率の挙動が小さくなる。そのため、振動低減機構モデル１４の設置数を増やし、伝播方向に対して帯状に形成することにより、広範囲の振動数域の振動に対してより大きな振動低減効果を発揮することが可能となる。 In case 6, the vibration reduction mechanism models 14 of Example 2-4 are provided in a band-like shape facing the vibration wave 21. As shown in Fig. 10, with the above configuration, vibrations of 5 Hz or more are almost not transmitted at the response magnifications _Mi of all mass points. In addition, the behavior of the response magnification is the smallest among the six types of cases examined. Therefore, by increasing the number of vibration reduction mechanism models 14 installed and forming them in a band-like shape in the propagation direction, it is possible to achieve a greater vibration reduction effect against vibrations in a wide range of frequencies.

ケース２からケース６の振動低減効果を振動低減レベル（振動低減機構がないケース１に対する応答倍率）で比較する。ケースｊ（ｊ＝２～６）におけるケース１に対する振動低減レベルη_ｊ（ｊ＝２～６）は次式により算出する。η_ｊ＞０なら該質点においてケース１よりも振動が増加し、η_ｊ＜０であれば該質点においてケース１よりも振動が減少したことを示す。図５乃至図１０より、本実施形態における質点Ｇ_２、Ｇ_３、Ｇ_４の加振振動数の変化に対する応答倍率の挙動はほぼ同様となるため、η_ｊの代表値として質点Ｇ_３の各ケースおよび各加振振動数動数に対するη_ｊを比較する。 The vibration reduction effects of Case 2 to Case 6 are compared in terms of vibration reduction level (response magnification relative to Case 1 without a vibration reduction mechanism). The vibration reduction level η _j (j = 2 to 6) of Case j (j = 2 to 6) relative to Case 1 is calculated by the following formula. If _{η j} > 0, it indicates that the vibration at that mass point is greater than in Case 1, and if η _j < 0, it indicates that the vibration at that mass point is less than in Case 1. As can be seen from Figures 5 to 10, the behavior of the response magnification relative to changes in the excitation frequency of mass points G ₂ , G ₃ , and G ₄ in this embodiment is almost similar, so η _j for each case and each excitation frequency of mass point G ₃ is compared as a representative value of η _j .

図１１に示すように、ケース２およびケース３は、地盤Ｇの卓越振動数４Ｈｚでの振動低減効果は約－３１ｄＢ（ケース１の約１／３０に低減）となるため低振動数域における振動低減効果は大きいが、高振動数域における振動低減効果はほとんどない。 As shown in Figure 11, in Cases 2 and 3, the vibration reduction effect at the predominant frequency of ground G of 4 Hz is approximately -31 dB (reduced to approximately 1/30 of Case 1), so the vibration reduction effect is large in the low frequency range, but there is almost no vibration reduction effect in the high frequency range.

また、ケース４は、高振動数域において約－３ｄＢの振動低減効果があるが、低振動数域における振動低減効果はケース２、３と比較すると小さく、低振動数側にシフトした地盤Ｇの卓越振動数の近傍では振動波２１との共振により振動が増加する。 In addition, case 4 has a vibration reduction effect of approximately -3 dB in the high frequency range, but the vibration reduction effect in the low frequency range is smaller than cases 2 and 3, and vibration increases due to resonance with vibration wave 21 near the dominant frequency of ground G, which has shifted to the low frequency side.

また、ケース５は、実施例１の振動低減機構モデル１４の設置により、ケース４で見られた低振動数域における共振特性が大きく改善され、低振動数域においてもケース１、ケース２と同等の振動低減効果が得られる。また、３．５Ｈｚ以上の全振動数域においてケース１、ケース２よりも高い振動低減効果が得られる。 In addition, in case 5, by installing the vibration reduction mechanism model 14 of Example 1, the resonance characteristics in the low frequency range seen in case 4 are greatly improved, and a vibration reduction effect equivalent to cases 1 and 2 is obtained even in the low frequency range. Also, a higher vibration reduction effect than cases 1 and 2 is obtained in the entire frequency range of 3.5 Hz or higher.

また、ケース６は、ケース４、ケース５のような錘を載荷させる構成を備えなくても、実施例２－４の振動低減機構モデル１４を設けることで、慣性質量ψを増大させ、増大させた慣性質量ψが錘と同様に作用することにより、全振動数域においてケース５と同等以上の振動低減効果を発揮することが可能となる。 In addition, even though Case 6 does not have a configuration for loading a weight like Cases 4 and 5, by providing the vibration reduction mechanism model 14 of Example 2-4, the inertial mass ψ can be increased, and the increased inertial mass ψ acts in the same way as a weight, making it possible to achieve a vibration reduction effect equal to or greater than that of Case 5 across the entire frequency range.

以上より、ケース５のように回転慣性質量ダンパー７の慣性質量と杭体３の軸剛性から形成したＴＭＤ動吸振器機構と錘８を載荷させる構成とを併用した振動低減機構により、低振動数域で同調効果を発揮しつつ、高振動数域で振動低減することができる。つまり、杭体３の軸剛性、回転慣性質量ダンパー７の慣性質量の値を調整することで、回転慣性質量ダンパー７の固有振動数を加振振動数や低振動数域である地盤Ｇの卓越振動数に合わせる（同調させる）。ＴＭＤ動吸振器機構の固有振動数ｆ_ｋは、杭体３の軸剛性をｋ、回転慣性質量ダンパー７の慣性質量をψとすると、次式で算出される。
この機構により、振動低減機構１はＴＭＤ動吸振器として機能し、同調振動数の近傍の振動を大きく低減させることができる。 From the above, the vibration reduction mechanism using the TMD dynamic vibration absorber mechanism formed from the inertial mass of the rotary inertia mass damper 7 and the axial rigidity of the pile body 3 in combination with the configuration of loading the weight 8 as in Case 5 can reduce vibration in the high frequency range while exerting a tuning effect in the low frequency range. In other words, by adjusting the axial rigidity of the pile body 3 and the inertial mass of the rotary inertia mass damper 7, the natural frequency of the rotary inertia mass damper 7 is matched (tuned) to the excitation frequency or the predominant frequency of the ground G, which is in the low frequency range. The natural frequency _fk of the TMD dynamic vibration absorber mechanism is calculated by the following formula, where k is the axial rigidity of the pile body 3 and ψ is the inertial mass of the rotary inertia mass damper 7.
This mechanism allows the vibration reduction mechanism 1 to function as a TMD dynamic vibration absorber, and can significantly reduce vibrations near the tuned frequency.

また、ケース６のように複数の帯状のＴＭＤ機構によって杭体３の軸剛性を高めることにより、回転慣性質量ダンパー７の慣性質量が錘８の質量に加算されたときと同様の振動低減効果を発揮する。該慣性質量は、回転慣性質量ダンパー７内の回転錘７３の質量の数百倍から数千倍になる。そのため、軽量な回転慣性質量ダンパー７の設置により巨大な錘８の質量を付加したのと同等の振動低減効果が得られることとなる。上記の構成により、広範囲の振動数域にわたり所望の振動低減効果を発揮することができる。 In addition, by increasing the axial stiffness of the pile body 3 using multiple band-shaped TMD mechanisms as in case 6, the same vibration reduction effect is achieved as when the inertial mass of the rotary inertia mass damper 7 is added to the mass of the weight 8. The inertial mass is several hundred to several thousand times the mass of the rotary weight 73 in the rotary inertia mass damper 7. Therefore, by installing a lightweight rotary inertia mass damper 7, a vibration reduction effect equivalent to that achieved by adding the mass of a huge weight 8 can be achieved. With the above configuration, the desired vibration reduction effect can be achieved over a wide range of vibration frequencies.

また、ケース６のように振動低減機構１を帯状の防振帯１２として構成することにより、１つの架台６に帯状に設けられる複数の杭体３の軸剛性と複数の回転慣性質量ダンパー７の慣性質量を調整することで、回転慣性質量ダンパー７を複数の異なる振動数に対して同調させることができる。そのため、１つの架台６と錘８を複数の回転慣性質量ダンパー７で共有化できる。上記の機構により、従来のＴＭＤ動吸振器のように同調振動数毎に錘とばねによる振動低減機構を設ける必要がなく、振動低減機構１の錘は慣性質量ダンパーの小さな質量で代替でき、ばねも杭の軸剛性を用いることで軽量かつコンパクトな機構となる。また、振動低減機構１は、巨大な機構や広い設置場所を要することなく所望の振動低減効果を発揮できる構成とすることができる。 In addition, by configuring the vibration reduction mechanism 1 as a belt-shaped vibration isolation belt 12 as in case 6, the axial stiffness of the multiple pile bodies 3 arranged in a belt shape on one base 6 and the inertial mass of the multiple rotational inertia mass dampers 7 can be adjusted to tune the rotational inertia mass dampers 7 to multiple different vibration frequencies. Therefore, one base 6 and weight 8 can be shared by multiple rotational inertia mass dampers 7. With the above mechanism, there is no need to provide a vibration reduction mechanism using weights and springs for each tuned vibration frequency as in the conventional TMD dynamic vibration absorber, and the weight of the vibration reduction mechanism 1 can be replaced by the small mass of the inertial mass damper, and the spring uses the axial stiffness of the pile, resulting in a lightweight and compact mechanism. In addition, the vibration reduction mechanism 1 can be configured to achieve the desired vibration reduction effect without requiring a huge mechanism or a large installation space.

第一架台部材４および第二架台部材５は、Ｈ型鋼により形成されることで、曲げ剛性や曲げ強度に対する断面効率を向上させることができる。そのため、振動低減機構１は、錘８による上載荷重や架台６の上部に配置されている第二架台部材５の重量による破損を防止することが可能となる。 The first and second mounting members 4 and 5 are made of H-shaped steel, which improves the cross-sectional efficiency with respect to bending rigidity and bending strength. This makes it possible for the vibration reduction mechanism 1 to prevent damage caused by the load placed on top of the weight 8 or the weight of the second mounting member 5 that is placed on top of the mounting 6.

地盤面補強層９は、架台６（第一架台部材４）と地盤Ｇとの間に設けられることで、錘８による上載荷重や振動低減機構１の重量により振動低減機構１が設置されている地盤Ｇの沈下を抑制することができる。そのため、振動低減機構１の各部位の配設位置のずれの発生等による振動低減効果の低下を防ぐことが可能となる。 The ground surface reinforcing layer 9 is provided between the frame 6 (first frame member 4) and the ground G, and can suppress the subsidence of the ground G on which the vibration reduction mechanism 1 is installed due to the load applied by the weight of the vibration reduction mechanism 1 and the weight of the weight 8. This makes it possible to prevent a decrease in the vibration reduction effect due to the occurrence of deviations in the installation positions of each part of the vibration reduction mechanism 1, etc.

以上、本発明による振動低減機構および振動低減方法の実施形態について説明したが、本発明は上記の実施形態に限定されるものではなく、その趣旨を逸脱しない範囲で適宜変更可能である。
例えば、上記の実施形態では、図１および図２に示すように振動低減機構１は、Ｘ方向に防振帯１２を備えるが、振動波２１は全方向に伝播する波とされる。そのため、例えば振動障害予防箇所が振動発生箇所２の周囲に位置する場合は、振動発生箇所２を包囲するように防振帯１２を形成した振動低減機構１としてもよい。 Although the embodiments of the vibration reduction mechanism and vibration reduction method according to the present invention have been described above, the present invention is not limited to the above-mentioned embodiments and can be modified as appropriate without departing from the spirit of the present invention.
1 and 2, the vibration reduction mechanism 1 has the vibration isolation band 12 in the X direction, but the vibration wave 21 is a wave that propagates in all directions. Therefore, for example, when the vibration disorder prevention location is located around the vibration generation location 2, the vibration reduction mechanism 1 may have the vibration isolation band 12 formed to surround the vibration generation location 2.

また、上記の本実施形態では、杭体３と、回転慣性質量ダンパー７と、架台６と、錘８とがＺ方向に直列配置されているが、回転慣性質量ダンパー７とＺ方向並列にオイルダンパー等の粘性減衰装置を付加して減衰係数を付加する構成としてもよいし、回転慣性質量ダンパー７を慣性質量と粘性減衰を同時に付与できる慣性コマとして振動低減機構１を構成してもよい。また、杭の軸剛性が過大な場合は、慣性質量ダンパーに付加ばねｋ´を直列して追加し、杭の軸剛性と付加ばねとの直列ばね剛性をｋとしてもよい。 In addition, in the above embodiment, the pile body 3, the rotational inertia mass damper 7, the base 6, and the weight 8 are arranged in series in the Z direction, but a viscous damping device such as an oil damper may be added in parallel with the rotational inertia mass damper 7 in the Z direction to add a damping coefficient, or the vibration reduction mechanism 1 may be configured with the rotational inertia mass damper 7 as an inertial top that can simultaneously provide inertial mass and viscous damping. Also, if the axial stiffness of the pile is excessive, an additional spring k' may be added in series with the inertial mass damper, and the series spring stiffness of the axial stiffness of the pile and the additional spring may be k.

１振動低減機構
２振動発生箇所
３杭体
４第一架台部材
５第二架台部材
６架台
７回転慣性質量ダンパー
８錘
９地盤面補強層
１１振動障害予防箇所
３１根入れ部
３２杭頭部
４１下側フランジ
５３上側フランジ
５１下側フランジ
９２支持地盤 REFERENCE SIGNS LIST 1 vibration reduction mechanism 2 vibration generation location 3 pile body 4 first frame member 5 second frame member 6 frame 7 rotational inertia mass damper 8 weight 9 ground surface reinforcement layer 11 vibration damage prevention location 31 embedded portion 32 pile head 41 lower flange 53 upper flange 51 lower flange 92 supporting ground

Claims

It is provided between a vibration generating point and a vibration disorder prevention point on a propagation path of a vibration wave generated from the vibration generating point,
A pile body including an embedded portion that is embedded into the supporting ground and reduces the peripheral friction force of the peripheral portion, and a pile head portion located on the ground surface;
A stand including a first stand member made of steel and arranged adjacent to both sides of the pile body when viewed from the front on the ground surface, and a second stand member made of steel and arranged on an upper portion of the first stand member;
A rotary inertia mass damper is disposed between the pile body and the second frame member between the first frame members, the upper end of the rotary inertia mass damper being connected to the second frame member and the lower end of the rotary inertia mass damper being connected to the pile head portion;
Equipped with
Vibration reduction mechanism.

A weight is provided on an upper portion of the second frame member and applies an upper load to the rotary inertia mass damper.
The vibration reduction mechanism according to claim 1 .

The pile body and the rotary inertia mass damper are provided in series in a direction perpendicular to the propagation path,
the second mounting member is provided on top of each of the rotary inertia mass dampers,
The first mounting member and the second mounting member are arranged in a grid shape in a plan view.
The vibration reduction mechanism according to claim 1 or 2.

The first frame member and the second frame member are formed of H-shaped steel,
The lower flange of the first mounting member contacts the ground surface,
a lower flange of the second frame member is connected to an upper flange of the first frame member and to the rotary inertia mass damper,
The first mounting member and the second mounting member are arranged so that the directions of the H-shapes of the first mounting member and the second mounting member are perpendicular to each other in a plan view.
The vibration reduction mechanism according to claim 1 .

A ground surface reinforcing layer is formed around the pile body,
The first mounting member is provided on the upper part of the ground surface reinforcing layer.
The vibration reduction mechanism according to claim 1 .

A vibration reduction method, characterized in that the vibration reduction mechanism according to any one of claims 1 to 5 is provided between a vibration generation location and a vibration disorder prevention location on the propagation path of vibration waves generated from the vibration generation location.