JP2004317364A - Device for quick loading test of pile - Google Patents

Device for quick loading test of pile Download PDF

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JP2004317364A
JP2004317364A JP2003113094A JP2003113094A JP2004317364A JP 2004317364 A JP2004317364 A JP 2004317364A JP 2003113094 A JP2003113094 A JP 2003113094A JP 2003113094 A JP2003113094 A JP 2003113094A JP 2004317364 A JP2004317364 A JP 2004317364A
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load
pile
inertial mass
rapid
weight
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JP4098145B2 (en
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Satoshi Fujita
聡 藤田
Osamu Furuya
治 古屋
Shigenori Kanemichi
繁紀 金道
Kosaku Takano
公作 高野
Atsuyuki Oishi
淳之 大石
Hiroshi Kurabayashi
浩 倉林
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Tokyo Denki University
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Tokyo Denki University
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Abstract

<P>PROBLEM TO BE SOLVED: To attain about 0.05-0.2 sec of target loading time for a quick loading test to enhance testing precision. <P>SOLUTION: In this device 1 for a quick loading test of a pile 50, a weight 5 is dropped onto an inertia mass 4, and a drop impact load is made to act on a pile head 51 via the inertia mass 4 to conduct the quick loading test. A load transmission device 3 combined with an elastomer 11 having a linear or nonlinear characteristic and a damping element 12 is arranged between the pile head 51 and the inertia mass 4, and the pile head 51 is applied with a great load for the target loading time in the drop impact when dropping the weight 5, by combination of an elastic action of the elastomer 11 and a damping action of the damping element 12 in the load transmission device 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、土木、建築構造物の施工の際に使用される杭の急速載荷試験装置に関する。
【０００２】
【従来の技術】
土木、建築構造物の施工に際して、杭の支持力を正確に知ることは極めて重要である。そのため、従来においては、この種の試験として、所謂静的載荷試験やハンマー打撃による所謂衝撃載荷試験が行われている。
しかしながら、前者の静的載荷試験は、かなり正確な試験データを得ることはできるが、試験データ取得までに長時間を要し、更に試験設備が大がかりになるため試験費用が大きくなる。従って、試験し得る杭の数量も限られてくる。
また、後者の衝撃載荷試験は、前者に比べて時間的、費用的には有利であるが、得られるデータは動的抵抗成分が含まれるため、解析により杭の支持力評価のための静的抵抗成分を考察する必要がある。従って、杭の支持力は波動の影響を除去する必要があること、また、載荷時間が０．０１乃至０．０２秒と極めて短いため測定値から正確に杭の支持力を推定することが困難である。
【０００３】
これに対して、杭の正確な支持力の把握と経済的、合理的な試験方法として静的載荷試験と衝撃載荷試験の中間に位置する所謂急速載荷試験が注目されている。この急速載荷試験は、静的試験での載荷時間概ね３０分と、衝撃載荷試験の載荷時間概ね０．０１乃至０．０２秒との中間を目指すもので、載荷時間としては約０．０５乃至０．２秒を目標としている。
【０００４】
現在行われている急速載荷試験としては、例えば、杭と重錘（モンケン）の間にコイルばねを定置し、重錘を落下させることで衝撃荷重を与える所謂「スードスタティック」試験、坑頭に反力体を配置し高圧ガスや火薬の爆発燃焼力により反力体を急速に打ち上げ、その時の慣性反力を杭頭に作用させることにより衝撃を与える所謂「スタナミック」試験等がある。
【０００５】
また、最近ではスードスタティック試験方式のコイルばねの代わりに、クッション材を用いた所謂「ＦＭ（Ｆａｌｌｉｎｇ Ｍａｓｓ）」試験等も行われているが、いずれにしても載荷時間が目標値に達していない。
更に、スタナミック試験の場合、燃焼火薬の監督官庁への使用届手続きで４週間程度の日数を要するために、作業現場においてスピィーディな対応が困難である等の問題もある。
【０００６】
特許文献１には、重錘と杭頭との間に高分子化合物等からなる緩衝材を配置した急速載荷試験装置が開示されている。しかし、特許文献１の急速載荷試験装置の場合、簡略な構成ではあるものの、高分子化合物等からなる緩衝材による高周波の荷重成分の発生を抑制することを目的としており、上述した載荷時間の目標値を達成することは難しい。
【０００７】
【特許文献１】
特開２００２−３０３５７０号公報
【０００８】
【発明が解決しようとする課題】
本発明は、上述した従来の実情に鑑み開発されたものであり、その目的とするところは、従来技術で解決されなければならない急速載荷試験で一番重要で、且つ、難しい事項は、長い載荷時間を確保しつつ杭頑に大きな衝撃荷重を伝達することであることを考慮し、急速載荷試験の目標載荷時間約０．０５乃至０．２秒を達成し、試験精度向上を可能とするとともに、試験時間短縮、費用低減、及び環境への配慮も良好な杭の急速載荷試験装置を提供することにある。
【０００９】
【課題を解決するための手段】
請求項１記載の発明に係る杭の急速載荷試験装置は、重錘を慣性マス上に落下させ、慣性マスを介して杭頭に落下衝撃荷重を作用させて急速載荷試験を行う杭の急速載荷試験装置であって、杭頭と慣性マスとの間に、線形或いは非線形特性を持った弾性体と、減衰要素とを組み合わせた荷重伝達装置を配置し、荷重伝達装置における弾性体の弾性作用及び減衰要素の減衰作用の組み合わせにより、前記重錘を落下させたときの落下衝撃時に杭頭に大きな荷重を長い時間与えることができるようにしたことを特徴とするものである。
【００１０】
請求項２記載の発明に係る杭の急速載荷試験装置は、重錘を慣性マス上に落下させ、慣性マス、衝撃荷重検出手段を介して杭頭に落下衝撃荷重を作用させて急速載荷試験を行う杭の急速載荷試験装置であって、前記衝撃荷重検出手段により衝撃荷重の検出を行うようにしたことを特徴とするものである。
請求項１、２記載の発明によれば、請求項１記載の発明の作用に加えて、衝撃荷重検出手段により衝撃荷重の検出を行い、衝撃荷重の解析に供することができる。
【００１１】
請求項３記載の発明に係る杭の急速載荷試験装置は、請求項１又は２記載の急速載荷試験装置において、前記荷重伝達装置における前記弾性体が、金属系、ゴム系、油圧系、粘弾性系の要素の単独又は複数の組み合わせにより構成されるものであることを特徴とする。
請求項３記載の発明によれば、前記弾性体を、金属系、ゴム系、油圧系、粘弾性系の要素の単独又は複数の組み合わせとした構成で、請求項１又は２記載の発明の作用を発揮させることができる。
【００１２】
請求項４記載の発明に係る杭の急速載荷試験装置は、請求項１乃至３のいずれかに記載の急速載荷試験装置において、前記荷重伝達装置における減衰要素が、粘性系、摩擦系、弾塑性系の要素の単独又は複数の組み合わせにより構成されるものであることを特徴とする。
請求項４記載の発明によれば、前記減衰要素を、粘性系、摩擦系、弾塑性系の要素の単独又は複数の組み合わせとした構成で、請求項１乃至３のいずれかに記載の発明の作用を発揮させることができる。
【００１３】
請求項５記載の発明に係る杭の急速載荷試験装置は、請求項１乃至４のいずれかに記載の急速載荷試験装置において、前記慣性マスが、鋼材からなり、重錘との接触部に緩衝材を備えることを特徴とする。
請求項５記載の発明によれば、慣性マスの重錘との接触部に配置した緩衝材の緩衝作用をも加えた構成で請求項１乃至４のいずれかに記載の発明の作用を発揮させることができる。
【００１４】
請求項６記載の発明に係る杭の急速載荷試験装置は、請求項１乃至５のいずれかに記載の急速載荷試験装置において、前記重錘を落下させたときの落下衝撃時に杭頭に与えられる載荷時間は、０．０５秒又はそれ以上であることを特徴とする。
請求項６記載の発明によれば、前記重錘を落下させたときの落下衝撃時に杭頭に与えられる載荷時間を０．０５秒又はそれ以上として請求項１乃至５のいずれかに記載の発明の作用を発揮させることができる。
【００１５】
【発明の実施の形態】
以下、本発明に係る実施の形態を図面を参照して詳細に説明する。
（実施の形態１）
図１乃至図４は本発明の実施の形態１に係る杭（試験杭）５０の急速載荷試験装置１を示すものである。
この急速載荷試験装置１は、地面ＧＬに打ち込まれた杭５０の杭頭５１に対して落下衝撃荷重を作用させて急速載荷試験を行うものであり、杭頭５１上に配置した衝撃荷重検出手段である円柱状のロードセル２と、このロードセル２上に配置した荷重伝達装置３と、この荷重伝達装置３上に配置した例えば四角柱状の慣性マス４と、この慣性マス４の上方に配置され該慣性マス４に対して落下衝撃を与える例えば四角柱状の重錘５とを有している。
【００１６】
前記ロードセル２、荷重伝達装置３、慣性マス４及び重錘５は、ロードセル２上に垂直状態に立設けた垂直軸体（真矢）６を中心として同心的に下から順に配置している。
前記杭頭５１とロードセル２の下端との間には、例えば四角板状の台座７を介在させ、杭頭５１とロードセル２の上端との間には、例えば四角板状の台座８を介在させている。
【００１７】
前記荷重伝達装置３は、図４にも示すように、線形或いは非線形特性を持ったコイルバネからなる弾性体１１と、この弾性体１１の回りに垂直軸体６に関して９０度間隔で垂直配置した合計４個の例えば油圧シリンダからなる減衰要素１２とを組み合わせて構成している。
【００１８】
前記各減衰要素１２の下端側は、図３にも示すように、前記台座８に対して水平配置に取り付けた下部取り付け治具１３により支持され、また、減衰要素１２の上端側は、図２にも示すように、前記慣性マス４の側壁に水平配置に取り付けた上部取り付け治具１４により支持され、これにより、４個の減衰要素１２は前記台座８及び慣性マス４の外側で前記弾性体１１を囲む状態で垂直配置している。
【００１９】
前記慣性マス４は、例えば鋼材からなり、重錘５との接触部、すなわち慣性マス４の上面に板状の例えばゴム材等からなる緩衝材１５を備えている。
【００２０】
前記荷重伝達装置３における弾性体１１としては、前記コイルバネを用いる他、金属系（例えばコイルバネ、皿バネ等）、ゴム系（例えば発泡ウレタン等）、油圧系、粘弾性系の各要素の単独又は複数の組み合わせにより構成することができる。
【００２１】
また、前記減衰要素１２は、油圧シリンダの他、粘性系ダンパー、摩擦系ダンパー、弾塑性系ダンパーの各要素の単独又は複数の組み合わせにより構成することができる。
【００２２】
本実施の形態に係る急速載荷試験装置１により急速載荷試験を行う際には、重錘５を慣性マス４上に落下させ、慣性マス４、ロードセル２を介して杭頭５１に落下衝撃荷重を作用させて杭５０に対する急速載荷試験を行う。
これにより、荷重伝達装置３における弾性体１１の弾性作用及び減衰要素１２の減衰作用の組み合わせにより、更には慣性マス４の重錘５との接触部に配置した緩衝材１５の重錘５に対する緩衝作用により、前記重錘５を落下させたときの落下衝撃時に杭頭５１に大きな荷重を長い時間（例えば、０．０５乃至０．２秒）与えることができる。本実施の形態に係る急速載荷試験装置１では、本装置１により重錘５を落下させたときの落下衝撃時に杭頭５１に与えられる大きな荷重の時間、すなわち載荷時間は、例えば、０．０５乃至０．２秒、或いは０．０５秒又はそれ以上である。
【００２３】
ここで、本実施の形態に係る急速載荷試験の一例について説明する。
例えば、重錘５の重量をｍ１＝２０００ｋｇ（２ｔｆ）、慣性マス４の重量をｍ２＝２０００ｋｇ（２ｔｆ）（本実施の形態）、ｍ２＝１００ｋｇ（０．１ｔｆ）（慣性マス４が無いとした場合）としたとき、慣性マス４を使用した場合と、慣性マス４を使用しない場合の載荷荷重及び載荷時間（周波数）について以下に説明する。
重錘５が自由落下したときの衝突直前の速度ｖ１は、ｖ１＝√（２ｇＨ）（ｍ／ｓ）で表される。ここにｇは重力加速度、Ｈは落下距離である。
重錘５が慣性マス４と衝突するとき、反発係数ｅ＝０．５６（但し鋼鉄と鋼鉄の場合）とすると、重錘５、慣性マス４の衝突後の速度ｖ１’、ｖ２’は、質量保存の法則により、下記数１、数２で各々表すことができる。
【数１】

Figure 2004317364
【数２】
Figure 2004317364
【００２４】
前記重錘５の落下距離Ｈを５ｍとして、重錘５、慣性マス４の衝突直前の速度ｖ１、ｖ２、衝突直後の速度ｖ１’、ｖ２’から、杭５０（杭頭５１）に対する載荷荷重及び載荷時間（周波数）を計算すると、図７に示すようになる。
図７に示す結果から明らかなように、載荷時間（周波数）を慣性マス４を使用した場合と、使用しない場合とで同じ（＝１０Ｈｚ（０．１秒））とした場合には、慣性マス４を使用した場合の載荷荷重Ｆは９９ｔｆ、慣性マス４を使用しない場合の載荷荷重Ｆは９ｔｆとなり、慣性マス４を使用した方が使用しない場合に比べ１１倍の載荷荷重Ｆを杭５０（杭頭５１）に付与することができる。
逆に、杭５０（杭頭５１）に付与する載荷荷重Ｆを、慣性マス４を使用した場合と、使用しない場合とで同じ（９９ｔｆ）にしようとすると、載荷時間（周波数）は慣性マス４を使用した場合には１０Ｈｚ（０．１秒）であるのに対して、慣性マス４を使用しない場合には１０６Ｈｚ（約０．０１秒）となり、慣性マス４を使用した方が使用しない場合に比べ約１０倍長い載荷時間を得ることができる。
【００２５】
そして、前記ロードセル２により杭頭５１に作用する衝撃荷重の検出を行って、図示していないがデータ処理手段に送ることで衝撃荷重のデータ解析を行うことが可能となる。
【００２６】
このように本実施の形態１では、重錘５の衝撃を受けると同時に荷重伝達装置３を介して杭頭５１に長い時間を掛けて大きな衝撃荷重を与えることができ、前述した従来技術では達成することができなかった載荷時間が長く、高精度の急速載荷試験が可能な急速載荷試験装置１を提供することができる。
【００２７】
また、本実施の形態１では、杭５０と慣性マス４との間に前記荷重伝達装置３を配置した簡略な構成であることから、試験時間の短縮、試験費用の低減を図ることができ、繰り返し試験も可能であり、機動性も持ち合わせ、更には爆薬等を用いないことから環境への配慮も良好な急速載荷試験装置１を提供できる。
【００２８】
（実施の形態２）
図５、図６は、本発明に係る実施の形態２を示すものであり、本実施の形態２に係る杭の急速載荷試験装置は、基本的構成は実施の形態１の場合と同様であるが、前記荷重伝達装置３に代替して、１個又は２以上の複数個、例えば４個のコイルバネからなる弾性体２１を例えば四角柱状の減衰要素２２内に埋設した構成の荷重伝達装置３Ａを用いることが特徴である。
図５中の符号８ａは慣性マス４の下端との間に配置する台座である。
【００２９】
この荷重伝達装置３Ａを用いて構成した急速載荷試験装置によっても、前述した実施の形態１の急速載荷試験装置１と同様な作用、効果を発揮させることができる。
【発明の効果】
以上詳述した本発明によれば以下の各効果を奏する。
請求項１記載の発明によれば、簡略な構成でありながら、重錘を落下させたときの落下衝撃時に杭に大きな荷重を長い時間与えることが可能となり、高精度の荷重試験を行うことができ、試験時間の短縮、試験費用の低減を図ることができ、繰り返し試験も可能であり、機動性も持ち合わせ、更には爆薬等を用いないことから環境への配慮も可能な急速載荷試験装置を提供できる。
請求項２記載の発明によれば、請求項１記載の発明の効果に加えて、衝撃荷重検出手段により衝撃荷重の検出を行い、衝撃荷重の解析に供することができる急速載荷試験装置を提供できる。
請求項３記載の発明によれば、前記弾性体を、金属系、ゴム系、油圧系、粘弾性系の要素の単独又は複数の組み合わせとした構成で、請求項１又は２記載の発明の効果を奏する急速載荷試験装置を提供できる。
請求項４記載の発明によれば、前記減衰要素を、粘性系、摩擦系、弾塑性系の要素の単独又は複数の組み合わせとした構成で、請求項１乃至３記載の発明の効果を奏する急速載荷試験装置を提供できる。
請求項５記載の発明によれば、慣性マスの重錘との接触部に配置した緩衝材の緩衝作用をも加えた構成で、請求項１乃至４記載の発明の効果を奏する急速載荷試験装置を提供できる。
請求項６記載の発明によれば、前記重錘を落下させたときの落下衝撃時に杭頭に与えられる載荷時間を０．０５秒又はそれ以上として請求項１乃至５記載の発明の効果を奏する急速載荷試験装置を提供できる。
【図面の簡単な説明】
【図１】本発明の実施の形態１に係る杭の急速載荷試験装置を示す概略構成図である。
【図２】図１のＡ−Ａ線断面図である。
【図３】図１のＢ−Ｂ線断面図である。
【図４】本発明の実施の形態に係る杭の急速載荷試験装置における荷重伝達装置のみを実線で示す概略構成図である。
【図５】本発明の実施の形態２に係る杭の急速載荷試験装置における荷重伝達装置を示す概略部分断面図である。
【図６】図５のＣ−Ｃ線断面図である。
【図７】本発明の実施の形態１に係る載荷試験結果を示す表である。
【符号の説明】
１ 急速載荷試験装置
２ ロードセル
３ 荷重伝達装置
３Ａ 荷重伝達装置
４ 慣性マス
５ 重錘
６ 垂直軸体
７ 台座
８ 台座
８ａ 台座
１１ 弾性体
１２ 減衰要素
１３ 下部取り付け治具
１４ 上部取り付け治具
１５ 緩衝材
２１ 弾性体
２２ 減衰要素
５０ 杭
５１ 杭頭
ＧＬ 地面[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a pile quick loading test device used for construction of civil engineering and building structures.
[0002]
[Prior art]
It is extremely important to accurately know the bearing capacity of piles when constructing civil engineering and building structures. Therefore, conventionally, as this type of test, a so-called static loading test and a so-called impact loading test by hammering have been performed.
However, the former static loading test can obtain fairly accurate test data, but it takes a long time to obtain the test data, and the test equipment becomes large, so that the test cost increases. Therefore, the number of piles that can be tested is also limited.
In addition, the latter impact loading test is more advantageous in terms of time and cost than the former, but the obtained data includes a dynamic resistance component. It is necessary to consider the resistance component. Therefore, it is necessary to eliminate the influence of the wave on the bearing capacity of the pile, and it is difficult to accurately estimate the bearing capacity of the pile from the measured values because the loading time is extremely short, 0.01 to 0.02 seconds. It is.
[0003]
On the other hand, a so-called rapid loading test, which is located between a static loading test and an impact loading test, has attracted attention as an economical and rational test method for accurately grasping the bearing capacity of a pile. This rapid loading test aims at a time between a loading time of about 30 minutes in the static test and a loading time of about 0.01 to 0.02 seconds in the impact loading test, and a loading time of about 0.05 to 0.02 seconds. The goal is 0.2 seconds.
[0004]
For example, a so-called “sood static” test in which a coil spring is fixed between a pile and a weight (Monken) and an impact load is applied by dropping the weight, There is a so-called "stanamic" test in which a reaction body is arranged, the reaction body is rapidly launched by the explosive combustion force of high-pressure gas or explosive, and an impact is exerted by applying an inertial reaction force at that time to the pile head.
[0005]
In recent years, a so-called “FM (Falling Mass)” test using a cushion material instead of the coil spring of the pseudo static test method has been performed, but in any case, the loading time has not reached the target value. .
Furthermore, in the case of the stunnic test, the procedure for reporting the use of the combustion explosive to the regulatory agency requires about four weeks, so that there is a problem that it is difficult to respond quickly at the work site.
[0006]
Patent Literature 1 discloses a rapid load test device in which a buffer material made of a polymer compound or the like is arranged between a weight and a pile head. However, in the case of the rapid loading test apparatus disclosed in Patent Document 1, although the configuration is simple, the purpose is to suppress the generation of high-frequency load components due to a buffer material made of a polymer compound or the like. It is difficult to achieve value.
[0007]
[Patent Document 1]
JP, 2002-303570, A
[Problems to be solved by the invention]
The present invention has been developed in view of the above-mentioned conventional circumstances, and the object thereof is that the most important and difficult matter in the rapid loading test that must be solved by the prior art is long loading. In consideration of transmitting a large impact load stubbornly while securing time, achieve the target loading time of about 0.05 to 0.2 seconds for the rapid loading test, and improve the test accuracy. It is another object of the present invention to provide a pile quick loading test device that can reduce the test time, reduce the cost, and consider the environment.
[0009]
[Means for Solving the Problems]
The pile rapid loading test device according to the first aspect of the present invention is a pile rapid loading test device in which a weight is dropped onto an inertial mass and a drop impact load is applied to the pile head via the inertial mass to perform a rapid loading test. A test device, in which a load transmitting device that combines an elastic body having linear or non-linear characteristics and a damping element is disposed between a pile head and an inertial mass, and the elastic action of the elastic body in the load transmitting device and A large load can be applied to the pile head for a long time at the time of a drop impact when the weight is dropped by a combination of the damping effects of the damping elements.
[0010]
The pile rapid loading test apparatus according to the invention of claim 2 performs a rapid loading test by dropping a weight onto an inertial mass and applying a drop impact load to a pile head via an inertial mass and impact load detecting means. A rapid loading test device for piles to be performed, wherein an impact load is detected by the impact load detecting means.
According to the first and second aspects of the present invention, in addition to the operation of the first aspect of the present invention, the impact load can be detected by the impact load detecting means and analyzed for the impact load.
[0011]
According to a third aspect of the present invention, in the rapid load test device for a pile according to the first or second aspect, the elastic body in the load transmitting device is made of a metal, a rubber, a hydraulic, a viscoelasticity. It is characterized by being constituted by one or a combination of a plurality of system elements.
According to the third aspect of the present invention, the elastic body has a structure in which a metal-based, rubber-based, hydraulic-based, or visco-elastic-based element is used alone or in combination. Can be demonstrated.
[0012]
According to a fourth aspect of the present invention, in the rapid load test device for a pile according to any one of the first to third aspects, the damping element in the load transmitting device is a viscous system, a friction system, or an elasto-plastic. It is characterized by being constituted by one or a combination of a plurality of system elements.
According to the invention as set forth in claim 4, the damping element is configured to be a single element or a combination of a plurality of elements of a viscous system, a friction system, and an elasto-plastic system. The action can be exerted.
[0013]
According to a fifth aspect of the present invention, in the rapid load test device for a pile according to any one of the first to fourth aspects, the inertial mass is made of a steel material, and a buffer portion is provided at a contact portion with the weight. It is characterized by having a material.
According to the fifth aspect of the present invention, the function of the invention according to any one of the first to fourth aspects is exerted by a configuration in which a buffering action of a buffer material arranged at a contact portion of the inertial mass with the weight is added. be able to.
[0014]
According to a sixth aspect of the present invention, in the rapid loading test device for a pile according to any one of the first to fifth aspects, the pile is applied to a pile head at the time of a drop impact when the weight is dropped. The loading time is characterized by being 0.05 seconds or longer.
According to the invention as set forth in claim 6, the loading time given to the pile head at the time of a drop impact when the weight is dropped is set to 0.05 seconds or more, the invention as set forth in any one of claims 1 to 5 Can be exerted.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.
(Embodiment 1)
FIG. 1 to FIG. 4 show a rapid loading test device 1 for a pile (test pile) 50 according to Embodiment 1 of the present invention.
The rapid loading test device 1 performs a rapid loading test by applying a drop impact load to a pile head 51 of a pile 50 driven into the ground GL, and performs an impact load detecting means disposed on the pile head 51. , A load transmitting device 3 disposed on the load cell 2, an inertial mass 4 in the form of, for example, a quadrangular prism disposed on the load transmitting device 3, and a load transmitting device 3 disposed above the inertial mass 4. It has, for example, a square pillar-shaped weight 5 that gives a drop impact to the inertial mass 4.
[0016]
The load cell 2, the load transmitting device 3, the inertial mass 4, and the weight 5 are concentrically arranged in order from the bottom around a vertical shaft (a true arrow) 6 provided upright on the load cell 2.
For example, a square plate-shaped pedestal 7 is interposed between the pile head 51 and the lower end of the load cell 2, and, for example, a square plate-shaped pedestal 8 is interposed between the pile head 51 and the upper end of the load cell 2. ing.
[0017]
As shown in FIG. 4, the load transmitting device 3 includes an elastic body 11 formed of a coil spring having linear or non-linear characteristics, and a vertical arrangement around the elastic body 11 at 90 ° intervals with respect to the vertical shaft body 6. It is configured by combining four damping elements 12 composed of, for example, hydraulic cylinders.
[0018]
As shown in FIG. 3, the lower end of each of the damping elements 12 is supported by a lower mounting jig 13 which is mounted horizontally with respect to the pedestal 8. As shown in FIG. 3, the damping element 12 is supported by an upper mounting jig 14 mounted on the side wall of the inertial mass 4 in a horizontal arrangement, so that the four damping elements 12 are provided outside the pedestal 8 and the inertial mass 4 by the elastic body. 11 are vertically arranged so as to surround them.
[0019]
The inertial mass 4 is made of, for example, a steel material, and includes a plate-like cushioning material 15 made of, for example, a rubber material on a contact portion with the weight 5, that is, on the upper surface of the inertial mass 4.
[0020]
As the elastic body 11 in the load transmitting device 3, in addition to using the coil spring, a metal-based (for example, a coil spring, a disc spring, or the like), a rubber-based (for example, urethane foam), a hydraulic system, or a viscoelastic system may be used alone or It can be configured by a plurality of combinations.
[0021]
Further, the damping element 12 can be constituted by a single element or a combination of plural elements of a viscous damper, a friction damper, and an elasto-plastic damper in addition to the hydraulic cylinder.
[0022]
When performing a rapid loading test by the rapid loading test device 1 according to the present embodiment, the weight 5 is dropped onto the inertial mass 4, and a drop impact load is applied to the pile head 51 via the inertial mass 4 and the load cell 2. A rapid loading test is performed on the pile 50 by acting.
Thereby, by the combination of the elastic action of the elastic body 11 and the damping action of the damping element 12 in the load transmitting device 3, furthermore, the cushioning material 15 arranged at the contact portion of the inertial mass 4 with the weight 5 absorbs the weight 5 against the weight 5. By the action, a large load can be applied to the pile head 51 for a long time (for example, 0.05 to 0.2 seconds) at the time of a drop impact when the weight 5 is dropped. In the rapid loading test device 1 according to the present embodiment, the time of a large load applied to the pile head 51 at the time of a drop impact when the weight 5 is dropped by the device 1, that is, the loading time is, for example, 0.05. To 0.2 seconds, or 0.05 seconds or more.
[0023]
Here, an example of the rapid loading test according to the present embodiment will be described.
For example, the weight of the weight 5 is m 1 = 2000 kg (2 tf), the weight of the inertial mass 4 is m 2 = 2000 kg ( 2 tf) (this embodiment), and m 2 = 100 kg (0.1 tf) (the inertial mass 4 is The case where the inertial mass 4 is used and the case where the inertial mass 4 is not used, the loading load and the loading time (frequency) when the inertial mass 4 is not used will be described below.
The speed v 1 immediately before the collision when the weight 5 falls freely is expressed by v 1 = √ (2 gH) (m / s). Here, g is the gravitational acceleration, and H is the falling distance.
When the weight 5 collides with the inertial mass 4 and the coefficient of restitution e = 0.56 (in the case of steel and steel), the velocities v 1 ′ and v 2 ′ after the collision of the weight 5 and the inertial mass 4 are as follows. According to the law of conservation of mass, they can be expressed by the following equations 1 and 2, respectively.
(Equation 1)
Figure 2004317364
(Equation 2)
Figure 2004317364
[0024]
Assuming that the falling distance H of the weight 5 is 5 m, the pile 50 (pile head 51) is obtained from the velocities v 1 and v 2 immediately before the collision of the weight 5 and the inertial mass 4 and the velocities v 1 ′ and v 2 ′ immediately after the collision. FIG. 7 shows the calculated load and load time (frequency) for.
As is clear from the results shown in FIG. 7, when the loading time (frequency) is the same (= 10 Hz (0.1 second)) between the case where the inertial mass 4 is used and the case where it is not used, the inertial mass 4 is 99 tf, and the load F when the inertial mass 4 is not used is 9 tf. The load 50 is 11 times larger when the inertial mass 4 is not used than when the inertial mass 4 is not used. Pile head 51).
Conversely, if the load F applied to the pile 50 (pile head 51) is set to be the same (99 tf) when the inertial mass 4 is used and when it is not used, the loading time (frequency) is reduced by the inertial mass 4 When using the inertial mass 4, the frequency is 10 Hz (0.1 second), whereas when the inertial mass 4 is not used, the frequency is 106 Hz (about 0.01 second). Approximately 10 times longer loading time can be obtained.
[0025]
The impact load acting on the pile head 51 is detected by the load cell 2 and sent to a data processing unit (not shown), whereby the impact load data can be analyzed.
[0026]
As described above, in the first embodiment, a large impact load can be applied to the pile head 51 via the load transmitting device 3 over a long period of time while receiving the impact of the weight 5. It is possible to provide the rapid loading test apparatus 1 in which the loading time that could not be performed is long, and the rapid loading test with high accuracy can be performed.
[0027]
Further, in the first embodiment, since the load transmitting device 3 is arranged between the pile 50 and the inertial mass 4 in a simple configuration, the test time can be reduced and the test cost can be reduced. It is possible to provide a rapid loading test apparatus 1 that can perform repeated tests, has mobility, and does not use explosives and the like, and has good environmental considerations.
[0028]
(Embodiment 2)
FIGS. 5 and 6 show a second embodiment according to the present invention. The basic structure of the pile quick loading test device according to the second embodiment is the same as that of the first embodiment. However, instead of the load transmitting device 3, there is provided a load transmitting device 3A having a configuration in which one or two or more, for example, four, elastic members 21 composed of coil springs are embedded in a quadrangular prism-shaped damping element 22, for example. The feature is to use.
Reference numeral 8a in FIG. 5 denotes a pedestal disposed between the inertial mass 4 and the lower end.
[0029]
The same function and effect as those of the above-described quick load test device 1 of the first embodiment can also be exerted by the quick load test device configured using the load transmitting device 3A.
【The invention's effect】
According to the present invention described above, the following effects can be obtained.
According to the first aspect of the present invention, it is possible to apply a large load to the pile for a long time at the time of a drop impact when the weight is dropped, with a simple configuration, and to perform a high-precision load test. A rapid loading test device that can reduce test time and test cost, can perform repeated tests, has mobility, and is environmentally friendly because it does not use explosives. Can be provided.
According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, it is possible to provide a rapid loading test apparatus capable of detecting an impact load by the impact load detecting means and analyzing the impact load. .
According to the third aspect of the present invention, the elastic body has a configuration in which a metal-based, rubber-based, hydraulic-based, or visco-elastic-based element is used alone or in combination. Can be provided.
According to the fourth aspect of the present invention, the damping element is constituted by a single element or a combination of a plurality of elements of a viscous type, a friction type, and an elasto-plastic type. A load test device can be provided.
According to the fifth aspect of the present invention, a rapid loading test apparatus having the effect of the first to fourth aspects of the present invention is provided with a configuration in which a buffering action of a buffer material arranged at a contact portion of the inertial mass with the weight is also added. Can be provided.
According to the sixth aspect of the present invention, the loading time given to the pile head at the time of a drop impact when the weight is dropped is set to 0.05 second or more, so that the effects of the first to fifth aspects of the invention are exhibited. A rapid loading test device can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a rapid loading test device for piles according to Embodiment 1 of the present invention.
FIG. 2 is a sectional view taken along line AA of FIG.
FIG. 3 is a sectional view taken along line BB of FIG. 1;
FIG. 4 is a schematic configuration diagram showing only a load transmission device in a rapid loading test device for piles according to an embodiment of the present invention by a solid line.
FIG. 5 is a schematic partial cross-sectional view showing a load transmitting device in a rapid load test device for piles according to Embodiment 2 of the present invention.
FIG. 6 is a sectional view taken along line CC of FIG. 5;
FIG. 7 is a table showing a load test result according to the first embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rapid loading test apparatus 2 Load cell 3 Load transmission device 3A Load transmission device 4 Inertial mass 5 Weight 6 Vertical shaft 7 Pedestal 8 Pedestal 8a Pedestal 11 Elastic body 12 Damping element 13 Lower mounting jig 14 Upper mounting jig 15 Buffer material 21 elastic body 22 damping element 50 pile 51 pile head GL ground

Claims (6)

重錘を慣性マス上に落下させ、慣性マスを介して杭頭に落下衝撃荷重を作用させて急速載荷試験を行う杭の急速載荷試験装置であって、
杭頭と慣性マスとの間に、線形或いは非線形特性を持った弾性体と、減衰要素とを組み合わせた荷重伝達装置を配置し、
荷重伝達装置における弾性体の弾性作用及び減衰要素の減衰作用の組み合わせにより、前記重錘を落下させたときの落下衝撃時に杭頭に大きな荷重を長い時間与えることができるようにしたことを特徴とする杭の急速載荷試験装置。A rapid load test device for a pile that performs a rapid load test by dropping a weight onto an inertial mass and applying a drop impact load to a pile head via the inertial mass,
A load transmission device that combines an elastic body with linear or nonlinear characteristics and a damping element is placed between the pile head and the inertial mass,
By combining the elastic action of the elastic body and the damping action of the damping element in the load transmitting device, a large load can be applied to the pile head for a long time at the time of a drop impact when the weight is dropped. Load testing equipment for piles. 重錘を慣性マス上に落下させ、慣性マス、衝撃荷重検出手段を介して杭頭に落下衝撃荷重を作用させて急速載荷試験を行う杭の急速載荷試験装置であって、
前記衝撃荷重検出手段により衝撃荷重の検出を行うようにしたことを特徴とする杭の急速載荷試験装置。A rapid load test apparatus for a pile, in which a weight is dropped onto an inertial mass, and a drop impact load is applied to a pile head via an inertial mass and an impact load detecting means to perform a rapid load test,
A rapid loading test device for piles, wherein the impact load detecting means detects an impact load. 前記荷重伝達装置における前記弾性体は、金属系、ゴム系、油圧系、粘弾性系の要素の単独又は複数の組み合わせにより構成されるものであることを特徴とする請求項１又は２記載の杭の急速載荷試験装置。3. The pile according to claim 1, wherein the elastic body in the load transmitting device is configured by one or a combination of a plurality of metal, rubber, hydraulic, and viscoelastic elements. 4. Rapid loading test equipment. 前記荷重伝達装置における減衰要素は、粘性系、摩擦系、弾塑性系の要素の単独又は複数の組み合わせにより構成されるものであることを特徴とする請求項１乃至３のいずれかに記載の杭の急速載荷試験装置。The pile according to any one of claims 1 to 3, wherein the damping element in the load transmission device is configured by a single element or a combination of a plurality of elements of a viscous system, a friction system, and an elasto-plastic system. Rapid loading test equipment. 前記慣性マスは、鋼材からなり、重錘との接触部に緩衝材を備えることを特徴とする請求項１乃至４のいずれかに記載の杭の急速載荷試験装置。The rapid load test device for piles according to any one of claims 1 to 4, wherein the inertial mass is made of a steel material, and has a cushioning material at a contact portion with the weight. 前記重錘を落下させたときの落下衝撃時に杭頭に与えられる載荷時間は、０．０５秒又はそれ以上であることを特徴とする請求項１乃至５のいずれかに記載の杭の急速載荷試験装置。The rapid loading of a pile according to any one of claims 1 to 5, wherein a loading time given to the pile head at the time of a drop impact when the weight is dropped is 0.05 seconds or more. Testing equipment.
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