JP3858003B2 - Magnetic exploration method and apparatus - Google Patents

Description

【０００８】
ｍは、磁気量
ｒは、第１の磁気センサ部から磁性物体までの距離
Ｈ₁は、第１の磁気センサ部が検出した磁性物体の磁界の強さ
Ｈ₂は、第２の磁気センサ部が検出した磁性物体の磁界の強さ
Ｘｐ，Ｙｐ，Ｚｐは、第１の磁気センサ部の３軸方向の磁界の強さ
ｘｐ，ｙｐ，ｚｐは、第２の磁気センサ部の３軸方向の磁界の強さ
ｄは、第１の磁気センサ部と第２の磁気センサ部との距離である。
【０００９】
掘削孔は鉛直な孔である。掘削孔の直径、深さは限定されない。
ガイド管の素材は、非磁性体であれば限定されない。例えばアルミニウムでもよい。また、ガイド管の直径、長さは、掘削孔の直径、深さに応じて適宜変更される。
磁気探査される磁性物体の素材は限定されない。例えば、鉄、ニッケルなどの磁性を有する金属であればよい。磁性物体の形状、大きさも任意である。
【００１０】
第１の磁気センサ部と第２の磁気センサ部とは、同じ構造で同じ検出精度を有するものが好ましい。また、異なる構造で異なる検出精度のものでもよい。ただし、検出精度が異なるものの場合には、移動体の移動方向とは反対側の端部に配置された磁気センサ部の精度を高める方が好ましい。これは、磁性物体の検出時において、常時、移動体の移動方向の端部側に配置された磁気センサ部の方が、それとは反対側の磁気センサ部に比べて、磁性物体より遠くなるためである。
移動体における両磁気センサ部の具体的な位置、および、両磁気センサ部の離間距離は限定されない。両磁気センサ部が、移動体の移動方向の両側部に離間していればよい。移動体の素材、形状は限定されない。移動体の大きさ（直径）は、ガイド管の直径に応じて変更される。
【００１１】
第１の磁気センサ部と第２の磁気センサ部との区別は限定されない。例えば、進行方向の磁気センサ部を第１の磁気センサ部とし、進行方向とは反対側の磁気センサ部を第２の磁気センサ部としてもよい。または、これとは反対でもよい。さらには、移動方向に関係なく、一方の磁気センサ部を第１の磁気センサ部とし、他方の磁気センサ部を第２の磁気センサ部としてもよい。
移動体の移動手段は限定されない。例えば、駆動源を有してガイドローラをガイド溝内で転動して移動させてもよい。また、ウインチを利用した自動昇降により移動させてもよい。
【００１２】
両磁気センサ部による磁気探査方法は、３軸磁気センサによる探査方法であれば限定されない。各磁気センサ部を構成する３つの磁気センサは、各軸線をＸ方向およびＹ方向さらにはＺ方向に向け、互いに近接配置することができる。磁気センサの種類は限定されない。例えば、磁気発振方式の磁気センサを採用することができる。その他、フラックスゲート型磁気センサでもよい。フラックスゲート型磁気センサとは、高透磁率磁性コアのＢ−Ｈ特性が入力磁界によりシフトすることを利用した磁気センサである。
検出データの値の差とは、両磁気センサ部のＸ方向の成分の差だけでも、両磁気センサ部のＹ方向の成分の差だけでも、両磁気センサ部のＺ方向の成分の差だけでもよい。また、両磁気センサ部のＸ方向の成分およびＹ方向の成分だけでもよいし、両磁気センサ部のＸ方向の成分とＺ方向の成分だけでもよい。または、両磁気センサ部のＹ方向の成分とＺ方向の成分だけでもよい。さらには、両磁気センサ部の全ての成分でもよい。
【００１３】
請求項２に記載の発明は、前記磁気探査工程での移動体の移動は、前記ガイド管に、該ガイド管の軸線方向に沿って形成されたガイド溝内で、前記移動体に設けられたガイドローラを転動させることで行う請求項１に記載の磁気探査方法である。
ガイド管の軸線方向とは直交する面でのガイド溝の断面形状は限定されない。例えば、コの字形またはＵ字形でもよい。ガイド溝は、例えばガイド管の軸線方向の全長にわたって形成される。
【００１４】
請求項３に記載の発明は、地面を鉛直に掘削して形成された掘削孔に挿入される非磁性体のガイド管に、該ガイド管の軸線方向に向かって移動自在に挿入され、該移動方向の両側部には、地中に埋設された磁性物体を同時に検出する第１の磁気センサ部と第２の磁気センサ部とがそれぞれ離間配置された移動体と、該移動体を、前記ガイド管内で、該ガイド管の軸線方向に沿って、かつ前記第１の磁気センサ部側の端部を下に向けて移動させる移動手段と、前記移動体を移動させながら、前記第１の磁気センサ部により得られた検出信号に基づき、前記磁性物体を磁気量として演算処理する演算処理手段とを備え、前記第１の磁気センサ部と第２の磁気センサ部とは、特定の１軸方向のみの感度が高い３つの磁気センサを、各軸が互いに直交するようにＸ方向、Ｙ方向、Ｚ方向に個々に配置した３軸磁気センサで、前記演算処理手段では、前記第１の磁気センサ部が、前記磁性物体と同じ垂直面内で該磁性物体の上端と直交する位置に達した時、予め記憶された次式に基づき、前記磁性物体の磁界の強さを計測する磁気探査装置である。
ここで次式とは、
【００１５】
【数４】

【００１６】
ｍは、磁気量
ｒは、第１の磁気センサ部から磁性物体までの距離
Ｈ₁は、第１の磁気センサ部が検出した磁性物体の磁界の強さ
Ｈ₂は、第２の磁気センサ部が検出した磁性物体の磁界の強さ
Ｘｐ，Ｙｐ，Ｚｐは、第１の磁気センサ部の３軸方向の磁界の強さ
ｘｐ，ｙｐ，ｚｐは、第２の磁気センサ部の３軸方向の磁界の強さ
ｄは、第１の磁気センサ部と第２の磁気センサ部との距離である。
【００１７】
請求項４に記載の発明は、前記ガイド管には、該ガイド管の軸線方向に向かってガイド溝が形成され、前記移動体にはガイド溝を転動するガイドローラが設けられた請求項３に記載の磁気探査装置である。
【００１８】
【作用】
請求項１の磁気探査方法および請求項３の磁気探査装置によれば、磁性物体の磁気探査時において、移動体は、第１の磁気センサ部側の端部を下に向け、その軸線方向に向かってガイド管内を移動しながら、第１の磁気センサ部と第２の磁気センサ部とにより、土中に埋設された例えば長尺な鋼管杭（鋼矢板）などの帯磁物（強磁性物体）を探査する。帯磁物は長軸方向に磁化されている。そのため、磁気探査時において、測定位置から帯磁物の磁極のいずれかまでの距離が帯磁物の長軸方向の長さより短い場合、帯磁物を磁気単極として捉えるのが一般的である。
そこで、第１の磁気センサ部が、磁性物体と同じ垂直面内で磁性物体の上端と直交する位置に達した時、磁気量ｍの帯磁物から距離ｒだけ離れた地点での帯磁物の磁界の強さＨは、次式で求められる。
【００１９】
【数５】

【００２０】
移動体の両端部には、軸線方向に向かって距離ｄだけ離れた位置に、第１の磁気センサ部と第２の磁気センサ部とがそれぞれ配設されている。そのため、第１の磁気センサ部が検出した磁界の強さＨ₁と、第２の磁気センサ部が検出した磁界の強さＨ₂とは、次式で求められる。
【００２１】
【数６】

【００２２】
Ｘｐ，Ｙｐ，Ｚｐは、第１の磁気センサ部の３軸方向の磁界の強さ
ｘｐ，ｙｐ，ｚｐは、第２の磁気センサ部の３軸方向の磁界の強さ
ｄは、第１の磁気センサ部と第２の磁気センサ部との距離である。
【００２３】
これにより、従来の磁気センサ部を軸線回りに回転させるものとは異なり、連続的に磁性物体の磁気探査を行うことができる。よって、磁気探査の作業性が高まり、探査時間を短縮することができる。しかも、移動体の移動方向に向かって離間した２つの磁気センサ部により磁性物体を同時に検出するので、磁性物体を正確に探査することができる。
【００２４】
そして、両磁気センサ部には、それぞれ特定の１軸方向のみに感度が高い３つの磁気センサが、各軸を互いに直交するように配置された３軸磁気センサを採用している。そのため、土中に埋設された磁性物体は、第１の磁性センサ部および第２の磁性センサ部において、Ｘ方向、Ｙ方向、Ｚ方向の３軸方向から立体的に探査されることになる。これにより、磁性物体の磁化の強さ、位置を正確に把握することが可能になり、探査精度を高めることができる。
【００２５】
特に、請求項２の磁気探査方法および請求項４の磁気探査装置によれば、移動体のカイド管内での移動時、移動体は、ガイド管のガイド溝内でガイドローラを転動させながら移動する。その結果、移動中の移動体は、ガイド管内でその軸線回りに回転するおそれが解消される。よって、探査中の移動体の動揺ノイズが減少し、大きな測定誤差を発生させることなく、探査することができる。
【００２６】
【発明の実施の形態】
以下、この発明の実施例を図面を参照して説明する。
図１〜図６において、１０はこの発明の一実施例に係る磁気探査装置で、この磁気探査装置１０は、地面を掘削して形成された掘削孔１１に挿入される非磁性体のガイド管１２に、ガイド管１２の軸線方向に向かって移動自在に挿入され、移動方向の両側部には、地中に埋設された磁性物体１３を検出する第１の磁気センサ部１４と第２の磁気センサ部１５とがそれぞれ離間配置された移動体１６と、移動体１６を、ガイド管１２内で、ガイド管１２の軸線方向に沿って移動させる移動手段１７と、移動体１６を移動させながら、第１の磁気センサ部１４により得られた検出信号に基づき、磁性物体１３を磁気量として演算処理するパソコン（演算処理手段）とを備えている。
【００２７】
一実施例では、磁気探査装置１０を用いて、磁性物体１３の位置、磁化の強さを探査する（図１）。ここでの磁性物体１３は、橋脚の基礎付近に埋設された鉄製構造物、具体的には鋼管杭、鋼矢板などである。
移動体１６は、チタンからなる円柱形状の本体部１６ａを有している（図２）。移動体１６の本体部１６ａの若干小径化した上端部側の端面には、吊下用のワイヤ１９と電気接続用のケーブル２０とが連結されている。また、本体部１６ａの若干大径化した下端部には、第１の磁気センサ部１４が埋設されている。そして、移動体１６の上端部付近には、第２の磁気センサ部１５が埋設されている。両磁気センサ部１４，１５の離間した距離ｄは２５ｃｍである。また、移動体１６の軸線方向の両端部には、フランジ１６ｂを介して、軸線回りに９０度毎に合計４つのガイドローラＲがそれぞれ配設されている。
【００２８】
次に、第１の磁気センサ部１４および第２の磁気センサ部１５を詳細に説明する。
両磁気センサ部１４，１５は、特定の１軸方向のみの感度が高い３つの磁気センサ（ＸセンサＳｘ、ＹセンサＳｙ、ＺセンサＳｚ）を、各軸が互いに直交するように配置した３軸磁気センサである（図２）。ここでは、各磁気センサＳｘ，Ｓｙ，Ｓｚとして、全て磁気発振方式の同じ磁気センサ（株式会社エムティアイ製、製品名ＨＭ−３５１０）を採用している。
【００２９】
第１の磁気センサ部１４からの検出信号は、接続ボックス２１、第１の磁気センサ部１４用の３軸磁界測定器２２ＡおよびＡ／Ｄ変換器２３を経て、パソコン１８に入力される（図３）。そして、パソコン１８内で時分割的にインターフェイス回路（Ｉ／Ｏ）とバスとを介して、演算部（ＣＰＵ）で演算処理され、データ化（第１の検出データ）される。また、第２の磁気センサ部１５からの検出信号は、接続ボックス２１、第２の磁気センサ部１５用の３軸磁界測定器２２ＢおよびＡ／Ｄ変換器２３を経て、パソコン１８に入力される。そして、同様にデータ化（第２の検出データ）される。３軸磁界測定器２２Ａ，２２Ｂは、株式会社エムティアイ製、製品名ＨＭ−３５１０である。これは、直流磁界のＸ、Ｙ、Ｚ軸成分を同時に計測可能で、最小分解能は０．１マイクロテスラである。
パソコン１８に内蔵されたＲＯＭには、磁性物体の磁界の強さを計測し、磁性探査時に利用される次式が登録されている。
【００３０】
【数７】

【００３１】
ｍは、磁気量
ｒは、第１の磁気センサ部から磁性物体までの距離
Ｈ₁は、第１の磁気センサ部が検出した磁性物体の磁界の強さ
Ｈ₂は、第２の磁気センサ部が検出した磁性物体の磁界の強さ
Ｘｐ，Ｙｐ，Ｚｐは、第１の磁気センサ部の３軸方向の磁界の強さ
ｘｐ，ｙｐ，ｚｐは、第２の磁気センサ部の３軸方向の磁界の強さ
ｄは、第１の磁気センサ部と第２の磁気センサ部との距離である。
【００３２】
次に、図１〜図６を参照して、一実施例に係る磁気探査装置１０を使用した磁気探査方法を説明する。ここでは、磁性物体１３は鋼管杭で、測定位置から磁性物体１３の上側の磁極までの距離が、磁性物体１３の長軸方向の長さより短いものとする。
まず、図４に示すように、探査地点にボーリングマシン２４を据え付け、所定深さの掘削孔１１を鉛直に形成する。具体的には、地面の探査地点上にやぐら２５を組み、ボーリングマシン２４を設置する。ボーリングマシン２４は、駆動源となる発動機２９のほか、回転、給進装置を備えたスイベルヘッド、ホイスト、トランスミッションなどにより構成される。
【００３３】
掘削時には、ボーリングマシン２４により、探査地点に垂設された挿入案内パイプ３３を介して、短尺な管状のケーシング（鉄製）を順次継ぎ足しながら、地面を所定の探査長分だけ鉛直に掘削する。これにより、掘削後、長尺なケーシング３４が組み立てられる。ケーシング３４の内径は、例えば１４０ｍｍである。次に、ケーシング３４内に、短尺な塩化ビニル樹脂製の塩ビ管５０を、順次、継ぎ足しながら挿入する。塩ビ管５０の内径は、例えば１１０ｍｍである。
その後、塩ビ管５０に、直径９２ｍｍの短尺なアルミニウム製のガイド管１２を順次継ぎ足しながら挿入する。これにより、掘削孔１１内に、所定長さの塩ビ管５０を介して、長尺なガイド管１２が鉛直に挿入される。ガイド管１２には、その軸線周りに９０度毎に合計４つのガイド溝１２ａが形成されている（図５（ａ））。各ガイド溝１２ａは、移動体１６の走行用の溝で、ガイド管１２の軸線方向の全長にわたって形成されている。ガイド管１２の孔底側の端部は、保護キャップにより蓋止めされている。
【００３４】
その後、図１に示すように、探査地点の周辺からボーリングマシン２４を撤去し、探査地点の真上に、電動ウインチ３５が搭載された三脚３６を配置する。三脚３６と電動ウインチ３５とにより移動手段１７が構成される。電動ウインチ３５は、三脚３６の３本の脚部の軸支部に設けられ、移動体１６の上端面に連結されたワイヤ１９の巻き取り、繰出しを行う。その後、作業者が移動体１６をガイド管１２の上端の開口部からガイド管１２の管内に挿入する。電動ウインチ３５をワイヤ１９の繰り出し側に操作し、移動体１６をガイド管１２内に徐々に挿入して行く。
このとき、移動体１６はガイド管１２を下降しながら、第１の磁気センサ部１４と第２の磁気センサ部１５とにより、土中の磁性物体１３（基礎鋼管杭など）を磁気探査する。両磁気センサ部１４，１５からの検出信号は、接続ボックス２１、３軸磁界測定器２２およびＡ／Ｄ変換器２３を経て、パソコン１８にそれぞれ入力される。そして、パソコン１８内で時分割的にインターフェイス回路（Ｉ／Ｏ）とバスとを介して、演算器（ＣＰＵ）で演算処理され、データ化される。このとき、第１の磁気センサ部１４からのデータは第１の検出データとなる。また、第２の磁気センサ部１５からのデータは、第２の検出データとなる。
【００３５】
前述したように、鋼管杭の磁性物体１３は、その長軸方向に磁化されている。しかも、測定位置から磁性物体１３の磁極（上端）までの距離は、磁性物体１３の長軸方向の長さより短い。そのため、慣用的に磁性物体１３を磁気単極として捉えることができる。
よって、磁気量ｍの磁性物体１３から距離ｒだけ離れた地点での磁性物体１３の磁界の強さＨは、次式で求められる。
【００３６】
【数８】

【００３７】
移動体１６の両端部には、軸線方向に向かって距離ｄだけ離れた位置に、第１の磁気センサ部１４と第２の磁気センサ部１５とがそれぞれ配設されている（図６）。ｄは２５ｃｍである。そのため、第１の磁気センサ部１４が検出した磁界の強さＨ₁と、第２の磁気センサ部１５が検出した磁界の強さＨ₂とは、次式で求められる。
【００３８】
【数９】

【００３９】
Ｘｐ，Ｙｐ，Ｚｐは、第１の磁気センサ部１４の３軸方向の磁界の強さ
ｘｐ，ｙｐ，ｚｐは、第２の磁気センサ部１５の３軸方向の磁界の強さである。
【００４０】
これにより、従来の磁気センサ部を軸線回りに回転させるものとは異なり、連続的に磁性物体１３の磁気探査を行える。よって、磁気探査の作業性が高まり、探査時間を短縮することができる。しかも、移動体１６の移動方向に離間した２つの磁気センサ部１４，１５を用いて磁性物体１３を同時に探査するので、磁性物体１３を正確に探査することができる。また、前記式(1) 〜式(4) を利用し、両磁気センサ部１４，１５による磁性物体１３の同時検出を行うようにしたので、回路プログラムの設定を簡単に行うことができる。
【００４１】
さらに、両磁気センサ部１４，１５では、ＸセンサＳｘ、ＹセンサＳｙ、ＺセンサＳｚにより磁性物体１３が３軸方向から立体的に探査される。このように３軸方向から同時に磁気探査するようにしたので、磁性物体１３の磁化の強さ、位置を正確に把握することができ、探査精度が高まる。しかも、磁気探査装置１０は、従来装置のように両磁気センサ部１４，１５が軸線回りに回転しない。すなわち、移動体１６に伴って、鉛直方向に移動するだけで探査が行える。その結果、磁性物体１３の連続的な磁気探査を行うことができる。よって、磁気探査の作業性が高まり、探査時間を短縮することができる。
また、移動体１６の移動時、移動体１６は、ガイド管１２のガイド溝１２ａ内でガイドローラＲを転動させながら移動する。そのため、移動中の移動体１６は、ガイド管１２内でその軸線回りに回転するおそれが解消される。よって、探査中の移動体１６の動揺ノイズが減少し、大きな測定誤差を発生させることなく、探査することができる。
【００４２】
【発明の効果】
請求項１の磁気探査方法および請求項３の磁気探査装置によれば、磁気探査時、移動体をガイド管内でその軸線方向に移動させながら、両磁気センサ部により磁性物体を同時に検出して磁気探査するので、土中の磁性物体を連続的に探査することができる。その結果、磁気探査の作業性が高まり、探査時間を短縮することができる。しかも、探査精度を高めることができる。
さらに、両磁気センサ部には３軸磁気センサを配設したので、土中の磁性物体を立体的に探査することができる。その結果、磁性物体の磁化の強さ、位置を正確に把握することができ、探査精度がより以上に高まる。
【００４３】
特に、請求項２の磁気探査方法および請求項４の磁気探査装置によれば、ガイド管のガイド溝内で走行ローラを転動させて移動体を移動させるように構成したので、移動中の移動体が、ガイド管内でその軸線回りに回転するおそれが解消される。その結果、動揺ノイズが減少し、大きな測定誤差が発生しなくなる。
【図面の簡単な説明】
【図１】 この発明の一実施例に係る磁気探査装置による磁気探査作業中を示す説明図である。
【図２】 この発明の一実施例に係る磁気探査装置の一部を構成する移動体の正面図である。
【図３】 この発明の一実施例に係る磁気探査装置の電気制御系を示すブロック図である。
【図４】 この発明の一実施例に係る磁気探査方法における地面に掘削孔を形成し、その掘削孔にガイド管を挿入する工程を示す説明図である。
【図５】 （ａ）は、この発明の一実施例に係る磁気探査装置に利用される挿入案内パイプおよびガイド管の正面図である。 （ｂ）は、この発明の一実施例に係る磁気探査装置に利用されるガイド管の低面図である。
【図６】 この発明の一実施例に係る磁気探査方法における両磁気センサ部による磁性物体の検出方法を示す模式図である。
【符号の説明】
１０ 磁気探査方装置、
１１ 掘削孔、
１２ ガイド管、
１２ａ ガイド溝、
１３ 磁性物体、
１４ 第１の磁気センサ部、
１５ 第２の磁気センサ部、
１６ 移動体、
１８ パソコン（磁気探査手段）、
Ｒ ガイドローラ、
Ｓｐ Ｘセンサ（磁気センサ）、
Ｓｐ Ｙセンサ（磁気センサ）、
Ｓｐ Ｚセンサ（磁気センサ）。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic exploration method and apparatus for exploring a magnetic object embedded in soil from its inherent magnetic component.
[0002]
[Prior art]
As a magnetic exploration device for exploring the position and size of an iron structure (steel pipe pile, steel sheet pile, etc.) embedded in the vicinity of the foundation of a pier, for example, one described in Patent Document 1 is known. The magnetic exploration device of Patent Document 1 includes a magnetic sensor unit in which three magnetic sensors each having directivity in the X direction, the Y direction, or the Z direction are disposed at substantially the same position in the casing, and the magnetic sensor unit Rotation mechanism.
In the exploration method using the apparatus of Patent Document 1, the magnetic sensor unit is inserted into a drilling hole formed by excavating the ground, and when the magnetic sensor unit reaches a predetermined depth position of the drilling hole, the magnetic sensor unit is rotated by a rotating mechanism. Is rotated by a predetermined angle around the axis. At this time, the rotation of the magnetic sensor unit is stopped at each angular position, and then the magnetic quantity is measured to collect the magnetic quantity data, and the magnetic object is probed three-dimensionally.
[0003]
[Patent Document 1]
JP 2000-227481 A (first page, FIG. 1)
[0004]
[Problems to be solved by the invention]
However, according to the conventional magnetic exploration apparatus, during the magnetic exploration, the magnetic object is searched by rotating the magnetic sensor unit by a predetermined angle by the rotation mechanism at the predetermined depth position of the excavation hole. For this reason, continuous magnetic exploration cannot be performed, the operation during exploration is troublesome and workability is poor, and the exploration takes a long time.
Therefore, for example, it is conceivable to continuously perform magnetic exploration while rotating the magnetic sensor unit by a rotating mechanism. However, if this method is employed, the measurement error increases. This is because a large measurement error occurs if the magnetic sensor (electromagnetic coil) rotates around the axis even a little during measurement. In addition, even with this method, the magnetic sensor unit must be rotated at a fixed position for measurement only when the magnetic sensor unit is moved in the axial direction of the drilling hole. I have to let it. From the above, the conventional magnetic exploration for rotating the magnetic sensor unit has not been practical.
[0005]
OBJECT OF THE INVENTION
The present invention provides a magnetic exploration method and apparatus that can perform continuous magnetic exploration, improve exploration workability, increase exploration accuracy, and reduce exploration time. And that is the purpose.
In addition, the present invention eliminates the possibility that the moving moving body rotates around the axis in the guide tube, thereby reducing the fluctuation noise during the search and preventing the occurrence of a large measurement error. It is an object of the present invention to provide a device.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, a tube insertion step of inserting a non-magnetic guide tube into an excavation hole formed by excavating the ground vertically, and a first detection of a magnetic object embedded in the ground. The magnetic sensor unit and the second magnetic sensor unit are arranged on the guide tube with the moving body arranged on both sides in the moving direction spaced apart from each other with the end on the first magnetic sensor unit side facing down. A movable body insertion step for movably inserting the first magnetic sensor unit and the second magnetic sensor unit while moving the movable body inserted into the guide tube toward the axial direction of the guide tube. And a magnetic exploration step for magnetic exploration of the magnetic object at the same time, wherein the first magnetic sensor unit and the second magnetic sensor unit include three magnetic sensors having high sensitivity only in one specific axial direction. , X direction, Y direction, Z direction individually so that each axis is orthogonal to each other In three-axis magnetic sensors location, in the magnetic survey step, the first magnetic sensor unit, when it reaches a position perpendicular to the upper end of the magnetic body in the same vertical plane and the magnetic object, according to the following formulas The magnetic exploration method performs magnetic exploration by measuring the magnetic field strength of the magnetic object.
Here, the following equation is
[0007]
[Equation 3]

[0008]
m is the magnetic quantity r is the distance from the first magnetic sensor unit to the magnetic object H ₁ is the magnetic field strength of the magnetic object detected by the first magnetic sensor unit H ₂ is the second magnetic sensor unit The magnetic field strength of the magnetic object detected by Xp, Yp, Zp is the magnetic field strength in the three-axis direction of the first magnetic sensor unit. Xp, yp, zp is the three-axis direction of the second magnetic sensor unit. The strength d of the magnetic field is the distance between the first magnetic sensor unit and the second magnetic sensor unit.
[0009]
Wellbore is a vertical hole. The diameter and depth of the borehole are not limited.
The material of the guide tube is not limited as long as it is a non-magnetic material. For example, aluminum may be used. Further, the diameter and length of the guide tube are appropriately changed according to the diameter and depth of the excavation hole.
The material of the magnetic object to be magnetically explored is not limited. For example, any metal having magnetism such as iron or nickel may be used. The shape and size of the magnetic object are also arbitrary.
[0010]
It is preferable that the first magnetic sensor unit and the second magnetic sensor unit have the same structure and the same detection accuracy. Further, different structures with different detection accuracy may be used. However, when the detection accuracy is different, it is preferable to increase the accuracy of the magnetic sensor unit arranged at the end opposite to the moving direction of the moving body. This is because when detecting a magnetic object, the magnetic sensor unit arranged on the end side in the moving direction of the moving body is always farther than the magnetic object compared to the magnetic sensor unit on the opposite side. It is.
The specific position of both magnetic sensor parts in a moving body and the separation distance of both magnetic sensor parts are not limited. Both magnetic sensor parts should just be spaced apart in the both sides of the moving direction of a moving body. The material and shape of the moving body are not limited. The size (diameter) of the moving body is changed according to the diameter of the guide tube.
[0011]
The distinction between the first magnetic sensor unit and the second magnetic sensor unit is not limited. For example, the magnetic sensor unit in the traveling direction may be the first magnetic sensor unit, and the magnetic sensor unit on the side opposite to the traveling direction may be the second magnetic sensor unit. Or it may be the opposite. Furthermore, regardless of the moving direction, one magnetic sensor unit may be the first magnetic sensor unit, and the other magnetic sensor unit may be the second magnetic sensor unit.
The moving means of the moving body is not limited. For example, a guide source may be provided and the guide roller may roll and move in the guide groove. Moreover, you may move by the automatic raising / lowering using a winch.
[0012]
The magnetic search method using both magnetic sensor units is not limited as long as it is a search method using a three-axis magnetic sensor. The three magnetic sensors constituting each magnetic sensor unit can be arranged close to each other with their axes directed in the X direction, Y direction, and further in the Z direction. The kind of magnetic sensor is not limited. For example, a magnetic oscillation type magnetic sensor can be employed. In addition, a flux gate type magnetic sensor may be used. A fluxgate type magnetic sensor is a magnetic sensor that utilizes the fact that the BH characteristic of a high permeability magnetic core is shifted by an input magnetic field.
The difference in the value of the detected data may be only the difference in the X direction component of both magnetic sensor units, the difference in the Y direction component of both magnetic sensor units, or the difference in the Z direction component of both magnetic sensor units. Good. Further, only the X-direction component and the Y-direction component of both magnetic sensor units may be used, or only the X-direction component and the Z-direction component of both magnetic sensor units may be used. Alternatively, only the Y-direction component and the Z-direction component of both magnetic sensor units may be used. Furthermore, all components of both magnetic sensor units may be used.
[0013]
According to a second aspect of the present invention, the movement of the moving body in the magnetic exploration step is provided in the moving body in a guide groove formed in the guide tube along the axial direction of the guide tube. The magnetic exploration method according to claim 1 performed by rolling a guide roller.
The cross-sectional shape of the guide groove in a plane orthogonal to the axial direction of the guide tube is not limited. For example, it may be U-shaped or U-shaped. The guide groove is formed over the entire length in the axial direction of the guide tube, for example.
[0014]
The invention according to claim 3 is inserted into a non-magnetic guide tube inserted into a drilling hole formed by excavating the ground vertically , and is movable in the axial direction of the guide tube. A moving body in which a first magnetic sensor unit and a second magnetic sensor unit that simultaneously detect magnetic objects embedded in the ground are spaced apart from each other on both sides of the direction; A moving means for moving the end on the first magnetic sensor section side downward along the axial direction of the guide pipe in the pipe , and the first magnetic sensor while moving the moving body Based on a detection signal obtained by the unit, and a calculation processing means for calculating the magnetic object as a magnetic quantity, wherein the first magnetic sensor unit and the second magnetic sensor unit are only in a specific one-axis direction. Three magnetic sensors with high sensitivity, each axis is orthogonal to each other X direction so that, in the Y-direction, the three-axis magnetic sensor disposed individually in the Z direction, in the processing means, said first magnetic sensor unit, of the magnetic body in the same vertical plane and the magnetic object When reaching a position orthogonal to the upper end, the magnetic exploration device measures the magnetic field strength of the magnetic object based on the following formula stored in advance.
Here, the following equation is
[0015]
[Expression 4]

[0016]
m is the magnetic quantity r is the distance from the first magnetic sensor unit to the magnetic object H ₁ is the magnetic field strength of the magnetic object detected by the first magnetic sensor unit H ₂ is the second magnetic sensor unit The magnetic field strength of the magnetic object detected by Xp, Yp, Zp is the magnetic field strength in the three-axis direction of the first magnetic sensor unit xp, yp, zp is the three-axis direction of the second magnetic sensor unit The strength d of the magnetic field is the distance between the first magnetic sensor unit and the second magnetic sensor unit.
[0017]
According to a fourth aspect of the present invention, in the guide tube, a guide groove is formed in an axial direction of the guide tube, and the movable body is provided with a guide roller for rolling the guide groove. The magnetic exploration device described in 1.
[0018]
[Action]
According to the magnetic exploration method of claim 1 and the magnetic exploration apparatus of claim 3, when the magnetic exploration of the magnetic object is performed , the moving body faces the end on the first magnetic sensor portion side downward and in the axial direction Magnetic material (ferromagnetic object) such as a long steel pipe pile (steel sheet pile) embedded in the soil by the first magnetic sensor part and the second magnetic sensor part while moving in the guide pipe Exploring. The magnetic material is magnetized in the major axis direction. Therefore, at the time of magnetic exploration, when the distance from the measurement position to one of the magnetic poles of the magnetic material is shorter than the length in the major axis direction of the magnetic material, the magnetic material is generally regarded as a magnetic single pole.
Therefore, when the first magnetic sensor unit reaches a position perpendicular to the upper end of the magnetic object in the same vertical plane as the magnetic object, the magnetic field of the magnetic substance at a point away from the magnetic object having the magnetic quantity m by the distance r. Is obtained by the following equation.
[0019]
[Equation 5]

[0020]
A first magnetic sensor unit and a second magnetic sensor unit are disposed at both ends of the moving body at positions separated by a distance d in the axial direction. Therefore, the magnetic field strength H ₁ detected by the _first magnetic sensor unit and the magnetic field strength H ₂ detected by the second magnetic sensor unit are obtained by the following equations.
[0021]
[Formula 6]

[0022]
Xp, Yp, Zp is the strength of the magnetic field in the three-axis direction of the first magnetic sensor part. Xp, yp, zp is the strength of the magnetic field in the three-axis direction of the second magnetic sensor part. It is the distance between the magnetic sensor unit and the second magnetic sensor unit.
[0023]
Thereby, unlike what rotates the conventional magnetic sensor part around an axis line, a magnetic search of a magnetic object can be performed continuously. Therefore, the workability of magnetic exploration is improved and the exploration time can be shortened. In addition, since the magnetic object is simultaneously detected by the two magnetic sensor units separated in the moving direction of the moving body, the magnetic object can be accurately searched.
[0024]
Each of the magnetic sensor units employs a three-axis magnetic sensor in which three magnetic sensors each having high sensitivity only in a specific one-axis direction are arranged so that the respective axes are orthogonal to each other. Therefore, the magnetic object embedded in the soil is three-dimensionally searched from the three axial directions of the X direction, the Y direction, and the Z direction in the first magnetic sensor unit and the second magnetic sensor unit. As a result, it is possible to accurately grasp the magnetization intensity and position of the magnetic object, and the search accuracy can be improved.
[0025]
In particular, according to the magnetic exploration method of claim 2 and the magnetic exploration apparatus of claim 4, when the moving body moves in the guide tube, the moving body moves while rolling the guide roller in the guide groove of the guide tube. To do. As a result, the possibility that the moving moving body rotates around its axis within the guide tube is eliminated. As a result, the noise of the moving object under search is reduced, and the search can be performed without causing a large measurement error.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
1 to 6, reference numeral 10 denotes a magnetic exploration device according to an embodiment of the present invention. The magnetic exploration device 10 is a non-magnetic guide tube inserted into an excavation hole 11 formed by excavating the ground. 12, a first magnetic sensor unit 14 and a second magnetism for detecting a magnetic object 13 embedded in the ground on both sides in the moving direction. While moving the moving body 16 in which the sensor unit 15 is spaced apart, the moving means 16 that moves the moving body 16 along the axial direction of the guide tube 12 in the guide tube 12, and moving the moving body 16, Based on the detection signal obtained by the first magnetic sensor unit 14, a personal computer (arithmetic processing means) that performs arithmetic processing using the magnetic object 13 as a magnetic quantity is provided.
[0027]
In one embodiment, the magnetic exploration device 10 is used to probe the position of the magnetic object 13 and the strength of magnetization (FIG. 1). The magnetic object 13 here is an iron structure embedded in the vicinity of the foundation of the pier, specifically a steel pipe pile, a steel sheet pile, or the like.
The moving body 16 has a cylindrical main body 16a made of titanium (FIG. 2). A suspension wire 19 and an electrical connection cable 20 are coupled to the end surface of the main body portion 16a of the movable body 16 on the upper end portion side, which is slightly reduced in diameter. A first magnetic sensor portion 14 is embedded in the lower end portion of the main body portion 16a having a slightly larger diameter. A second magnetic sensor unit 15 is embedded near the upper end of the moving body 16. A distance d between the magnetic sensor portions 14 and 15 is 25 cm. Further, a total of four guide rollers R are disposed at both ends in the axial direction of the moving body 16 every 90 degrees around the axial line through the flange 16b.
[0028]
Next, the first magnetic sensor unit 14 and the second magnetic sensor unit 15 will be described in detail.
Both magnetic sensor units 14 and 15 are three axes in which three magnetic sensors (X sensor Sx, Y sensor Sy, Z sensor Sz) having high sensitivity only in a specific one axis direction are arranged so that the respective axes are orthogonal to each other. It is a magnetic sensor (FIG. 2). Here, as each magnetic sensor Sx, Sy, Sz, the same magnetic sensor of the magnetic oscillation system (product name HM-3510, manufactured by MTI Corporation) is adopted.
[0029]
The detection signal from the first magnetic sensor unit 14 is input to the personal computer 18 through the connection box 21, the three-axis magnetic field measuring device 22A for the first magnetic sensor unit 14, and the A / D converter 23 (see FIG. 3). Then, in the personal computer 18, the arithmetic processing unit (CPU) performs arithmetic processing through the interface circuit (I / O) and the bus in a time-sharing manner, and is converted into data (first detection data). The detection signal from the second magnetic sensor unit 15 is input to the personal computer 18 through the connection box 21, the three-axis magnetic field measuring device 22 </ b> B for the second magnetic sensor unit 15, and the A / D converter 23. . Similarly, it is converted into data (second detection data). The triaxial magnetic field measuring devices 22A and 22B are product names HM-3510 manufactured by MIT Corporation. This can measure the X, Y, and Z axis components of the DC magnetic field simultaneously, and the minimum resolution is 0.1 microtesla.
In the ROM built in the personal computer 18, the following formula used for measuring the magnetic field strength of a magnetic object and used for magnetic exploration is registered.
[0030]
[Expression 7]

[0031]
m is the magnetic quantity r is the distance from the first magnetic sensor unit to the magnetic object H ₁ is the magnetic field strength of the magnetic object detected by the first magnetic sensor unit H ₂ is the second magnetic sensor unit The magnetic field strength of the magnetic object detected by Xp, Yp, Zp is the magnetic field strength in the three-axis direction of the first magnetic sensor unit xp, yp, zp is the three-axis direction of the second magnetic sensor unit The strength d of the magnetic field is the distance between the first magnetic sensor unit and the second magnetic sensor unit.
[0032]
Next, a magnetic exploration method using the magnetic exploration device 10 according to an embodiment will be described with reference to FIGS. Here, the magnetic object 13 is a steel pipe pile, and the distance from the measurement position to the magnetic pole on the upper side of the magnetic object 13 is shorter than the length of the magnetic object 13 in the major axis direction.
First, as shown in FIG. 4, the boring machine 24 is installed at the exploration point, and the excavation hole 11 having a predetermined depth is formed vertically. Specifically, the tower 25 is assembled on the ground exploration point and the boring machine 24 is installed. The boring machine 24 includes a motor 29 serving as a driving source, a swivel head equipped with a rotation / feed device, a hoist, a transmission, and the like.
[0033]
During excavation, the boring machine 24 excavates the ground vertically by a predetermined exploration length while sequentially adding short tubular casings (made of iron) through an insertion guide pipe 33 suspended at the exploration point. Thereby, the long casing 34 is assembled after excavation. The inner diameter of the casing 34 is 140 mm, for example. Next, a short vinyl chloride resin-made polyvinyl chloride pipe 50 is inserted into the casing 34 in succession. The inner diameter of the PVC pipe 50 is, for example, 110 mm.
Thereafter, a short aluminum guide tube 12 having a diameter of 92 mm is inserted into the polyvinyl chloride tube 50 while being sequentially added. As a result, the long guide tube 12 is vertically inserted into the excavation hole 11 through the PVC tube 50 having a predetermined length. A total of four guide grooves 12a are formed around the axis of the guide tube 12 every 90 degrees (FIG. 5A). Each guide groove 12 a is a travel groove of the moving body 16 and is formed over the entire length of the guide tube 12 in the axial direction. The end of the guide tube 12 on the bottom side is covered with a protective cap.
[0034]
Thereafter, as shown in FIG. 1, the boring machine 24 is removed from the vicinity of the exploration point, and a tripod 36 on which the electric winch 35 is mounted is disposed immediately above the exploration point. The tripping unit 36 and the electric winch 35 constitute the moving means 17. The electric winch 35 is provided on the shaft support portion of the three legs of the tripod 36 and winds and feeds the wire 19 connected to the upper end surface of the moving body 16. Thereafter, the operator inserts the moving body 16 into the tube of the guide tube 12 from the opening at the upper end of the guide tube 12. The electric winch 35 is operated to the feeding side of the wire 19 and the moving body 16 is gradually inserted into the guide tube 12.
At this time, the moving body 16 magnetically searches the magnetic object 13 (such as a foundation steel pipe pile) in the soil by using the first magnetic sensor unit 14 and the second magnetic sensor unit 15 while descending the guide tube 12. Detection signals from both magnetic sensor units 14 and 15 are input to the personal computer 18 through the connection box 21, the triaxial magnetic field measuring device 22 and the A / D converter 23. Then, in the personal computer 18, the arithmetic unit (CPU) performs arithmetic processing through the interface circuit (I / O) and the bus in a time-division manner, and is converted into data. At this time, the data from the first magnetic sensor unit 14 becomes the first detection data. The data from the second magnetic sensor unit 15 is second detection data.
[0035]
As described above, the magnetic object 13 of the steel pipe pile is magnetized in the major axis direction. Moreover, the distance from the measurement position to the magnetic pole (upper end) of the magnetic object 13 is shorter than the length of the magnetic object 13 in the major axis direction. Therefore, the magnetic object 13 can be conventionally regarded as a magnetic monopole.
Therefore, the magnetic field strength H of the magnetic object 13 at a point away from the magnetic object 13 having the magnetic quantity m by the distance r can be obtained by the following equation.
[0036]
[Equation 8]

[0037]
A first magnetic sensor unit 14 and a second magnetic sensor unit 15 are respectively disposed at both ends of the moving body 16 at positions separated by a distance d in the axial direction (FIG. 6). d is 25 cm. Therefore, the intensity H ₁ of the magnetic field by the first magnetic sensor unit 14 detects, from the intensity of H ₂ magnetic fields second magnetic sensor unit 15 has detected is calculated by the following equation.
[0038]
[Equation 9]

[0039]
Xp, Yp, Zp are the magnetic field strengths in the three-axis direction of the first magnetic sensor unit 14 xp, yp, zp are the magnetic field strengths in the three-axis direction of the second magnetic sensor unit 15.
[0040]
Thereby, unlike the conventional one in which the conventional magnetic sensor unit is rotated around the axis, the magnetic exploration of the magnetic object 13 can be performed continuously. Therefore, the workability of magnetic exploration is improved and the exploration time can be shortened. In addition, since the magnetic object 13 is simultaneously searched using the two magnetic sensor units 14 and 15 separated in the moving direction of the moving body 16, the magnetic object 13 can be accurately searched. In addition, since the magnetic object 13 is simultaneously detected by the magnetic sensor units 14 and 15 using the equations (1) to (4), the circuit program can be easily set.
[0041]
Furthermore, in both the magnetic sensor units 14 and 15, the magnetic object 13 is three-dimensionally searched from the three axis directions by the X sensor Sx, the Y sensor Sy, and the Z sensor Sz. Since the magnetic exploration is simultaneously performed from the three axis directions as described above, the strength and position of the magnetization of the magnetic object 13 can be accurately grasped, and the exploration accuracy is improved. In addition, in the magnetic exploration device 10, both magnetic sensor units 14 and 15 do not rotate around the axis unlike the conventional device. In other words, the search can be performed only by moving in the vertical direction along with the moving body 16. As a result, continuous magnetic exploration of the magnetic object 13 can be performed. Therefore, the workability of magnetic exploration is improved and the exploration time can be shortened.
Further, when the moving body 16 moves, the moving body 16 moves while rolling the guide roller R in the guide groove 12 a of the guide tube 12. This eliminates the possibility that the moving mobile body 16 rotates around its axis in the guide tube 12. Therefore, the shaking noise of the moving body 16 during the search is reduced, and the search can be performed without generating a large measurement error.
[0042]
【The invention's effect】
According to the magnetic exploration method of claim 1 and the magnetic exploration apparatus of claim 3, during magnetic exploration, the magnetic object is simultaneously detected by both magnetic sensor portions while moving the moving body in the guide tube in the axial direction. Since exploration is performed, magnetic objects in the soil can be explored continuously. As a result, the workability of magnetic exploration is improved and the exploration time can be shortened. In addition, the search accuracy can be increased.
Furthermore, since the three-axis magnetic sensor is provided in both magnetic sensor units, the magnetic object in the soil can be explored in three dimensions. As a result, the magnetization intensity and position of the magnetic object can be accurately grasped, and the exploration accuracy is further increased.
[0043]
In particular, according to the magnetic exploration method of claim 2 and the magnetic exploration apparatus of claim 4, the moving roller is moved by rolling the traveling roller in the guide groove of the guide tube. The risk of the body rotating around its axis in the guide tube is eliminated. As a result, fluctuation noise is reduced and no large measurement error occurs.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a magnetic exploration operation performed by a magnetic exploration apparatus according to an embodiment of the present invention.
FIG. 2 is a front view of a moving body constituting a part of the magnetic exploration device according to one embodiment of the present invention.
FIG. 3 is a block diagram showing an electric control system of the magnetic exploration apparatus according to one embodiment of the present invention.
FIG. 4 is an explanatory diagram showing a process of forming a drilling hole in the ground and inserting a guide tube into the drilling hole in the magnetic exploration method according to one embodiment of the present invention.
FIG. 5 (a) is a front view of an insertion guide pipe and a guide pipe used in the magnetic survey apparatus according to one embodiment of the present invention. (B) is a bottom view of a guide tube used in a magnetic exploration device according to one embodiment of the present invention.
FIG. 6 is a schematic diagram showing a magnetic object detection method using both magnetic sensor units in the magnetic exploration method according to one embodiment of the present invention.
[Explanation of symbols]
10 Magnetic exploration device,
11 drilling holes,
12 guide tube,
12a guide groove,
13 Magnetic objects,
14 1st magnetic sensor part,
15 2nd magnetic sensor part,
16 Mobile body,
18 PC (magnetic exploration means),
R guide roller,
Sp X sensor (magnetic sensor),
Sp Y sensor (magnetic sensor),
Sp Z sensor (magnetic sensor).

Claims (4)

A tube insertion step of inserting a non-magnetic guide tube into the excavation hole formed by excavating the ground vertically ;
A moving body in which a first magnetic sensor unit and a second magnetic sensor unit for detecting a magnetic object embedded in the ground are arranged apart on both sides in the moving direction is referred to as the first magnetic sensor unit. A movable body insertion step of movably inserting the guide tube with the side end facing downward ;
The magnetic object is simultaneously magnetically explored using the first magnetic sensor unit and the second magnetic sensor unit while moving the moving body inserted in the guide tube in the axial direction of the guide tube. A magnetic exploration process,
The first magnetic sensor unit and the second magnetic sensor unit include three magnetic sensors having high sensitivity only in one specific axial direction in the X direction, the Y direction, and the Z direction so that the respective axes are orthogonal to each other. 3 axis magnetic sensor arranged individually,
In the magnetic exploration step, when the first magnetic sensor unit reaches a position orthogonal to the upper end of the magnetic object in the same vertical plane as the magnetic object, the magnetic field strength of the magnetic object is calculated based on the following equation. Magnetic exploration method that measures the magnetic field and conducts magnetic exploration.

m is the magnetic quantity r is the distance from the first magnetic sensor unit to the magnetic object H ₁ is the magnetic field strength of the magnetic object detected by the first magnetic sensor unit H ₂ is the second magnetic sensor unit The magnetic field strength of the magnetic object detected by Xp, Yp, Zp is the magnetic field strength in the three-axis direction of the first magnetic sensor unit. Xp, yp, zp is the three-axis direction of the second magnetic sensor unit. The strength d of the magnetic field is the distance between the first magnetic sensor unit and the second magnetic sensor unit.   The moving body is moved in the magnetic exploration step by rolling a guide roller provided on the moving body in a guide groove formed along the axial direction of the guide pipe. The magnetic exploration method according to claim 1. A non-magnetic guide tube inserted into a drilling hole formed by excavating the ground vertically is inserted movably in the axial direction of the guide tube. A moving body in which a first magnetic sensor unit and a second magnetic sensor unit that simultaneously detect a magnetic object embedded in the first and second magnetic sensor units are spaced apart from each other;
Moving means for moving the movable body in the guide tube along the axial direction of the guide tube and with the end on the first magnetic sensor unit side facing down ;
Computation processing means for computing the magnetic object as a magnetic quantity based on the detection signal obtained by the first magnetic sensor unit while moving the moving body,
The first magnetic sensor unit and the second magnetic sensor unit include three magnetic sensors having high sensitivity only in one specific axial direction in the X direction, the Y direction, and the Z direction so that the respective axes are orthogonal to each other. 3 axis magnetic sensor arranged individually,
In the arithmetic processing means, when the first magnetic sensor unit reaches a position orthogonal to the upper end of the magnetic object in the same vertical plane as the magnetic object, the magnetic object is based on the following stored formula: Magnetic exploration device that measures the strength of the magnetic field.

m is the magnetic quantity r is the distance from the first magnetic sensor unit to the magnetic object H ₁ is the magnetic field strength of the magnetic object detected by the first magnetic sensor unit H ₂ is the second magnetic sensor unit The magnetic field strength of the magnetic object detected by Xp, Yp, Zp is the magnetic field strength in the three-axis direction of the first magnetic sensor unit. Xp, yp, zp is the three-axis direction of the second magnetic sensor unit. The strength d of the magnetic field is the distance between the first magnetic sensor unit and the second magnetic sensor unit.   The magnetic exploration device according to claim 3, wherein a guide groove is formed in the guide tube in an axial direction of the guide tube, and the moving body is provided with a guide roller that rolls on the guide groove.

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