【正文】 出判斷。一個標準的鉸接縫橫端面，主梁內(nèi)部的24 根鋼筋束很難被檢測到，因為除了鉸接縫外，鋼絞線在施加預應力之后又被 現(xiàn)澆的混凝土所包裹。但是，仍然存在的問題是管道周圍的高密度的鐵元素會對雷達信號產(chǎn)生強烈的干擾，而實際上在這一寬 102mm， 150mm~800mm 的混凝土區(qū)域內(nèi)正埋有許多高致密的鋼板。 為了對比，選定了 10 個觀測孔，小孔是垂直向下鉆進導管。為了便于使用內(nèi)徑表面檢測儀，小孔直徑必須有 25mm 寬，結(jié)果顯示愛丁堡大學的研究成果的準確度在 60%左右。結(jié)果顯示，在超過 60%的案例中，雷達的檢測是準確的。 然而用內(nèi)徑表面檢查儀檢測時，很難判定裂縫的實際尺寸大小以及在錨索套管中延伸的距離，盡管這些裂縫僅占套管不到 25%的部分。在少數(shù)幾個案例中，在沙漿表面能明顯地看到預應力鋼絞線，但沒有跡象表明有水滲透了進去。 數(shù)字雷達測試 這種測試方法是利用無線電頻率的雷達天線的穿透性。最高的頻率能帶來最好的分辯率，但會減小其在混凝土中的穿透深度。 雷達掃描到的數(shù)據(jù)被記錄到 GSSISIR 系統(tǒng)中，這種系統(tǒng)與雷達發(fā)射脈沖和 記錄數(shù)據(jù)相對應。這種轉(zhuǎn)換是使用一種 16 位的模擬信號變流器，它能使數(shù)據(jù)獲得相當高的分辨率，以便用于后續(xù)的數(shù)據(jù)處理。在可視化校對之后，將這些數(shù)據(jù)儲存在一個 ，用于后面的分析和處理。 沿著軌跡做特別的標記，再通過記錄元件或天線把這個軌跡描述下來。）后張法分析需要運用特殊的處理軟件。除了 這些能變換顏色的設備外，還可能使用用來過濾水平線和豎直線的特殊程序。 一個更為先進的軟件能夠顯示專用雷達脈沖掃描的區(qū)域，在單獨檢測錨索周圍狀況時，它是一種特別有價值元件。 結(jié)論 一個關于橋梁研究平 臺的雛形已經(jīng)在歐洲誕生。 雷達勘察可以顯示后張法鋼絞線孔道內(nèi)部的大部分缺陷區(qū)域。 Bridge research in Europe A brief outline is given of the development of the European Union, together with the research platform in Europe. The special case of posttensioned bridges in the UK is discussed. In order to illustrate the type of European research being undertaken, an example is given from the University of Edinburgh portfolio: relating to the identification of voids in posttensioned concrete bridges using digital impulse radar. Introduction The challenge in any research arena is to harness the findings of different research groups to identify a coherent mass of data, which enables research and practice to be better focused. A particular challenge exists with respect to Europe where language barriers are inevitably very significant. The European Community was formed in the 1960s based upon a political will within continental Europe to avoid the European civil wars, which developed into World War 2 from 1939 to 1945. The strong political motivation formed the original munity of which Britain was not a member. Many of the continental countries saw Britain’s interest as being purely economic. The 1970s saw Britain joining what was then the European Economic Community (EEC) and the 1990s has seen the widening of the munity to a European Union, EU, with certain political goals together with the objective of a mon European currency. Notwithstanding these financial and political developments, civil engineering and bridge engineering in particular have found great difficulty in forming any kind of mon thread. Indeed the educational systems for University training are quite different between Britain and the European continental countries. The formation of the EU funding schemes —. Socrates, Brite Euram and other programs have helped significantly. The Socrates scheme is based upon the exchange of students between Universities in different member states. The Brite Euram scheme has involved technical research grants given to consortia of academics and industrial partners within a number of the states— a Brite Euram bid would normally be led by an industrialist. In terms of dissemination of knowledge, two quite different strands appear to have emerged. The UK and the USA have concentrated primarily upon disseminating basic research in refereed journal publications: ASCE, ICE and other journals. Whereas the continental Europeans have frequently disseminated basic research at conferences where the circulation of the proceedings is restricted. Additionally, language barriers have proved to be very difficult to break down. In countries where English is a strong second language there has been enthusiastic participation in international conferences based within continental Europe —. Germany, Italy, Belgium, The Netherlands and Switzerland. However, countries where English is not a strong second language have been hesitant participants }—. France. European research Examples of research relating to bridges in Europe can be divided into three types of structure: Masonry arch bridges Britain has the largest stock of masonry arch bridges. In certain regions of the UK up to 60% of the road bridges are historic stone masonry arch br