本文選題：探地雷達 + 數(shù)值模擬��； 參考：《廣西大學》2014年碩士論文

【摘要】：探地雷達是在隧道襯砌健康檢測、隧道超前預報等工程中廣泛使用的物探工具。它以無損、高效、分辨率高的特點深受工程人員的親睞。然而,在我國探地雷達的應用還處于初級階段,在實際工程中很多問題亟待解決,例如,探測參數(shù)的設置尚無統(tǒng)一標準以及探測圖像的解譯缺少依據(jù)等。這些問題的存在影響了雷達探測的準確性。本文通過數(shù)值模擬和物理模擬方法,結合在岑溪大隧道、垌尾隧道以及嶺腳隧道中的襯砌檢測經(jīng)驗,對探地雷達在公路隧道襯砌檢測和超前預報中的應用進行研究,本文研究的主要成果如下： 1.采用二維的時域有限差分法,對探地雷達進行正演模擬。從麥克斯韋電磁方程出發(fā),推導出TM波在二維空間的有限差分方程,借助完全匹配邊界條件解決在有限空間內模擬電磁波在無限空間傳播的問題,使用Matlab軟件編寫模擬程序,對隧道襯砌檢測和超前預報中典型的地電模型進行正演模擬,取得了正演圖像,為實際應用中的反演提供依據(jù)。 2.分別進行隧道襯砌和超前預報不良地質體模型試驗。通過隧道襯砌模型試驗,研究了鋼筋網(wǎng)對于雷達信號的屏蔽作用,混凝土齡期對雷達波速的影響,二襯分界面位置的判斷方法,以及襯砌中空洞、不密實、鋼拱架、鋼筋網(wǎng)的辨識方法。通過對隧道超前預報不良地質體(破碎帶、富水區(qū)、中空溶洞、含水溶洞、節(jié)理)的模擬,獲取了其典型圖像,并和數(shù)值模擬中得到的圖像進行對比,總結了圖像特征。 3.研究了計算巖溶洞穴尺寸方法,并通過試驗,分別驗證了波速替換法、漸近線法在計算洞穴尺寸中可靠性和準確性。 4.根據(jù)岑溪大隧道、垌尾隧道以及嶺腳隧道的襯砌檢測實例,對探地雷達在襯砌檢測中參數(shù)設置、數(shù)據(jù)分析的方法進行研究。結合實際開挖情況,得到了各種襯砌缺陷所對應的典型圖形,并對比數(shù)值模擬和物理模擬結果,總結圖像特征,為襯砌檢測中的圖像解譯提供依據(jù)。
[Abstract]:Ground penetrating radar (GPR) is a widely used geophysical tool in tunnel lining health detection and tunnel advance prediction. It has the characteristics of nondestructive, high efficiency and high resolution. However, the application of GPR in China is still in its infancy, and many problems need to be solved in practical engineering. For example, there is no uniform standard for the setting of detection parameters and there is no basis for interpretation of detection images. These problems affect the accuracy of radar detection. In this paper, through numerical simulation and physical simulation, combined with the lining detection experience in Cenxi large tunnel, Tongwei tunnel and Lingjiao tunnel, the application of ground penetrating radar in highway tunnel lining detection and advance prediction is studied. The main results of this paper are as follows: 1. The forward modeling of ground penetrating radar is carried out by using two dimensional finite difference time domain method. Based on Maxwell's electromagnetic equation, the finite difference equation of TM wave in two-dimensional space is derived. The problem of simulating electromagnetic wave propagation in finite space is solved by means of perfectly matched boundary condition. The simulation program is written with Matlab software. The forward modeling of typical geoelectric model in tunnel lining detection and prediction is carried out, and the forward image is obtained, which provides the basis for inversion in practical application. 2. Model tests of tunnel lining and advanced prediction of poor geological bodies were carried out respectively. Through tunnel lining model test, the shielding effect of steel mesh on radar signal, the influence of concrete age on radar wave velocity, the method of judging the location of interface between two linings and the hollow, undense and steel arch frame of lining are studied. Identification method of reinforcement mesh. The typical images of poor geological bodies (broken zone, water-rich area, hollow cavity, water-containing cave, joint) are obtained by simulation of tunnel advanced prediction, and compared with those obtained in numerical simulation, the image features are summarized. 3. The method of calculating the size of karst cave is studied and the reliability and accuracy of wave velocity replacement method and asymptote method in calculating cave size are verified by experiments. 4. Based on the lining detection examples of Cenxi large tunnel, Tongwei tunnel and Lingjiao tunnel, the parameter setting and data analysis method of ground penetrating radar in lining detection are studied. Combined with the actual excavation situation, the typical figures corresponding to various lining defects are obtained, and the results of numerical simulation and physical simulation are compared, and the image features are summarized, which provides the basis for image interpretation in lining detection.
【學位授予單位】：廣西大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U459.2;U456.33

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