【摘要】：作為巖土加固、穩(wěn)定結構的最經(jīng)濟、高效的方法,巖土錨固技術誕生之日起就得到了工程技術人員的親睞。不當?shù)氖┕すに嚰斑\營管理會把預應力錨索變成一個可能使工程毀于一旦的“定時炸彈”,因此預應力錨索錨固質量也一直是人們關注的焦點問題,而作為衡量錨索的錨固質量的重要參數(shù)——錨下有效預應力(錨固力)自然也受到人們的關注。但是巖土錨固工程屬于長期、隱蔽工程,這給錨下有效預應力(錨固力)的檢測帶來了一定的困難。探索高效、準確、經(jīng)濟實用的檢測方法,成為擺在巖土工作者面前的一個課題。因此,本文立題對此開展研究。本文對錨索預應力的損失機制展開研究,主要研究了預應力錨索內(nèi)錨固段荷載分布、錨索失效和錨索預應力損失的影響因素。首先,在前人研究的基礎上,研究了第一粘結面和第二粘結面的剪應力分布模式,兩個粘結面的剪力分布模式有較明顯差異:剪切應力的峰值及其位置均不相同;然后,根據(jù)現(xiàn)有的工程調(diào)研資料分析了五種不同的錨索失效形式:外錨固段失效、錨束體斷裂、第一粘結面滑移破壞、第二粘結面滑移破壞、被加固巖土體破壞;最后,通過分析預應力損失的影響因素,得出了錨下有效預應力(錨固力)的理論計算公式sde-=NNN0,為有效預應力判定標準的制定提供參考。針對工程實踐中對錨索預應力的檢測只注重整個錨索的預應力,對錨索中每根鋼絞線的預應力的不均勻情況較少涉及的情況,本文提出了不均勻度的概念,并通過兩種不同的反拉方法——整體反拉法和分組反拉法——對此展開理論和試驗研究。首先,詳細分析了反拉法檢測過程中錨束體應力-應變變化關系,建立錨索有效預應力判定標準;然后根據(jù)工程實踐和理論分析,對現(xiàn)行技術規(guī)范《公路橋涵施工技術規(guī)范》中關于有效預應力合格標準的表述提出自己的見解;最后,通過現(xiàn)場的試驗對分組反拉法的檢測精度、對鋼絞線應力不均勻度、有效預應力合格標準進行研究。本文對基于聲彈性理論的無損檢測方法的工程可行性進行了初步討論。首先,對該無損檢測方法的兩個關鍵問題——聲彈性系數(shù)確定和彈性波的選擇——進行了討論;接下來,通過對試驗數(shù)據(jù)的處理和分析,驗證了該無損檢測方法的工程可行性;最后,對無損檢測方法的檢測精度影響因素和在工程中的應用前景進行討論。
[Abstract]:As the most economical and efficient method to strengthen and stabilize the structure of rock and soil, the Anchorage technology of rock and soil has been favored by engineers and technicians since its birth. Improper construction technology and operation management will turn the prestressed anchor cable into a "time bomb" which may destroy the project. Therefore, the quality of prestressed anchor cable anchoring has always been the focus of attention. As an important parameter to evaluate the anchoring quality of anchor cables, the effective prestress under anchor (anchoring force) is also concerned by people. However, geotechnical anchoring works belong to long-term and hidden projects, which bring some difficulties to the detection of effective prestressing force under anchors. It has become a subject for geotechnical workers to explore efficient, accurate and economical detection methods. Therefore, this article raises the topic to carry on the research to this. In this paper, the loss mechanism of prestressed cable is studied, and the factors influencing the load distribution, the failure of anchor cable and the prestress loss of prestressed cable are studied. Firstly, on the basis of previous studies, the shear stress distribution modes of the first and the second bonding surfaces are studied. The shear stress distribution modes of the two bonding surfaces are obviously different: the peak value and the location of the shear stress are different; Then, according to the existing engineering investigation data, five different failure forms of anchor cable are analyzed: failure of external anchoring section, fracture of anchor body, slip failure of the first bond plane, slip failure of the second bond surface, and failure of the strengthened rock and soil; Finally, by analyzing the influencing factors of prestress loss, the theoretical calculation formula of effective prestress under anchor (Anchorage force) is obtained. Sde-=NNN0, provides a reference for the determination of effective prestressing force. In view of the fact that the detection of anchor cable prestress only pays attention to the prestress of the whole anchor cable in engineering practice, and the non-uniformity of the prestress of each steel strand in the anchor cable is less concerned, the concept of non-uniformity degree is put forward in this paper. The theoretical and experimental studies are carried out through two different backpull methods, the global backpull method and the group backpull method. Firstly, the relationship between stress and strain of Anchorage is analyzed in detail, and the criterion of effective prestress of anchor cable is established. Then according to the engineering practice and theoretical analysis, the author puts forward his own opinion on the expression of the qualified standard of effective prestress in the current technical code of highway bridge and culvert construction. Finally, through the field test, the test accuracy of the group back pull method, the stress inhomogeneity of steel strand and the qualified standard of effective prestress are studied. In this paper, the engineering feasibility of nondestructive testing method based on acoustic elasticity theory is discussed. Firstly, two key problems of the NDT method, namely, the determination of acoustic elastic coefficient and the selection of elastic wave, are discussed, and the engineering feasibility of the NDT method is verified by processing and analyzing the test data. Finally, the influencing factors of nondestructive testing method and its application prospect in engineering are discussed.
【學位授予單位】：重慶交通大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U416

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