【摘要】：無粘結環(huán)錨預應力混凝土襯砌結構是應用在水工隧洞中的一種新型結構形式，該結構主要適用于襯砌圍巖地質(zhì)條件較差，襯砌中的水壓力較大，以及襯砌產(chǎn)生開裂之后水滲入圍巖導致周圍建筑物失穩(wěn)的水工隧洞結構中。作為一種新型的結構形式，無粘結預應力混凝土襯砌具有其特殊的優(yōu)點：襯砌中鋼絞線采用雙圈環(huán)繞的形式，使襯砌中的壓應力分布更加均勻，錨索的沿程預應力損失更小，與有粘結襯砌相比有效預壓應力增大，因此襯砌的厚度可以適當減小，這樣就能夠節(jié)省材料，減小開挖量，降低施工的難度和工程造價，有效的加快施工進度。鑒于無粘結環(huán)錨預應力混凝土襯砌具有的優(yōu)勢，這種結構在我國水工隧洞中有著廣闊的應用前景。黃河小浪底排沙洞是我國第一例采用無粘結雙圈環(huán)繞預應力混凝土襯砌這種結構形式的水工隧洞。 在施工階段，小浪底排沙洞中埋設了混凝土應變計、鋼筋計、無應力計、錨索測力計、滲壓計和測縫計等154支觀測儀器。小浪底排沙洞從1997年施工，1999年投入運行，使用至今已十幾年。在此期間，排沙洞經(jīng)歷了各種設計工況的考驗。工程中所埋設的觀測儀器積累了數(shù)萬組觀測數(shù)據(jù)。本文對這些采集的數(shù)據(jù)進行了系統(tǒng)的整理分析，以了解小浪底工程排沙洞在施工與運行過程中混凝土襯砌應力、應變發(fā)展變化的規(guī)律，從而判斷結構是否合理和安全。 本文應用ANSYS有限元分析軟件對小浪底排沙洞進行建模分析，分別對錨索張拉階段的施工期和加水壓后的運行期的襯砌應力狀態(tài)進行分析，并將結果與監(jiān)測數(shù)據(jù)進行對比，看出兩者具有很好的一致性。結果表明，在整個襯砌結構中，錨具槽部位的受力狀態(tài)是最復雜的，最大最小環(huán)向應力均出現(xiàn)在錨具槽附近，軸向和徑向還出現(xiàn)了較小的拉應力。 針對在小浪底排沙洞襯砌施工和運行過程中暴露出的問題，尤其是錨具槽部位的漏油等現(xiàn)象，本文對小浪底排沙洞環(huán)錨預應力混凝土襯砌的結構設計方案、預應力筋的布置以及錨具槽的布置等內(nèi)容進行優(yōu)化設計，，并采用有限元軟件模擬分析。研究結果表明：優(yōu)化后的結構薄弱區(qū)范圍明顯減小，錨具槽附近的應力分布更均勻，具有明顯的經(jīng)濟效益，對于今后的工程具有一定的參考價值。 根據(jù)實測數(shù)據(jù)和模擬結果對整個無粘結預應力排沙隧洞段的安全使用狀態(tài)進行評價分析，采用定性與定量結合的方法，并主要通過錨索測力計的監(jiān)測數(shù)據(jù)、滲壓計的監(jiān)測數(shù)據(jù)、襯砌混凝土的應力狀態(tài)這三個指標進行安全評價分析。結果表明，通過安全評價，認為排沙洞能保證正常使用，不會出現(xiàn)開裂和滲漏。文中建立的小浪底排沙洞施工和運行過程中的安全狀態(tài)預警預報系統(tǒng)，可以對今后類似工程的設計優(yōu)化和這種新型結構的推廣使用提供依據(jù)。
[Abstract]:The unbonded ring anchor prestressed concrete lining structure is a new type of structure used in hydraulic tunnel. The structure is mainly suitable for the poor geological conditions of the surrounding rock of the lining and the high water pressure in the lining. And the structure of hydraulic tunnel where water seeps into surrounding rock and causes instability of surrounding buildings after cracking of lining. As a new type of structure, unbonded prestressed concrete lining has its special advantages: the steel strand in the lining is surrounded by double loops, which makes the distribution of compressive stress in the lining more uniform and the loss of prestress along the cable less. Compared with the bonded lining, the effective precompression stress increases, so the thickness of the lining can be reduced appropriately, which can save the material, reduce the amount of excavation, reduce the difficulty of construction and project cost, and effectively accelerate the construction progress. In view of the advantages of unbonded ring anchor prestressed concrete lining, this kind of structure has a broad application prospect in hydraulic tunnels in China. Xiaolangdi sand discharge tunnel of the Yellow River is the first hydraulic tunnel in China with unbonded double-ring surrounding prestressed concrete lining. In the construction stage, 154 observation instruments, such as concrete strain gauge, steel bar meter, non-stress gauge, anchor cable dynamometer, pressure gauge and joint gauge, are embedded in the Xiaolangdi sand discharge tunnel. Xiaolangdi sand drainage tunnel was constructed in 1997 and put into operation in 1999. It has been used for more than ten years. During this period, the sand drainage tunnel has experienced the test of various design conditions. The observation instruments embedded in the project have accumulated tens of thousands of observation data. In this paper, the collected data are systematically analyzed in order to understand the development and variation of concrete lining stress and strain during the construction and operation of the sand drain tunnel of Xiaolangdi Project, and to judge whether the structure is reasonable and safe. In this paper, ANSYS finite element analysis software is used to model and analyze the sand discharge tunnel in Xiaolangdi. The stress state of lining during the construction period of the tension stage of the anchor cable and the running period after adding water pressure are analyzed respectively, and the results are compared with the monitoring data. We can see that there is a good consistency between the two. The results show that the stress state of the slot is the most complex in the whole lining structure, the maximum and minimum circumferential stress appear near the Anchorage slot, and the axial and radial tensile stresses are smaller. In view of the problems exposed during the construction and operation of the Xiaolangdi sand drainage tunnel, especially the leakage of the Anchorage slot, the structural design scheme of the prestressed concrete lining for the ring anchor of the Xiaolangdi sand drain tunnel is presented in this paper. The layout of prestressing tendons and the arrangement of anchors are optimized, and the finite element software is used to simulate the design. The results show that the weak area of the optimized structure is obviously reduced, the stress distribution near the Anchorage slot is more uniform, and it has obvious economic benefit, which has certain reference value for the future engineering. According to the measured data and simulation results, the safe operation state of the whole unbonded prestressed sand discharge tunnel is evaluated and analyzed. The qualitative and quantitative methods are adopted, and the monitoring data of the anchor cable dynamometer and the osmotic pressure meter are mainly used. The stress state of lining concrete is evaluated and analyzed. The results show that, through safety evaluation, it is considered that sand drainage holes can be used normally without cracking and leakage. The early warning and prediction system of the safety state in the construction and operation of Xiaolangdi sand drainage tunnel can provide the basis for the design optimization of similar projects and the popularization and application of this new structure in the future.
【學位授予單位】：天津大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TV332

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本文編號：2214021