本文選題：PCCP　切入點：承載機理　出處：《武漢大學》2014年博士論文　論文類型：學位論文

【摘要】：輸水管線的安全與耐久是社會發(fā)展和人民安居樂業(yè)的必要保障。近年來,預應力鋼筒混凝土管廣泛應用于南水北調等大型輸水工程。因此預應力鋼筒混凝土管承載機理、破壞形態(tài)和安全耐久性能的研究,對保證生產運營的安全順暢有非常重要的理論與實踐意義。本文針對預應力鋼筒混凝土管,立足于管道的結構性能分析和耐久性理論研究兩方面,主要開展如下研究工作： 一、回顧了PCCP結構設計理論的發(fā)展過程,認為目前的PCCP結構計算理論不能反映PCCP作為多層結構沿管壁厚度方向上的應力分布特征。在此基礎上,對PCCP的結構計算方法進行了改進,完善了符合PCCP實際服役環(huán)境的荷載計算理論和截面應力分析模型。二、建立了反映PCCP截面特性的二維平面有限元模型和反映PCCP鋼絲螺旋纏繞和復雜層間關系的三維實體有限元模型,按照PCCP的生產工藝流程,對PCCP從生產制造到最終破壞的全過程進行了模擬,得到了PCCP在各種工況下的受力狀態(tài)和結構響應,并且通過與理論分析結果和相關試驗結果對比驗證,證明了有限元模型及分析方法的正確性。通過在模型中合理的考慮砂漿層與管芯、管芯與鋼絲之間復雜的相互作用關系,獲得了在各種工況下,砂漿層的剝蝕、開裂情況,以及預應力鋼絲預應力損失情況。 三、通過分析不同埋深和不同內水壓力對PCCP受力性能的影響,研究了不同荷載類型對PCCP結構響應規(guī)律的影響,發(fā)現(xiàn)PCCP具有兩種不同的破壞形態(tài),并且破壞形態(tài)與管道埋深有關,深埋時PCCP受外壓破壞,淺埋時PCCP受內壓破壞。提出現(xiàn)行設計規(guī)范僅考慮了PCCP受內壓破壞的極限狀態(tài)。研究了內水壓力改變下,PCCP結構受力響應的變化規(guī)律,模擬了結構在內水壓力作用下的破壞過程,研究了PCCP在內水壓力作用下的破壞機理和破壞形態(tài)；結合前人進行的PCCP外壓破壞試驗研究成果,建立了PCCP兩種破壞形態(tài)下的承載能力極限狀態(tài)方程,通過算例證明本文提出的承載能力極限狀態(tài)方程可作為現(xiàn)行設計規(guī)范的有益補充。 四、分析了管芯混凝土厚度、砂漿層厚度、鋼筒位置、鋼筒厚度、鋼絲直徑和鋼絲間距變化對PCCP結構性能的影響,以此提出了砂漿層、預應力鋼絲、管芯混凝土和鋼筒在PCCP承載過程中分別發(fā)揮的功能作用。研究了PCCP結構尺寸變化對結構性能影響的規(guī)律,提出了能指導PCCP各結構部件布置和結構設計的重要工程結論,建立了能用于結構優(yōu)化的反映PCCP關鍵截面應力與結構尺寸變化關系的分析公式。 五、分析了造成PCCP結構耐久性退化的多種因素,認為氯離子侵蝕對PCCP耐久性危害最大,并提出基于氯離子侵蝕的PCCP壽命評估準則和耐久性設計方法。研究了氯離子侵蝕PCCP的機理,發(fā)現(xiàn)氯離子侵蝕PCCP呈二維擴散規(guī)律,并且管道截面半徑及預應力鋼絲和鋼筒均對PCCP內部的氯離子濃度分布有顯著影響,結合PCCP的截面特征建立了PCCP氯離子擴散理論模型及PCCP剩余使用壽命評估模型。 六、研究了氯鹽環(huán)境下預應力鋼絲的腐蝕特性,提出氯離子侵蝕PCCP將造成三種腐蝕結果：局部預應力損失、局部鋼絲銹蝕和鋼絲銹斷。針對三種腐蝕結果,分別建立PCCP局部預應力損失模型、PCCP局部鋼絲銹蝕模型和PCCP鋼絲斷裂模型,研究預應力鋼絲腐蝕損傷對PCCP結構性能的影響,提出預應力鋼絲腐蝕將降低PCCP的承載能力,顯著影響PCCP的耐久性能。
[Abstract]:Safety and durability of the water pipeline is necessary for social development and people's live and work in peace. In recent years, the prestressed concrete cylinder pipe is widely used in large-scale water diversion project of South to North Water Diversion Project. So the prestressed concrete cylinder pipe bearing mechanism, failure mode and safety of durability, to ensure there is very important theoretical and practical significance of safety the smooth production operation. Based on the prestressed concrete cylinder pipe, two based on pipeline structure durability performance analysis and theoretical research, the main research work carried out as follows:
A review of the development process, the design theory of the structure of PCCP, PCCP believes that the current structure of the theoretical calculation can not reflect the PCCP as a multilayer structure along wall thickness on the stress distribution characteristics. On this basis, the calculating method of the PCCP structure was improved, improve the service environment of the actual loads in accordance with PCCP calculation theory and cross section the stress analysis model. Two, establish a plane finite element model to reflect the PCCP section characteristics and reflect the three-dimensional finite element model of PCCP steel wire spiral winding and complex relations between layers, according to the production process of PCCP, the PCCP was used to simulate the whole process from production to final failure, obtained in a variety of PCCP under the condition of stress response and structure, and through the comparative analysis of test results and relevant test results and theory, to prove the correctness of the finite element model and the analysis method. Through the Considering the complex interaction between the mortar layer and the core and the core and the steel wire, the erosion and cracking of the mortar layer and the prestress loss of the prestressed steel wire under various conditions are obtained.
Three, we analyze the effect of different depth and different water pressure on PCCP mechanical properties, the effects of different load types on the structure of PCCP response, PCCP has found two different failure modes and failure modes and the buried depth of pipeline, buried PCCP under external pressure damage, shallow PCCP under internal pressure damage. Proposed the design specification only consider the limit state PCCP under internal pressure damage. On the internal pressure changes, changes of stress response in PCCP structures, to simulate the failure process of the structure in the water pressure under the action of PCCP, the failure mechanism of the inner water pressure and failure form; the destructive test combined with some previous results of PCCP external pressure, a bearing capacity limit state equation PCCP two kinds of failure mode, it is proved that the bearing capacity limit state equation is proposed in this paper can be used as the current A useful supplement to the design specification.
Four, analysis of the tube core thickness of concrete, mortar layer thickness, the thickness of steel tube, steel tube, influence of wire diameter and wire spacing changes on the PCCP structure performance, this proposed mortar layer, prestressed steel wire, pipe core concrete and steel tube in PCCP bearing function are played in the process. The effect of PCCP the structure size changes on the structure and properties of the law, put forward an important engineering layout and structural design guide PCCP parts can be used to reflect the conclusion, established PCCP critical section structure optimization analysis formula of force and structure size change.
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本文編號：1652213