【摘要】：倒虹吸管作為應用廣泛的交叉工程和重要的隱蔽工程,在國際上素有生命線工程之稱,其結構的應力、變形與外形尺寸、填土厚度、填土性質、初始邊界條件等因素之間存在著復雜的相互作用,而且除滿足正常輸水要求外,對結構進行合理的設計也十分必要。因此,為保證整個結構體系的穩(wěn)定、安全和經(jīng)濟性,對倒虹吸結構和周圍土體進行合理的分析和計算,進而對結構進行優(yōu)化設計就顯得尤為重要。本文基于數(shù)值模擬法,以黑龍江省依安農場河北灌區(qū)主干渠穿西太平川溝倒虹吸工程為研究對象,通過運用有限元分析軟件ANSYS,首先對工程運行中遇到的5種工況,采用鋼筋混凝土的整體式模式,建立原設計方案下的管身和周圍土體的三維實體模型,分別分析管身和周圍土體的應力和變形。其次結合分析得到的管身應力值,對倒虹吸的初始斷面及配筋進行優(yōu)化,并利用分離式的配筋形式,對優(yōu)化后的倒虹吸管身進行兩種較不利工況下的模擬分析,驗證改進后設計方案的可靠性,對比優(yōu)化前后的工程量和造價,分析其經(jīng)濟性。本文的主要研究內容和結論如下:(1)介紹有限元的基本原理及分析過程、ANSYS的求解步驟,分別總結概括混凝土、鋼筋、土體三種材料的本構關系和破壞準則及鋼筋混凝土有限元分析中鋼筋的處理方式。(2)根據(jù)原設計方案中管身的有限元分析結果,可得出在工程運行的5種工況中,管身混凝土最大拉、壓應力均遠未超過其設計值且有較大的富余,管身較不利工況出現(xiàn)在管內無水的完建和檢修工況。(3)根據(jù)原設計方案中管身周圍土體的有限元分析結果,可得出在不同工況下,土體整體是穩(wěn)定的,最大沉降量發(fā)生在完建期,位于管身兩側回填土的自由表面處,其值為16.2 mm。管身整體沉降均勻,最大下沉量約為10.3 mm,滿足倒虹吸管對地基沉降量的設計要求。管身地基最大壓應力值為114 k Pa,地基承載力較好,滿足本工程地基承載力的設計要求。(4)結合ANSYS數(shù)值模擬得到的洞身應力值,對初始的倒虹吸結構進行優(yōu)化設計,根據(jù)改進后結構的有限元分析結果,可以發(fā)現(xiàn)優(yōu)化后的倒虹吸結構是安全的。通過對比優(yōu)化前后的工程造價,發(fā)現(xiàn)改進后的設計方案可以使造價大幅降低。
[Abstract]:Inverted siphon, as a widely used cross-engineering and important concealed engineering, is known as lifeline engineering in the world. There are complex interactions among the stress, deformation and shape of the structure, fill thickness, fill properties, initial boundary conditions and other factors. Besides satisfying the normal water conveyance requirements, the structure is reasonable. Therefore, in order to ensure the stability, safety and economy of the whole structure system, it is very important to analyze and calculate the inverted siphon structure and surrounding soil reasonably, and then optimize the design of the structure. The inverted siphon ditch project is taken as the research object. Firstly, by using the finite element analysis software ANSYS, the three-dimensional solid model of the pipe body and the surrounding soil body under the original design scheme is established for the five working conditions encountered in the project operation. Then the stress and deformation of the pipe body and the surrounding soil body are analyzed respectively. The obtained stress value of the pipe body is used to optimize the initial section and reinforcement of the inverted siphon, and the optimized inverted siphon pipe body is simulated and analyzed under two unfavorable working conditions by using the separated reinforcement form. The reliability of the improved design scheme is verified, and the cost and quantity of the project before and after optimization are compared to analyze its economy. The research contents and conclusions are as follows: (1) Introduce the basic principle and analysis process of finite element method, and the solving steps of ANSYS, summarize the constitutive relation and failure criteria of concrete, steel bar and soil, and the treatment method of steel bar in the finite element analysis of reinforced concrete. (2) According to the finite element analysis results of pipe body in the original design scheme, It can be concluded that the maximum tensile and compressive stresses of the concrete in the pipe body are far from the design values and have greater redundancy in the five working conditions of the project. The unfavorable working conditions of the pipe body appear in the complete and maintenance conditions without water in the pipe. (3) According to the finite element analysis results of the soil around the pipe body in the original design, the soil integrity under different working conditions can be obtained. The maximum settlement occurs at the free surface of the backfill on both sides of the pipe body, and its value is 16.2 mm. The overall settlement of the pipe body is uniform. The maximum settlement is about 10.3 mm, which meets the design requirements of the inverted siphon for the settlement of the foundation. The design requirement of foundation bearing capacity. (4) Combining with the stress value of the cave body obtained by ANSYS numerical simulation, the initial inverted siphon structure is optimized. According to the finite element analysis results of the improved structure, it can be found that the optimized inverted siphon structure is safe. By comparing the engineering cost before and after optimization, it is found that the improved design scheme is feasible. So that the cost will be greatly reduced.
【學位授予單位】：東北農業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TV672.5

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