【摘要】：沉管隧道地基處理是沉管隧道施工中最重要的環(huán)節(jié)之一,砂流法由于其特有的優(yōu)點,現(xiàn)已成為硬質(zhì)地基上沉管隧道基礎(chǔ)處理的首選。沉管隧道基礎(chǔ)處理成功與否,直接關(guān)系到沉管隧道的服役與安全,一旦出現(xiàn)超過允許值的沉降或不均勻沉降,無論規(guī)模大小,后續(xù)的處理將非常困難,甚至是不可處理的。因此,對沉管隧道砂流法地基處理機理及設(shè)計方法的研究,確保管節(jié)與基礎(chǔ)密實接觸,具有重要的工程意義。砂流法砂盤成型過程復(fù)雜,砂的運動主要靠流場作為傳輸,而又反過來影響流體的流場,且目前對砂流法的研究較少涉及砂流法理論研究,故有必要從理論角度分析砂流法處理沉管隧道地基的全過程,實現(xiàn)優(yōu)化、指導(dǎo)砂流法施工的目的。文中自行研制了砂流法施工的砂盤探測器,解決了水下基槽試驗環(huán)境中的實時探測難題;設(shè)計了大型砂流法全尺度試驗?zāi)Ｐ拖到y(tǒng),同時實現(xiàn)了不同基槽深度、砂水比、施工邊界等工況下的對比模型試驗,得出試驗中砂盤發(fā)展、水壓力變化規(guī)律,進而分析得出砂盤成型過程以及試驗中參數(shù)變化對砂流法施工的影響;依據(jù)固—液兩相流理論,實現(xiàn)了砂、水兩相間的耦合作用,為砂流法理論分析提供基礎(chǔ),數(shù)值實現(xiàn)砂流法砂盤成型過程;數(shù)值試驗實現(xiàn)了不同砂水比、基槽深度、邊界條件工況下的砂流法處理過程,以及不同河流流速、水位等對基槽內(nèi)砂盤成型的影響,討論砂流在各種復(fù)雜工況下的響應(yīng)情況。本文得出的主要結(jié)論有以下幾點:(1)砂流法中砂顆粒自噴入到沉積的運動軌跡經(jīng)歷了“上升區(qū)”、“輸送區(qū)”與“沉積區(qū)”三個過程,砂盤的發(fā)展經(jīng)歷了“堆積”與“擴展”兩個階段。(2)砂流法中砂水比、基槽深度的變化均對基槽內(nèi)水壓力、砂盤軸向發(fā)展、沖擊坑尺寸和流縫寬度等影響較大;砂流法施工中理想砂水比為0.1~0.15,較合理基槽深度為0.8m~1.0m。(3)砂流法在具有較小流速的基槽內(nèi)施工,砂盤最終半徑可達到設(shè)計要求,但形狀將表現(xiàn)為下游邊界曲率半徑更小上游邊界曲率半徑更大的水滴形。(4)已成型砂盤的邊界對擬施工砂盤小半徑范圍內(nèi)的影響較小,但在砂盤相交處區(qū)域的填滿度與密實度均不高。(5)相對于砂盤平行布置方案,交錯布置方案中的密實度與填滿度更高。砂盤設(shè)計與施工過程應(yīng)保證砂盤對稱布置,盡可能保證砂盤較大面積的重疊,避免砂盤施工過程中產(chǎn)生小銳角邊界區(qū)域。
[Abstract]:The foundation treatment of the immersed tube tunnel is one of the most important links in the construction of the immersed tube tunnel, and the sand flow method has become the first choice for the foundation treatment of the immersed tube tunnel on the hard foundation due to its unique advantages. If the foundation treatment of the immersed tube tunnel is successful or not, it is directly related to the service and safety of the immersed tube tunnel. Therefore, the research on the foundation treatment mechanism and design method of the sand-flow method of the immersed tube tunnel ensures that the pipe joint is in close contact with the foundation and has important engineering significance. The sand-flow method is complicated in the forming process, the movement of the sand mainly depends on the flow field as the transmission, which in turn affects the flow field of the fluid, and the research on the sand flow method is less involved in the sand flow theory study, so it is necessary to analyze the whole process of the sand flow method to treat the immersed tube tunnel foundation from the theoretical angle. And the purpose of optimizing and guiding the construction of the sand flow method is realized. In this paper, a sand-disk detector for sand-flow construction is developed, and the real-time detection problem in the underwater base-tank test environment is solved; a large-scale sand-flow method full-scale test model system is designed, and a comparison model test under the conditions of different base groove depth, sand-water ratio, construction boundary and the like is realized, According to the two-phase flow theory of solid-liquid two-phase flow theory, the coupling effect between sand and water is realized, and the foundation is provided for the theoretical analysis of sand flow method. In this paper, the sand-flow process of sand-flow method is realized by numerical experiments, and the influence of different sand-water ratio, base-groove depth, boundary condition and sand-flow process under the condition of boundary condition, and the influence of different river flow rate and water level on the formation of the sand-plate in the base tank are realized, and the response of the sand-flow under various complicated working conditions is discussed. The main conclusions are as follows: (1) The self-injection of the sand particles in the sand-flow process through the three processes of the "rising area", the "transport area" and the "sedimentary area", and the development of the sand disk has experienced two stages of the "build up" and the "expand". (2) The change of the sand-water ratio and the base-groove depth in the sand-flow method has great influence on the water pressure in the base tank, the axial development of the sand disc, the size of the impact pit and the width of the flow, and the ideal sand-water ratio in the sand-flow method is 0.1-0.15, and the depth of the reasonable base groove is 0.8-1.0m. (3) The sand flow method is constructed in a base tank with a small flow velocity, and the final radius of the sand disk can reach the design requirements, but the shape will appear as a water drop with a smaller radius of curvature of the downstream boundary and a larger radius of curvature. (4) The influence of the boundary of the formed sand disk on the small radius of the sand disk to be constructed is small, but the filling degree and the compactness of the area at the intersection of the sand disc are not high. And (5) the arrangement scheme is arranged in parallel with respect to the sand table, and the compactness and the filling degree in the staggered arrangement scheme are higher. The design and construction process of the sand table shall ensure the symmetrical arrangement of the sand disk, ensure the overlapping of the large area of the sand disc as much as possible, and avoid the small acute angle boundary area during the construction of the sand disc.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：U455.4;U459.5

【引證文獻】

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1 茹玉英;王開榮;;泥沙沉降計算公式對比分析[A];水文泥沙研究新進展——中國水力發(fā)電工程學(xué)會水文泥沙專業(yè)委員會第八屆學(xué)術(shù)討論會論文集[C];2010年

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本文編號：2443425