【摘要】：土石壩建造在水利工程中有著悠久的歷史,和其他壩型相比較,土石壩造價(jià)低,因而被作為一種普遍使用的壩體類型。其中埋設(shè)于土石壩的壩下涵管是一種重要的輸水建筑物,壩下涵管直接埋設(shè)于壩體,需要承受頂部壩體填土壓力、地基不均勻沉降的影響,在與壩體填土接觸部位還需要承受滲流沖刷的作用,破壞后會(huì)對(duì)工程造成嚴(yán)重的損失。一直以來(lái),在土石壩的規(guī)劃設(shè)計(jì)及參數(shù)分析中,通常偏重于滲流分析和穩(wěn)定計(jì)算;對(duì)涵管的研究則偏重于涵管的受力、沉降的計(jì)算等結(jié)構(gòu)計(jì)算分析。而對(duì)于在壩體穩(wěn)定滲流期,涵管與壩體填土接觸滲流的研究開(kāi)展較少。本文為了研究壩下涵管周圍接觸滲流問(wèn)題,介紹了滲流理論的發(fā)展歷程和基本方法,建立了穩(wěn)定滲流期壩體及壩下涵管三維有限元分析模型。通過(guò)對(duì)土石壩常見(jiàn)非線性問(wèn)題分析模型的比較,最終確定摩爾-庫(kù)倫模型作為本文土石壩有限元分析的本構(gòu)模型。針對(duì)不同計(jì)算工況,分別建立了壩體及壩下涵管應(yīng)力計(jì)算模型、壩體及壩下涵管三維滲流分析計(jì)算模型。根據(jù)所開(kāi)展的工作得出了以下結(jié)論:(1)涵管所受應(yīng)力及豎向位移計(jì)算上埋式涵管管頂垂直土壓力時(shí),應(yīng)考慮涵管兩側(cè)土體的不均勻沉降的“拖曳摩擦”作用所帶來(lái)的應(yīng)力增加。涵管頂部所受豎向應(yīng)力呈不均勻分布,在涵管上方,隨著距離涵管頂部中心線的距離的增加,涵管頂部所受到的豎向應(yīng)力增加。在涵管外側(cè),豎向應(yīng)力先減小后增加,逐漸趨于穩(wěn)定。隨著距離涵管中心線距離的增加,涵管頂部豎向位移逐漸增加,之后逐漸趨于穩(wěn)定。(2)無(wú)截水環(huán)時(shí)涵管周圍滲流涵管周圍土體滲流速度、滲流量隨涵管周圍土體滲透系數(shù)的升高而增大,當(dāng)不設(shè)置截水環(huán)時(shí),即使涵管周圍土體的滲透系數(shù)有所變化,但沿程滲透坡降幾乎無(wú)變化,而僅在滲流出口處,滲透坡降隨著涵管周圍土體滲透系數(shù)的增大而略有減小。(3)截水環(huán)對(duì)涵管周圍滲流場(chǎng)的影響涵管增設(shè)截水環(huán)可以有效降低涵管周圍滲流速度、滲流量,降低涵管周圍滲流出口處的滲透坡降,對(duì)預(yù)防涵管周圍土體接觸沖刷的發(fā)生起到重要作用。截水環(huán)的效果也跟截水環(huán)的尺寸和數(shù)量有關(guān),在一定的尺寸和數(shù)量范圍情況下,截水環(huán)的數(shù)量越多、尺寸越大,其防止涵管周圍滲透破壞的效果也越好。超過(guò)一定的尺寸和數(shù)量后,截水環(huán)的影響效果差別不大。
[Abstract]:Earth-rock dam construction has a long history in water conservancy engineering. Compared with other dam types, earth-rock dam has a low cost, so it is widely used as a dam body type. The culvert under the dam buried in the earth-rock dam is an important water conveyance structure, and the culvert under the dam is directly buried in the dam body, which needs to bear the influence of the fill earth pressure on the top dam and the uneven settlement of the foundation. In contact with the fill of the dam, it is necessary to bear the role of seepage and scour, which will cause serious damage to the project. In the planning, design and parameter analysis of earth-rock dams, emphasis is usually placed on seepage analysis and stability calculation, while the study on culverts is focused on structural calculation and analysis such as the stress of culvert and the calculation of settlement. However, the research on contact seepage between culvert and fill is less in the steady seepage period. In this paper, in order to study the contact seepage around culvert under dam, the development history and basic method of seepage theory are introduced, and the three-dimensional finite element analysis model of dam body and culvert under dam during steady seepage period is established. Through the comparison of common nonlinear analysis models of earth-rock dams, the Moor-Coulomb model is finally determined as the constitutive model of the finite element analysis of earth-rock dams in this paper. According to different calculation conditions, the stress calculation models of dam body and culvert under dam, and the three-dimensional seepage analysis model of dam body and culvert under dam are established respectively. According to the work carried out, the following conclusions are obtained: (1) when the stress and vertical displacement of the culvert pipe are calculated, the vertical earth pressure of the top of the buried culvert pipe is calculated. The stress increase caused by "drag friction" of uneven settlement of soil on both sides of culvert should be considered. The vertical stress on the top of culvert is distributed unevenly, and the vertical stress on the top of culvert increases with the increase of distance from the centerline of culvert top. On the outside of the culvert, the vertical stress decreases first and then increases, and then tends to be stable. With the increase of the distance from the center line of culvert, the vertical displacement of culvert top increases gradually, and then tends to stabilize gradually. (2) seepage velocity of soil around culvert pipe without water cut ring, The seepage flow rate increases with the increase of soil permeability coefficient around culvert pipe. Even if the permeability coefficient of soil around culvert pipe is changed, the seepage gradient is almost unchanged, but only at the seepage outlet. The seepage gradient decreases slightly with the increase of soil permeability coefficient around culvert pipe. (3) the influence of water cut ring on seepage field around culvert pipe can effectively reduce the seepage velocity and flow rate around culvert pipe. Reducing the seepage slope at the seepage outlet around culvert plays an important role in preventing contact erosion of soil around culvert. The effect of the water cutoff ring is also related to the size and quantity of the intercepting ring. Under certain size and quantity range, the larger the number and the larger the size, the better the effect of preventing seepage damage around the culvert. After a certain size and quantity, the effect of the water cutoff ring is not different.
【學(xué)位授予單位】：鄭州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TV223.4

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