【摘要】：本文針對北方廣大季節(jié)性凍土灌區(qū)的裝配式U型混凝土渠道襯砌受凍脹破壞的問題,立足寧夏銀北灌區(qū)五段混凝土襯砌渠道和寧夏大學文萃校區(qū)裝配式U型混凝土渠襯砌渠道凍脹觀測試驗區(qū),采用調(diào)查研究、現(xiàn)場觀測和計算機數(shù)值模擬方法,對U型混凝土渠道襯砌板及橫縫凍脹破壞數(shù)值模擬進行了較為系統(tǒng)的研究,為裝配式U型混凝土渠道防滲抗凍技術推廣提供了理論依據(jù)。本文主要研究成果如下:(1)通過混凝土襯砌渠道田間凍脹試驗觀測分析得出:2015年12月下旬至次年1月下旬為渠基土低溫期與凍脹量高值區(qū)間,溫度最小值與凍脹量峰值往往出現(xiàn)在這一區(qū)間。渠基土溫度與凍脹力、凍脹量關系密切,隨著溫度的降低,凍脹力、凍脹量均有升高的趨勢。陽坡直線段處、陽坡弧線段處、陰坡直線段處、陽坡弧線段處四處受凍脹影響程度明顯不同,其中陰坡弧段渠基土凍脹量最大。(2)通過銀北灌區(qū)U型混凝土襯砌渠道實地測量分析,確定了渠道襯砌有限元模型幾何參數(shù):襯砌板的寬度為40cm、傾角為22度、厚度為6cm,橫縫的寬度設定在3-18cm的取值范圍,混凝土強度為C15-C30。通過裂縫觀測分析得出:凍脹裂縫出現(xiàn)位置一般在弧線段與直線段的交界處,寬度在2mm左右,且橫縫比襯砌板的凍脹破壞情況嚴重,陰坡襯砌板比陽坡襯砌板的破壞情況嚴重。(3)通過U型混凝土襯砌渠道凍脹數(shù)值模擬分析得出:橫縫混凝土強度增加,有利于渠道抵抗凍脹,尤其在兩段直線段表現(xiàn)的較為明顯,而在橫縫的兩段弧線段的差異性并不大。通過不同混凝土強度最大凍脹位移減小量的比較,選用強度級別為C25的混凝土作為橫縫材性比較適宜;在橫縫寬度不斷增加的過程中,橫縫凍脹位移在不斷減少,當橫縫寬度為15cm時,陰坡最大凍脹位移減小量最大,可以作為渠道設計時橫縫寬度的參考值。U型混凝土渠道的凍脹破壞主要出現(xiàn)在直線段與弧線段銜接處,陰坡凍脹破壞情況比陽坡更為嚴重,橫縫比襯砌板更容易受到凍脹破壞的影響,數(shù)值模擬裂縫特征與實際凍脹裂縫觀測結(jié)果基本相吻合。
[Abstract]:This paper aims at the problem of frost heaving damage to the prefabricated U-type concrete channel lining in the vast seasonal frozen soil irrigated area in the north of China. Based on the experimental area of frost heave observation of five-section concrete lining channel in Yinbei Irrigation District of Ningxia University and the assembled U-type concrete canal lining channel in Wenzi Campus of Ningxia University, the methods of investigation, field observation and computer numerical simulation are adopted. The numerical simulation of frost heaving failure of U type concrete channel lining slabs and transverse joints is studied systematically, which provides a theoretical basis for the popularization of prefabricated U type concrete channel anti-seepage and anti-freezing technology. The main research results of this paper are as follows: (1) through the observation and analysis of the field frost heave test of concrete lining channel, it is concluded that the period from late December 2015 to late January of next year is the period of low temperature and the high value of frost heave. The minimum temperature and the peak value of frost heave often appear in this range. The temperature of the base soil is closely related to the frost heave force and the frost heave quantity, and with the decrease of the temperature, the frost heave force and the frost heave volume are all increasing. The influence of frost heaving on sunny slope, sunny slope arc line, shade slope straight line and sunny slope arc is obviously different. Among them, the frost heave of the base soil in the arc section of the overcast slope is the largest. (2) through the field measurement and analysis of the U-type concrete lining channel in Yinbei Irrigation District, the geometric parameters of the finite element model of the channel lining are determined: the width of the lining plate is 40 cm, the inclination angle is 22 degrees, The thickness is 6 cm, the width of transverse joint is set in the range of 3-18cm, and the strength of concrete is C15-C30. Through the observation and analysis of cracks, it is concluded that the position of frost heaving crack is generally at the junction of arc section and straight line section, the width is about 2mm, and the transverse joint is more serious than the frost heaving damage of lining plate. (3) through numerical simulation analysis of frost heave of U type concrete lining channel, it is concluded that the strength of transverse joint concrete is increased, which is helpful to resist frost heave, especially in two straight sections. However, the difference between the two arcs in the transverse seam is not great. Through the comparison of the maximum frost heaving displacement of different concrete strength, the concrete with strength grade C25 is suitable for the transverse joint, and the frost heave displacement of the transverse joint decreases continuously with the increasing of the width of the transverse joint. When the width of transverse joint is 15cm, the maximum frost heave displacement of shady slope decreases the most, which can be used as the reference value of transverse joint width. The frost heave damage of shady slope is more serious than that of sunny slope, and the transverse joint is more easily affected by frost heave failure than the lining slab, and the numerical simulation crack characteristics are basically consistent with the observed results of the actual frost heave crack.
【學位授予單位】：寧夏大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TV544;TV698.2

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