小型U形渠道混凝土衬砌冻胀破坏力学模型的研究

发布时间：2018-06-10 16:21

本文选题：小型U形渠道 + 混凝土衬砌结构　；参考：《宁夏大学》2014年硕士论文

【摘要】：随着社会经济的不断发展,我国的水资源矛盾日益突出,提倡节水型农业及合理利用水资源势在必行。渠道防渗衬砌是减少农业灌溉输水损失的有效方法。宁夏引黄灌区作为一个历史悠久的灌区,近年来修建了大量的渠道防渗工程,其中U形混凝土衬砌渠道由于水力条件好、占地面积少、抗冻胀性能好而被广泛应用于支、斗、农等各级渠道中。但是,因冬季负温的作用,渠基土发生冻胀,从而使混凝土衬砌渠道发生不同程度的冻胀破坏,有的甚至失去防渗作用。因此,混凝土衬砌渠道防冻胀破坏已经成为一个亟待解决的问题。本文通过阅读和分析大量文献资料,论述了国内外渠道防渗抗冻胀技术的发展现状,总结了渠道抗冻胀破坏的技术措施,以宁夏引黄灌区中小型U形渠道为研究背景,针对目前U形混凝土衬砌板冻胀破坏力学特点及其变化规律的理论研究还有待完善的现状,重点进行了小型U形渠道混凝土衬砌冻胀破坏的受力分析与建立相应力学分析模型的研究工作,并采用有限元数值方法,对小型U形渠道衬砌结构冻胀作用下的纵向变形问题进行了相应的三维数值模拟分析。具体研究内容与研究结果如下： (1)探讨了混凝土衬砌渠道冻胀破坏的主要影响因素；根据渠道衬砌结构形式分析了几种目前应用普遍、不同断面衬砌渠道的冻胀破坏机理和破坏特征。重点分析两拼式U形和整体式U形混凝土衬砌渠道的冻胀特点。 (2)通过对小型的两拼式和整体式U形渠道混凝土衬砌冻胀破坏特征及破坏原因的分析,确定了在法向冻胀力、法向冻结力、切向冻结力和重力共同作用下混凝土衬砌整体结构的计算简图,建立了这两种衬砌结构冻胀破坏的力学模型并推导出冻胀控制内力及最大拉应力的计算公式,结合混凝土板的抗裂条件,给出了胀裂部位、衬砌板厚及抗冻胀破坏验算的方法。 (3)针对实际工程,运用大型有限元软件ANSYS对考虑纵向变形整体式U形混凝土衬砌渠道的冻胀进行三维数值模拟分析,得到了衬砌渠道温度场、应力场和变形场的分布规律,模拟结果与野外试验观测结果基本一致,由此表明,本文采用的考虑纵向变形整体式U形混凝土衬砌渠道的数值模拟方法是合理的,可为小型整体式U形混凝土衬砌渠道的设计提供科学合理的分析方法。
[Abstract]:With the development of social economy, the contradiction of water resources in our country is becoming more and more prominent. It is imperative to advocate water-saving agriculture and rational use of water resources. Canal seepage prevention lining is an effective method to reduce the water loss of agricultural irrigation. As a irrigation area with a long history, Ningxia Yellow River Irrigation District has built a large number of canal seepage control projects in recent years. Among them, U-shaped concrete lining channels are widely used in branches and buckets because of their good hydraulic conditions, small area, good frost resistance and swelling performance. Agriculture and other levels of channels. However, due to the effect of negative temperature in winter, frost heaving occurs in the base soil of the canal, which results in frost heaving damage of concrete lining canal to varying degrees, and some even lose its anti-seepage effect. The frost-resistant damage of concrete lining channel has become an urgent problem to be solved. Through reading and analyzing a large number of documents, this paper discusses the development status of anti-seepage and anti-frost heaving technology at home and abroad, summarizes the technical measures of channel anti-freezing and anti-frost damage, and takes the small and medium-sized U-shaped channel in Ningxia Yellow River diversion Irrigation District as the research background. In view of the present theoretical research on the characteristics of frost heaving failure force and its changing law of U-shaped concrete lining slab, it is still necessary to perfect the present situation. The stress analysis of frost heaving failure of small U-shaped channel concrete lining and the establishment of corresponding mechanical analysis model are emphatically carried out, and the finite element numerical method is adopted. The longitudinal deformation of small U-channel lining structure under frost heaving is analyzed by three-dimensional numerical simulation. The concrete research contents and results are as follows: (1) the main influencing factors of frost heaving failure of concrete lining channel are discussed, and several kinds of common application are analyzed according to the structural form of channel lining. Frost heaving failure mechanism and failure characteristics of different cross section lining channels. The characteristics of frost heaving of two-type U-shaped and integral U-shaped concrete lining channels are emphatically analyzed. By analyzing the characteristics and causes of frost heaving of concrete lining of small two-type and integral U-shaped channels, the normal frost heaving force is determined, and the frost heaving force of the concrete lining in the normal direction is determined through the analysis of the characteristics and causes of frost heaving in the concrete lining of the U-shaped and integral U-shaped channels. The calculation diagram of concrete lining integral structure under the combined action of normal freezing force, tangential freezing force and gravity is presented. The mechanical models of frost heave failure of these two kinds of lining structures are established, and the formulas of frost heaving control internal force and maximum tensile stress are deduced. Combined with the crack resistance conditions of concrete slabs, this paper gives the methods of checking the crack position, thickness of lining slabs and frost heaving resistance. The three-dimensional numerical simulation analysis of frost heaving of U-shaped concrete lining canal considering longitudinal deformation is carried out by using the large-scale finite element software ANSYS. The distribution law of temperature field, stress field and deformation field of lining channel is obtained. The simulation results are in good agreement with the field test results, which shows that the numerical simulation method for the longitudinal deformation integral U-shaped concrete lining channel is reasonable. It can provide a scientific and reasonable analysis method for the design of small integral U-shaped concrete lining channel.
【学位授予单位】：宁夏大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV31;TV672;TV698.26

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