复合防渗衬砌渠道冻胀破坏力学模型及数值模拟研究

发布时间：2018-06-30 04:01

本文选题：复合衬砌 + 冻胀破坏　；参考：《石河子大学》2014年硕士论文

【摘要】：水资源短缺是一个全球性问题，我国是一个水资源严重紧缺的国家。我国人均水量远低于世界平均水平，仅为全球人均水量的四分之一，排在世界第110位。而我国是农业大国，水资源短缺和水资源不合理地开发利用造成的浪费现象制约着我国农业的发展。农业水资源浪费主要体现在灌溉方面，我国农业灌溉用水达到了农业用水量的九成以上，而渠道输水过程中因渗漏造成的损失占农业用水量的近一半，达到我国总用水量的三分之一。为有效减少渠道输水损失，发展节水农业，渠道衬砌防渗工程被广泛使用。但在我国北方寒冷冻土区，普遍存在渠道冻胀破坏现象，近年来膜料和混凝土刚柔结合的复合衬砌形式具有适应变形，防渗抗冻等特点，被广泛采用，，但对复合衬砌形式防冻害缺乏具体的数学计算。本文在分析总结大量文献基础上，做了以下工作：（1）讨论了渠基土壤产生冻胀的机理及影响因素，分析了各种形式渠道的破坏特征，总结了渠道防渗抗冻胀的基本措施。（2）针对梯形、弧底梯形和U形三种断面的膜与混凝土结合的复合衬砌渠道，从实际工程出发，根据渠道冻胀的基本规律，通过假设建立了复合防渗衬砌渠道冻胀破坏的力学模型，给出了内力计算公式、抗裂验算公式并进行了厚度验算。通过计算表明，采用土工膜与混凝土结合的复合衬砌形式与素混凝土衬砌形式相比，三种断面渠道的有效冻胀力分别减小4.9%、2.6%、7.7%；有效切向约束力分别减小11.3%、7%、19.2%；渠道坡板拉应力分别减小16.7%、3.9%、8%；渠道底板拉应力分别减小6.1%、4%、7.5%，从力学角度证明了复合衬砌形式有利于渠道的防渗抗冻胀。（3）利用ANSYS有限元分析软件对梯形、弧底梯形和U形三种断面的复合衬砌渠道的冻胀进行了数值模拟，得到了其温度场、应力变形场，并进行了分析。温度场等值线与衬砌板面平行分布，在坡板顶部位移值最大；梯形渠道在坡板与底板交界处应力值较大，弧底梯形渠道弧形底部应力值较大，U形渠道弧底应力值较大；阴坡应力值、变形值均大于阳坡。模拟结果与实际冻胀情况相符合，与力学分析相互印证，揭示了渠道冻胀破坏的机理。通过软件模拟结果和力学模型计算结果对比分析，复合衬砌渠道冻胀力的分布和冻胀变形的规律基本一致，渠道的冻胀破坏是在水分、温度、土质等因素共同作用下发生的，说明了本文提出的简化力学模型和有限元模拟方法是可行的，对复合衬砌渠道的进一步应用具有现实意义。
[Abstract]:Water shortage is a global problem, China is a serious shortage of water resources. China's per capita water is far below the world average, only 1/4 of the world's per capita water, ranking 110th in the world. However, China is a big agricultural country. The shortage of water resources and the waste caused by unreasonable exploitation and utilization of water resources restrict the development of agriculture in China. The waste of agricultural water resources is mainly reflected in irrigation. The agricultural irrigation water consumption in our country has reached more than 90% of the agricultural water consumption, and the loss caused by leakage in the course of canal water conveyance accounts for nearly half of the agricultural water consumption. It reaches 1/3 of the total water consumption in China. In order to effectively reduce channel water loss and develop water-saving agriculture, canal lining anti-seepage engineering is widely used. However, in the cold and frozen soil regions of northern China, the frost heaving failure of the canal is common. In recent years, the composite lining with the combination of membrane material and concrete rigid and flexible has been widely used because of its characteristics such as adaptability to deformation, anti-seepage and anti-freezing, etc. However, the concrete mathematical calculation for the frost damage of composite lining form is lacking. Based on the analysis and summary of a large number of literatures, the following works have been done in this paper: (1) the mechanism of frost heaving in canal soil and its influencing factors are discussed, and the damage characteristics of various forms of canal are analyzed. The basic measures to prevent seepage and frost heaving of canal are summarized. (2) aiming at the composite lining channel of trapezoid, arc bottom trapezoid and U-shaped section, according to the basic law of channel frost heaving, The mechanical model of frost heaving failure of composite impervious lining canal is established by assuming that the internal force calculation formula and crack resistance checking formula are given and the thickness check calculation is carried out. The calculation results show that the effective frost heaving force of the three cross-section canals is decreased by 4.92.6and 7.7in the composite lining with geomembrane and concrete, and the effective tangential binding force decreases by 11.37.2and 19.2respectively. The tensile stress of channel slope is reduced by 16.7and 3.9. the tensile stress of channel bottom is decreased by 6.1and 7.5. from the angle of mechanics, it is proved that the composite lining is beneficial to the anti-seepage, anti-frost and anti-heaving of the canal. (3) the trapezoid is analyzed by ANSYS finite element analysis software. The frost heaving of the composite lining channel with three types of arc bottom trapezoid and U-shaped section is simulated numerically. The temperature field, stress and deformation field are obtained and analyzed. The temperature field isoline distributes parallel with the lining slab surface, the displacement value at the top of the slope plate is the largest, the stress value of trapezoidal channel is larger at the junction of slope slab and bottom slab, and the stress value of arc bottom is larger than that of U-shaped channel. The stress and deformation of shady slope are higher than that of sunny slope. The simulation results are in agreement with the actual frost heaving, and the mechanism of channel frost heave failure is revealed. By comparing and analyzing the results of software simulation and mechanical model calculation, it is found that the distribution of frost heave force and the law of frost heave deformation are basically the same, and the frost heave failure of the canal occurs under the joint action of water, temperature, soil quality and so on. The simplified mechanical model and finite element simulation method proposed in this paper are feasible and have practical significance for the further application of composite lining channel.
【学位授予单位】：石河子大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV672;TV698.26

【参考文献】