掺MgO补偿收缩混凝土在渠道衬砌中的应用研究

发布时间：2018-04-03 22:24

本文选题：渠道衬砌　切入点：膨胀混凝土　出处：《西北农林科技大学》2014年硕士论文

【摘要】：在水资源日益匮乏的今天，渠道渗漏损失过大，渠系水有效利用率偏低成为我国农田灌溉重点关注的问题。使用具有抗裂防渗性能的混凝土材料衬砌，是目前我国渠道防渗工程的重要措施之一。本文针对渠道衬砌混凝土，特别是预制衬砌渠道的填缝砂浆干缩变形大，漏水严重这一长期困扰灌区生产的技术难题，研究补偿收缩混凝土的特性，确定符合渠道衬砌要求的补偿收缩混凝土配合比，，制定出一套较为精确的渠道衬砌板抗裂防渗方案，替代传统的砂浆填缝材料。这对增强渠道工程的耐久性、水资源的节约以及提高工程的经济性具有重要意义。本文主要分三部分进行研究，第一部分以混凝土的收缩特性为研究对象，结合渠道衬砌板的结构及受力特点，推导出梯形渠道衬砌板收缩量的计算公式；第二部分以UEA-S膨胀剂、MgO膨胀剂、水胶比三因素为研究对象，进行三元二次旋转正交试验，得到新型补偿收缩混凝土的配合比以及限制膨胀率最优的掺量组合。第三部分，以具体的渠道衬砌板实例为研究对象，以无缝设计理论为基础，因地制宜，制定出一套适合当地气候及施工条件的渠道衬砌板防渗措施。由以上思路，本文的主要研究成果是：（1）根据热传导方程及第三类边界条件，结合温度变化规律，得到渠道衬砌板在环境温度影响下的收缩机理；同理根据湿度扩散方程与边界条件，得到渠道衬砌板在环境湿度影响下的收缩机理。（2）单掺UEA-S膨胀剂在掺量为12%时最优；当UEA-S掺量定为10%时，MgO掺量3%左右最优，即两者比例为3~3.5时补偿收缩效果最好，且MgO膨胀剂对后期补偿效果明显。（3）以UEA-S掺量、MgO掺量及水胶比三因素为研究对象，进行三元二次旋转正交试验，得到各因素对补偿收缩混凝土限制膨胀率影响程度的大小依次为：UEA-S掺量＞水胶比＞MgO掺量。UEA-S与MgO掺量对限制膨胀率的影响规律均呈现出先增大后减小的趋势。通过效应分析和混凝土力学性能综合考虑，最终得到混凝土的最优配合比即三因素的最优组合为：UEA-S的掺量10%，MgO膨胀剂的掺量3%，水胶比0.55。 (4）利用无缝设计理论，由伸缩缝间距计算公式可以看出，添加膨胀剂后对混凝土的综合温差有显著的减小作用，渠道衬砌板的无缝设计需要根据具体收缩量及膨胀剂的掺量做出特定的设计施工方案。
[Abstract]:With the increasing shortage of water resources, the loss of canal leakage is too large and the effective utilization ratio of canal system water is low, which has become the key issue of farmland irrigation in China.It is one of the most important measures to use concrete lining with crack resistance and seepage resistance.In this paper, the characteristics of compensating shrinkage concrete have been studied in view of the technical problem that the cement mortar dry-shrinkage and serious water leakage of canal lining concrete, especially the precast lining channel, have been perplexing the production of irrigation area for a long time.The ratio of compensating shrinkage concrete in accordance with the requirements of channel lining is determined and a set of more accurate anti-crack and anti-seepage scheme of channel lining plate is worked out to replace the traditional mortar filling material.It is of great significance to enhance the durability of channel engineering, save water resources and improve the economy of the project.This paper is mainly divided into three parts. The first part takes the shrinkage characteristic of concrete as the research object and deduces the formula of the shrinkage of the trapezoidal channel lining plate combined with the structure and stress characteristics of the tunnel lining slab.In the second part, taking UEA-S expansion agent and water / binder ratio as the object of study, ternary quadratic rotation orthogonal test is carried out to obtain the mix ratio of new compensating shrinkage concrete and the optimal admixture combination to limit the expansion rate.The third part takes the concrete channel lining board as the research object, takes the seamless design theory as the foundation, according to the local conditions, formulates a set of seepage prevention measures suitable for the local climate and construction conditions.Based on the above ideas, the main research results of this paper are as follows:1) according to the heat conduction equation and the boundary conditions of the third type, combining with the law of temperature change, the shrinkage mechanism of the channel lining plate under the influence of ambient temperature is obtained, and the same principle is obtained according to the humidity diffusion equation and boundary conditions.The shrinkage mechanism of channel lining is obtained under the influence of environmental humidity.(2) when the amount of UEA-S expander is 12, the UEA-S content is about 3%, that is, when the ratio of the two is 3 ~ 3.5, the effect of compensating shrinkage is the best, and the effect of MgO expander is obvious in the later period.(3) taking the three factors of UEA-S content and water / binder ratio as the object of study, the ternary quadratic rotation orthogonal test was carried out.The results show that the influence of different factors on the limited expansion ratio of concrete with compensating shrinkage is in the order of: UEA-S content > water-binder ratio > MgO content. UEA-S and MgO content have a tendency of increasing first and then decreasing.Through the analysis of the effects and the comprehensive consideration of the mechanical properties of concrete, the optimal mix ratio of concrete is obtained, that is, the optimal combination of three factors is the proportion of 10% UEA-S and the amount of MgO expansion agent, and the ratio of water to binder is 0.55.4) by using the theory of seamless design, it can be seen from the formula of expansion joint spacing that the comprehensive temperature difference of concrete can be significantly reduced by adding expansion agent.The seamless design of channel lining need to make a specific design and construction scheme according to the specific shrinkage and expansion agent content.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV544

【共引文献】