【作者】 宋春香；

【导师】 娄宗科；

【作者基本信息】 西北农林科技大学 ， 农业水土工程， 2007， 硕士

【摘要】 混凝土防渗是最为广泛的渠道防渗技术措施。在混凝土渠道衬砌中,裂缝是最主要的问题之一。工程实例表明,收缩往往引起裂缝,导致混凝土力学性能及抗渗性能下降,影响防渗效果,缩短渠道的使用寿命,并造成大量的经济损失。本文在分析前人关于混凝土裂缝控制成果的基础上,应用三元二次正交旋转组合设计安排实验,研究了影响混凝土膨胀率和力学特性的主要影响规律,探讨了补偿收缩混凝土在渠道防渗工程中应用的可行性和超长结构设计方法。主要研究结果如下:(1)回归出以膨胀率为因变量的三元二次回归方程,对影响补偿收缩混凝土膨胀率的因素进行主效应分析、单因子效应及两因子间交互效应分析,得出粉煤灰在本次实验中是显著因子。粉煤灰作为掺合料能减少混凝土的用水量,抑制混凝土的收缩;另外,粉煤灰在水泥浆体中由于微集料效应及火山灰反应生成大量水化C-S-H凝胶,填充了孔隙,相应补偿了部分干缩。(2)在补偿收缩混凝土中,膨胀剂通过与水泥的水化、硬化过程中产生大量的钙矾石晶体,这些晶体能吸水膨胀,从而使混凝土产生膨胀。只有膨胀剂在合适的掺量时,就能达到最好的补偿收缩的功效。(3)水灰比与混凝土膨胀之间的关系比较复杂,水灰比不仅影响膨胀剂的水化过程,而且影响混凝土强度的发展。综合比较得出本实验中的最优膨胀剂掺量、粉煤灰掺量及水灰比为:膨胀剂掺量为10%,粉煤灰掺量为40%,水灰比为0.4。(4)针对渠道少留伸缩缝,但又要控制混凝土裂缝等问题的实际情况,本文从膨胀混凝土的补偿收缩原理出发,论述了无缝设计的含义及其理论依据,提出了膨胀带的设置方法及构造措施,用膨胀混凝土与普通混凝土交错、连续浇注的方式代替传统只用伸缩缝的方法,达到无缝超长结构设计和伸缩缝联合补偿渠道收缩应力的目的。最终提出设置膨胀带的原则和数量及伸缩缝的合理间距。更多还原

【Abstract】 The concrete in seepage control of irrigation canal is one of the most widely used technologies. The uppermost problem is the crack in canal lining concrete. Many examples of engineering project indicate that, the cracks which caused concrete shrinkage will decrease the mechanical performance of concrete, affect the using life and water-tight and water conservation of canal. At the same time, the crack will cause the economic lost. The thesis analyzed the research result of predecessor,made use of the second-degree polynomial regression analysis and orthogonal rotation design to arrange the experiment, researched The law of influence of concrete on expansion ratio and mechanical property, discussed the application feasibility of shrinkage compensating concrete and design of super-long reinforced concrete structure for impervious channels. Main results are as follows:(1)The thesis analysis the main effect、single factor effect and the interaction effect of each factor .Fly-ash was the remarkable factors,It as mixture in concrete can decrcase the water quantity, suppress the concrete shrinkage. At the time, the pozzolanic effect of fly-ash could make C-S-H sol-gels which could fill the pore structure. So fly-ash could compensate the concrete shrinkage.(2)The crystal of ettringite is the product of expansive agent and cement hydrated and consolidated in compensation shrinkage concrete project. As a result these water-absorption crystals will cause the concrete micro-expansive. The compensation shrinkage of concrete has the best effcet , which the admixture of expansive agent is appropriate.(3)The relationship between water-cement ratio and expansive of the concrete is rather complicated. Water-cement ratio could affect the hydration process and strength devlopment of concrete. The experiment results indicated that, an addition of 10% expansive agent, 40% fly-ash and water cement ratio 0.4, is the optimum admixture.(4)We had to solve the problem of concrete shrinkage and have few post-poured strip of concrete canal. The no-seam design and construction of super-length concrete structure is a new-typed of design and construction method. The article stated the principe of compensated shrinkage concrete, discused the theoretical and meaning of no-seam design and construction of super-length concrete structure; proposed the designing methods of expansive belt and tectonic measures. We could use super-long structure’s joint less design and expansion joint to achieve the stress compensation. Finally,the thesis proposes the principles of installing expansive belt and widening spacing of expansion joint.更多还原