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三峡大坝的混凝土施工引用美国产的塔式皮带布料机,该设备采用软管溜筒垂直运输混凝土,利用软管溜筒与混凝土的相互作用来限制混凝土的流动速度,这种浇筑方式的主要特点是:限制混凝土的终端速度、布料范围广、经济快速,受到工程设计施工人员的重视。针对这种施工方法,以分析混凝土的流动为主,考虑溜管中混凝土与管壁的相互作用,混凝土自身特性,混凝土之间的相互作用,运用欧拉法建立了在重力作用下混凝土在溜管中流变的三维、二维、一维数学模型。三维模型和二维模型较完善,但由于边界条件和初值难以给定,求解困难。一维模型比较简单,容易求解,因此,本文用一维模型对三峡中使用的软管溜筒中混凝土的流变进行求证。结果表明,如果软管溜筒小于8m,混凝土的速度梯度很小,所受的剪应力很小,重力起主要作用,所以采用软管溜筒和让混凝土在自由落体下运动的效果几乎是一样的。如果软管溜筒大于8m,混凝土在软管内下落到8m后速度梯度逐渐增大,剪应力增大,将使混凝土的下落速度减缓。因此,采用软管溜筒能很好地遏止混凝土的下落速度,防止分离。
The concrete construction of the Three Gorges Dam refers to the towering belt conveyor manufactured in the United States. The equipment uses vertical hose for conveying concrete and uses the interaction between the hose and the concrete to limit the flow rate of concrete. The main method of pouring Characteristics are: to limit the terminal speed of concrete, fabric a wide range of rapid economic, engineering design and construction by the emphasis. In view of this kind of construction method, the concrete flow is mainly analyzed. Considering the interaction between the concrete and the pipe wall in the slide pipe, the characteristics of the concrete and the interaction between the concrete, the Euler method is used to establish the concrete under the action of gravity Tube in the three-dimensional, two-dimensional, one-dimensional mathematical model. Three-dimensional model and two-dimensional model are more perfect, but because of the boundary conditions and the initial value is difficult to give, difficult to solve. The one-dimensional model is relatively simple and easy to solve. Therefore, a one-dimensional model is used to verify the rheological behavior of the concrete used in the three-gorge flexible tube. The results show that if the hose is less than 8m, the velocity gradient of the concrete is very small, the shear stress suffered is very small and the gravity plays a major role. Therefore, the effect of using the hose roller and letting the concrete move under free fall is almost the same of. If the hose chute is greater than 8m, the velocity gradient of the concrete gradually increases within 8m of the hose and the shear stress will increase, which will slow down the concrete drop. Therefore, the use of hose slide tube can well stop the concrete falling speed, to prevent separation.