一、砼自流对泵送施工的影响泵送砼施工时,在倾斜或垂直管道中的新拌砼,即使没有其他外力作用,也可能因自重而流动,即发生自流。自流现象对于砼泵送有重要影响。在向高处输送时,输送管的倾斜若超过了自流角度(见表1和图1),升高段管道中的砼的重力会作用到砼泵的分配阀上,如分配阀密封不良,处于阀的压送侧的砼中的灰浆会被挤向阀的吸入侧,造成管道中的砼析水,流动度降低。这种情况在连续泵送时不明显,当泵送中止时,输送管中的水份和灰 I. Influence of the self-flow on the pumping construction When the pumping concrete is being used, new concrete in the inclined or vertical pipeline may flow due to its own weight even if there is no other external force, ie, self-flow occurs. The phenomenon of self-flow has a significant influence on pumping. When transporting to a high place, if the inclination of the conveying pipe exceeds the free flow angle (see Table 1 and Figure 1), the gravity of the crucible in the riser pipe will act on the distribution valve of the crucible pump. If the distribution valve is poorly sealed, The grout in the crucible on the pressure-feed side of the valve is squeezed toward the suction side of the valve, causing decanted water in the pipeline, and the fluidity is reduced. This condition is not noticeable when pumping continuously, when the pump is suspended, the moisture and ash in the pipe