复合衬砌结构的预应力混凝土配比试验研究北大核心CSCD

为了解决高内压复合衬砌内衬混凝土浇筑易出现顶拱脱空、密集区浇筑不密实等施工难点,本文针对三种不同配合比预应力混凝土在双层钢绞线衬砌结构中的应用,开展洞外地面足尺模型试验研究。采用一种适用于监测顶拱脱空的装置以控制混凝土浇筑质量,对不同配合比的混凝土在双层预应力筋束衬砌结构中的浇筑效果进行对比分析。研究表明:将普通混凝土的骨料从二级配改为一级配,并采用合理的振捣工艺,可取得较好的浇筑效果;自密实混凝土可改善顶拱脱空和提高浇筑质量,但需控制材料收缩和徐变变形,并做好温控措施;混凝土在8~10天后温度趋于平缓,建议钢绞线张拉时混凝土养护时间不宜少于14天。

Experimental study on prestressed concrete mix proportions for composite lining structure

To solve the concrete pouring difficulties in the construction of a composite lining under high internal pressure, such as the void forming in the vault and low pouring compactness in dense areas, this study conducts full-scale model tests for application of three different mix proportions of prestressed concrete in a double-layered steel strands lining structure. Concrete pouring quality is controlled by a device suitable for monitoring the voids in the vault, and pouring effects of different mix proportions are compared and analyzed. The results show that (1) better pouring effect is obtained by changing the aggregate of ordinary concrete from two-graded to one-graded and adopting a reasonable vibrating technology. (2) Self-compacting concrete can reduce the voids in the vault and improve pouring quality, but it needs to control material shrinkage and creep deformation and take certain temperature control measures. (3) The temperature of concrete flattens out in 8 - 10 days. This study recommends that in the case of the steel strands under tension, the curing should not be less than 14 days.