和若铁路桥墩装配式连接工艺研究

Modular Construction Techniques for Piers of Bridges on Hetian-Ruoqiang Railway

和若铁路属于极度干旱地区铁路,线路全长825 km,桥梁全长84 km,32 m及以下简支T梁占95%以上,采用4种低高度双圆柱空心墩(墩高H≤8 m、H=10 m、H=12 m、H=15 m)。桥址处降雨量小、蒸发量大,桥墩类型少且为低高度墩,桥墩与承台、盖梁结构适合采用装配式连接工艺。为选择合适的桥墩装配式连接工艺,进行了8 m、12 m、15 m高的墩柱与盖梁预制,以及墩柱与承台、盖梁装配式连接工艺试验研究。结果表明:采用台座上立式浇筑法预制桥墩和预制矩形盖梁连接工艺满足设计要求;桥墩与承台和盖梁连接采用灌浆套筒连接、插槽式现浇混凝土连接和ZSM自锚式预应力连接工艺均满足设计要求,预应力连接方式最符合装配式快速施工要求;对预应力连接方式进一步优化,全线桥墩使用P锚预应力装配式连接工艺。

The Hetian-Ruoqiang Railway,located in the hyper-arid region with light precipitation and intense evaporation,has a total length of 825 km,with 84 km carried by bridges.Of these bridges,the simply-supported T beam bridges with spans equal to or less than 32 m account for 95%.The piers are all twin-hollow-column piers with four heights(H≤8 m,H=10 m,H=12 m and H=15 m).Given the environmental condition at the bridge site and sizes of the piers,modular construction was implemented for the piers,pile caps and cap beams.To find out proper modular connection techniques for the piers,experimental studies were conducted to examine the feasibility of the prefabrication of the columns(8 m,12 m and 15 m in height)and cap beams as well as the modular assembly of the pier columns,pile caps and cap beams.The results demonstrated that casting piers and rectangular cap beams in vertical position on the molding bed could meet the design requirements.The piers could be connected with the pile caps and cap beams via grouted sleeves,cast-in-situ pocket connection and ZSM self-anchored prestressing tendons,and the connection realized by prestressing tendons was considered the best option.And after optimization,the P-anchor prestressing tendon connection was employed for all the piers along the railway.