Abstract:

In order to solve the problems in the construction with cutandcover topdown method, i.e. deviation and breakage of the embedded connector for underground diaphragm wall; poor appearance quality of concrete when the construction board adopts ground formwork; uncontrollable quality of concrete when the sidewall adopts full formwork support or inclined bracing frame; uncompacted concrete pouring when waterproof treatment of horizontal construction joint is not enough and easy water leakage of sidewall induced by premature formwork dismantling not enough thermal insulation and moisture holding up. The key technological improvements in the construction of Xiangxicun Station on Shenzhen Metro Line 9 are discussed. Some conclusions are drawn as follows: (1) The usage of connector has been effectively improved by using angle steel and cover plate to accurately locate and protect the embedded connector for underground diaphragm wall. (2) The concrete has a good appearance quality when the structural template adopts short bracket system. (3) The construction is convenient and the concrete pouring quality can be guaranteed when the sidewall adopts movable unilateral formwork system. (4) The waterproof effect of joints can be improved by improving treating method for joints between sidewall and roof. (5) The concrete curing condition and waterproof quality of sidewall can be effectively guaranteed by adopting doubledeck formwork curing system.

Key words: metro station, cut and cover topdown method, connector positioning and protection, short bracket, movable unilateral formwork, doubledeck formwork curing, waterproof treatment of horizontal construction joint