装配式地铁车站结构接缝防水关键技术研究与应用

Research and Application of Key Technology of Joint Waterproofing for Prefabricated Metro Station Structures

装配式地铁车站结构的接缝防水性能一直备受行业的关注,针对装配式车站的结构构造、构件制作及施工工艺等特点,对与接缝防水性能高度相关的“接缝张开量”和“密封垫错位量”两个关键参数的主要影响因素和控制指标进行分析,结合密封垫防水性能试验研究及实际工程应用监测结果,充分论证接头接缝“两垫+一注+一嵌”多道防线的关键技术。双道密封垫以三元乙丙橡胶(EPDM)弹性密封垫作为主防水,复合遇水膨胀橡胶作为加强防水,形成复合式多孔多槽形密封垫,密封垫为接缝防水主要防线,注浆和嵌缝为辅助防线。研究和实际应用表明,装配式车站结构的接缝防水,不仅在防水构造措施方面与盾构隧道不同,而且在各项控制标准方面也存在较大差异,张开量10 mm、错位量5 mm是装配式车站结构接缝防水性能控制的合理指标;单道防水密封垫,在张开量10 mm、错位量5 mm的情况下,能抵抗水压力1.0 MPa,满足埋深30 m车站结构抵抗2~3倍水头压力的性能要求,并在使用100年后,仍存在约67%的残余应力值,具有长期耐水压性能;双道防水密封垫,较单道密封垫防水性能提高有限,提高率在20%~30%之间,但在衬砌外道密封垫出现局部漏水时,双道密封垫的优势显著;从接缝合理张拉锁紧荷载的角度考虑,三元乙丙橡胶密封垫的硬度需要较常规盾构隧道密封垫降低5 SHA,即采用60 SHA,其单位长度完全压缩荷载指标不大于40 kN/m。目前已建和在建车站工程,实测结构接缝最大张开量和表面最大错台量均满足接缝防水性能控制标准的要求,在未设置外包防水层的情况下,接缝无渗漏水现象发生。

The joint waterproof performance of prefabricated metro station structures has received significant attention from the industry.In view of the structure characteristics,component manufacturing,and construction technology of prefabricated station structures,this study analyzes the main influence factors and control indexes of the two key parameters of“joint gap”and“gasket offset”that are highly related to joint waterproof performance.Experimental research and actual engineering applications have demonstrated the excellent performance of the multiple waterproof lines method of“two gaskets+one injection+one embedding”of joint seams.The two gaskets use an ethylene-propylene terpolymer(EPDM)elastic sealing gasket as the main waterproof material and a composite water-swelling rubber as reinforced waterproofing to form a composite multi-grooved porous sealing gasket.The sealing gasket is the main defense line of the joint waterproof line,and the auxiliary defense lines are the grouting and caulking lines.Research and practical applications have shown that the joint waterproofing of prefabricated station structures is different from that of shield tunnels,not only in terms of waterproof structural measures but also in various control standards.A gap of 10 mm and an offset of 5 mm are reasonable indicators for the joint waterproof performance control of prefabricated station structures.A single waterproof sealing gasket can resist a water pressure of 1.0 MPa under a 10-mm gap and 5-mm offset and meet the performance requirements of a station structure with a buried depth of 30 m to resist 2–3 times the head pressure.After 100 years of use,it still has an approximately 67%residual stress value and high long-term water pressure resistance performance.Double seal gaskets provide limited improvement in waterproof performance compared to that of a single sealing gasket with an improvement rate of 20%–30%.However,when a local water leakage exists in the outer sealing gasket of a lining,double-sealing gaskets have significant advantages.With a reasonable joint tensile load,the hardness of an EPDM rubber gasket needs to be reduced by 5SHA compared with that of a conventional shield tunnel,i.e.,60SHA is adopted,and the complete compression load index per unit length is less than 40 kN/m.According to existing and under-construction projects,the maximum measured gap of a joint for a station structure and the maximum offset of the surface satisfy the requirements of the joint waterproof performance control standard.In the case with no external waterproof layer,no leakage occurred at the joint.