富水地层地铁明挖结构抗浮破坏模式研究

不同地层结构的抗浮设计存在很大区别,位于富水地层中的地铁车站,结构抗浮问题尤为突出。以厦门地铁典型车站为研究对象,采用室内模型试验与ABAQUS有限元模拟相结合的方法,研究地铁车站位于富水地层中的抗浮破坏模式,并提出抗浮措施。结果表明:富水地层中的地铁车站抗浮破坏模式为整体抗浮失效,由于车站侧壁摩阻力作用,结构并非突然浮起,而是整体上浮位移增长速率加快,破坏时板柱节点处的应变较底板其他部位偏大;上浮破坏时底板处孔隙水压力变化趋势与水体水压一致,由于渗流损失,底板处孔隙水压力需折减,折减系数约为0.79~0.85;抗浮设计时可考虑利用围护结构,改变渗流路径,增大水头折减。

Study on Anti-floating Failure Mode of Subway Open-Cut Structure in Water-Rich Stratum

The anti-floating design of different stratum structures varies greatly. Anti-floating problems of subway stations in water-rich stratum should arouse people's attention. The anti-floating failure mode of the subway station in a water-rich stratum is obtained by combining the indoor model test with ABAQUS finite element simulation, and specific anti-floating measures are suggested based on the findings. The typical Xiamen urban rail transit station is used as the research object. The results show that the overall anti-floating failure mechanism of the subway station situated in a water-rich stratum is caused by friction on the sidewall of the station. The floating displacement growth rate is accelerating, yet the structure is not suddenly floating. The strain at the floor and column joint is larger than other parts of the floor. The trend of pore water pressure at the soil under the bottom floor is consistent with the water pressure after the station structure floats. The pore water pressure at the soil under the bottom floor needs to be reduced, and the reduction coefficient is about 0.79-0.85. In the anti-floating design, it should be considered to set up retaining structures such as continuous underground walls to change the seepage path and increase the head loss.