富水砂层地铁隧道盾构掘进过程中，盾构中心回转体出现机械故障，为给开舱检修提供安全的作业环境，提出一种盾构开挖面垂直冻结联合洞内水平冻结的方法，并详细介绍冻结帷幕设计及强度验算、冻结孔及测温孔的布置、冻结施工工艺等；
结合现场测试，详细讨论温度场、土舱内冻胀力的发展过程。结果表明： 1）积极冻结期间各垂直测温孔温度下降趋势大致相同，但不同区域冻土温度下降速率有明显差异，冻结管排内冻土受叠加冷却效应，冻土发展速率是管排外的2.8倍； 2）盾构散热对周围土体降温有显著影响，需加强保温措施，防止冷量的损失； 3）水平冻结管受盾构结构限制，布置数量少且间距大，水平冻结壁的发展速度要小于垂直冻结壁； 4）土舱内测点温度与入土深度呈线性关系，入土深度越大的测温点受土舱面板散热影响越小，降温速率越快。
During shield tunneling process of a metro tunnel in
water-rich sandy layer, rotating
body of the shield central body mechanically malfunctioned, thus a safe
operating environment should be provided for shield chamber opening and
repairing. Herein, a combined vertical excavation face freezing and in-tunnel horizontal freezing method is proposed. Additionally, the
design and strength recalculation of freezing curtain, layout of freezing and
temperature holes, and freezing construction are elaborated. Finally, based on
field tests, the development processes of the temperature field and the frost
heave force in soil chamber are discussed in detail. The results illustrate the
following: (1) Temperature drop trend of each vertical temperature hole is
almost the same during active freezing, whereas the freezing temperature drop
rates in different areas vary obviously. The freezing development rate of
frozen soil in the freezing pipe rows is 2.8 times higher than that outside the
rows due to the influence of superimposed cooling effect. (2) The heat
dissipation of the shield machine reduces the temperature of surrounding soil
body significantly, thus heat preservation measures should be strengthened. (3)
Development rate of horizontal freezing wall is slower than that of vertical
freezing wall due to less horizontal freezing pipes and large space restricted
by the shield structure. (4) The temperature of the measurement point in the
soil chamber is linearly related to depth of hole in soil. The larger the depth
of hole in soil of the measurement point, the smaller the effect of heat
dissipation of the soil chamber panel, and the faster the cooling rate.
