城市盾构隧道水平冻结地层加固的数值分析

Numerical Analysis on theHorizontal Ground Freeing Reinforcement inCity Shield Tunnel

冻结地层加固法是一种环境影响小、加固效果好的地层加固方法，人工冻结壁的形成是一个复杂的热-力耦合问题。依托实际盾构隧道始发施工中冻结加固工程，采用有限差分软件Flac3D建立数值模型分析了地铁隧道水平冻结施工中温度场随时间的发展和分布特征，同时采用准热-力耦合的方法，分析了冻结施工中地表冻胀隆起变形规律。分析结果表明：冻结壁模拟交圈时间和设计交圈时间基本一致；冻结壁交圈前，地表冻胀隆起位移速率快，冻结壁交圈之后，地表冻胀变形逐渐趋近稳定。计算结论可供设计和施工参考，提供了一种简便的人工冻结加固施工的数值模拟方法。

Soil frozenreinforcementmethod, which has the advantage of little impact on the environment, is a good approach to reinforce ground. The formation of frozen wall is a complicated issue involving the thermal-solid coupling field. Based on the practical frozen project in shield tunnel originating construction, this paper analysis the development and distribution of artificially frozen wall with time by using the finite difference software of Flac3D. Furthermore, the frost heave of ground surface has been researched in this paper. Research found that： The overlap time of freezing wall is consistent with the design time; Before the overlap of freezing wall, the deformation rate of frost heave is fast, however, after the overlap of freezing wall, the deformation of frost heave gradually become stable. The eonclusioncan provide a reference for design and construction, it also provides a simple method to analysis the artificial freezing construction by the way of numerical simulation.