冻结水泥土搅拌桩温度场数值分析

Numerical Analysis of Temperature Field in Frozen Ground Improved by Deep Cement Mixing

为解决现有人工冻结法施工后周围地层产生冻胀融沉所引发不良后果的问题,冻结水泥土搅拌桩应运而生。在对冻结水泥土搅拌桩的施工工艺简单介绍的基础上,运用有限元软件对工字形冻结管单管冻结时水泥土的温度场发展规律进行研究。主要得出:冻结水泥土搅拌桩在保证地层承载力和防水性能的基础上,既可提高水泥土搅拌桩的抗剪和抗弯能力,也可减少水泥用量;冻结20 d时,-10℃冻土帷幕水平方向半径发展到120 mm,40 d时发展到180 mm;工字形冻结管所形成的冻土帷幕呈椭圆形分布向外发展,竖直方向发展较快;路径3上冻结初期靠近翼缘的分析点降温较快,冻结后期各点温度趋于一致。所得结果可为今后类似工程设计提供理论参考依据。

In order to mitigate the excessive ground movement caused by the melting of frozen ground,the freezing ground method and deep cement mixing method can be used together. In this paper,the construction procedures of freezing ground method together with deep cement mixing method were introduced. The temperature field formed by the I-shaped freezing pipes was simulated by finite element analysis with consideration of deep cement mixing. It has been found that the freezing ground method together with deep cement mixing method can enhance bearing capacity and lower the permeability of cement-admixed soils. The shear strength and stiffness were also found to be enhanced for this kind of ground,and also the cement content can reduce. For 20 days of freezing,the freezing curtain can reach 120 mm in the horizontal direction of the- 10° C curve,and reach 180 mm for 40 days of freezing. The shape of freezing curtain was ellipse around the I-shaped freezing pipes and the develop rate along the depth direction was relatively faster. The recording points located at the edge of the pipe had higher temperature decline rate than the others. All recording points had approximately temperature changing trend at the end of freezing process. The analysis results obtained in this study may be of use in design in similar projects.