水泥改良土地层联络通道冻结温度场分析

Analysis of freezing temperature field in connecting passage of cement improved soil layer

地铁工程联络通道施工中,人工冻结加固土层的温度场研究目前大部分还是集中在天然土层方面,对水泥改良土地层中冻结温度场的发展与特性研究较少。文章系统研究水泥改良对联络通道地层冻结温度场的影响,建立联络通道冻结开挖三维数值模型,考虑导热系数、比热容、相变潜热等影响因素,综合实测数据以及试验,对天然土层以及水泥改良土层中冻结温度场的发展和分布规律进行分析,研究结果表明:相比于天然淤泥质土地层,水泥改良土冻结温度场发展速度更快,但冻结效应稍差,积极冻结期的前33d,冻结温度场发展较为迅速,相邻冻结锋面相交后,温度场发展速度开始下降。水泥改良后,土层冻结温度场的发展对导热系数的变化最为敏感,比热容的变化次之,相变潜热变化的影响十分微小。研究成果表明:人工冻结配合水泥改良对淤泥质土地层具有显著的加固效果。

In the construction of connecting passages in subway projects,most of the researches on the temperature field of artificially frozen soil layers are currently concentrated on the natural soil layer,while less attention is paid to the development and characteristics of the frozen temperature field in the cement-improved soil layer.This paper systematically studies the effect of cement improvement on the freezing temperature field of the connecting passage,and a three-dimensional numerical model of the freezing excavation of the connecting passage is established.Considering the thermal conductivity,specific heat capacity,latent heat of phase change and other influencing factors,comprehensively measured data and experiments,the development and distribution of the freezing temperature field in natural soil layers and cement-improved soil layers is analyzed.The research results indicates that compared with the natural silty soil layer,the cement-modified soil has faster development of freezing temperature field and weaker freezing effect.In the first 33 days of the active freezing period,the freezing temperature field develops fast,but develops slowly after the adjacent freezing fronts intersect.After the cement is improved,the development of the soil freezing temperature field is most sensitive to the change of thermal conductivity.The heat capacity and the latent heat of phase also have influence to some extent..The research results verify that the measurement integrating the artificial freezing combined with the cement improvement has a significant reinforcement effect on the silty soil layer.