地铁联络通道冻结法施工土体含水量对地表变形影响的试验研究

Study on the Influence of Soil Moisture Content on Surface Deformation During the Construction of Subway Connecting Passage by Freezing Method

为探究地铁联络通道冻结法施工土体含水量对地表变形的影响,基于冻结法施工地表变形模拟试验,总结了土体冻融过程中的地表变形规律,并结合土体含水量试验,分析了不同土体含水量下冻结法施工中地表变形的响应特性。试验结果表明:①在土体冻胀、融沉影响范围内,地表不同位置的冻胀结束时间基本相同,但融沉结束时间存在差异;②冻结管布置圈中心的地表冻胀位移和融沉位移均比两侧大,且地表平均冻胀速率也比两侧大,但地表不同位置的平均融沉速率存在差异;③土体的冻胀与融沉并非互逆过程,地表融沉位移通常大于对应的地表冻胀位移,且冻胀位移量越大,融沉位移超出冻胀位移的比例越高;④土体含水量越高,地表冻胀、融沉位移量越大,冻结期间地表的平均冻胀速率随土体含水量的升高而增大。

In order to explore the influence of soil moisture content on surface deformation of the subway connecting passage by freezing construction method,based on the simulation test of ground deformation,the law of surface deformation during the freezing and thawing process of soil mass was summarized.Combined with soil moisture content test,the response characteristics of surface deformation are analyzed with different soil moisture content.The results show that the end time of frost heaving at different locations on the surface is basically the same within the influence range of soil frost heaving and thawing settlement.But the end time of thawing settlement is different;The surface frost heave displacement and thaw settlement displacement at the center of the freezing pipe layout circle are larger than those at both sides.The average ground frost heave rate is also larger than those at both sides.But the average ground thaw settlement rate is different;The frost heave and thaw settlement of soil mass are not reciprocal processes.The surface thaw settlement displacement is usually greater than the corresponding surface frost heave displacement.The larger the frost heave displacement is,the higher the excess ratio is;The higher the soil moisture content,the greater the frost heave and thaw settlement displacement of the surface.During the freezing period,the average frost heave rate of the surface increases with the increase of the soil moisture content.