冻结法施工中的冻土特性试验研究

Experimental analysis on frozen soils behavior in freezing method construction

为获得冻结法施工中土体冻胀融沉特性规律,以某地下联络通道工程为原型,根据相似理论,进行了水平冻结模型试验。结果表明,冻胀融沉过程中,土体温度先迅速降低后升高,维持在0℃一段时间后,继续缓慢升高至室温;土压力值先增加后减小,其中,竖向土压力值随深度的增加而增大,相同埋深下,距冻结管越近,水平土压力值越大;土体融化固结沉降值明显大于冻胀位移值,土体竖向位移较水平位移变化显著。积极冻结期内土体温度降低速率变慢,且埋深越大、距冻结孔越近,土体温度降低越快、降幅越大;无侧限土体压力值先增加后减小,侧限土体压力值则逐渐增大,全封闭土压力值变化率更显著。

In order to obtain frost heave and thawing settlement of frozen soils behavior,an underground connected aisle was studied through the model test based on similarity theory.The results indicate that,the soil temperature firstly decreases rapidly,then increases and maintains 0 ℃ for a while,at last continues to slowly rise to room temperature in the whole process.The soil pressure value goes up firstly and then goes down,and that of vertical pressure increases exponentially with the increasing of depth,meanwhile the distance from the freezing tube is more closer,the horizontal pressure is more bigger.Contrast with frost heave displacement,the thawing settlement value is greater,and the vertical displacement is more significant than the horizontal as well.In positive frozen period,the temperature reducing rate becomes slower,the greater depth and closer distance from the freezing hole,the greater decline speed and amplitude come up.Unlike vertical restriction soil always increases,the soil pressure value of unlimited presents a first increasing and then decreasing trend,while the variable rate is bigger with complete restriction situation.