双向冻结-单向融化土压缩性及水分迁移试验研究

通过室内冻融试验,研究双向冻结-单向融化作用下不同冻前含水率和干密度对青藏粉黏土压缩特性的影响及水分迁移的变化规律。试验结果表明:(1)大梯度冻融作用使低密度土压缩性减小,使高密度土压缩性增大;而小梯度冻融作用使低、高密度土的压缩性均减小;(2)随着冻前含水率的增加,大梯度冻融作用使土体压缩性增大,但变化幅度逐渐减小,小梯度冻融作用的土体压缩性变化并不明显;(3)随着冻结梯度的增加,不同干密度融土相对压缩系数均呈现先减小后增加的变化趋势,不同冻前含水率融土相对压缩系数总体呈增大趋势;(4)温度梯度冻结后,试样含水率分布从上冷端到下冷端呈增大-减小-增大的变化规律,随着冻结温度梯度的减小,试样中部含水率先增大后减小。

Experimental study of the water migration and compression of soils under double direction freezing-one direction thawing

The freezing-thawing experiments were performed to investigate the effect of pre-freezing moisture content and dry density on the compression and water migration in Qinghai-Tibet silty clay under double-direction freezing and one-direction thawing. The results show that (1) under large thermal gradients, the compressibility of the soil decreases at low initial densities and increases at high initial densities after freeze-thaw cycles, whereas under small thermal gradients, the soil compressibility constantly decreases; (2) As the pre-freezing moisture content increases, the soil compressibility under larger thermal gradients increases and approaches to a stable value, whereas it remains practically unchanged under small thermal gradients; (3) As the thermal gradient increases, all the compressibility coefficients of melted soils at different densities decrease first, and then increase, and the compressibility coefficients of melted soils under different pre-freezing water contents increase; (4) The water contents in the frozen specimen first increase, then decrease and finally increase from the top to the bottom. As the thermal gradient descends, the water content in the middle part of the specimen increases first and then decreases.