冻融循环对土结构性影响的试验研究及影响机制分析

基于室内试验，研究了土颗粒与土孔隙在冻融循环过程中的变化情况，发现在反复冻融过程中，土样产生了颗粒破碎，从而导致土的液塑限、塑性指数、比表面积均有所增大。通过压汞试验，发现冻融循环还会使土样中的大、中孔隙含量总体增加，小孔隙的含量减少，而微孔隙的含量基本保持不变。在经历了15次冻融循环后，颗粒组成、孔隙分布及比表面积等均趋于稳定。通过分析土的三相组成在水分相变和迁移过程中的相互影响和作用，认为土的三相组成是冻融过程中水分相变和迁移的基础，冻融过程中水分相变、冰晶生长和水分迁移对土颗粒和孔隙的反作用力，是冻融循环对土结构性影响的根本原因。

Impact of freezing and thawing cycles on structure of soils and its mechanism analysis by laboratory testing

A series of laboratory experiments is conducted to study the changes in soil particles and pores under freezing and thawing cycles. The results show that during cyclic freezing-thawing processes, grain breakages occur within the soil particles, leading to a progressive increase in plastic limit, plasticity index and specific surface area of the soil. Meanwhile, the pore size distribution, tested by mercury intrusion porosimetry (MIP), is also changed in the processes as macro pores increase, small pores reduce and micro pores almost remain unchanged. All the structural indexes, including particle composition, pore distribution specific surface area, tend towards stable after 15 freezing and thawing cycles. The intrinsic influence of soil’s three-phase components during freezing and thawing cycles is discussed; and it is considered as the fundamentals of the water phase change and moisture migration among soil particles. Correspondingly, the reaction of water phase change and migration on soil particles and pores is considered to be the primary cause of the change of soil structures.