Frost heave experiments on saturated sandstone and tuff with an open crack are conducted under uniform and unidirectional freezing conditions. Frost heave of crack in sandstone with high permeability is more significant under uniform freezing condition than that under unidirectional freezing condition. However, frost heave of crack in tuff with low permeability is more significant under unidirectional freezing condition. To illustrate the reasons for this phenomenon, a numerical model on the freezing processes of saturated rock with an open crack considering the latent heat of pore water and water in crack is proposed and confirmed to be reliable. Numerical results show that a frozen shell that blocks the migration of water in crack to rock develops first in the outer part of the rock before the freezing of water in crack under uniform freezing condition. However, the migration path of water in crack to the unfrozen rock under freezing front exists under unidirectional freezing condition. The freezing process and permeability of rock together determine the migration of water in crack and lead to the different frost heave modes of crack for various permeable rocks under different freezing conditions. The frost heave modes of crack in rock with low or high permeability are similar under uniform freezing condition because water migration is blocked by a frozen shell and is irrelevant to rock permeability. For high permeability rock, the frost heave of crack will be weakened due to water migration under unidirectional freezing condition; however, the frost heave of crack would be more significant for low permeability rock because water migration is blocked under unidirectional freezing condition. Therefore, the freezing condition and rock permeability determine the frost heave of rock with crack together, and this should be concerned in cold regions engineering applications.

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不同冻结条件下含开裂饱和岩石的冻胀和冻结过程

在均匀和单向冻结条件下对饱和砂岩和凝灰岩的开裂冻胀试验进行了研究。在均匀冻结条件下，高渗透率砂岩裂缝的冻胀比在单向冻结条件下更为明显。但是，在单向冻结条件下，低渗透性凝灰岩中裂纹的冻胀更为明显。为了说明这种现象的原因，提出了考虑孔隙水潜热和裂缝中水的潜热的开裂饱和岩石冻结过程的数值模型，并被证明是可靠的。数值结果表明，在均匀冻结条件下，在裂缝中冻结水之前，先在岩石的外部首先形成阻止裂缝中水向岩石迁移的冻结壳。但是，在单向冻结条件下，冻结前裂缝中的水向未冻结岩石的迁移路径存在。岩石的冻结过程和渗透率共同决定了裂缝中水的运移，并导致了不同冻结条件下各种渗透性岩石的裂缝冻胀模式不同。在均匀冻结条件下，低渗透率或高渗透率岩石的裂纹冻胀模式相似，这是因为水的运移受冻结壳的阻碍，与岩石渗透率无关。对于高渗透率的岩石，在单向冻结条件下，水分的迁移会削弱裂纹的冻胀力。然而，对于低渗透率岩石，裂纹的冻胀将更为显着，因为在单向冻结条件下水的迁移受到了阻碍。因此，冻结条件和岩石渗透率共同决定了带有裂纹的岩石的冻胀，这在寒冷地区的工程应用中应予以关注。