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压力对冻土孔隙特征及冷生组构的形成具有重要影响,多向均匀加压(气压)和单向加压有侧限的方式对孔隙变化的影响截然不同。负温相同时,冻土中总孔隙体积和大孔径的数量在大气压环境下最小最少,在小于大气压的环境下(真空)最大最多,在高于大气的环境下随气压增高而增大增多,冻土构造从网状向多枝状过渡,试样边缘部位孔隙变化比中心部位大,压力梯度是制约孔隙变化的致导因素。气压相同时,冻土中总孔隙特征随负温降低而增大,冻土构造中的网格从大变小,从粗变细,这时冻胀是制约孔隙变化的致导因素。单向加压正冻土中由于水分迁移、冰分凝和冻胀,总孔隙体积随土柱剖面变化,但与冻前相比均减小且从层状构造向网状过渡。
Pressure has an important influence on the pore characteristics of frozen soil and the formation of cold-forming fabrics. The effect of multi-directional uniform pressure (pressure) and unidirectional pressurization with confinement on the pore change is quite different. When the negative temperature is the same, the total pore volume and the number of large pores in the frozen soil are the least under the atmospheric pressure environment, the largest under the atmospheric pressure (vacuum) environment, and increase with the increase of the atmospheric pressure under the atmosphere. The permafrost structure transitions from a net shape to a multi-branched shape. The change in pores at the edge of the sample is larger than the center, and the pressure gradient is the leading factor that restricts the change of pores. When the air pressure is the same, the total porosity in the frozen soil increases with the decrease of the negative temperature, and the grid in the frozen soil structure decreases from large to coarse, and frost heaving is the leading factor that restricts the pore change. In the unidirectional pressurized frozen soils, the total pore volume changes with the soil column profile due to moisture migration, ice segregation, and frost heave, but decreases compared with that before freezing, and transitions from layered structure to mesh.