摘要
通过恒温条件下粗颗粒土盐胀试验 ,对粗颗粒土盐胀特性进行了分析和讨论 ,试验结果表明 ,粗颗粒土不具有强烈盐胀特性 .然而 ,粗颗粒土体一旦形成硫酸钠盐聚集层后 ,遇外来水分 ,会发生突发的破坏性盐胀 ,造成建筑物的破坏 .
Soils with Na\-2SO\-4 are one of the special soils in salinized soil regions, from which engineering always suffers. Salt ions in the soils are partly released and crystallized, and migrated from warm section to cool section and from wet section to dry section under temperature gradient, as well as evaporation. Thus, soil expands and salt expansion occurs. A salt expansion experiment for coarse grain saline soil and coarse grain soil with salty layers was design to study the process of salt expansion. At the same time, salt expansion with and without salty layers is compared. It is found that under a constant temperature, salt expansion of coarse\|grain soil is smaller when temperature in the upper layers >0 ℃. The salt expansion amount increases with decreasing temperature when temperature in the upper layers >0 ℃, and decreases with decreasing temperature after reaching a definite value, because of the overburden load. Salt expansion amount will reach the maximum when temperature at the upper layers arrives \{-5\} ℃. From the view of temperature change at the upper layers and the process of salt expansion deformation, temperature at the upper layers will reach \{-5.0\} ℃ after the test is conducted for 10 h. However, temperature at 3 cm depth is only about 0 ℃. Freezing temperature of a sample is about \{-2.06\} ℃ (measured value) under this test condition. The sample has not been frozen, thus, no deformation is caused by frost heave. Deformation amount in this moment is 62.8% of the total deformation amount. When temperature at the upper layers is constant after 30 h, temperature at 6 cm depth is 0 ℃, freezing front is not more than 6 cm. Frost heave occurs in the upper part of the sample. Therefore, deformation is the result of salt expansion, and then enhanced by frost heave. The salt expansion deformation for coarse grain soil with salty layers is obviously greater than that for coarse grain saline soil without salty layers in any temperature range. When temperature >0 ℃
出处
《冰川冻土》
CSCD
北大核心
2001年第3期238-243,共6页
Journal of Glaciology and Geocryology
