不同因素对排水沟渠水平冻胀力的影响

多年冻土地区的排水沟渠经常遭受水平冻胀力的破坏，严重影响构筑物的服役性能。根据青藏高原多年冻土区路基坡脚U型槽排水沟渠的现场试验，并通过数值计算与理论分析，分析了结构埋深、粗颗粒换填范围以及结构形式对其温度场和水平冻胀力的影响。结果表明：改变工况，对土体温度场分布的形状影响较小，仅对其大小有一定影响。不同工况下水平冻胀力均沿深度非均匀分布，最大水平冻胀力主要出现在结构中部，而其上部和下部较小，结构侧壁在1/2至1/3处易发生冻胀破坏。梯形结构所受的水平冻胀力较U型结构增大13%～15%左右，但其分布形式基本相同。因此，U型结构在降低水平冻胀力方面优于梯形结构。随着换填范围增大，排水沟渠的水平冻胀力最大值逐渐减小；对于埋深1.7 m的排水沟渠来说，其侧边的0～2.8 m是影响水平冻胀力的主要换填宽度范围，而当换填宽度超过2.8 m后，水平冻胀力几乎不再降低。

Influence of different factors on horizontal frost heaving force against canal

In permafrost regions, canal is usually subjected to the horizontal frost heaving force, which impairs service life of canal. Based on the field test of U-shape subgrade canal in permafrost regions of Qinghai-Tibet plateau and the results of numerical calculation, the influences of canal depth, water content and width of surrounding soil replacement on temperature field and horizontal frost heaving characters were analyzed. The results indicate that U-shape canal depth, water content of soils as well as the width of surrounding soil replacement only have influence on temperature values of surrounding soils, but not on the shape of temperature contour of soils. The horizontal frost heaving force firstly increases and then gradually decreases along the depth of the structure, exhibiting varying values. The maximum frost heaving force occurs at about 1/2-1/3 depth of canal, which has the highest probability to have frost force-induced failure. The horizontal frost heaving force against the trapezoidal canal is about 13%-15% more than against the U-shape canal with the same depth. However, the horizontal frost heaving forces against two different canals have almost the same contour characteristics. The U-shape canal is superior to the trapezoidal structure in the perspective of reducing the horizontal frost heaving force. The more the width of soil replacing, the less the maximum horizontal frost heaving force. For the U-shape canal with 1.7 m in depth, the horizontal frost heaving force changes obviously when the width of soil replacement is from 0 to 2.8 m. However, the change is hardly seen when the width is beyond 2.8 m.