多年冻土区U型槽的水平冻胀特性试验及理论研究

发布时间：2018-05-03 14:43

本文选题：多年冻土 + U型排水渠道　；参考：《北京交通大学》2017年硕士论文

【摘要】：在多年冻土区,U型排水渠道经常遭受水平冻胀力的破坏,严重影响构筑物的服役性能。本文以青藏高原多年冻土区路基边坡U型槽排水渠道为研究对象,采用现场试验、理论分析和数值计算相结合的手段,研究了多年冻土区U型槽的水平冻胀力分布特征,建立了多年冻土区U型槽的水热力三场耦合数值模型,分析了 U型槽埋深、周围土体含水量、周围土体换填范围及结构形式对温度场及水平冻胀力的影响。本文主要研究成果如下:(1)U型槽周围土体的温度和外界温度具有强烈的相关性,结构周围土体温度在2月份达到最低,其周围活动层完全冻结。(2)作用于结构上的水平冻胀力沿深度非均匀分布,随深度先增大后减小并在结构的1/2～1/3处达到水平冻胀力峰值;同时,随U型槽周围土体温度的降低作用于结构的水平冻胀力也随之增大,并在2月份水平冻胀力达到最大状态。(3)不同埋深条件下,水平冻胀力均沿埋深非均匀分布,其数值大小在结构中部存在明显差异,主要体现在2月份水平冻胀力最大时刻,埋深0.7m、1.7和3mU型槽在0.35m、0.65m和1.65m处,水平冻胀力峰值分别为20.45kPa、31.65kPa和 40.14kPa。(4)不同含水量条件下,水平冻胀力分布与基本模型相同但数值大小随含水量的增加而增大,主要体现在2月份,含水量11%、15%和20%均在0.6m左右水平冻胀力达到峰值分别为31.65kPa、36.72kPa和38.86kPa。(5)不同换填范围条件下,水平冻胀力峰值及位置均有显著变化,侧边土体的0～2.8m换填范围是影响水平冻胀力的主要范围,换填超过2.8m后,水平冻胀力几乎不再降低。(6)相同埋深条件下,梯形结构产生的水平冻胀力相比U型结构增大13%～15%左右,而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。
[Abstract]:In permafrost regions, U-type drainage channels are often damaged by horizontal frost heaving force, which seriously affects the service performance of structures. In this paper, the horizontal frost heaving force distribution characteristics of U type trench in permafrost region of Qinghai-Xizang Plateau are studied by means of field test, theoretical analysis and numerical calculation. A numerical model of three coupled hydro-thermal fields for U-groove in permafrost region is established. The influences of the depth of U-groove, the water content of surrounding soil, the range and structure of the surrounding soil on the temperature field and horizontal frost heaving force are analyzed. The main results of this paper are as follows: the temperature of the soil around the U-shaped trough is strongly correlated with the outside temperature, and the temperature of the soil around the structure reaches the lowest in February. The horizontal frost heaving force on the structure is distributed inhomogeneously along the depth, first increases with the depth, then decreases and reaches the peak value at 1 / 2 / 1 / 3 of the structure. The horizontal frost heave force of the structure increases with the decrease of soil temperature around the U-shaped channel, and the horizontal frost heave force is distributed inhomogeneously along the buried depth under the condition that the horizontal frost heave force reaches the maximum in February. There are obvious differences between the values in the middle of the structure, mainly at the maximum time of horizontal frost heaving force in February, under the conditions of 0.35mPa 0.65m and 1.65m, and 20.45kPa5kPa 31.65kPa and 40.14kPa.f4, respectively), and the buried depth of 0.7mc1.7and 3mU trough are 0.35mPa-0.65m and 1.65m, respectively. The distribution of horizontal frost heave force is the same as that of the basic model, but the numerical value increases with the increase of water content, mainly in February, when the water content of 1115% and 20% reaches the peak value of 31.65 KPA 36.72 KPA and 38.86 KPA. The peak value and position of horizontal frost heaving force have significant changes. The range of 0 ~ 2.8m of lateral soil mass is the main range affecting horizontal frost heaving force. When the horizontal frost heaving force exceeds 2.8 m, the horizontal frost heave force almost no longer decreases under the same burying depth. The horizontal frost heaving force produced by trapezoidal structure is about 13% higher than that of U type structure, and its distribution is basically the same. Therefore, U type structure is superior to trapezoidal structure in reducing horizontal frost heave force.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV672

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