冻融循环下盐渍土风致疲劳动力特性的试验研究

发布时间：2019-02-14 14:20

【摘要】：我国经济在飞速发展,化石能源不断消耗,环境污染日益严重,迫切需要大力发展清洁能源。而在我国的西北地区有着丰富的风力资源,同时,“十二五”规划的完成,使得我国在风力资源的利用上有了诸多成就。由于我国地域辽阔,不同区域的地质条件差异较大,西北地区分布着大量的盐渍土,该地区气候恶劣,低温雨雪天气频发。严峻的气候条件及特殊的风机地基土,对风机机组在建设期及运营中提出了巨大的挑战。本文以内蒙古中西部某盐渍土地基上风电场建设为例,研究盐渍土地基在风致疲劳荷载、冻融作用及盐分的影响下其动静强度的变化规律。首先,分析冻融次数及含盐量对盐渍土静强度的影响;进而,对建设场地自然风进行模拟与等效,确定作用于地基土的风致疲劳荷载形式并进行试验,分析风致疲劳荷载作用时,土体动力特性与冻融循环次数、地基土含盐量间的关系,总结当含盐量一定时地基土经受相同的冻融循环作用后,其动应力与静应力之间的关系;最后,通过土体结构损伤理论分析风致疲劳荷载、冻融循环及盐分作用下盐渍土的强度损伤机理,并确定各因素影响的显著性水平。研究发现:(1)冻融循环作用下,盐渍土的粘聚力及内摩擦角随冻融次数逐渐降低,当冻融次数超过5次后,其减小速率会出现减缓的趋势。(2)当含盐量从0%变化到6%时,盐渍土的粘聚力及内摩擦角会呈现先减小后增大的趋势,变化速率与冻融次数有关。(3)试验条件相同时,风致疲劳荷载作用下,土体的极限动应力较静应力会有不同程度的减小;冻融作用下,土体的极限动应力会随着冻融次数的增加呈降低趋势。(4)风致疲劳荷载、含盐量及冻融循环均会使盐渍土产生损伤,含盐量及冻融循环对土体强度损伤的影响显著。
[Abstract]:With the rapid development of economy, fossil energy consumption and environmental pollution, it is urgent to develop clean energy. In the northwest of China, there are abundant wind resources. At the same time, with the completion of the 12th Five-Year Plan, China has made a lot of achievements in the utilization of wind resources. Because of the vast territory and the great difference of geological conditions in different regions, there is a large amount of saline soil distributed in Northwest China, which has a bad climate and frequent low temperature rain and snow weather. The severe climatic conditions and special foundation soil of the fan have brought great challenges to the fan unit during the construction period and operation. Taking the wind farm construction on a salinized soil foundation in the central and western part of Inner Mongolia as an example, this paper studies the dynamic and dynamic strength of the saline soil foundation under the influence of wind-induced fatigue load, freezing and thawing and salt content. Firstly, the influence of freeze-thaw times and salt content on the static strength of saline soil is analyzed. Then, the natural wind of the construction site is simulated and equivalent, the wind-induced fatigue load forms acting on the foundation soil are determined and tested, and the dynamic characteristics of soil and the number of freeze-thaw cycles are analyzed when the wind-induced fatigue load is acted on. The relationship between dynamic stress and static stress of foundation soil under the same freeze-thaw cycle is summarized. Finally, the mechanism of strength damage of saline soil under the action of wind induced fatigue load, freeze-thaw cycle and salt is analyzed by the theory of soil structure damage, and the significance of each factor is determined. The results are as follows: (1) under the action of freeze-thaw cycle, the cohesion and internal friction angle of saline soil gradually decrease with the number of freeze-thaw times, when the freeze-thaw times exceed 5 times, (2) when the salt content changes from 0% to 6%, the cohesive force and internal friction angle of saline soil will decrease first and then increase. The rate of change is related to the number of freeze-thaw. (3) when the test conditions are the same, the ultimate dynamic stress of soil will decrease in varying degrees compared with the static stress under the action of wind-induced fatigue load; Under the action of freeze-thaw, the ultimate dynamic stress of soil will decrease with the increase of freeze-thaw times. (4) Wind-induced fatigue load, salt content and freeze-thaw cycle will cause damage to saline soil. The effect of salt content and freeze-thaw cycle on soil strength damage is significant.
【学位授予单位】：内蒙古工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM614

【参考文献】