Experimental Study On Wind- Induced Fatigue Dynamic Characteristic Of Saline Soil Under Freeze-thaw Cycles

As a problem,fossil consumption is increasing and environmental pollution is more serious in China with the rapid development of China's economy,so clean energy need to be popularized on a large scale.However,there are lots of wind resources in the northwest region of China,and China get many achievements in use of wind resources when Twelth Five-Year Plan was completed.In China,geological condition of different region is diverse,in especial,there are lots of saline soil and severe weather in northwest region.Severe weather and special foundation soil of pose a large challenge to aerogenerator during construction and operation period.In this paper,the construction of wind farm on a saline soil foundation in the Inner Mongolia Midwest is taken as an example,the dynamic and static strength characteristics of the saline soil foundation under the influence of wind-induced fatigue load,freeze-thaw and salt are stutied.First,the influence that freeze-thaw cycles and different salt content generate on the static strength of saline soil is analyzed.Then,the natural winds of the construction site are simulated,and the form of wind-induced fatigue load which effect on the foundation soil is determined and the experiment is carried out;the relationship between the dynamic characteristics of the soil and the freeze-thaw cycles and the salt content of the foundation soil is analyzed;the relationship between the dynamic stress and the static stress of saline soil under the same freeze-thaw cycle and salt content is analyzed.Finally,the damage mechanism of saline soil under wind-induced fatigue load,freeze-thaw cycle and salt was analyzed by soil structure damage theory,and the significance level of each factor was determined.The results are as follows:(1)Under the freeze-thaw cycle,with the freeze-thaw cycles increase,the cohesion and internal friction angle of the saline soil decrease,and the decreasing rate may be reduce when the freeze-thaw cycles over five times.(2)With the salt content from 0% change to 6%,the cohesion and internal friction angle of the saline soil decrease first and then increase,and the rate of change is related to the times of freeze-thaw cycles.(3)Under the same test condition,the ultimate dynamic stress of the soil is small than the ultimate static stress;with freeze-thaw cycles increase,the ultimate dynamic stress decrease.(4)Damage happened in saline soil under the wind-induced fatigue load,salt and freezethaw cycles.The salt and the freeze-thaw cycles have a significant effect on the soil strength damage.