基于DMA与有限元相结合获取的黄土阻尼振幅特性研究
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摘要
土体的阻尼是土层与地基地震反应分析时影响到工程的安全和经济性的重要参数,但其测试方法有待创新。为了研究黄土的阻尼振幅特性,本研究基于能量耗散原理,借助动态热机械分析仪(DMA)和盒土有限元应变能分析,得到了黄土阻尼振幅特性测试新方法,基于该方法获得了不同影响因素下的黄土阻尼振幅特性曲线。研究结果表明,对于黄土,在不同含水率、不同填充率和不同频率下,其最优阻尼峰值均出现在振幅100μm附近;含水率过高或过低都会使黄土的阻尼损耗因子降低;100%的体积填充率时盒土结构阻尼较优;振幅小于100μm时更低频振动下黄土的阻尼值更高。
The damping of soil is an important parameter that affects the safety and economy of the project in seismic response analysis of soil and foundation, but its test method needs to be innovated. In order to study the damping amplitude characteristics of loess, based on the principle of energy dissipation, a new method for testing the amplitude characteristics of loess damping have been obtained by means of dynamic Thermal Mechanical Analyzer(DMA) and finite element strain energy analysis of box soil, and the amplitude characteristic curves of loess damping under different influencing factors are obtained based on this new method. The experimental results show that for loess, the peak value of damping appears near the amplitude of 100 microns at different water content, filling rate and frequency. If the water content is too high or too low, the damping loss factor of loess will be reduced. When the volume filling rate is 100%, the damping of box soil structure is better. When the vibration amplitude is less than 100 microns,the damping value of loess is higherunder lower frequency vibration.
The damping of soil is an important parameter that affects the safety and economy of the project in seismic response analysis of soil and foundation, but its test method needs to be innovated. In order to study the damping amplitude characteristics of loess, based on the principle of energy dissipation, a new method for testing the amplitude characteristics of loess damping have been obtained by means of dynamic Thermal Mechanical Analyzer(DMA) and finite element strain energy analysis of box soil, and the amplitude characteristic curves of loess damping under different influencing factors are obtained based on this new method. The experimental results show that for loess, the peak value of damping appears near the amplitude of 100 microns at different water content, filling rate and frequency. If the water content is too high or too low, the damping loss factor of loess will be reduced. When the volume filling rate is 100%, the damping of box soil structure is better. When the vibration amplitude is less than 100 microns,the damping value of loess is higherunder lower frequency vibration.
引文
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[2]李识博,王常明,王念秦,等.黄土三轴试验的颗粒流数值模拟[J].中国公路学报,2013,26(6):22–29.
[3]Sitharam T G,Ravishankar B V,Vinod J S. Liquefaction and pore water pressure generation in sand—a cyclic strain approach[J]. Journal of Earthquake and Tsunami,2008,2(3):227–240.
[4]Chiaro G,Kiyota T,Koseki J. Strain localization characteristics of loose saturated toyoura sand in undrained cyclic torsional shear tests with initial static shear[J]. Soils and Foundations,2013,53(1):23–34.
[5]Eskisar T,Karakan E,Altun S. Evaluation of cyclic stress–strain and liquefaction behavior of izmir sand[J]. Arabian Journal for Science and Engineering,2014,39(11):7513–7524.
[6]王峻,钟秀梅,柴少峰,等.动荷载作用下粉煤灰改良黄土的动应力-应变关系研究[J].世界地震工程,2015,31(1):45–51.
[7]Ma W,Wang L,Li X,et al. A novel linear relationship for calculating dynamic shear modulus of geomaterials[J]. Journal of Wuhan University of Technology,2016,31(4):838–842.
[8]王谦,李娜,王平,等.甘南地区黄土的动模量与阻尼比特性研究[J].岩土工程学报,2017,39(S1):192–197.
[9]王志杰,骆亚生,王瑞瑞,等.不同地区原状黄土动剪切模量与阻尼比试验研究[J].岩土工程学报,2010,32(9):1464–1469.
[10]李慧.河北黄土动剪切模量与阻尼比试验研究[D].天津:河北工业大学,2015.
[11]李焱.不同振动频率下非饱和黄土的动力特性研究[D].杨凌:西北农林科技大学,2010.
[12]王峻.粉煤灰改性黄土动力特性研究[C]//全国建筑工程勘察科技情报网、全国建筑工程勘察科技情报网华北情报站、中国建筑学会工程勘察分会:中国建筑学会工程勘察分会,2016:91-96.
[13]罗飞,何依婷,赵淑萍,等.分级加载下冻土阻尼比的试验研究[J].岩土力学,2015,36(11):3143–3149.
[14]Chen H,Jiang Y,Niu C,et al. Dynamic characteristics of saturated loess under different confining pressures:a microscopic analysis[J].Bulletin of Engineering Geology&the Environment,2017(7):1–14.
[15]Cheng X,Li X,Nie J,et al. Research on the dynamic parameters of loess[J]. Geotechnical and Geological Engineering,2018(1):1–17.
[16]王志杰.复杂初始应力状态下黄土动剪切模量与阻尼比特性试验研究[D].杨凌:西北农林科技大学,2010.
[17]申权.土体阻尼测试新方法及其阻尼性能变化规律的研究[D].南昌:南昌航空大学,2013.