动荷载作用下重塑黏质粉土的弹性变形研究
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摘要
以宁波黏质粉土为对象,在不同排水、围压、动应力以及温度条件下,开展了一系列动三轴试验,研究了土体的弹性变形特性,建立了考虑围压影响的动弹性模量和弹性应变关系的经验公式,并给出了不同围压、动应力下动弹性模量和弹性应变计算公式。结果表明:随着振次的增加,动弹性模量(弹性应变)迅速减小(增大),并有较为明显的极值点,随后有一定的恢复,最终趋于稳定;温度越高,动弹性模量值越大,弹性应变越小,土体出现热硬化现象;建立的计算公式可用于长期动荷载作用后黏质粉土的动弹性模量和弹性应变计算。
Cyclic triaxial tests on the Ningbo saturated remolded clayey silt were carried out to study the effects of drainage condition,confining pressure,dynamic stress and temperature on the dynamic characteristics of soil. An empirical formula considering the effect of confining pressure,for the relationship between the dynamic elastic modulus and elastic strain was built. In addition,two empirical formulas for calculating the dynamic elastic modulus and the elastic strain under different confining pressure and dynamic stress were also established. The results show that with the increase of the number of vibration times,the dynamic elastic modulus and elastic strain at first change rapidly up to their extreme points and then after the extreme points,the dynamic elastic modulus and elastic strain gradually recover and approach to their stable state. The higher the temperature,the greater the value of dynamic elastic modulus and the smaller the elastic strain( thermal hardening). The empirical formulas can be used to calculate the dynamic elastic modulus and the elastic strain of clayey silt after enduring long-term vibration load.
Cyclic triaxial tests on the Ningbo saturated remolded clayey silt were carried out to study the effects of drainage condition,confining pressure,dynamic stress and temperature on the dynamic characteristics of soil. An empirical formula considering the effect of confining pressure,for the relationship between the dynamic elastic modulus and elastic strain was built. In addition,two empirical formulas for calculating the dynamic elastic modulus and the elastic strain under different confining pressure and dynamic stress were also established. The results show that with the increase of the number of vibration times,the dynamic elastic modulus and elastic strain at first change rapidly up to their extreme points and then after the extreme points,the dynamic elastic modulus and elastic strain gradually recover and approach to their stable state. The higher the temperature,the greater the value of dynamic elastic modulus and the smaller the elastic strain( thermal hardening). The empirical formulas can be used to calculate the dynamic elastic modulus and the elastic strain of clayey silt after enduring long-term vibration load.
引文
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[2]HYDE A F L,BROWN S F.The plastic deformation of a silty clay under creep andrepeated loading[J].Geotechnique1976,26(1):173-84.
[3]GUO L,WANG J,CAI Y Q,et al.Undrained deformationbehavior of saturated soft clay under long-term cyclic loading[J].Soil.Dyn.Earthq.Eng.,2013,50:28-37.
[4]SEED H B,MARTIN P P,LYSMER J.Pore-water pressure changes during soil liquefaction[J].Journal of Geotechnical and Geoenvironmental Engineering,1976,102:12074.
[5]WANG J,GUO L,CAI Y Q,et al.Strain and pore pressure development onsoft marine clay in triaxial tests with a large number of cycles[J].Ocean.Eng.,2013,74:125-32.
[6]刘干斌,范思婷,陈斌,等.考虑温度影响的饱和软黏土累积变形特性研究[J].岩土工程学报,2016,38(7):1238-1245.LIU Ganbin,FAN Siting,CHEN Bin,et al.Characteristics of cumulative deformation of saturated soft clay considering temperature effect[J].Chinese Journal of Geotechnical Engineering,2016,38(7):1238-1245.
[7]高博,张鸿儒.邯郸与太原两地粉土动力特性的试验研究[J].工程地质学报,2008,l6(4):502-506.GAO Bo,ZHANG Hongru.Cyclical tri-axial tests for dynamic modulus characteristics of silty soils at six sites in Handan and Taiyuan[J].Journal of Engineering Geology,2008,16(4):502-506.
[8]范思婷,刘干斌,陈斌,等.考虑温度影响的饱和软黏土应变软化研究[J].振动与冲击,2017,36(6):1-6.FAN Siting,LIU Ganbin,CHEN Bin,et al.Study on strain softening of saturated soft clay considering temperature effect[J].Journal of Vibration and Shock,2017,36(6):1-6.
[9]SUN L,GU C,WANG P.Effects of cyclic confining pressure on the deformation characteristics of natural soft clay[J].Soil Dynamics and Earthquake Engineering,2015,78:99-109.
[10]王元战,杨攀博,孙熙平,等.循环荷载下软黏土强度弱化研究及其动力计算应用[J].岩土工程学报,2015,37(5):821-828.WANG Yuanzhan,YANG Panbo,SUN Xiping,et al.Strength weakening of soft clay under cyclic loading and its dynamic calculation[J].Chinese Journal of Geotechnical Engineering,2015,37(5):821-828.
[11]王树刚,王如竹,朱颖心.北京地铁地下空间温度的测量与分析[J].地下空间,2002,22(4):339-343.WANG Shugang,WANG Yuzhu,ZHU Yingxin.Measurement and analysis of temperature in underground space of beijing subway[J].Underground Space,2002,22(4):339-343.
[12]胡增辉,李晓昭,赵晓豹,等.隧道围岩温度场分布的数值分析及预测[J].地下空间与工程学报,2009,5(5):867-872.HU Zenghui,LI Xiaozhao,ZHAO Xiaobao,et al.Analysis and prediction of the temperature distribution around tunnels[J].Chinese Journal of Underground Space and Engineering,2009,5(5):867-872.
[13]陈正发,朱合华,闫治国,等.高温后上海软黏土的物理性能试验研究[J].岩土工程学报,2015,37(5):924-931.CHEN Zhengfa,ZHU Hehua,YAN Zhiguo,et al.Experimental study on physical properties of Shanghai soft clay under high temperatures[J].Chinese Journal of Geotechnical Engineering,2015,37(5):924-931.
[14]刘干斌,范思婷,叶俊能,等.温控动三轴试验装置的研制及应用[J].岩石力学与工程学报,2015,34(7):1345-1352.LIU Ganbin,FAN Siting,YE Junneng,et al.Development and application of a temperature-controlled dynamic triaxial test system[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(7):1345-1352.
[15]LUNNE T,BERRE T,ANDERSEN K H,et al.Effects of sample disturbance and consolidation procedures on measured shear strength of soft marine Norwegian clays[J].Canadian Geotechnical Journal,2006,43(7):726-750.