初始应力条件对压实黄土动强度影响的研究
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摘要
建筑物地基或土坡中的土体在受到地震或其他动荷载作用前往往处于复杂的初始应力状态,对原有的DTC-199型周期扭转荷载三轴仪进行简单的改造后,可以进行压实黄土在这种固结应力状态下动强度的试验研究。试验结果表明,在其他初始固结应力条件不变时,初始主应力方向角α0对压实黄土的动强度具有显著的影响,初始中主应力系数b0对动强度的影响较小;随着α0的增大,动强度逐渐降低,并在α0=90o时达到最小值,最大降幅在40%左右;b0对压实黄土的动强度的影响具有放大效应和区间效应,b0从0增大至0.5时,动强度逐渐增大,b0从0.5增大至1时,动强度逐渐减小,增加的幅度小于降低的幅度约5%。
The soils under the foundation of building or within the slope are usually in complex initial stress state before subjected to cyclic loading induced by earthquake or other dynamic loadings;after reforming the DTC-199 torsional cyclic load triaxial apparatus,the dynamic strength of compacted loess can be tested under this consolidation stress conditions.Results show that the initial angle α0 of principal stress has a considerable influence on the dynamic strength of compacted loess when other initial consolidation stress conditions are fixed;the initial coefficient b0 of intermediate principal stress has little influence on the dynamic strength of compacted loess;with the increase of α0,dynamic strength reduces gradually and it reaches minimum when α0 is 90o;maximum reduction range is about 40 %.The initial coefficient of intermediate principal stress has interval effects and amplification effect on the dynamic strength of compacted loess.When b0 increases from 0 to 0.5,the dynamic strength increases;and when b0 increases from 0.5 to 1,the dynamic strength decreases;the rate of increasing is less than rate reduction about 5 %.
The soils under the foundation of building or within the slope are usually in complex initial stress state before subjected to cyclic loading induced by earthquake or other dynamic loadings;after reforming the DTC-199 torsional cyclic load triaxial apparatus,the dynamic strength of compacted loess can be tested under this consolidation stress conditions.Results show that the initial angle α0 of principal stress has a considerable influence on the dynamic strength of compacted loess when other initial consolidation stress conditions are fixed;the initial coefficient b0 of intermediate principal stress has little influence on the dynamic strength of compacted loess;with the increase of α0,dynamic strength reduces gradually and it reaches minimum when α0 is 90o;maximum reduction range is about 40 %.The initial coefficient of intermediate principal stress has interval effects and amplification effect on the dynamic strength of compacted loess.When b0 increases from 0 to 0.5,the dynamic strength increases;and when b0 increases from 0.5 to 1,the dynamic strength decreases;the rate of increasing is less than rate reduction about 5 %.
引文
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[2]郭莹,栾茂田,史旦达,等.初始应力条件对松砂动力变形特性影响的试验研究[J].岩土力学,2005,26(8):1195-1200.GUO Ying,LUAN Mao-tian,SHI Dan-da,et al,Experimental study of effect of initial stress condition on dynamic behavior and deformation parameters of loose sands[J].Rock and Soil Mechanics,2005,26(8):1195-1200.
[3]郭莹,张小玲,栾茂田,等.初始中主应力系数对中密粉煤灰动模量阻尼比影响的实验研究[J].岩土力学,2008,29(3):591-595.GUO Ying,ZHANG Xiao-ling,LUAN Mao-tian,et al,Experimental study of effect of initial intermediate principal stress coefficient on dynamic shear modulus and damping ratio of medium-dense fly ash[J].Rock and Soil Mechanics,2008,29(3):591-595.
[4]蔡袁强,王军,徐长节.初始偏应力作用对萧山软黏土动弹模量与阻尼影响实验研究[J].岩土力学,2007,28(11):2291-2296.CAI Yuan-qiang,WANG Jun,XU Chang-jie.Experimental study of dynamic elastic modulus and damping ratio of Xiaoshan saturated soft clay considering initial deviator stress[J].Rock and Soil Mechanics,2007,28(11):2291-2296.
[5]付磊,王洪瑾,周景星.主应力偏角对砂砾料动力特性影响的试验研究[J].岩土工程学报,2000,22(4):435-440.FU Lei,WANG Hong-jin,ZHOU Jing-xing.Effect of the initial rotation angle of principal stress on the dynamic properties of soil[J].Chinese Journal of Geotechnical Engineering,2000,22(4):435-440.
[6]中华人民共和国水利部.SL237-1999土工试验规程[S].北京:中国水利水电出版社,1999.
[7]谢定义.土动力学[M].西安:西安交通大学出版社,1987.
[8]郭莹.复杂应力条件下饱和松砂的不排水动力特性试验研究[D].大连:大连理工大学,2003.
[9]王洪瑾,马奇国,周景星,等.土在复杂应力状态下的动力特性研究[J].水利学报.1996,(4):57-64.WANG Hong-jin,MA Qi-guo,ZHOU Jing-xing,et al.A study of dynamic Characteristics of soil in complex stress state[J].Journal of Hydraulic Engineering,1996,(4):57-64.
[10]许顺成.复杂应力条件下饱和砂土剪切特性及本构模型的实验研究[D].大连:大连理工大学,2006.
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