摘要
为了研究试样壁厚对空心扭剪试验中扭剪应力分布不均匀的影响,从假设土体为线弹性角度对空心扭剪试样横截面上扭剪应力的分布规律进行了理论推导,同时采用邓肯E-ν模型对不同壁厚的5组空心圆柱试样的扭剪过程进行三维有限元模拟,分析了在试验中以扭剪应力平均值和主应力轴旋转角平均值代替真实值所产生的误差与试样壁厚的关系。结果表明,外径相同的试样,壁厚越厚,横截面上的扭剪应力和主应力轴旋转角沿半径方向的分布越不均匀;利用试验中常用的扭剪应力平均值和主应力旋转角平均值代替真实值会产生误差,且误差随着壁厚的增大而增大;若将扭剪应力平均相对误差和主应力轴旋转角最大相对误差控制在10%以内,则内外径比不小于0.7,建议空心扭剪试样的尺寸取为外半径70mm、壁厚20mm、高度250mm。
In order to study the influences of thickness on stress of soil specimens in hollow cylinder test,the distribution of circumferential shear stress at cross-section and principal stress axes rotation angle have been considered as uniform and used as average in hollow cylindrical torsional shear tests.In fact,they are nonuniform.In order to study how large the nonuniformity is,and under what conditions it can be ignored,the theoretical deduction and analysis was employed to linear-elastic constitutive model.In addition,specimens with different thickness were simulated by 3-D finite element with Duncan's E-ν model.The results show that the degree of nonuniformity will increases when the specimen thickness increases.The errors of circumferential shear stress and torsional shear will also increase.If the degree of stress and rotation angle nonuniformity are both controlled within 10%,the ratio of inner radius and outer radius of specimens has to be larger than 0.7.A new specimen with appropriate dimensions are proposed,which can be that outer radius is 70 mm,thickness is 20 mm and height is 250 mm.
出处
《水电能源科学》
北大核心
2017年第5期145-148,共4页
Water Resources and Power
关键词
土体
空心扭剪
壁厚
扭剪应力
有限元
soil
hollow torsional shear
wall thickness
shear stress
finite element
