简易轴向拉伸试验仪设计及试样合理尺寸的试验研究

发布时间：2018-05-29 07:05

本文选题：黄土 + 抗拉试验　；参考：《铁道标准设计》2016年09期

【摘要】：针对现有土工抗拉仪存在的缺陷与不足,设计改良出一套简易轴向拉伸试验仪。通过四角调节螺栓和夹具设计,消除摩擦阻力和端部应力集中,通过轴心线的控制避免试样偏心受拉。可以完成不同尺寸长方体试样的抗拉试验。由于目前试样尺寸没有统一标准,为了得到试样的规范尺寸并分析试样尺寸对抗拉特性的影响,利用设计的拉伸装置,对不同截面和长细比试样进行试验。得到的试验结果有:ω=18.0%,ρd=1.30 g/cm3时,不同截面试样平均抗拉强度值在14.2~14.6 k Pa,平均极限位移值在8×10-2~9×10-2mm;ω=22.0%,ρd=1.45 g/cm3时,不同长细比试样平均抗拉强度值在14.4~14.9 k Pa,平均极限位移值与长细比的关系式可表示为b=9.706 7×(l/a)-6.97。分析表明:只要试样的物理状态(含水率ω和干密度ρd)相同,不论含水率ω是否小于或大于塑限值,抗拉强度值均不受截面和长细比的影响;含水率ω低于塑限值时,极限拉伸位移不随试样的截面变化;含水率高于塑限值时,极限拉伸位移与长细比呈递增的线性关系。计算每组试样抗拉强度值的极差和标准差并分析数据的离散性,结合制样难易程度和用土量等方面综合考虑,提出截面边长2.5 cm,长细比3的试样尺寸较为合理,为今后开展土体抗拉强度研究提供可靠依据。
[Abstract]:In view of the defects and shortcomings of the existing geotechnical tensile tester, a set of simple axial tensile tester was designed and improved. The friction resistance and stress concentration at the end are eliminated by adjusting the bolts and clamps in four angles, and the eccentric tension of the specimen is avoided by the control of the axis line. The tensile tests of cuboid specimens with different sizes can be completed. Because there is no uniform standard for specimen size at present, in order to obtain the standard size of the specimen and analyze the influence of the specimen size on the tensile properties, the different cross-section and aspect ratio samples are tested by the designed tensile device. The experimental results are as follows: the average tensile strength of specimens with different sections is 14.2N14.6 KPA, the average limit displacement is 9 脳 10-2mm at 蠅 _ (18.0) and 蟻 _ d _ (1.30) g/cm3, and the average limit displacement is 8 脳 10 ~ (-2) ~ 9 脳 10 ~ (-2) mm, 蠅 _ (22) and 蟻 _ d ~ (1.45) g/cm3, respectively. The average tensile strength of specimens with different slenderness ratios is 14.4 ~ 14.9 KPA, and the relationship between the average ultimate displacement value and the aspect ratio can be expressed as b _ (9.7067) 脳 l / a ~ (-1) / a ~ (-6.97). The analysis shows that as long as the physical state of the sample (moisture content 蠅 and dry density 蟻 d) is the same, whether or not the moisture content 蠅 is less than or greater than the plastic limit value, the tensile strength value will not be affected by the cross section and the aspect ratio, and when the moisture content 蠅 is lower than the plastic limit value, The ultimate tensile displacement does not change with the cross section of the specimen, and when the moisture content is higher than the plastic limit, the linear relationship between the ultimate tensile displacement and the aspect ratio is increasing. By calculating the range and standard deviation of tensile strength of each group of specimens and analyzing the discreteness of the data, considering the difficulty of sample preparation and the amount of soil used, it is proposed that the sample size with a cross section length of 2.5 cm and a slenderness ratio of 3 is more reasonable. It provides a reliable basis for the study of soil tensile strength in the future.
【作者单位】：石家庄铁道大学土木工程学院;南京水利科学研究院;
【基金】：国家自然基金项目(50978172) 铁道部科技研究开发计划项目(2010G018-B-4) 国家大学生创新创业训练计划(201410107018)
【分类号】：TU415

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