关键词: 拉压试验仪; 非饱和黄土; 新型拉伸仪; 抗拉强度; 尺寸效应;

Abstract: The tensile strength of soil is the theoretical basis for studying the characteristics of tensile failure.At present, although indoor testing methods of tensile strength were various, most of them have certain limitations, so it is difficult to accurately obtain the true tensile strength of soil.In this paper, we compared and analyzed the existing test devices and test methods, so improved the traditional test devicesand finally develop a new type of uniaxial tension and compression tester and matching sample preparation devices.Based on the new device, we carried outa tensile strength test on the undisturbed Q2 loess in Lintong area.The failure pattern and mechanism of unsaturated loess were analyzed by combining with the generation mechanism of the tensile strength of the loess.The test results indicated that the tensile strength of unsaturated loess decreased as a power function with the increase of water content.Furthermore, the tensile strength of unsaturated loess was affected by the sample size and shape under different height-diameter ratio, which had an obvious size effect.The relationship between tensile strength and height-diameter ratio exhibited a negative exponential law ina certainwater content.When the height-diameter ratio was greater than 2.64,the size effect disappeared.

Key words: unsaturated loess; new type of tension and compression tester; tensile strength; size effect;