土工直剪试验质量控制因素研究及应用

Application of Quality Control Factors for Direct Shear Test in Geotechnical Engineering

土工直剪试验是岩土工程中最常见的获取土体抗剪强度指标的室内试验手段,在工程建设过程中应用十分广泛。为明确土工直剪试验控制因素,提高直剪试验质量,借助离散元方法建立土工直剪试验的二维数值模型并进行计算,所得结论如下:(1)剪切盒纵横比会影响剪胀效应的测试值,可通过使用较小纵横比的剪切盒以获得更加精确的剪胀效应测试值;(2)剪切带的垂直和水平法向应力相等,因此主应力和应变速率的方向是同轴的,故直剪试验不能进行非共轴的相关分析工作。研究结果对于提高土工直剪试验质量提供了可靠的数据支持。

The direct shear test is the most common laboratory test method in the geotechnical engineering to estimate the soil shear strength indices.Currently,it is widely used in the engineering projects.To evaluate the control factors for the direct shear test and improve the quality of testing,this paper establishes a two-dimensional numerical model of the direct shear test by using the discrete element method.The conclusions are as follows:(1)The aspect ratio of the shear box will affect the test value of the shear effect;More accurate shear effect test values can be obtained by using a shear box with a smaller aspect ratio;(2)The vertical and horizontal normal stresses of the shear band are equal,so the direction of the principal stress and strain rate is coaxial.Therefore,the direct shear test cannot carry out non-coaxial correlation analysis.The results of this paper pro-vide reliable data support for improving the quality of the direct shear test.