土石混合料中物质组成复杂、结构分布不规律,采样进行室内试验相对困难,因此最好通过现场原位剪切试验获取某特定工程最具针对性的力学参数;但超粒径颗粒的存在,使得将常规原位剪切试验运用于土石混合料力学参数取值时存在诸多问题,会对试验结果造成不可忽视的影响。对原位直剪试验和原位水平推剪试验这2类常见试验中存在的问题进行分析和对比。结果表明:原位水平推剪试验更适用于土石混合料此类非均匀体;通过对比几组原位试验结果,发现2类原位剪切试验得到的内摩擦角相近,但是黏聚力的值差异性较大。最后,对土石混合料原位水平推剪试验的参数取值提出了建议。

In-situ shear test is an optimum means of obtaining targeted strength parameters of rock-soil aggregate for specific project as sampling and in-door test are demanding because of the complex composition and irregular structure of soil-rock mixture. Nonetheless, problems arise in conventional in-situ shear test due to large particles, posing unneglectable impact on test results. In view of this, we compared and analysed the problems in in-situ shear test and horizontal push-shear test, and concluded that horizontal push-shear test is more suitable for heterogeneous body such as soil-rock mixture. We also found that the internal friction angles obtained by the two methods are close, whereas cohesions differ greatly. Finally, we gave some suggestions on determining the parameter values for in-situ pull-shear test.