STUDY ON IN-SITU TESTS OF MECHANICAL CHARACTERISTICS ON SOIL-ROCK AGGREGATE
土石混合体力学特性的原位试验研究

Soil-rock aggregate(RSA)is a special kind of geomaterial composed of soils and irregular rock blocks.The mechanical properties of RSA are rarely known although RSA distributes here and there in the mountainous area in China.In-situ large-scale test can explore the mechanical properties of RSA effectively since RSA is described as a kind of heterogeneous and nonuniform material.Here,the method of in-situ test for soils and rocks is referred;and a practical procedure of in-situ test for RSA is proposed and normalized including the method of push-shear test and press-shear test,equipments,steps,and some key points.Combined with the typical RSA at the Baiyian Landslide in the Three Gorges Reservoir area,23 large-scale in-situ tests(including push-shear and press-shear)are carried out.The curves of shear stress-displacement,curves of shear strength,failure mode,and shear strength parameters for RSA with different rock contents,sample sizes and stress states are obtained from tests.The results show that RSA has typical complete curves of stress-strain,strain softening,and high internal friction angle,which are caused by the special structure of RSA.It is also indicated that rock content is an important factor for strength and failure mode of RSA and that dimension effect is observed in the in-situ tests of RSA.The procedure of in-situ tests and results obtained from the tests can provide scientific data for further study of RSA.