True triaxial experimental research on shear behaviors of sand under different intermediate principal stresses and different stress paths

In order to investigate the effect of stress paths and intermediate principal stress coefficientonthe relation curves between q-e1,q/p-e1 and strength index j of sand,a series of true triaxial drainedshear tests were conducted on Fujian standard sand. The strength envelope on the plane of π of nonlinearunified strength model of geo-materials was verified by the friction angle and the measured strength value.The friction angle was tested by the experiments of triaxial tension and compression,while the strength val-ue was obtained in the cases of different intermediate principal stresses. The results show that when thestress path is exactly the same,the shearing strength parameters q and stress ratio q/p of sand decreases,but intensity index ? increases with increasing of intermediate principal stress coefficient. The bigger the in-termediate principal stress coefficient the more obvious the shear dilatancy of sand. Different stress paths intriaxial shear test of sand havegreat influence on the shearing strength q, but for strength index ? andstress ratio q/p. The nonlinear strength property of sand can be described very well by the nonlinear unifiedstrength model of geo-materials.