EVOLUTION CHARACTERISTICS OF ELASTIC MODULUS AND ENERGY OF BIOTITE QUARTZ SCHIST UNDER CYCLIC LOADING AND UNLOAD-ING TEST
The biotite quartz schist is a typical anisotropic rock.To study its damage evolution law and anisotropic characteristics,equal plastic strain cyclic loading and unloading tests were carried out on samples with schistosity angles of 0°,45°,and 90°.The results show that the failure modes of specimens with different schistosity plane an-gles are distinct,with tension fracture phenomena observed in the 0°schistosity samples and shear fracture phenom-ena in the 45°schistosity samples being particularly pronounced.With an increase in plastic strain,the elastic mod-ulus of biotite quartz schist first strengthens and then weakens.This phenomenon is more evident under high confi-ning pressure.The turning point in the weakening stage is consistent with the corresponding plastic strain when the initiation strength is stable.As an evaluation index of rock damage and the deterioration process,the elastic modu-lus is less affected by the angles of schistosity than the integrity coefficient.In the process of the internal energy evo-lution of rock,the relationship between dissipated energy and the angles of schistosity is 0°>90°>45°.The relation-ship between the decreasing rate of dissipated energy and elastic energy is 45°>90°>0°.The corresponding plastic strain of the elastic energy and dissipated energy when it evolves to a stable state is the same as that of damaged strength.This study explores the mechanical behavior of damage evolution of biotite quartz schist through the analy-sis of the evolution characteristics of elastic modulus and energy.
Biotite quartz schistAnisotropyCyclic loading and unloadingElastic modulusEnergy