非均质岩石破裂及声发射演化数值模拟

摘要

Based on strain softening constitutive model,a damage softening constitutive model of heterogeneous rocks was established by considering the heterogeneity of rock material and the weakening characteristics of mechanical properties during damage process.The difference scheme of damage softening constitutive model was deduced and the further development of the damage softening constitutive model was achieved in FLAC3D under VC++ environment.The influence of different homogenization on mechanical properties and acoustic emission characteristic of rocks were numerically investigated.The results show that material heterogeneity has remarkable influence on the mechanical properties of rock samples.With the increase of material heterogeneity, there is a transition from ductile behavior into brittle fracture in rock failure.Meanwhile,peak strength and peak strain of rocks gradually increase,but residual strength of rocks gradually decreases.It is also found that the through-going shear fractures in the rock specimen lag behind for the more heterogeneous rock.Furthermore, there is a transition from low intensity and high frequency to high intensity and low frequency in AE characteristics of rock under uniaxial loading with an increase in heterogeneity of rock,and three typical AE patterns,swarm shock,foreshock-main shock-aftershock,and main shock,can be observed.%在应变软化本构模型的基础上,考虑岩石材料非均质性和损伤过程中力学性质的弱化特性,建立了非均质岩石损伤软化本构模型,推导了损伤软化本构模型的差分格式,在VC++环境下实现了损伤软化本构模型在FLAC3D中的二次开发.研究了不同均质度对岩石变形强度等力学特性的影响,以及岩石破坏过程中的声发射演化特性.研究表明:随着岩石均质度的增高,岩石的破坏过程由延性向脆性转化,岩石峰值强度和峰值应变不断增大,而残余强度降低;当岩石均质度较低时,岩石破坏剪切带的形成会发生滞后,随着均质度的增加,单轴加载条件下岩石声发射体现出由强度低、频率高向强度高、频率低转化的特性,并表现出群震型、前震—主震—余震型和主震型3种典型模式.