裂隙化岩体应变软化损伤本构模型探讨

首先,针对基于Lemaitre应变等价性假说之岩石损伤模型的局限性与不足,在深入探讨裂隙化岩体变形损伤机制的基础上,考虑裂隙化岩体受载后体积发生变化的影响,采用空隙率反映裂隙化岩体变形过程中的空隙或岩体体积变化,并通过裂隙化岩体微观受力分析,建立裂隙化岩体损伤模型;然后,通过深入研究裂隙化岩体有效应力与宏观名义应力的关系,并引进统计损伤理论,建立裂隙化岩体应变软化损伤统计本构模型,同时提出其参数确定方法,该模型能够充分反映裂隙化岩体的应变软化特性,尤其是能较好地模拟裂隙化岩体变形初期空隙的压密阶段,同时,模型参数确定无需通过非常规岩石力学试验,且参数物理意义明确,应用将较为方便;最后,通过与前人研究成果和实测结果的比较分析,表明该模型的合理性与可行性。

DISCUSSION ON STRAIN SOFTENING DAMAGE CONSTITUTIVE MODEL FOR FISSURED ROCK MASS

Firstly,according to the limitations and deficiencies of the rock damage model based on the Lemaitre's hypothesis of strain equivalence,the concept of ratio of voids was applied to describe the volume change of voids or rock mass during the process of deformation of fissured rock mass on the basis of further discussion on the damage mechanism of deformation for fissured rock mass and considering the effect of volume change of fissured rock mass under loading.And a damage model for fissured rock mass was established by analyzing the force upon fissured rock mass on microscopic scale.Secondly,a strain softening damage constitutive model for fissured rock mass was brought forward by thoroughly investigating the relationship between the effective stress and macroscopic nominal stress and introducing the statistical damage theory.Meanwhile,a method to determine the model parameters was developed.This model can fully reflect the property of strain softening of deformation for fissured rock mass;especially it can be used to well simulate the initial phase of compression of voids in the process of fissured rock mass deformation.There is no need for unconventional rock mechanics test to determine the model parameters,moreover,the physical meanings of the model parameters are explicit.Thus,this model is more convenient for use.Finally,the rationality and feasibility of the model are identified by comparative analyses between the existing research results and measured date.