破裂岩石力学模型探讨

岩体是被地质构造弱面切割的地质体,它的特征是不连续、不均质和各向异性。用完整岩石试件在常规压力机上所获得的试验结果,不能很好地代表岩体的工程性质。但是,利用刚性很大的压力机对完整及破裂岩石作试验所获得的应力-应变全过程的后部份,以及循环加载-卸载曲线,在力学性质及破裂发展过程等方面,都与工程岩体十分相似。本文根据作者对多种岩石获得的应力-应变全图及循环加载-卸载试验结果,提出两种变参数单元模型,即变弹性模量的虎克体和变屈服极限的圣维南体,并由此而组成四种模拟破裂岩石的力学模型,导出相应的本构方程。根据岩石应力-应变全过程的试验结果,可以求出本构方程中的有关参数。通过模型与试验结果的对比,证明了模型的可用性,为今后讨论破裂岩体的稳定性及其支护分析提供了参考模型。

Mechanical Models of Fractured Rock

Rock mass, as a rule, is a geological mass cut by the geological structural weak planes. It's characteristic featuers are discontinuity, inhomogenity and anisotropy.The results obtained from the compression tests in a conventional loading machine oa intact rock specimen appear to be inadequate to represent the engineering properties of rock mass,but in utilizing of stiffness testing machine the negative slope part of the stress-strain curves and the fatigue testing curves for the intact rock specimen are more fully representive of the intrinsic rock properties in the mechanical behavior and failure processes.Based on the results of various rock we present two basic mathematical models with variable mechanical parameters,i, e. Hookean body with variable elastic modulus and Saitit-Venant's body with variable yield-limit. From these simple models four mechanical models modelling the properties of the fractured rock have been developed and the corespondending constitutive equations have been developed. From the results of tests for determining the complete stress-strain curve, the parameters in the constitutive equations of fractured rock can de obtained, thus the constitutive equations are given. Based on the comparision between model analysis and testing results it is shown that these models are practicable and applicable,and they provide reference models for the further discussion of the stability of the fractured rock mass and the mechanism of its support.