基于破坏类型的本溪灰岩本构关系研究

Research on the Constitutive Relation of Benxi Limestone Based on Failure Types

根据单轴和三轴条件下本溪灰岩的压缩试验和峰后循环加载试验,总结本溪灰岩的强度、变形随围压的变化规律,研究不同围压下本溪灰岩的破坏过程和重复加载过程,分析不同应力条件下本溪灰岩破坏的方式。结果表明:本溪灰岩在应力刚过峰值且未完全进入残余强度阶段,其弹性模量与峰前相同,此阶段进行循环加载时,新的峰值应力低于卸载点应力;在残余强度阶段,残余强度不再随重复加载发生明显变化;采用比较峰值时的环向弹性应变值与环向应变值的方法来判别本溪灰岩的破坏类型是可行的;不同围压下,本溪灰岩的破坏方式有张性破坏和剪切破坏2种类型,这2种破坏方式下本构模型的控制参数是不同的。分别选取了环向应变和剪切应变作为控制参数建立了本构模型,该模型很好地描述了本溪灰岩峰后阶段的应力脆性跌落现象及应力与应变的关系。

Based on the uniaxial and triaxial compression mechanical tests and the cyclic loading tests in the post-peak period of Benxi limestone,its strength and deformation with different confining pressures,processes of failure and cyclic loading,and failure types in different stress were studied.The results showed that in the post-peak but the strength has not decreased to the residual strength period,the elastic modulus is equal to the elastic modulus in pre-peak,and the new peak stress will be lower than the stress of starting unloading.In the period that the strength decreases to the residual strength,the strength will not decrease with the cyclic loading.It is viable to adopt the method that comparing circumferential elastic strain with circumferential strain of peak to judge the failure type of Benxi limestone.There are two failure types that are tensile failure and shear failure for Benxi limestone in different confining pressures,and the relation between rock damage and failure should be considered in founding the constitutive model.Based on this,circumferential strain and shear strain were selected as the distribution variables in the new statistical constitutive model which describes the brittle stress-drop and relation between stress and strain in the post-peak period very well.