岩石压缩能量演化规律及非线性演化模型研究

Study on evolution law of rock compression energy and nonlinear evolution model

为了研究岩石在不同围压作用下的压缩能量演化规律,采用MTS815.02试验机对阜新恒大煤矿砂岩进行不同围压下三轴压缩试验,通过能量法计算出不同条件下的弹性能变化曲线,分析不同围压作用下岩石压缩能量演化规律,以及在同一围压作用下弹性模量对弹性能变化规律的影响。基于广义虎克定律和能量守恒定律,并考虑弹性能与能量释放率的关系,引入微元强度的概念,建立一种新型的能量非线性演化模型。结果表明:随着围压增大,岩石的弹性能和总能量在峰值处的数值基本呈线性增大趋势,且常规三轴压缩时的能量远大于单轴压缩时的能量,说明围压可以有效提升岩石的储能能力;在峰前阶段,模型曲线与试验数据拟合程度较高,在峰后阶段,模型曲线也可以较好地描述弹性能与轴向应变之间的关系,模型曲线与试验曲线具有良好的拟合度。这表明该模型更加接近围岩实际的变形破坏演化规律,建立的模型可以较好地反映岩石弹性能-应变变化关系,且建立的模型中的参数都可以通过试验进行确定,引入的分布参数也具有明确的物理意义。模型曲线与峰后试验曲线虽然有较大的偏离,但该模型不仅能描述峰前阶段曲线变化规律,也对峰后曲线变化规律有所描述,弥补了原有能量模型不能描述峰后曲线变化规律的缺点。

In order to study the evolution law of compressive energy of rocks under different confining pressures,MTS815.02 testing machine was used to perform triaxial compression tests on Fuxin Hengda coal mine sandstone under different confining pressures,and the elastic energy change curves under different conditions were calculated by energy calculation method.The law of rock energy evolution under different confining pressures and the influence of elastic modulus on the variation of elastic energy under the same confining pressure were analyzed.Based on the generalized Hooke′s law and the law of conservation of energy and the relationship between elastic energy and energy release rate,a new energy nonlinear evolution model was established by introducing the concept of micro-element strength.The results showed that with the increase of confining pressure,the elastic energy and total energy of the rock showed a linear increase trend at the peak point and the energy in conventional triaxial compression was much larger than that of uniaxial compression.It showed that the confining pressure can effectively improve the bearing capacity of the rock.In the pre-peak stage,the model curve was fitted to the test data to a higher degree,and in the post-peak stage,the model curve could also better describe the relationship between elastic energy and axial strain.The overall model curve had a good fit with the test curve.This indicates that the model is closer to the actual deformation and failure evolution law of the surrounding rock,and the established model can better reflect the relationship between rock elastic energystrain changes,and the parameters in the damage model could be determined through experiments.The introduced distribution parameters also has obvious physical meaning.Although the model curve and the post-peak test curve have large deviations,the model can not only describe the curve change law of the pre-peak stage,but also describe the change law of the post-peak curve,which makes up for the shortcomings of the original energy model that can not describe the curve of the post-peak curve.