混合岩变形及损伤演化试验研究

Experimental study on deformation and damage evolution of mixed rock

利用SAM-2000型岩石伺服试验系统和DS2声发射监测仪,对混合岩进行三轴压缩声发射试验,根据声发射参数,分析三轴压缩条件下岩石的损伤演化特征。试验结果表明:轴应变随着围压的变化呈线性正相关关系;每当混合岩岩样出现裂缝时,累计声发射振铃计数数值即发生骤增,且随着围压的增大,岩石破裂前声发射特征参数呈突发性特征;建立了混合岩体应变损伤演化模型,该混合岩体应变损伤演化模型描述混合岩损伤过程分为初始损伤阶段、损伤稳定发展阶段、损伤加速发展阶段和损伤破坏阶段;低围压下混合岩主要发生弹脆性破坏,随着围压的增大,混合岩由弹脆性向延性转换,混合岩在20 MPa围压压缩过程中由延性转化为塑性。该结果合理地反映了由低围压到高围压,混合岩由弹脆性到弹延性再到弹塑性的转化。

Acoustic emission tests under triaxial compression of limestone are carried out by SAM-2000 servo-controlled rock mechanical test system and DS2 acoustic emission monitor.The characteristics of mixed rock damage evolution under triaxial compression are analyzed through acoustic emission parameters.The results show that the axial strain has a linear positive correlation with the change of confining pressure;whenever there is a crack in the mixed rock sample,the cumulative acoustic emission ringing count will increase sharply,and with the increase of confining pressure,the acoustic emission characteristic parameters on the eve of rock rupture will exhibit sudden characteristics.The strain damage evolution model of the mixed rock mass is established.The strain damage evolution model of mixed rock mass is established.The strain damage evolution model of mixed rock mass is described.The mixed rock strain damage evolution model describes the mixed rock damage process divided into initial damage stage,damage stable development stage,accelerated damage development stage and damage stage;the elastic brittle failure occurs mainly in the mixed rock under low confining pressure.With the increase of confining pressure,the mixed rock transforms from elastic brittleness to ductility.The mixed rock transforms from ductile state to plastic state during 20 MPa confining compression.The results are reasonably reflect the transformation from elastic confining to elastic ductility to elastoplasticity from low confining pressure to high confining pressure.