水力耦合作用下含裂隙灰岩三轴试验研究

Triaxial test study on fractured limestone under hydraulic coupling

利用水力耦合试验系统,对取自郭家岩坝址区灰岩进行了变形破坏过程中的渗透特性以及声发射规律研究。结果表明:砂岩在渗透作用下的强度存在明显的围压效应,其基本呈线性关系;砂岩形变与声发射之间各阶段的变化呈对应关系,压密及弹性阶段声发射振铃计数较低,屈服阶段声发射振铃计数较高且在峰值前后达到最大值,峰后残余变形阶段声发射振铃计数略有回落;渗透率呈两阶段变化特征,在压密及弹性阶段前期逐渐略有减小,屈服阶段后逐渐增加,并在峰值前后达到最大值;基于试验成果建立起渗透率与损伤变量之间的函数关系,并通过两者关系揭示了砂岩渗透系数变化的根本原因在于试件内部损伤的累积。

A series of triaxial tests are carried out by using rock mechanical test system of hydraulic coupling in order to investigate the phenomenon of permeability and the acoustic emission about limestone under triaxial compression.The results show that in the process of triaxial stress loading,the permeability and acoustic emission is corresponding with the stress and strain in different stages.In the stage of compaction,permeability is slightly lower with the increase of stress,acoustic emission ringing count is low;in the stage of elasticity,permeability stays steady and ringing count is still low;in the stage of yield,permeability increases gradually until the peak,the ringing count also increases as the generation and development of new cracks;in the stage of remnant,permeability and ringing count are lower under the effect of confining pressure.A damage model is established through the number of acoustic emission events reflected the damage evolution of materials in the process of deformation and failure,and the model could reflect the inner factors in the process of material deformation.By relating permeability with damage,the reason of permeability changes of the limestone in the process of loading is explained.