不同卸围压速率下灰岩卸荷力学特性试验研究  

Experimental research on unloading mechanical properties of limestone under different confining pressure unloading rates

作　　者：周传涛 ZHOU Chuantao(China Railway 20th Bureau Group 4th Engineering Co.Ltd.,Qingdao 266061,China)

机构地区：[1]中铁二十局集团第四工程有限公司,山东青岛266061

出　　处：《实验技术与管理》2022年第10期30-35,共6页Experimental Technology and Management

摘　　要：围岩卸围压力学特性对于了解围岩破裂机制、准确地判断围岩稳定性具有重要意义,为了更全面地认识卸围压速率对岩石力学特性的影响,对灰岩进行不同卸围压速率梯度的三轴卸围压试验,基于卸围压速率的变化,分析灰岩力学特性及变形破坏特征。结果表明,在卸围压过程中:①当卸围压速率为0.5 MPa/min时,环向应变和体积应变达到最大值,其环向应变围压增量比和体积应变围压增量比也达到最大值,分别为0.514和1.027。②当围压卸荷率在较低水平时,不同卸围压速率下的变形模量和泊松比对围压卸荷率不敏感,当围压卸荷率增大到50%时,变形模量明显增大,泊松比明显降低。③卸围压速率较低时,试样表面产生较多轴向张拉裂隙,整体以张拉破坏为主;卸围压速率增大时,破坏形式由张拉破坏转变为剪切破坏为主。The mechanical behavior of surrounding rock under unloading confining pressure condition has a great significance for understanding the failure mechanism and accurately judging the stability of surrounding rock.In order to have a more comprehensive understanding of the effect of confining pressure unloading rate on rock mechanical properties,triaxial confining pressure unloading tests with different confining pressure unloading rate gradients are carried out on limestone,and mechanical properties and deformation and failure characteristics of limestone are analyzed based on the change of confining pressure unloading rate.The results show that in the process of unloading confining pressure:①When the unloading rate is 0.5 MPa/min,the circumferential strain and volumetric strain reach the maximum value,and so do the circumferential strain and volumetric strain confining pressure increment ratio,which are 0.514 and 1.027 respectively.②When the confining pressure unloading rate is at a low level,the deformation modulus and Poisson's ratio are not sensitive to the confining pressure unloading rate at different unloading rates.When the confining pressure unloading rate increases to 50%,the deformation modulus increases significantly and Poisson’s ratio decreases significantly.③When the confining pressure unloading rate is low,there are more axial tensile cracks on the surface of the specimen,and the tensile failure is the main failure.When the confining pressure unloading rate increases,the failure mode changes from tensile failure to shear failure.

关 键 词：卸荷试验 力学特性 变形特征 破坏模式 

分 类 号：TU45[建筑科学—岩土工程]