【摘要】 采用刚性伺服试验机和声发射仪器,研究了预置三维裂隙间距对砂浆材料力学特性的影响,总结了含裂隙试件的破坏过程。综合分析单轴压缩应力-应变曲线和声发射数据可知,含三维裂隙试件的破坏主要由预置裂隙扩展、贯通造成,破坏过程可以分为微裂纹萌生、预置裂隙起裂、扩展、贯通几个基本阶段,试件最终破坏型式为单斜面剪切破坏。裂隙间距d与椭圆形裂隙长轴2c之比(d/2c)在0～1范围内,随着d/2c值增大,试件起裂应力σi和峰值强度σp有降低的趋势。当d/2c值从1/3增至2/3时,σi和σp发生突降,可见此范围为影响强度的敏感区间。d/2c值为1的试件σi和σp最低,相对完整(无预置裂隙)试件分别降低了22.48%和18.60%。裂隙间距不同的试件σi和σp之比变化范围为83.1%～78.9%,且随d/2c值增大,σi/σp有下降趋势。可见裂隙间距越大,从起裂应力到峰值应力的承载空间越大,这对工程实践有一定参考价值。更多还原

【Abstract】 The rigid serve-controlled test machine and acoustic emission equipment are used to study the influence of space between 3D-cracks on the mechanical feature of mortar material;and the failure process of samples with pre-existing cracks is concluded.The analysis of complete stress-strain curves and AE data indicates that sample failure is due to the propagation and coalescence of cracks.Failure process of samples with pre-existing cracks could be divided into the following stages:microcrack initiation,initiation of pre-existing cracks,crack propagation and crack coalescence.The failure pattern is shear failure along single inclined plane.When the ratio of cracks space d and length of elliptic crack long axis 2c ranging from 0-1,as the ratio grows,the initiation stress and maximum stress of samples reduce.With the ratio d/2c growing from 1/3 to 2/3,the initiation stress and maximum stress fall suddenly,showing that this space scope is the sensitive range.When the ratio d/2c =1,the initiation stress and maximum stress of sample fall 22.48 % and 18.60 % respectively corresponding to the sample without pre-existing cracks.The ratio of initiation stress to maximum stress of all different samples ranges from 83.1 % to 78.9 %.As the ratio d/2c grows,the ratio of initiation stress to maximum stress declines,which indicates that as space d grows,the loading range between initiation stress and maximum stress increase.更多还原