卸荷路径下隧道围岩力学特性及变形机制研究  

Mechanical characteristics and deformation mechanism of tunnel surrounding rock under unloading

作　　者：张凯峰 ZHANG Kaifeng(China Railway 19 Bureau Group Third Engineering Co.,Ltd.,Shenyang 110136,Liaoning,China)

机构地区：[1]中铁十九局集团第三工程有限公司,辽宁沈阳110136

出　　处：《资源信息与工程》2024年第5期91-95,101,共6页Resource Information and Engineering

摘　　要：隧道等地下工程围岩开挖属于典型卸荷过程,文章结合辽宁某在建隧道的工程实际,对该隧道围岩(砂岩)进行了复杂应力路径下的卸荷试验,分析了试样在不同损伤(LD-弱损伤,HD-强损伤)状态下的变形破坏机制。对于三轴卸荷条件:在LD状态下,轴向应变ε_(1)呈先减后增变化趋势;在HD状态下,当卸荷速率较小时(v=0.01MPa/s),ε_(1)呈逐渐增大变化趋势,当卸荷速率较大时(v>0.01MPa/s),ε_(1)呈先减后增变化趋势。对于三轴循环加卸荷条件:卸荷过程中径向应变ε_(3)呈负增大,滞回曲线的面积随循环次数的增加而增大,当应力低于前一周期的最小应力时,ε_(3)的负增长速率迅速增大;在LD状态下,应变响应△ε_(1)随卸荷速率的增加而减小;在HD状态下,当卸荷速率较低时,△ε_(1)较大,之后呈波动变化趋势;在LD状态下,△ε_(1)和△ε_(3)的变化趋势有所不同,△ε_(3)随循环周期的增加而逐渐增大,而△ε_(1)在前5次循环周期内无明显变化趋势;在HD状态下,△ε_(1)和△ε_(3)呈逐渐增大趋势。研究结果可为揭示隧道等地下工程围岩的开挖卸荷破坏机制提供理论依据。Surrounding rock excavation of underground engineering such as tunnels is a typical unloading process.Based on the engineering practice of a tunnel under construction in Liaoning Province,the unloading test of surrounding rock(sandstone)was carried out under complex stress paths,and the deformation and damage mechanisms of the sample under different damage conditions(LD-weak damage,HD-strong damage)were analyzed.For the triaxial unloading condition,the axial strain ε_(1) shows a trend of decreasing first and then increasing in LD state,while in HD state,ε_(1)shows a trend of gradually increasing when the unloading rate is small(v=0.01 MPa/s),and decreasing first and then increasing when the unloading rate is large(v>0.01 MPa/s).For triaxial cyclic unloading condition,the radial strainε_(3)increases negatively during unloading,the area of the hysteresis curve increases with the increase of the number of cycles,and the negative growth rate ofε_(3)increases rapidly when the stress is below the minimum stress of the previous cycle.In LD state,the strain response△ε_(1)erdecreaseswiththeincrease of unloading rate;in HD state,the△ε_(1)eislargewhen theunloadingrateislow,and then it fluctuates.Thevariation trendsof△ε_(1)ei and△ε_(3)garedifferent in LD state,△ε_(3)egincreasesgradually withtheincreaseof cyclingcycles,while△ε_(1)hasno obvious trend in the first 5 cycling cycles;in HD state,△ε_(1)and△ε_(3),increase gradually.There searchre sultscan provideatheoretical basis for revealing the excavation unloading damage mechanism of the surrounding rock in tunnels and other underground projects.

关 键 词：隧道围岩 砂岩 应力路径 循环卸围压 卸荷速率 应变响应 

分 类 号：TU91[建筑科学—建筑理论]