摘要
作为一种典型软岩,盐岩力学特性的时间相关性显著,准确预测和评估盐穴储气库加卸载过程中的变形损伤能力,关系到能源储备库的长期安全稳定运行。为研究盐岩的速率效应,进行了不同加卸载速率的疲劳试验。基于现有蠕变本构模型,构建了速率效应方程,区分了加卸载过程中的蠕变塑性变形与加载塑性变形。研究结果表明:(1)盐岩的整体疲劳寿命、稳定变形阶段(即第2阶段)疲劳寿命占比基本随加卸载速率的增大而增大。(2)减速变形阶段(即第1阶段)疲劳寿命占比、稳定变形阶段平均残余应变基本随加卸载速率增大而减小。(3)速率耦合疲劳试验中,加卸载速率越大,残余应变越小,蠕变塑性变形随加卸载速率的增大而减小,当加卸载速率由0.04 kN/s增加至5 kN/s时,蠕变塑性变形在循环中的占比由85%下降至36%,呈现出负指数的关系。(4)整个循环加卸载过程中,加载塑性变形、蠕变塑性变形均呈现U型发展趋势,与盐岩疲劳过程的三阶段相对应。该研究结果可以为进一步分析盐岩蠕变塑性与加载塑性奠定基础。
As a typical soft rock,the mechanical properties of salt rock are time-dependent significantly,so the accurate prediction and evaluation of the deformation and damage capacity of salt cavern gas storage during loading and unloading are related to the long-term safe and stable operation of energy reserves.In order to study the rate effect of salt rock,fatigue tests at different loading and unloading rates were conducted.Based on the existing creep constitutive model,the rate effect equation was established to distinguish the creep plastic deformation and loading plastic deformation during loading and unloading.The results show that:(1)The overall fatigue life of salt rock and the proportion of fatigue life in stable deformation stage(the second stage)increase with the increase of loading and unloading rate.(2)The proportion of fatigue life in decelerated deformation stage(the first stage)and the average residual strain of stable deformation stage decrease with the increase of load rate.(3)In the rate-coupled fatigue test,the residual strain decreases with the increase of loading and unloading rate.The creep plastic deformation decreases with the increase of loading and unloading rate.When the loading rate increases from 0.04 kN/s to 5 kN/s,the proportion of creep plastic deformation in the cycle decreases from 85% to 36%,showing a negative exponential relationship.(4)In the full cyclic loading and unloading process,the plastic deformation of loading and creep presents a U-shaped development trend,which corresponds to the three stages of fatigue process of salt rock.The results of this study can lay a foundation for further analysis of creep plasticity and loading plasticity of salt rock.
作者
姜德义
杨镇宇
范金洋
李宗泽
锁进杰
陈结
JIANG De-yi;YANG Zhen-yu;FAN Jin-yang;LI Zong-ze;SUO Jin-jie;CHEN Jie(State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University,Chongqing 400044,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2023年第2期403-414,共12页
Rock and Soil Mechanics
基金
国家自然科学基金重点项目(No.51834003,No.52274073,No.52274199)。
关键词
盐岩
循环荷载
疲劳寿命
残余应变
速率效应
salt rock
cyclic loading
fatigue life
residual strain
rate effect
