摘要
土石坝在运营过程中,不同部位往往处于不同的应力水平。坝体在遭遇地震工况下,导致坝体内部不同部位会产生不同的地震附加应力,应力状态是影响粗颗粒材料动力特性的重要因素。为研究地震过程中应力状态的变化对坝体抗震性能的影响,本文开展不同围压、不同固结应力比及不同动应力条件下粗颗粒材料动力特性试验研究工作。研究表明:不同围压下最大动弹性模量值随着围压和固结应力比的提高逐渐增大,随着动应变的增大呈逐渐衰减趋势,衰减率随着围压和固结应力比的增加逐渐减慢;不同围压下阻尼比随着动应变的增大呈逐渐增大趋势;随着围压增加,阻尼比λ呈逐渐减小趋势;各级围压下最大动弹性模量值及阻尼比值均比较分散,不能依靠动应变对其进行归一化描述。在相同围压和固结应力比作用下,随着动应力的提高,动永久轴向变形和动永久体积均产生一定的增加;在相同围压和动应力作用下,动永久轴向变形随着固结应力比的提高而增加,动永久体积变形随着固结应力比的提高而略有降低;在相同的固结应力比和动应力作用下,随着围压的提高,动永久轴向变形和动永久体积均产生一定的增加;轴向动应变幅值是不均匀的,一般开始几周较大,后期会逐渐变小,在第10次循环左右,轴向动应变幅值逐渐趋向于定值。
In the course of operation,the different parts of earth rock dam are usually at different stress levels,accordingly,it will produce different seismic additional stress in different parts in the case of earthquake.The stress state is an important factor for the dynamic properties of coarse aggregate.In order to study the influence of the stress state on the seismic behavior of the dam,experimental research on dynamic characteristics of coarse granular materials under different confining pressures,different consolidation stress ratio and different dynamic stress were carried out.The results showed that under different confining pressures,the values of the largest dynamic elastic modulus gradually increased with the increase of the confining pressure and consolidated stress ratio and decreased with the increase of the dynamic strain,and the decreased ratio gradually decreased with the increase of the confining pressure and consolidated stress ratio.Under different confining pressure,the damping ratio gradually increased with the increase of the dynamic strain.With the increase of the confining pressure,the damping ratio λ exhibited a gradual decease tendency.The maximum dynamic elastic modulus and damping ratio under different confining pressures were scattered,and could not be described by dynamic strain.Under the same confining pressure and consolidated stress ratio,with the increase of the dynamic stress,the dynamic permanent axial deformation and volume both had a certain increase.Under the same confining pressure and dynamic stress,the dynamic permanent axial deformation increased with the increase of the onsolidated stress cratio,and the dynamic permanent volume deformation slightly decreased with the increase of the consolidated stress ratio.Under the same consolidated stress ratio and dynamic stress,with the increase of the confining pressure,the dynamic permanent axial deformation and volume both had a certain increase.The amplitude of the axial dynamic strain was not uniform,which was generally larger at the first several cycles and gradually become small at later stage and usually tended to a fixed valued at about the tenth cycle.
出处
《四川大学学报(工程科学版)》
CSCD
北大核心
2017年第S1期96-102,共7页
Journal of Sichuan University (Engineering Science Edition)
基金
国家自然科学基金重大研究计划集成项目资助(91215301)
国家自然科学基金重点资助项目(51539006)
国家自然科学基金青年基金资助项目(51309161)
关键词
应力状态
粗颗粒材料
动力特性
影响因素
试验研究
stress state
coarse aggregate
dynamic property
influence factor
experimental study