分级动荷载下土石混合体滞回曲线形态特征试验研究
Morphological characteristics of hysteretic curves of soil-rock mixture under stepped axial cyclic loading
黄锋 1米吉龙 1杨永浩 1董广法 1张班 1刘星辰1
作者信息
- 1. 重庆交通大学省部共建山区桥梁及隧道工程国家重点实验室,重庆 400074;重庆交通大学土木工程学院,重庆 400074
- 折叠
摘要
城市回填区地层多以松散土石混合体形式存在,自身结构孔隙率大、强度低、工程性能较差,对隧道施工扰动和地铁列车运行等动载作用十分敏感.滞回曲线可反映土体在动荷载作用下的变形、刚度及能量耗散等特征,研究土石混合体滞回曲线对回填区地铁的施工和运营安全具有重要意义.利用KTLDYN伺服电机控制式动三轴试验系统,采用分级加载的方式对回填区土石混合体试样进行了循环荷载试验,研究了含石量P、含水率ω、固结应力比kc和加载频率f对滞回曲线的形态特征(包括中心间距d、长轴斜率k、滞回曲线包围面积S和不闭合程度εp)和骨干曲线的影响.研究结果表明:土石混合体的典型滞回曲线整体呈长梭形,两端呈尖叶状.d、S、εp随着振级的增加呈非线性增大,k随着振级的增加呈对数关系衰减.同一振级下,d和εp随着P、kc和f的增大而减小,随着ω的增大先减小后增大;k随着P、kc和f的增大而增大,随着ω的增大先增大后减小;S与P呈正相关,随着ω的增大先增大后减小,随着kc和f的增大而减小.当动应变相同时,动应力和骨干曲线斜率均随P、kc和f的增大而不断增大;随ω的增大先增大后减小.
Abstract
The strata in urban backfill areas mostly exist in the form of loose soil-rock mixture,with high structural porosity,low strength,and poor engineering performance.They are sensitive to dynamic loads such as tunnel construction disturbance and subway train operation.The hysteretic curve can reflect the deformation,stiffness and energy dissipation of soil under dynamic load.It is of great significance to study the hysteretic curve of soil-rock mixture for the construction and operation safety of subway in backfill area.Using KTLDYN servo-controlled dynamic triaxial test system,the cyclic load test on soil-rock mixture samples in backfill area was carried out by means of cyclic loading.The effects of stone content(P),water content(ω),consolidation stress ratio(kc)and loading frequency(f)on the morphological characteristics(including adjacent center spacing(d),long axis slope(k),enclosing area(S)and degree of non-closure(εp))and backbone curves of hysteretic curves are investigated.The results show that the typical hysteretic curves of soil-rock mixture are in long fusiform shape on the whole,with pointed lobes at both ends.With the increase in vibration level,d,S and εp increase nonlinearly,while k decreases logarithmically.For the same vibration level,d and εp decrease with the increases of P,kc and f,and first decrease and then increase with the increase of ω k increases with the increases of P,kc and f,and increases first and then decreases with the increase of ω.S is positively correlated with P,increasing first and then decreasing with the increase of ω,and decreasing with the increases of kc and f.The dynamic stress and slope of backbone curve increase with the increases of P,kc and f when the dynamic stress variation is the same,and they first increase and then decrease with the increase of ω.
关键词
土石混合体/动三轴试验/滞回曲线/骨干曲线/动力特性Key words
soil-rock mixture/dynamic triaxial test/hysteretic curve/backbone curve/dynamic property引用本文复制引用
基金项目
重庆市自然科学基金面上项目(CSTC2020JCYJ-MSXMX0679)
重庆市自然科学基金面上项目(CSTB2022NSCQ-MSX0497)
山区桥梁及隧道工程国家重点实验室开放基金(SKLBT-19-006)
山区桥梁及隧道工程国家重点实验室开放基金(SKLBT-YF2106)
重庆市教委科学技术研究计划(KJQN202100717)
国家自然科学基金(52078090)
出版年
2024
国家科技期刊平台
NSTL
万方数据