循环荷载作用下昆明泥炭质土累积变形试验研究  

Experimental study on accumulated deformation characteristics of peaty soil in Kunming under cyclic loading

作　　者：黄娟[1] 宋银涛 袁铁映 丁祖德[3] 雷明锋[1] 肖国庆 HUANG Juan;SONG Yintao;YUAN Tieying;DING Zude;LEI Mingfeng;XIAO Guoqing(School of Civil Engineering,Central South University,Changsha 410083,China;Communications Planning Survey&Design Institute Co.Ltd.of Hunan Province,Changsha 410083,China;School of Architectural Engineering,Kunming University of Science and Technology,Kunming 650500,China)

机构地区：[1]中南大学土木工程学院,湖南长沙410083 [2]湖南省交通规划勘察设计院有限公司,湖南长沙410083 [3]昆明理工大学建筑工程学院,云南昆明650500

出　　处：《中南大学学报（自然科学版）》2023年第6期2190-2196,共7页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(U1934211);湖南省自然科学基金资助项目(2021JJ30825)。

摘　　要：通过DDS-70型动三轴试验对昆明泥炭质土在不同动应力幅值、固结比、围压和加载频率条件下的累积变形进行研究。研究结果表明:泥炭质土累积变形总体发展规律与一般软黏土的变形总体发展规律相同,即当动应力幅值越大、围压和加载频率越小时,累积变形越大,发展越快。当固结比K_c≤1.50时,累积变形随固结比增大而增大。泥炭质土的累积变形发展模式主要由动应力幅值和固结比共同决定,是外部动荷载和地基土静偏应力水平的综合反映。相比于一般软黏土,泥炭质土的初期累积变形增长速度更快,且达到累积变形破坏时的临界动应力小得多,泥炭质土的累积变形破坏更具有易发性和突发性。对于下卧土层为泥炭质土的地铁工程,当K_c≤1.50,且动应力σ_d≥60 kPa时,泥炭质土累积变形为破坏发散型,为保证其长期服役性能,应避免使泥炭质土处于这种不利的受力状态。The cumulative deformation of Kunming peaty soil was studied by DDS-70 dynamic triaxial test at different dynamic stress amplitudes,consolidation ratios,confining pressures and loading frequencies.The results show that the overall development law of peaty soil is the same as that of general soft clay.The larger the dynamic stress amplitude,while the smaller the confining pressure and loading frequency,the larger the cumulative deformation,and the faster the development.When the consolidation ratio Kc≤1.50,the cumulative deformation increases with the increase of the consolidation ratio.The cumulative deformation development model of peaty soil is mainly determined by dynamic stress amplitude and consolidation ratio,which is a comprehensive reflection of external dynamic load and static deviatoric stress of foundation soil.Compared with the general soft clay,the initial cumulative deformation of peaty soil grows faster,and the critical dynamic stress is much smaller when it reaches the cumulative deformation failure.The cumulative deformation failure of peaty soil is more prone and sudden.For metro project with underlying soil layer of peaty soil,when Kc≤1.50,andσd≥60 kPa,the cumulative deformation of the peat soil is destructive and divergent.In order to ensure its long-term service performance,the peat soil should be prevented from being in this unfavorable stress state.

关 键 词：泥炭质土 累积变形 破坏条件 动三轴试验 循环荷载 

分 类 号：TU435[建筑科学—岩土工程]