轴向卸荷条件下泥炭质土回弹变形试验研究  

An experimental study of the rebound deformation characteristics and mechanism of peaty soil under unloading

作　　者：余志华[1] 桂跃[1] 付坚[1] 曹净[1] 王兆昌 

机构地区：[1]昆明理工大学建筑工程学院,云南昆明650051 [2]中国有色金属工业昆明勘察设计研究院,云南昆明650051

出　　处：《水文地质工程地质》2015年第5期107-114,共8页Hydrogeology & Engineering Geology

基　　金：国家自然科学基金青年基金资助项目(51108217);云南省科技厅应用基础研究计划资助项目(2011FZ047);岩土力学与堤坝工程教育部重点实验室开放基金项目(GH201401)

摘　　要：为分析昆明湖相泥炭质土在轴向卸荷下的回弹行为,针对不同预压荷载土样进行了分级卸荷和完全卸荷条件下的一维压缩回弹试验。试验结果表明：分级卸荷时,不同预压荷载泥炭质土卸荷回弹率λ与卸荷比R有关,回弹变形临界卸荷比Rcr为0.5,强烈回弹卸荷比Ru为0.9;泥炭质土的最大回弹率λmax与预压荷载pr呈线性关系,预压荷载越大,最大回弹率λmax越大。完全卸荷时,泥炭质土的回弹变形具有明显的时间效应,可将回弹过程分为瞬时回弹、主回弹及次回弹三个阶段;预压荷载越大,回弹率越小,残余变形量越大。预压荷载50-400 kPa的泥炭质土次回弹系数Cre在0.05-0.16之间,且随着预压荷载的增大而增大。A series of experiments were conducted to examine the resilience deformation characteristics and mechanism of Kunming platue peaty soil under complete unloading and stepped unloading. The test results show that under stepped unloading condition, the rebound deformation ratio （A） is related to the unload ratio （R）, and the critical unload ratio （Rat） is 0.5 and the drasticly unload ratio （Ru） is 0.9. The maximum rebound deformation ratio increases linearly with the increasing preloading pressure, presenting that the bigger the pressure, the larger A max value will be. While under the complete unloading condition, the time effects obviously exist and the resilience deformation after unloading is divided into the immediate rebound stage, the primary rebound stage and the secondary rebound stage. The preloading is bigger, the rebound deformation ratio is less and the residual deformation is bigger. The secondary rebound coefficients （Cre） are between 0.05 and 0. 16; and the Crevalue increases as the preloading pressure increases.

关 键 词：泥炭质土 卸荷 回弹变形 预压 次回弹系数 

分 类 号：TU47[建筑科学—结构工程]