摘要
堆石料变形具有时间相关性。本文采用两河口特高砾石土心墙堆石坝的坝壳风干板岩堆石料开展不同应力加载速率下的大型侧限压缩试验,以及侧限压缩后卸载再加载试验、蠕变变形试验。对于侧限压缩试验,中低应力下,应力速率越高、变形增量越大、模量越小;高应力下,应力变形过程受应力速率的影响减小,规律反之,即应力速率越高、变形增量越小、模量越高。对应加载全过程,堆石料变形量总体随应力速率提高而增大。侧限压缩后卸载和再加载过程中形成滞回曲线,每次卸载-再加载中有一定的变形累积,每次变形累积增量随卸载-再加载次数逐渐减小,且各次卸载-再加载过程中的平均回弹/再压缩指数随卸载-再加载次数逐渐减小。一般地,应力速率越高,卸载和再加载变形量均更小。同时,应力速率越高,卸载-再加载循环中的变形累积增量越小、收敛也越快。以一定应力速率加载到特定荷载后的蠕变速率与蠕变时间在双对数坐标中近似为线性关系。初始蠕变速率随应力和应力速率增大而增大,而蠕变速率衰减速度随应力和应力速率增大而减小。
The deformation behaviors of rockfill material are time-dependent. In this work, large scale confined compression tests with the loading at different stress rates, successive unloading-reloading tests,and successive creep tests after the loading are conducted using test materials from the dry rockfill of slate designed for the shell material of the Lianghekou high gravelly-soil-core rockfill dam. The stress deformation process of the test material is obviously affected by its stress rate. For confined compression under medium-low stress, a higher stress rate leads to a larger deformation increment and a smaller confined compression modulus. Under high stress, the influence of stress rate on stress strain process weakens;however, a higher stress rate leads to a smaller deformation increment and a larger confined compression modulus, which is opposite to the medium-low stress case. During loading, rockfill deformation generally increases with the rising of stress rate. A hysteresis curve is formed during successive unloading-reloading at a constant stress rate after confined compression. A certain deformation is accumulated in each unloading-reloading cycle;the accumulation increment of each cycle is gradually decreased with the times of cycles, and the average rebound/recompression index is also decreased.Generally, for each cycle, a higher stress rate is related to smaller unloading deformation and reloading deformation, smaller accumulated deformation increment as well as faster convergence. The relationship between creep rate and creep time after loading is nearly linear in double logarithmic coordinates. As stress or stress rate increases, the initial creep rate grows, while the decay rate of creep rate is lowered.
作者
黄文超
张贵科
邓刚
张延亿
张茵琪
陈辉
HUANG Wenchao;ZHANG Guike;DENG Gang;ZHANG Yanyi;ZHANG Yinqi;CHEN Hui(State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin,China Institute of Water Resources and Hydropower Research,Beijing 100038;Key Laboratory of Water Project Construction and Safety,Ministry of Water Resources,China Institute of Water Resources and Hydropower Research,Beijing 100038;Yalong River Hydropower Development Company,Ltd,Chengdu 610065)
出处
《水力发电学报》
CSCD
北大核心
2022年第6期141-152,共12页
Journal of Hydroelectric Engineering
基金
中国水科院基本科研业务费项目(GE0145B032021)
雅砻江流域水电开发有限公司项目(0023-20XJ0080,0023-20XJ0082)。
关键词
应力速率
堆石料
压缩变形
加卸载循环
蠕变速率
stress rate
rockfill
compression deformation
loading-unloading cycle
creep rate
