为分析随着尾矿坝坝高的增加,处于尾矿库高埋深条件下的尾矿料在地震作用下是否会出现液化现象或发生较大永久变形,选择尾砂土进行高埋深条件下不同围压400,800,1 200 kPa的动强度试验,并进行尾砂土液化影响深度分析。分析成果表明高埋深条件下尾砂土的动应力随围压的增加而增大,随固结应力比的增加而增大,变化规律和小围压下的变化规律基本相同;高围压条件下,围压对液化应力比影响较大,液化应力比随围压的增加而减小,但归一化较差。采用规范的尾矿料地震液化判别方法,在尾砂土较小干密度和低固结应力比条件下,中部尾砂土存在大概率液化可能,随着地震作用应力比随埋深的逐渐折减,底部尾砂土可以不考虑液化问题
Abstract
Evaluating the seismic safety of tailing dam involves the liquefaction or even permanent deformation of tailings material at large buried depth in middle and low parts of tailings pond. In this paper, the dynamic strength of tailings sand in large buried depth was tested under different confining pressures (400 kPa, 800 kPa, and 1 200 kPa), and the influenced depth of liquefaction was investigated. Results manifested that the dynamic stress of tailings sand in large buried depth increased with the rising of confining pressure and consolidation stress ratio, while liquefaction stress ratio decreased with the increase of confining pressure. Except for the liquefaction stress ratio under high confining pressure, the rules of dynamic stress and liquefaction stress ratio varying with confining pressure and consolidation stress ratio under high confining pressure are in general the same as those under low confining pressure. According to the liquefaction judgment method recommended in standard, the tailings sand with small dry density and low consolidation stress ratio in the middle of tailings pond are most probably to experience liquefaction. On the contrary, for tailings sand in the bottom, liquefaction can be ignored as seismic stress ratio reduced gradually with buried depth.
关键词
尾矿坝 /
尾砂土 /
动强度试验 /
高埋深 /
液化深度
Key words
tailings dam /
tailings sand /
dynamic strength test /
large buried depth /
liquefaction depth
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基金
国家重点研发计划项目(2017YFC0404804);国家自然科学基金-雅砻江联合基金重点项目(U1765203);长江科学院创新团队项目(CKSF2015051/YT)
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