基于不同初始静偏应力的结构性软黏土动力特性试验研究

发布时间：2018-01-12 23:07

本文关键词：基于不同初始静偏应力的结构性软黏土动力特性试验研究　出处：《公路交通科技》2017年10期 　论文类型：期刊论文

【摘要】：以天津滨海新区结构性海积软土为研究对象,采用GCTS动静扭剪试验仪,基于正弦波与方波两种波形,在固结排水条件下施加不同初始静偏应力,通过考虑循环振次、应力幅值、振动频率以及围压等因素对土体结构的影响,研究结构性软黏土的动力特性。试验结果表明:初始静偏应力小于土体初始屈服应力时,施加静偏应力增加了土体固结度,提高了其结构强度,应变软化现象减弱,累积塑性应变曲线中屈服点对应的应力值大。初始静偏应力大于土体初始屈服应力时,土体初始结构破坏,出现严重的应变软化现象,累积塑性应变曲线迅速由稳定型转变为临界型,且在同条件下,方波应变值始终大于正弦波。孔压变化与初始静偏应力有关,随着静偏应力增大其孔压滞后现象严重。土体屈服应变随初始静偏应力增大而增加,静偏应力及振次相同时,方波作用下的土体屈服应变值小于正弦波。两种波形下,土体屈服应变随振次增加均呈减小趋势,且最终均会趋于一点,正弦波趋于相同数值下的振次远大于方波。土体动强度随应变标准提高而呈现增大趋势,应变标准为屈服应变值时,动强度曲线表现为先陡后缓,其他应变标准下动强度曲线较为平缓。两种波形下的动强度随振次增加而减小,最终均会趋于一点,且正弦波值大于方波。
[Abstract]:Taking the structural marine soft soil in Tianjin Binhai New area as the research object, using GCTS static and torsional shear test instrument, based on sinusoidal wave and square wave, different initial static deflection stress is applied under the condition of consolidation and drainage. The effects of cyclic vibration times, stress amplitude, vibration frequency and confining pressure on soil structure are considered. The dynamic characteristics of structural soft clay are studied. The experimental results show that when the initial static deflection stress is smaller than the initial yield stress, the application of static deflection stress increases the consolidation degree of the soil and improves its structural strength. The strain softening phenomenon is weakened and the stress corresponding to the yield point in the cumulative plastic strain curve is large. When the initial static deflection stress is larger than the initial yield stress of the soil the initial structure of the soil is destroyed and serious strain softening occurs. The cumulative plastic strain curve changes rapidly from stable type to critical type, and under the same conditions, the square wave strain value is always larger than sine wave. The change of pore pressure is related to the initial static stress. With the increase of static stress, the pore pressure lag phenomenon is serious, and the yield strain of soil increases with the increase of initial static stress, when the static stress and vibration times are the same. The yield strain of soil under square wave is smaller than that of sinusoidal wave. Under the two waveforms, the yield strain of soil decreases with the increase of vibration frequency, and will tend to a point in the end. The dynamic strength of soil increases with the increase of strain standard, when the strain standard is yield strain, the dynamic strength curve is steep first and then slow. The dynamic intensity curves under other strain standards are relatively gentle. The dynamic strength of the two waveforms decreases with the increase of vibration frequency, and eventually tends to a point, and the sine wave value is larger than the square wave.
【作者单位】：天津城建大学天津市软土特性与工程环境重点实验室;天津港中煤华能煤码头有限公司;
【基金】：国家自然科学基金项目(41372291) 天津市科技计划项目(15JCZDJC40600,15ZCZDSF00220)
【分类号】：U414
【正文快照】： strain value is always larger than the sine wave strain value under the same condition;(3)the pore pressurechange is associated with initial static deviatoric stress,the pore pressure lagging phenomenon is serious withthe increase of static deviatoric st

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