基于温度效应下二灰固化石油污染滨海盐渍土力学特性优化固化需求

温度是影响石油污染土性能的重要因素。依托滨海地区特有气候环境特点,借助抗压强度指标及应力-应变分布,从抗温敏性角度,优化石油污染滨海盐渍土对二灰的固化需求。研究结果表明:(1)在-20~40℃温度变化范围内,石油污染土抗压强度波动幅度高达1倍,采用二灰进行固化处理后,抗压强度波动缩小至10%~20%。二灰固化作用可将热敏性物质(石油、水、盐)吸附、包裹于胶体内外,增强对环境温度变化的抵抗性。(2)石油污染土及固化石油污染土的无侧限抗压强度均随温度变化呈先减小后增大趋势,10℃为强度转折点,也即最低点,实际工程中应加以重视。(3)温度作用下,固化石油污染土呈应变软化型破坏,且随温度及污染水平的增大,塑性变形阶段延长,轴向应变增大,出现四周型层状破坏。(4)土体自身的污染程度影响固化效果,高污染条件下抗压强度波动幅度约为40%,实际工程中应依据土体自身的污染程度调整固化配比。低污染土的固化配比选取只需略高于未污染土,过高固化配比并不利于增强稳定性,同比率石灰掺量的改变较粉煤灰的更有助于增强稳定性。污染水平≤6%的石油污染盐渍土,可选固化配比为石灰10%+粉煤灰20%。

Optimization of requirement for two kinds of ash solidified materials used in oil contaminated saline soil considering temperature sensitivity

Temperature is an important factor that affects properties of oil contaminated soil.This study considered the special characteristics of the climate environment in the coastal area and used unconfined compressive strength and stress-strain distribution to optimize the requirement for two kinds of ash solidified materials,and the temperature sensitivity was used as an evaluation criterion.Results indicate that the compressive strength of the oil contaminated soil significantly fluctuates,and it is up to two times in the temperature range of-20-40℃.However,the fluctuation reduces to 10%-20%after soil solidification with two kinds of ash.Solidified materials can adsorb and enclose the temperature sensitive substances(oil,water and salt)in the gel body and even outside,and then it can enhance the resistance to the variation of environmental temperature.The unconfined compressive strengths of oil contaminated soil and solidified soil decrease first and then increase with the increasing of temperature,and 10℃is the turning point,which is the lowest point.The results suggest that this temperature should be of particular concern in practical engineering.Under the action of temperature,the failure mode of solidified oil contaminated soil is strain-softening.With the increase of temperature and the contaminated level,the plastic deformation stage is prolonged,and the axial strain gradually increases.Finally,the surrounding layered damage occurs.The contaminated level of soil itself affects the solidified effect,and the fluctuation of compressive strength under a high level of contamination is about 40%.Therefore,in actual engineering,the solidified requirement should be adjusted according to the contaminated level.As to the soil with low contamination,the solidified requirement is only slightly higher than that of the uncontaminated soil,and too much solidification for the soil with low contamination is often counterproductive.Lime has more contribution than fly ash to soil stability under the same additive to soil ratio.As to the oil-contaminated saline soil with 6%contamination,the optional solidified condition is 10%lime+20%fly ash.