干湿循环对石灰粉煤灰固化石油污染土抗压强度的影响

EFFECT OF WETTING AND DRYING CYCLES ON THE COMPRESSIVE STRENGTH OF OIL-CONTAMINATED SOIL TREATED WITH LIME AND FLY ASH

中国北部沿海地区夏季多雨,春季干燥多风,土体吸水膨胀、脱水收缩,降低了固化土的抗压强度,研究固化土干湿交替条件下的力学稳定性是实现其工程利用的前提。室内模拟干湿循环,借助无侧限抗压强度指标探究石灰粉煤灰固化石油污染土的力学分布规律。结果表明:经历干湿循环后固化污染土的质量前6次下降较小,7~8次下降明显,9次后趋于稳定,最大下降幅度为4.5%;固化污染土的抗压强度随干湿循环次数的增加而增强,3次循环后抗压强度较初始强度增加了35%,之后逐渐减弱,7次循环后强度趋于稳定,稳定时强度达到初始强度的70%;固化污染土强度的水稳性随含油率的提高逐渐降低,破坏形态随干湿循环次数的增加由软化型逐渐向硬化型转变;当二灰比为0.75,抗干湿循环稳定性较好。石油污染土重新利用时应注意干湿循环对工程的影响。

In the northern coastal area of China,the alternated phenomenon of rainy season and dry-windy weather is threatening the soil stability.It needs to improve the mechanical properties of treated soil under dry and wet cycles before utilization.The mechanical distribution of oil contaminated soil treated with lime and fly ash are studied in this manuscript.Unconfined compressive strength index is chosen.Wet and dry cycle process is simulated.Results indicate the follows.(1)The quality of treated oil contaminated soil decreased with wet-dry cycle process.It presented small fluctuations in 6 times,then decreased significantly during 7-8 times,and stabilized finally after 9 times.The maximum decrease is 4.5%.(2)The compressive strength of oil contaminated soil treated with lime and fly ash increased first and then decreased with the increasing of dry and wet cycles.It reached the maximum at 3 times.It stabilized after 7 times.The residual strength was more than 70%of initial strength.So the oil contaminated soil treated with lime and fly ash had good water stability.(3)The water stability of treated oil contaminated soil reduced with the increasing of oil contamination levels.The failure gradually tended to hardening type with wet-dry cycle.The best proportion of lime and fly-ash was 0.75.Therefore,the oil-contaminated soil can be used as roadbed fill to achieve the purpose of recycling contaminated soil.