二灰固化石油污染盐渍土的力学增强演变机制

1)河北工业大学土木与交通学院,天津 300401; 2)河北省土木工程技术研究中心,天津 300401; 3)中航天建设工程有限公司,北京 100071

石油污染土; 无侧限抗压强度; 响应面法; 扫描电镜; 石灰粉煤灰固化; 滨海盐渍土

Formation and development of oil contaminated saline soil solidified with lime and fly ash
LI Min1, 2, WANG Chen1, and XIE Shoubin3

1)School of Civil Engineering and Transportation, Hebei University of Technology, Tianjin 300401, P.R.China2)Hebei Research Center of Civil Engineering Technology, Tianjin 300401, P.R.China3)Zhonghangtian Construction Engineering Co. Ltd., Beijing 100071, P.R.China

oil-contaminated soil; unconfined compressive strength; response surface methodology; scanning electron microscope; lime and fly ash treatment; inshore saline soil

DOI: 10.3724/SP.J.1249.2018.02119

备注

为实现石油污染土固化处置后资源化利用,通过无侧限抗压和扫描电镜试验,探讨在不同龄期下,石灰质量分数、粉煤灰质量分数和石油污染水平的交互作用,依托响应面法分析固化污染土强度的形成、发展及固化增强机制. 结果表明,固化初期(7 d内),污染水平较大和二灰质量分数较小(石灰4%、粉煤灰18%)均有利于改善土体整体性,过量二灰易于造成土体膨胀和水分进入; 固化中期(7~14 d),固化反应以化学作用为主,固化材料的火山灰反应致所需二灰质量分数增加较大; 石油的物理包容对火山灰反应存在延迟作用,导致固化后期(14~28 d)强度仍有较大增长,生成物与粉煤灰协同固化石油污染物和重度污染土形成结构疏松的大型团聚体,降低了生成物的结晶程度.建议针对重度石油污染土,适当延长龄期和增加二灰质量分数,以使强度趋于稳定,确保固化材料性能得到充分发挥.

To realize resource utilization of solidified oil contaminated soil, unconfined compressive strength and scanning electron microscope(SEM)experiments are used to quantify the interaction of lime content,fly ash content and oil-contaminated level under different curing periods. The response surface methodology is employed to optimize the formation and development of solidified soil strength and solidification mechanism. Results show that in the early curing(less than 7 d), the larger oil content and smaller lime and lay ash content(4% and 18%)are beneficial to the improvement of soil integrity, but excessive lime causes soil swelling and moisture entry. During the curing period of 7-14 d, solidified reaction is converted into chemical action, pozzolanic reaction between the solidified materials leads to a larger increase of lime and fly ash content. The pozzolanic reaction delayed by the physical entrapment of oil causes that the strength at the final stage of solidification(14-28 d)still increases greatly, the resultants and fly ash combined with solidified oil pollutants, and the heavily oil contaminated soil form large aggregates with loose structure which reduces the degree of crystallization of resultants. As to the heavily oil contaminated soil, it is suggested that we should properly increase the lime, fly ash content and extend curing period in order to stabilize the strength and ensure the performance of solidified materials.

·