石灰粉煤灰联合固化石油污染滨海盐渍土的力学特性

Mechanical properties of oil contaminated saline soil solidified with lime and fly ash

石油污染土物理力学性质较差,改善其强度是实现工程再利用的前提。以滨海地区石油污染盐渍土为研究对象,采用石灰粉煤灰进行固化处置,借助无侧限抗压强度试验,量化固化效果及各个因素的影响程度。结果表明:石灰粉煤灰联合固化可使石油污染土的抗压强度大幅提高,12%石灰+20%粉煤灰固化石油污染土的强度满足《公路路基设计规范》(JTG D30—2015)中关于二级公路上下路堤及地基土置换的抗压强度要求,且控制石油污染水平8%以内时,可满足高速公路、一级公路上下路堤中抗压强度指标要求;固化石油污染土的应力–应变曲线由直线加载、非线性上升及下降3个阶段组成,破坏模式呈应变软化型,随石油污染水平加剧,塑性变形部分增强;固化土的强度随石油污染水平加剧而下降,石油污染减缓固化反应速率,弱化石灰–粉煤灰–土颗粒间固化作用;对于石油污染水平为0~12%的盐渍土,适宜耦合条件为:12%石灰+22%粉煤灰,养护龄期28 d。

Physical and mechanical properties of oil contaminated soil is poor, thus improve its strength is the premise to reuse in engineering. Saline soil contaminated by oil was investigated and lime and fly ash were chosen as solidified materials. Unconfined compressive strength was analyzed to quantify the effectiveness and also to factors. Results indicate that： （1） lime and fly ash solidification can improved significantly the mechanical properties oil contaminated soil, the strength of solidified soi1（12% lime and 20% fly ash） meets the strength requirements to secondary highway up and down embankment and foundation replacement in Specifications for Design of Highway Subgrades （JTG D30--2015）, as oil contaminated level less than 8%, the strength reach to requirements of expressway and arterial highway. （2） Stress-strain curve of solidified soil include linear load, nonlinear rising and decline phase, and it presents strain softening damage. With the increasing of oil contaminated level, the plastic deformation is enhanced. （3） Strength of solidified soil decreased as oil contaminated level sintensified, oil contamination reduces the reaction rate, and then weakens solidification among lime, fly ash and soil particles. （4） For oil contaminated level within 12%, the suitable solidified parameters are 12% lime, 22% fly ash andcuring period of 28 d.