石油污染水平对固化参数的需求分析

Analysis of requirement of oil contaminated level for solidified parameters

针对受石油污染盐渍土后所引起的复杂环境岩土问题,选用石灰、粉煤灰为固化材料,通过三轴剪切和扫描电镜试验探讨石油污染水平对固化参数的需求机制。结果表明:固化污染土黏聚力c较内摩擦角φ对提高抗剪强度更加显著,随龄期的延长,变形模量和主应力差逐渐增大,破坏方式由应变硬化型转变为应变软化型脆性破坏。轻度污染(污染水平≤4%)对固化反应影响较小,适宜固化参数为6%石灰+20%粉煤灰+28 d,石油特性在养护初期对c,?值影响较大,二灰掺量的增加会引起膨胀效应和滑珠作用;中度污染(污染水平4%～8%),石油污染对抗剪强度体现为劣化作用,适宜固化参数为8%石灰+25%粉煤灰+28 d。养护初期,石油润滑性和黏滞性的转变点与石灰掺量、石油污染水平呈动态变化。重度污染(污染水平8%～12%)下,石油黏滞性随石灰掺量的增加而减小,石油的物理包容迟滞了火山灰反应的程度和速率,致使生成物结晶程度不良和养护后期强度仍保持较大增长,需增大固化材料掺量以遏制石油对材料的滞碍性和阻截水分作用。

Based on the problems existed in the complex environmental geotechnology caused by oil contaminated saline soil,lime and fly ash was chosen as solidified materials,triaxial shear strength and scanning electron microscope(SEM)experiments were carried out to analyze the requirement mechanism of solidified parameters to different oil contaminated level.Results indicated that:(1)Cohesion(c)of solidified soil was improved more remarkable than that of internal friction angle(φ).With lengthen of curing periods,soil deformation modulus and deviator stress was gradually increased,and the failure form was changed from strain hardening to strain softening.(2)Oil contamination had less effect on curing reaction as it was slight(contaminated level≤4%),and the suitable solidified parameters were lime of 6%+fly ash of 20%+curing period of 28 d.In addition,the c,φwere affected obviously by oil characteristics in the initial curing,and the problems of expansion and the slide action was caused by the increase of lime and fly ash content.(3)As regards oil contamination level of 4%–8%,shear strength was degraded by oil contamination,and the suitable solidified parameters were lime of 8%+fly ash of 25%+curing period of 28 d.There was dynamic variation among transition point of oil lubricity to viscosity,lime content and oil contaminated level in the initial curing.(4)For oil contamination level of 8%–12%,oil viscosity was decreased with the increasing of lime content,and then the extent and rate of pozzolanic reaction was delayed by the physical containment of oil.As an incomplete crystallization,strength was increased continually in later curing.Therefore,it suggested increasing the lime and fly ash content to solve the problem of oil obstruction on solidified material and of blocking on water migration as to heavily oil contaminated soil.