长期浸水状态下石膏土的承载特性试验研究

Experimental study on bearing capacity of gypsum soil under long-term immersion condition

以伊拉克某石化项目为依托,通过现场浸水载荷试验和室内土工试验探讨了石膏土在长期浸水状态下的承载性能和变形特性,分析了石膏土产生溶陷沉降的机理。研究结果表明:石膏土的溶陷性可参照盐渍土的浸水载荷试验进行评价和分析,在本试验条件下该地区石膏土层为轻微溶陷性土;长期浸水状态下石膏土的沉降量可增长4.7~6.48倍,承载力降低12.5%;石膏土的密实度、土中石膏及其他易溶盐水溶性大小对其承载力影响较大,浸水前后以石膏为主要成分的石膏土,石膏的含量沿深度降低62.6%~83.7%,总盐量降低44.1%~63.9%,有机质降低71.9%~82.4%,三氧化硫降低44.7%~46.8%,其他盐类降幅较大。研究结果可为类似工程的设计、施工及检测提供参考与借鉴。

Based on the project of a petrochemical project in Iraq, the bearing capacity and deformation characteristics of gypsum soil under long-term immersion state are discussed through the field immersion tests and indoor geotechnical tests. The settlement mechanism of the gypsum soil is analyzed. The study results show that the dissolution of the gypsum soil could be evaluated and analyzed according to the immersion tests of saline soil. Under the experimental conditions, the gypsum soil layer in this area exhibits a slight dissolution. The settlement of the gypsum soil immersed over a long period of time could increase by 4.7 -6.48 times and the bearing capacity could decrease by 12.5%. The compactness of the soil and the water solubility of gypsum and other salts have a great influence on the bearing capacity and deformation characteristics. Before and after soaking, the average amount of gypsum for the soil which is mainly composed of gypsum would decrease by 62.6%- 83.9% along the depths, the amount of total salt would averagely decrease by 44. 1% -63.9% , the amount of organic matter would averagely decrease by 71.9% - 82.4%, the amount of SO3 would averagely decrease by 44. 7% -46.8%, and the other kinds of salts would greatly decrease. The study results could provide the reference for the design, construction and testing of similar projects.