城市区域土体铁的化学行为与土体强度变异关系研究

统计了南宁市地下水中Fe的变化情况,实验研究了Fe的物理化学行为与土体强度之间的联系,并进一步研究了铁对土体强度影响的双向性.结果显示,城市区域将由于Fe的溶蚀、置换作用等使土体强度降低;城市区域CO2分压增高将促进土体中铁的溶蚀而使土体强度进一步恶化.在含水量相对较高时,铁质胶结物被溶解、迁移,土体强度降低;而在含水量相对较低时,铁质胶结物不易被溶解,而更趋向于发生沉淀反应,使土体对铁的吸附作用加强,从而使土体的强度增加.

Study on relationship between chemical action of Fe in soil and soil strength in urban region

The variation of Fe in groundwater of Nanning city is analysed in this paper. Based on a large amount of experimental data, a detailed discussion has been made on the relation between the physical and chemical reactions of Fe to the soil strength. Our analysis results show that the decrease of soil strength is resulted from the corrosion and replacement action of Fe in the soil of the urban areas. Furthermore, the increase of content of CO2 in air makes the corroding of Fe more seriously, thus, in the end, causing the soil strength deteriorating more quickly. At the same time, negative and positive mechanical effects have also been studied in this paper with the soil strength when the content of Fe in groundwater changes. To be exact, the result reveals that soil strength will fall because of dissolution and transfer of Fe in soil when water content of soil is relatively higher. However, when the water content of soil is rather lower, the deposition and adsorption of Fe in soil would be getting greater, which accounts for the enhancing of soil strength.