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通过室内试验,考察了去离子水及不同浓度总氮溶液对土体物理力学性能的影响,并通过土体矿物成分含量及微观形貌分析,对总氮溶液与土体作用机制进行了初步探讨。结果表明,总氮对土体物理力学性能影响明显:(1)土体塑性指数、相对密度和有效黏聚力随总氮溶液浓度增大而减小,有效内摩擦角随溶液浓度的增大而增大;(2)各浸泡条件下,土体应力-应变关系曲线变化规律基本一致,均呈应变硬化现象,土体剪切峰值随总氮溶液浓度的增大先减小后增大;(3)孔隙水压力随轴向应变的增加先增加,然后缓慢降低,最后曲线逐渐趋于水平,表现出较大的剪胀性;(4)总氮溶液与土体间相互作用主要包括离子交换作用、微生物分解作用和溶蚀及胶结作用,这些作用通过改变土体的矿物成分含量,使其微观形貌及孔隙特征发生明显变化,最终导致土体的宏观力学特性改变。
The effects of deionized water and different concentrations of total nitrogen solution on physical and mechanical properties of soil were investigated through laboratory experiments. The mechanism of action of total nitrogen solution and soil was discussed based on the analysis of mineral composition and microstructure of soil. . The results showed that total nitrogen significantly affected the physical and mechanical properties of soil: (1) The plastic index, relative density and effective cohesion of soil decreased with the increase of total nitrogen concentration. The effective internal friction angle increased with the increase of solution concentration (2) Under all immersion conditions, the change law of soil stress-strain curve is basically the same, which shows the phenomenon of strain hardening. The soil shear peak first decreases and then increases with the increase of total nitrogen solution concentration. (3) The pore water pressure first increases with the increase of axial strain, and then slowly decreases. Finally, the curve gradually tends to level and shows large dilatancy. (4) The interaction between total nitrogen solution and soil mainly includes ions Exchange, microbial decomposition and dissolution and cementation. These effects can change the macroscopic mechanical properties of the soil by changing the mineral content of the soil to make obvious changes in the micro-morphology and pore characteristics.