基于压汞法的改良土渗透特性研究

为探讨改良剂(水泥、固化剂)对土壤渗透性及微观孔隙分布的影响机理,以平原水库粉质黏土为研究对象,采用渗透试验和压汞试验,对改良土的渗透系数及微观孔隙进行研究。结果表明:固化剂使孔隙体积变小,降低改良土的渗透系数,但并非呈线性减小关系;当掺量为2%时,水泥和固化剂之间产生较大的抑制作用。固化剂速凝,可明显缩短施工周期,为工程抢修提供新的发展方向。水泥对改良土渗透性影响最大,随着水泥掺量增加,土体内部由大孔隙向小孔隙过渡。当龄期超过7d,土体渗透性降幅较大,大孔、中孔含量减少,微孔、极微孔逐渐增多;该研究建立了渗透系数与大孔、中大孔孔隙率的函数关系,为改良土作为防渗材料的稳定性分析提供理论依据。

Study on permeability characteristics of modified soil based on mercury intrusion

In order to study the effect of the modifier (cement and curing agent) on the soil permeability and micro-pore distribution, we studied the permeability of the modified soil and the micro-pores using the permeability test and the mercury intrusion test, with the silty clay in plain reservoirs as the research object. The results showed that the curing agent reduced the pore volume and the permeability coefficient of the modified soil, but the decline was not linear. When the content was 2%, there was an obvious inhibitory effect between the cement and the curing agent. The fast hardening of the curing agent could significantly shorten the construction period. This points out a new direction for engineering repair. In addition, the cement had the greatest influence on the permeability of modified soil. With the increase of cement content, the large pores within the soil would transition to small pores. After 7 days, the soil permeability declined sharply, the amount of large and intermediate pores decreased, and the micro-pores and ultra-micro-pores increased. This study has established a functional relationship between the permeability coefficient and the porosity of large pores and medium-large pores, and can provide a theoretical basis for the stability analysis of the modified soil as impervious material.