Abstract:In this study, two different landforms of reclaimed paddy fields in Nanxiong,Shaoguan, and Qingcheng Guangdong,Qingyuan were taken as examples. The rapid construction of impermeable layer
and soil characteristics were analyzed by water injection and harrowing, in-situ grouting and adding foreign soil. The water retention rate of Qingcheng project can reach 55% by mixing 10% of the soil, and the water retention rate of Nanxiong project can meet the water retention requirements by water injection and harrowing, and the water retention rate is above 50% . After the impermeable layer was constructed,the soil bulk density of the impermcable layer in Qingcheng was 1.55 ~1. 72 g/cm3, while that in Nanxiong was 1.53 ~1.61 g/cm. The soil texture of the impermeable layer in Qingcheng is loam, while that in Nanxiong is sandy loam. However, the content of sand particles larger than 2 mm in the impermeable layer in Qingcheng is twice than that in Nanxiong. The saturated hydraulic conductivity of Qingcheng impermeable layer is0.010~0.020mm/min.While that of Nanxiong impermcable layer is 0.045~0.113mm/min. The research proves that even sandy loam can meet the waler relention requirements of
paddy fields through water injection and harrowing or mixing process, so that the soil has the function of impermeable layer and tillage layer. More comprehensive analysis should be carried out on the qualitative analysis of soil, especially the consideration of the water retention effect of impermeable layer with large particle size sand and clay content.