适量砒砂岩改良风沙土的吸水和保水特性

该文研究了不同砒砂岩改良风沙土模式下的土壤入渗特征、饱和导水率和水分特征曲线,分析了不同模型对砒砂岩改良风沙土水分特征曲线的适用性和不同改良模式的土壤水力学特征,以期为评价砒砂岩改良风沙土水力学特性以及筛选合理改良模式提供科学依据。结果表明:砒砂岩可以有效降低风沙土的入渗率和饱和导水率,增加风沙土的饱和含水量和滞留含水量,增强风沙土的持水能力。VGM(m,n)模型可以拟合砒砂岩改良风沙土土壤水分特征曲线。同一改良模式下,土壤的入渗率、饱和导水率和饱和含水量随容重增大呈减小趋势;容积含水量在低吸力段随容重增大逐渐减小,在中高吸力段逐渐增大。砒砂岩和风沙土以25∶75比例混合的复配模式,可以有效改良风沙土的吸水和保水特性,可在实践中推广。

Improvement of water absorbing and holding capacities of sandy soil by appropriate amount of soft rock

Abstract: The contiguous areas of Shanxi, Shaanxi and Inner Mongolia in China are rich in mineral resources and serves as energy supply base. Desertification and soil - water losses are very serious problems in this area. Water is a main limiting factor of local ecological environment and the development of farming and animal husbandry. Soft rock is widely distributed in the area, which has strong water retention ability. Using soft rock to improve the sandy soil has a great potential, but little is known about the hydraulic properties of soft rock amended sandy soil. This study was conducted to understand the effect of different amount of soft rocks on water absorbing and holding capacities of sandy soil. In this paper, we measured the water infiltration, saturated hydraulic conductivity and soil water characteristic curves of soft rock and sandy soil mixtures. The various soil water characteristic curve models included in the RETC software was used to analyze the water absorbing and water holding properties of soft rock - sand soils mixtures. The objectives of this study were to evaluate the improvement of soft rock on the soil absorbing - holding water properties of sand soils, and to select optimal mixture ratio of the soft rock and sandy soil. The results showed that: 1) Soft rock significantly decreased the water infiltration rate and saturated hydraulic conductivity, but increased the saturate water content and residual water content, and hence increased the capacity of sandy soil to retain water. The saturated water content and residual water content of sandy soil increased with the amount of soft rock added into sandy soil. For the treatment of 25% soft rock and 75% sandy soil mixtures, the amended sandy soil have the similar saturated water content and soil water characteristic curve as the loess soils. 2) The effects of soft rock on water absorbing and holding capacities of sandy soil were significantly influenced by bulk density. Water infiltration rate, saturated hydraulic conductivity and saturated water content decreased with the increasing of the bulk density in the same mixture pattern. With the increase of bulk density of the mixture, the volumetric water content decreased at the low soil water suction condition, but increased at the relatively higher soil water suction condition. 3) RETC software contains eight models, and every model can be used to fit the soil water characteristic curves of soft rock amended sandy soil. Among the eight models, VGM (m, n) was the best model with the largest R2 and F value. 4) Parameter of VGM (m, n) model is an empirical parameter, the smaller the parameter, the slower the soil water released. Fitting results in VGM (m, n) showed that the parameter of the soil with the 25% soft rock and 75% sandy soil was less than sandy soil and greater than soft rock. The results from this study suggested that the mixture of 25% soft rock and 75% sandy soil can significantly improve the water absorbing and holding capacities of sandy soil and this mixture pattern can be recommended in practice.