Model And Experimental Study On Water Evaporation Of Mixed Soil

The evaporation of soil water is a normal natural phenomenon in people's daily life.It is one of the main ways to exchange soil-atmospheric materials and energy,and it is also an important part of the balance of surface heat and water.The evaporation of saturated soil is divided into three stages,namely constant evaporation stage,falling stage and residual stage.Saturated soil evaporates at a constant evaporation rate at the beginning of evaporation.As the evaporation process progresses,the evaporation rate decreases and enters falling stage.When the water content in the soil decreases to a certain degree,the evaporation rate will decrease to a stable low value,and the evaporation will enter the residual stage.The evaporation characteristics of soils also have a huge impact on soil cracking and engineering construction.Using the three stages of evaporation to analyze the effects of different factors on evaporation is extremely important for predicting engineering disasters.Through the indoor model test,three types of soil(sand,diatomite,loess)were used to carry out the evaporation disk test under different conditions.The effects of the particle size of soil,the salt content of soil,the mixing proportion of mixed soil and the sequence of double-layer soil on the evaporation process of soil were studied.The results show that the particle size of soil in the range of 0.1mm-2.0mm has little effect on soil evaporation;with the increase of soil salt content,the effect of soil evaporation inhibition is more obvious;with the increase of diatomite content,the duration of constant evaporation rate stage and the time of entering residual stage are longer,the evaporation time of mixed soil is longer,and the water holding capacity is increased.The composition of the main volume ratio in the mixed soil determines the evaporation characteristics;with the increase of the thickness of the overburden,the first stage of soil evaporation lasts longer,and the sequence has a great impact on the evaporation.When diatomite is located under the double-layer soil,the evaporation duration of the soil is significantly longer.In addition,the evaporation tests of different thickness soil were carried out.It was found that the evaporation process was prolonged with the increase of thickness.When the soil thickness is more than 3cm,the whole evaporation process can be observed well.A two-parameter model for calculating the evaporation process curve is derived,and the relationship between the evaporation process curve and the soil itself is established.The evaporation tests of mixed soils with different mixing ratios and diatomite with different thicknesses were carried out respectively.The formulas were derived and fitted according to the mixing ratios,thicknesses of the soil and their corresponding evaporation process curves.Through parameter research,It is found that there is a good functional relationship between the model parameters and the ratio of diatomite.Substituting the test data into the model to obtain different predicted evaporation curves,the results are in good agreement with the actual data,indicating that the model is practical.It is of great significance to predict the soil evaporation process under different conditions in nature and construction sites.