Study On The Influence Of Diving Depth On Phreatic Evaporation Under Non-stress Conditions

At home and abroad,the phreatic evaporation related research was conducted on the influence factors and influence mechanism in recent years,but most is only presented the relationship between soil and the buried depth on the macro,few studies different buried depth and the wind(i.e.,different air circulation)distribution characteristics of soil water content and the distribution mechanism.This thesis selects the permeability coefficient of small sand as the research object,studied the physical properties of sandy soil,designed a changeable diving and air velocity of the stress test apparatus.In the experiment designed the two initial conditions of the same sand column,by changing the air velocity on the surface of the sand column,to achieve the purpose of changing its surface atmospheric conditions,by the test of placed in sand column fixed buried deep in the soil temperature and soil moisture sensors,sensor collects two sand column fixed observation points on the soil moisture and soil temperature data changes over time.Based on the analysis of different diving depth and air flow,the correlation of air temperature and humidity is bad,however the correlation of the air temperature and soil surface temperature is stronger,in addition soil surface temperature change with the air temperature rise and fall.By adjusting the diving depth and wind speed on the studies of the soil temperature,with increasing buried depth,the soil surface and deep soil temperature reveal the greater the diversity.Under the same diving depth,with the speeding up of the air flow rate,the diversity of soil surface and deep soil temperature decreases.Through the comparison of evaporation under different wind speed conditions,the condition of soil moisture distribution and atmospheric moisture migration has a great influence,for a homogeneous medium,stability of diving evaporation intensity was positively related with air flow rate within a certain range,but when the air velocity reaches a certain extent,diving evaporation intensity reached the limit.Establish the above-mentioned model by hydrus-1D based on traditional model,it’s proved that the calculation of the value of phreatic evaporation is valid.