Screening Of Subcontracted Drainage Outsourcing Materials For Different Soils In Hetao Irrigation District

The Hetao Irrigation District of Inner Mongolia is located in an arid and semi-arid area.Affected by climatic conditions,poor irrigation and drainage,and high groundwater levels,soil salinization is severe.The improvement of salinized soil has always been an important content of agricultural production and research in irrigation districts.The underground pipe drainage technology is one of the important means to prevent and control soil salinization,and the appropriate outsourcing material is the guarantee of the drainage effect of the underground pipe.In this paper,the outsourcing materials for subsurface pipes are screened and researched.Theoretical calculations and indoor soil column simulation experiments are used to explore the subsurface pipe drainage outsourcing materials suitable for different soil qualities in Hetao Irrigation District.Provide theoretical and technical support.The main conclusions are as follows:(1)Research on preliminary screening of 6 types of subsurface drainage drainage materials shows that the sand filter has the best water permeability but poor soil retention;the results of the other 5 groups of geotextile tests show that the permeability coefficient and soil loss increase with the increase of the geotextile aperture,the clogging rate will continue to decrease with the increase of the geotextile aperture.Only 68 g/cm2 and 90 g/cm2 geotextiles meet the requirements of underground drainage drainage materials.The suitable aperture of geotextile is between 0.17?0.26 mm.(2)Based on the preliminary results of geotextile screening,further in-depth screening tests combined with sand filter materials were conducted.The results show that the sand filter materials in the outsourced materials have a better water permeability and anti-blocking effect.As the size increases,the permeability coefficient of the outsourcing material increases first and then decreases,and the clogging rate decreases first and then increases;the amount of soil loss has nothing to do with the choice of the size of the sand filter material,but only with the pore size of the geotextile.Aiming at the silty clay loam soil in the study area,it is recommended to use a combination of 68 g/cm2 geotextile and 0.9mm sand filter material as the outsourcing material for underground drainage.(3)The results of the study on the suitability of the outsourced materials for soil quality show that the higher the clay content in the soil,the worse the water permeability of the outsourced materials,and the more prone to soil loss and blockage.