Research On The Key Technologies For The Conservation And Reusing Of Topsoil Stripped In Cultivated Land Occupied By Construction Projects

Land provides the objective conditions for all aspects of clothing,food and living on which human beings depend on,which is the basis and source of all production and living activities.The cultivated land,especially the plentiful and high-quality cultivated land resources,is the most basic production data of agriculture.It is related to the national food security,the agricultural foundation is stable and the society can be held.Continued development.In China,the cultivated land itself has a series of problems,such as less per capita,lower quality,serious degradation and insufficient reserve,and the rapid development of the society and the continuous advancement of the process of urbanization.The new construction projects are inevitably and more and more occupied by the cultivated land.At the same time,the government departments and the construction units of our country have protected the peeled topsoil.The lack of awareness of protection and reutilization of land is lack of scientific and standard guidance,the resources of topsoil can not be effectively resettled,soil quality is seriously reduced,and serious waste is caused,which is very bad for agricultural production and food safety.Therefore,it is particularly important to develop high-quality cultivated land resources and strip soil conservation and reuse.1.The effect of different topsoil height on the bulk density of the underlying soil was preliminarily studied by applying different pressures on the heavy objects.The test results showed that the soil bulk density in the ground floor was 1.33,1.40,1.55,1.56,1.59,1.62,1.68,1.72 and 1.75g?cm~-33 under the pressure of the height corresponding to the height of the simulated heap at 1m to 9m.For the high quality topsoil that is unable to achieve"stripping and using",in the actual stacking process,the stacking height is preferably controlled below 3m.If the area of the storage area is limited and the mechanical conditions are satisfied and the soil is more viscous,the height of the stacking can be appropriately increased,but the maximum should not exceed 6m.2.The effects of different mulching measures on soil and water conservation and ecological conservation were studied preliminarily by artificial rainfall simulation.(1)Under the conditions of different rainfall intensity,the runoff and sediment content produced by the sloping surface of the experimental slope were the most,the next time covered the geo network,the least Trifolium repens was planted,and the 3 covering measures had a significant impact on the slope erosion.In the whole experiment,the benefit of reducing current in the geotechnical network is about 50%,and the benefit of the flow reduction of the clover is more significant and more than 82%,and the benefit of reducing sand is above 94%.On the whole,both the geo network and the white clover have completely controlled the erosion ability of the rain on the slope soil,and have better benefit of reducing the flow and reducing the sand,and the white clover plays a greater role.(2)The planting of white clover can also effectively improve soil nutrients.The content of total nitrogen,available phosphorus and available potassium in the soil will be enriched in the surface soil under the surface of the root system.At the same time,the nitrogen fixation effect of white clover has a good fixation effect on the nitrogen element in the soil.3.By selecting topsoil with different fertility levels,the effects of different remodelling techniques on backfill soil quality were preliminarily studied.There was no significant difference in the content of total nitrogen,organic matter,available potassium and available phosphorus in the soil before and after backfilling,which could effectively maintain the soil fertility level in different soil layers,and the mixed backfill treatment will mix the different soil layers evenly,and the content of nutrients in soil soil is also all followed by the stratified backfilling treatment.Homogenization treatment.Therefore,the soil fertility of the surface(0-20cm)is reduced,but the nutrient content of the underlying soil can be improved to a certain extent.In short,layered backfill can effectively ensure the quality of surface cultivated land and improve land productivity.4.The influence of the number of mechanical compaction on soil parameters under the conditions of different soil water content is preliminarily studied by using heavy hammer to simulate the common construction machinery crawler type bulldozer.(1)Under the same soil water content,the soil bulk density of the soil layer of 0-30cm can increase rapidly by 1 or 3 times,and then compacted after 3 compaction,and the change is not significant.(2)The effect of bulk density enlargement is positively correlated with water content.The higher the soil moisture content,the greater the soil moisture content,the greater the increase of the bulk density,but the further compaction,high water content(80%),the increase of bulk density increases rapidly,and the water content A(40%)and B(60%)still show a rapid increase,and the treatment of B>A.The soil layer of 30-60cm is compacted after 3 compaction,and its bulk density is further increased,and its increase range is larger than that of the upper layer 0-30cm soil layer.(3)After 3 compaction and further compaction,the decrease of soil layer decreased rapidly,and the stable settlement state was basically reached,and the B treatment with water content was the most stable.