| as a result of Tianjin Binhai New Area Ecological construction pace is accelerating recently, greenbelt coverage area expands unceasingly, scientific and effective improvement of dredger fill is emerging as a hot topic at home and abroad of saline soil improvement. The dredger fill from sea mud, salt, alkaline, soil clinging, cannot be used for ecological construction directly, for the improvement of dredger fill structure, improve the dredger fill desalination rate, improve ecological utilization value of blowing filling, this paper focuses on the research on the improvement of technology of dredger fill reducing alkali salt. Through the soil physicochemical properties analysis of the test area, and to investigate the regional groundwater and natural climate condition, the dredger fill factors existing in the normal growth of physicochemical environment on plant barrier. New polymer soil improvement agent PVA (polyvinyl alcohol) in this paper, through the indoor soil column leaching test, study the different types and the same type of different concentrations of PVA on the permeability of dredger fill, water stable aggregates, influence soil moisture, salinity, important physical and chemical factors of water soluble salt ions, alkali salinity and pH value decided to plant survival, and the effect of agglomeration effect change of the medium environment on PVA soil, aims to explore the feasibility of PVA improvement of dredger fill, for the coastal reclamation soil structure improvement provides new way and method.Test results show that the soil, Tianjin Nangang test area of10samples of soil salt content on19.31-35.15g/kg, Na+, Cl-content are, as the sodium chloride type saline soil; soil alkalinity in the28.87%～36.12%range, high soil salinity, alkalinity is extremely strong, its harsh physicochemical environment cannot provide growth conditions for plant. PVA indoor soil column simulated leaching experiment results show that, the models were205,217,220,224MB PVA can significantly increase the content of soil water stable aggregates, improve soil structure of dredger fill, enhance the permeability of soil so as to achieve the purpose of reducing alkali salt drainage. After leaching, application of the model PVA soil desalting rate is94%-98%, the soil alkalinity in front of32.31%leaching, leaching decreased, the maximum is7%, the lowest was1%, among them,224MB type PVA desalting rate top to98%, the leaching after alkalization degree decreased to1%, the improvement effect of dredger fill earth is best. While the control processing of the desalination rate was56.2%, the ESP after leaching for25%, the alkalization of soil properties have no obvious change. The change of PVA concentration has different effect on reclaimed soil physicochemical properties, experimental results show that, when the224MB type PVA concentration of0.08%,0.18%,0.28%,0.35%,0.45%, soil leachate conductivity decreased to1of the time needed for dS/m were182,154,158,114,142h, while the control is522h; salt leaching after PVA treated soil were less than1.45g/kg, the control is2.07g/kg; when the concentration of PVA were0.28%,0.35%,0.45%, blow fill alkaline properties can be significantly improved, in the soil treated with ESP below5%, the alkaline soil before the transition of non alkaline soil; soil pH value was increased more than before.Experimental results show that the soil chemistry, soil chemical environment (EC and pH) change has significant effect on PVA soil cohesion, when soil suspension EC in the4.58～14.52dS/m threshold range, the dredger fill water stable aggregates above0.25mm positive agglomeration effect; and when the EC is9.58～38.32dS/m, the below0.25mm positive agglomeration effect. Increased soil suspension medium pH, but strongly promoted PVA soil cohesion effect. |
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