本文選題：硫酸鹽漬土　切入點：路基　出處：《中南大學》2014年碩士論文

【摘要】：摘要：鹽漬土以其特殊的性質受到人們的重視,對鹽漬土的研究從最早的農業(yè)領域逐漸擴展到工程領域,國內外對鹽漬土的鹽脹、溶陷、濕陷和腐蝕的研究已比較普遍。硫酸鹽漬土以其含有硫酸鈉等易溶鹽而在外界溫度變化時發(fā)生鹽脹變形和融沉。在新疆極端氣候：晝夜溫差大、降水稀少、蒸發(fā)量大的作用下,硫酸鹽漬土的發(fā)育和鹽脹變形對當地的道路工程造成嚴重影響。新修建的道路因為路基內鹽分的遷移和周期性的鹽-凍脹變形而發(fā)生縱向開裂、隆起、冒水,最終導致道路使用壽命縮短。 本文以硫酸鹽漬土作為主要研究對象,在前人的研究基礎上對鹽分不均勻分布的硫酸鹽漬土進行了鹽脹高低溫循環(huán)試驗,提出上隔下疏型路基結構并進行了室內模型和現場試驗： (1)通過耦合理論分析硫酸鹽漬土水分、鹽分、外界溫度等因素對鹽脹變形的數值關系。 (2)對現場土樣物理參數的實驗分析,得出硫酸鹽漬土路基破壞的主要原因是路基中硫酸鹽向水泥穩(wěn)定層遷移聚集,在外界溫度周期變化產生鹽-凍脹變形最終導致道路破壞；通過高低溫循環(huán)試驗研究不同含鹽量、不同空間分布下的鹽脹變形規(guī)律。 (3)硫酸鹽漬土鹽脹高低溫循環(huán)試驗揭示硫酸鹽漬土中鹽分的不均勻分布對鹽脹的鹽漬土的鹽脹量有較大的影響�？傮w含鹽量一致時,當鹽分聚集于上部時鹽脹變形要比鹽分聚集于下部大。循環(huán)過程中鹽漬土鹽脹有殘余累積變形,且隨著循環(huán)次數的增加而減小。 (4)小模型試驗研究路基內設置不同形式和坡度的隔斷層,均能有效排出路基內過飽和鹽水,其中以V型正向隔斷層10-15。的排鹽效果較好。 (5)硫酸鹽漬土路基中設置保溫隔斷層＋疏排水層能有效控制路基內溫度變化幅度、隔斷路基內毛細水上升和鹽分遷移。有效減小路基鹽脹變形,減小硫酸鹽漬土地區(qū)道路路面的破壞。 (6)硫酸鹽漬土路基現場試驗正處于施工后一個自我平衡階段,其溫度有一定的滯后現象,道路中間的變形要比道路兩側的變形穩(wěn)定。
[Abstract]:Abstract: people pay more attention to salinized soil because of its special properties. The research on salinized soil has gradually expanded from the earliest agricultural field to the engineering field. The research on salt dilatation, dissolution, collapse and corrosion of saline soil at home and abroad has been quite common.Sulfate saline soil contains soluble salt such as sodium sulfate, which causes salt swelling and melt settling when the external temperature changes.In the extreme climate of Xinjiang, the development of sulphate soil and the deformation of salt expansion have a serious impact on the local road engineering under the action of big temperature difference between day and night, rare precipitation and large evaporation.The newly built road has been cracked longitudinally because of the salt migration and periodic salt-frost heave deformation in the roadbed, which leads to the shortening of the service life of the road.In this paper, the sulphuric acid saline soil is taken as the main research object. Based on the previous research, the salt expansion high and low temperature cycle test of the sulphate saline soil with uneven distribution of salt content is carried out.The upper and lower subgrade structure is put forward and the indoor model and field test are carried out.1) the numerical relationship between water content, salt content and external temperature of sulphuric acid salt soil is analyzed by coupling theory.2) based on the experimental analysis of the physical parameters of soil samples in the field, it is concluded that the main reason for the subgrade failure of sulphate saline soil is that the sulfate in the subgrade migrates and aggregates to the cement stable layer, and the salt-frost heave deformation eventually leads to the road failure during the periodic variation of the external temperature.The law of salt expansion and deformation under different salt content and different spatial distribution was studied by high and low temperature cycling test.(3) the high and low temperature cycling test of salt expansion in sulphate saline soil reveals that the uneven distribution of salt in sulphuric acid saline soil has a great influence on the salt expansion of salinized soil.When the total salt content is the same, the salt swelling deformation is larger when the salt is concentrated in the upper part than in the lower part.The residual accumulated deformation of salt swelling in salinized soil decreases with the increase of cycle times.The small model tests show that the supersaturated salt water in subgrade can be effectively discharged by setting different types and slopes of separated faults in subgrade, in which V type forward barrier fault 10-15 is used.The effect of salt removal is better.(5) the thermal insulation fault and drainage layer can effectively control the variation of temperature in the subgrade, and the capillary water rise and salt migration in the subgrade can be separated by setting the insulation fault and drainage layer in the subgrade of sulphate saline soil.Effectively reduce the salt expansion deformation of roadbed and reduce the damage of road surface in sulphuric acid soil area.6) the field test of sulphate saline soil roadbed is in a self-equilibrium stage after construction, and its temperature is lagging behind to some extent, and the deformation in the middle of the road is more stable than that on both sides of the road.
【學位授予單位】：中南大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U416.1

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