硫酸盐渍土路基盐胀防治机理研究

发布时间：2018-04-03 02:20

本文选题：硫酸盐渍土　切入点：路基　出处：《中南大学》2014年硕士论文

【摘要】：摘要：盐渍土以其特殊的性质受到人们的重视,对盐渍土的研究从最早的农业领域逐渐扩展到工程领域,国内外对盐渍土的盐胀、溶陷、湿陷和腐蚀的研究已比较普遍。硫酸盐渍土以其含有硫酸钠等易溶盐而在外界温度变化时发生盐胀变形和融沉。在新疆极端气候：昼夜温差大、降水稀少、蒸发量大的作用下,硫酸盐渍土的发育和盐胀变形对当地的道路工程造成严重影响。新修建的道路因为路基内盐分的迁移和周期性的盐-冻胀变形而发生纵向开裂、隆起、冒水,最终导致道路使用寿命缩短。本文以硫酸盐渍土作为主要研究对象,在前人的研究基础上对盐分不均匀分布的硫酸盐渍土进行了盐胀高低温循环试验,提出上隔下疏型路基结构并进行了室内模型和现场试验： (1)通过耦合理论分析硫酸盐渍土水分、盐分、外界温度等因素对盐胀变形的数值关系。 (2)对现场土样物理参数的实验分析,得出硫酸盐渍土路基破坏的主要原因是路基中硫酸盐向水泥稳定层迁移聚集,在外界温度周期变化产生盐-冻胀变形最终导致道路破坏；通过高低温循环试验研究不同含盐量、不同空间分布下的盐胀变形规律。 (3)硫酸盐渍土盐胀高低温循环试验揭示硫酸盐渍土中盐分的不均匀分布对盐胀的盐渍土的盐胀量有较大的影响。总体含盐量一致时,当盐分聚集于上部时盐胀变形要比盐分聚集于下部大。循环过程中盐渍土盐胀有残余累积变形,且随着循环次数的增加而减小。 (4)小模型试验研究路基内设置不同形式和坡度的隔断层,均能有效排出路基内过饱和盐水,其中以V型正向隔断层10-15。的排盐效果较好。 (5)硫酸盐渍土路基中设置保温隔断层＋疏排水层能有效控制路基内温度变化幅度、隔断路基内毛细水上升和盐分迁移。有效减小路基盐胀变形,减小硫酸盐渍土地区道路路面的破坏。 (6)硫酸盐渍土路基现场试验正处于施工后一个自我平衡阶段,其温度有一定的滞后现象,道路中间的变形要比道路两侧的变形稳定。
[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.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U416.1

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