南疆盐渍土路基盐—液—温共场的新型路基结构试验研究

发布时间：2018-02-12 01:49

本文关键词： 盐渍土路基侧隔下疏小模型试验现场试验路段　出处：《塔里木大学》2015年硕士论文　论文类型：学位论文

【摘要】：针对南疆盐渍土道路的冻胀、溶陷、翻浆等典型的道路破坏问题，以南疆阿拉尔市为依托，从改变盐渍土路基结构的方面考虑来防治盐渍土路基盐胀、冻胀、溶陷等病害的方法，提出了“侧隔下疏”的新型盐渍土路基结构形式，对研究区域的盐渍土进行取样测定其含水率、密度、颗粒级配等基本参数并通过配制土样进行导热系数、渗透系数、冻胀试验等相关实验；通过室内路基结构小模型实验,对路基两种不同形式坡度的疏水层进行对比分析研究，在“侧隔下疏”型路基结构中,疏水层、隔断层如何设置对盐渍土路基的盐胀病害可以减少；并对“侧隔下疏”式路基结构形式应用进行了理论分析，以阿拉尔市城市道路改建工程为现场试验并通过对其路基物理力学特性变形的监测得出如下结论：（1）路基中冻土层的形成对土壤中水、盐的迁移有很大影响，进而影响到盐渍土路基中盐分的分布。（2）试样渗透系数随着干密度的增大而减小逐渐趋于恒定,随着密度的增大，土颗粒之间的空隙不断减小，阻碍了渗透，使不同干密度的土壤与渗透系数的关系相对比较复杂。当干密度较大时,渗透系数随压实度的增大而减小；在较小干密度情况下,渗透系数随压实度的增大而增大,不均匀系数为10时,渗透系数达到极值,然后随密实度的增大而增大。（3）对试样的导热系数有影响的有含水量、含盐量和干密度,对导热系数影响最大的为含盐量,其次为含水量,干密度对导热系数的影响相对最小。导热系数随着干密度和含水量的增加而减小，随含盐量的增加而增大。（4）对于不含盐的土样，随着温度的降低只发生冻胀变形，单纯发生冻胀变形的土体总体变形量比较平缓，在消融后基本能恢复到初始状态；而当盐渍土发生盐冻胀变形时，随着时间的增加，变形量呈现有规律的上升状态，每次消融后都会有变形残余。（5）新型路基的小模型试验中通过设置不同坡度的隔断层，隔断层有倾角的能有效的加快排盐，同时能够增大排盐量、提高了排盐的效果；对于V型隔断层,角度并不是越大效果就会越好,而是有一个临界值是10°-15°；对于DV型隔断层,其效果是随着角度的增大而越来越明显,最后确定隔断层的角度10°为最佳角度。（6）侧隔下疏型路基结构中由于隔断层的存在,隔断林带水进入路基冻土层，在外部温度的变化下减少温度对水分及盐分迁移的影响；侧隔下疏型路基结构中由于下疏导层能疏导一部分路基内部水分,阻止毛细水上升到冻土层，，抑制路基表面的泛盐,减小了路基表面的盐胀和冻胀变形量。（7）现场试验还在一个自我平衡的时期，路基防盐胀的优越性还需要一个长期的检测分析。
[Abstract]:In view of the typical road damage problems, such as frost heaving, dissolving, and churning of the salinized soil road in the south of Xinjiang, taking Alar city of southern Xinjiang as the basis, considering the change of the subgrade structure of the salinized soil to prevent the salt heaving and frost heaving of the salinized soil roadbed, In this paper, a new type of subgrade structure of salinized soil is put forward, by which the basic parameters, such as moisture content, density, particle gradation and so on, are measured by sampling the saline soil in the study area, and the thermal conductivity of the soil sample is obtained by preparing the soil sample. Permeability coefficient, frost heaving test and so on, through the indoor subgrade structure small model experiment, carries on the contrast analysis to the subgrade two kinds of different forms of slope hydrophobic layer, in "the side partition is sparse" the type subgrade structure, the hydrophobic layer, How to set up the separated fault to reduce the salt swelling disease of the saline soil subgrade, and the application of the structural form of the "side off and sparse" subgrade is analyzed theoretically. Taking the urban road reconstruction project of Alar City as the field test and monitoring the deformation of its roadbed physical and mechanical properties, the following conclusions are drawn:. 1) the formation of permafrost in the subgrade has a great influence on the migration of water and salt in the soil, and then affects the distribution of the salt in the subgrade of the saline soil. (2) with the increase of dry density, the permeability coefficient of the sample tends to be constant, and with the increase of the density, the void between soil particles decreases, which hinders the permeability. The relationship between soil permeability coefficient and soil permeability coefficient of different dry density is relatively complicated. When dry density is high, permeability coefficient decreases with the increase of compaction degree, and with the increase of compaction degree, the permeability coefficient increases with the increase of compaction degree when dry density is small. The inhomogeneity coefficient is 10:00, the permeability coefficient reaches the extreme value, and then increases with the increase of compactness. (3) the moisture content, salt content and dry density have the most influence on the thermal conductivity of the sample, and the salt content and the water content have the greatest influence on the thermal conductivity of the sample. The effect of dry density on thermal conductivity is relatively minimal. The thermal conductivity decreases with the increase of dry density and water content, and increases with the increase of salt content. 4) for soil samples without salt, only frost-heaving deformation occurs with the decrease of temperature, and the total deformation amount of soil with only frost-heaving deformation is relatively gentle, which can be basically restored to its initial state after ablation, but when salinized soil is subjected to salt-heaving deformation, With the increase of time, the amount of deformation increases regularly, and there will be residual deformation after each ablation. 5) in the small model test of the new subgrade, the inclined fault can accelerate the salt discharge effectively by setting different slope isolation faults, and at the same time, it can increase the amount of salt discharge and improve the effect of salt removal. The greater the angle is, the better the effect will be, but there is a critical value of 10 掳-15 掳. For DV type isolated fault, the effect becomes more and more obvious with the increase of angle. Finally, the angle of 10 掳is determined as the best angle. (6) because of the existence of separated fault, the water of separated forest belt enters the permafrost of roadbed, and the influence of temperature on water and salt migration is reduced with the change of external temperature. In the subgrade structure with side separation, the lower layer can drain a part of the subgrade internal moisture, prevent the capillary water from rising to the permafrost, restrain the oversalt on the surface of the roadbed, and reduce the amount of salt heave and frost heave deformation on the surface of the subgrade. The field test is still in a period of self-balance, and the superiority of anti-salt expansion of roadbed needs a long-term test and analysis.
【学位授予单位】：塔里木大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U416.16

【参考文献】