沙漠区风积沙路基水盐迁移规律

胡建荣; 张宏; 张海龙; 闫晓辉; 李梁

沙漠区风积沙路基水盐迁移规律

1.
长安大学工程设计研究院有限公司, 陕西西安 710064
2.
内蒙古大学交通学院, 内蒙古呼和浩特 010070

基金项目:

国家自然科学基金项目 51468047

内蒙古自然科学基金项目 2016MS0531

内蒙古交通科技项目 NJ2012-10

详细信息

作者简介:
胡建荣(1972-), 男, 陕西西安人, 长安大学高级工程师, 从事公路结构设计与养护研究

中图分类号: U416.166
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出版历程
- 收稿日期: 2017-02-21
- 刊出日期: 2017-06-25

Water-salt migration laws of aeolian sand subgrade in desert area

1.
Civil Engineering Design Academy Co., Ltd., Chang'an University, Xi'an 710064, Shaanxi, China
2.
Transportation Institute, Inner Mongolia University, Hohhot 010070, Inner Mongolia, China

More Information

Author Bio:
HU Jian-rong(1972-), male, senior engineer, +86-29-82334609, 82078720@qq.com

摘要

摘要: 以沙漠区风积沙路基土为依托, 检测了典型路面病害路段不同深度试样的化学成分, 基于土水势原理, 分析了路基内盐分与水分的迁移特点; 以95%的压实度分层填筑土样, 采用自制试验装置测试模型土柱的含水率与导电率, 研究了最佳含水率条件下温度梯度对路基内水盐迁移规律的影响。研究结果表明: 病害路段路基土为细沙, 基层与路基土含盐成分均以可溶性硫酸钠与钾盐为主, 在-6℃~0℃会形成Na₂SO₄·10H₂O, 发生体积膨胀, 当遇到外界水分的进入, 就会加剧路基土盐胀和路面隆起破坏; 路基压实一周后, 土样5cm深度处含水率降低了1%~2%, 硫酸根含量降低了0.05%~0.06%, 在35cm深度处含水率升高了0.5%~0.8%, 硫酸根含量降低了0.12%~0.14%, 在重力势与压实的双重作用下, 均质土体出现快速且明显的水盐分层现象; 在外界温度作用下, 土样25cm深度范围内温差为20℃~30℃, 超过25cm深度范围, 温差约为1℃, 随着深度增加, 温度梯度变化量逐渐减小, 最终趋于0;风积沙路基内部水盐分布随深度先降低后增加, 水盐场随深度分布呈现“对勾”状规律; 风积沙路基内部的水盐迁移是由气、液两态混合作用的结果, 在高温作用下, 路基顶面10cm范围内水气迁移占据了主要的迁移方式, 而在10cm以下主要由细沙构成的风积沙内无法形成有效的毛细水上升孔道, 水分主要以薄膜水的形式进行迁移, 在降温作用下, 液态水携带盐分上升, 在路基顶面形成盐分积聚现象。
- 路基工程 /
- 风积沙路基 /
- 含水率 /
- 含盐量 /
- 模型试验 /
- 水盐迁移
Abstract: Based on aeolian sand subgrade soil in desert area, the chemical compositions of samples at different depths at the typical pavement-distressed section were tested, and the migration characteristics of salinity and moisture in subgrade were analyzed based on soil water potential principle.The soil was layered filling with the compaction degree of 95%, the moisture content and electric conductivity of soil pillar model were tested by using self-made experimental device, and the influence of temperature gradient on the water-salt migration rules in subgrade under the condition of optimum water content was analyzed.Research result shows that the subgrade soil of distressed section is fine sand, and sodium sulfate and sylvite are main salt components in both base and subgrade soil.Na₂SO₄ ·10H₂O generates at low temperature -6 ℃-0 ℃to lead to the volume expansion of soil.The salt expansion of subgrade soil and the upheaval destruction of pavement are aggravated because of the entrance of external moisture.After a week of subgrade compaction, the water content reduces by 1%-2% and the content of sulfate radical reduces by 0.05%-0.06% at depth of 5 cm, and the water content improves by 0.5%-0.8% and the content of sulfate radical reduces by 0.12%-0.14% at depth of 35 cm.Under the dual-action of gravity potential and compaction, quick and obvious water-salt stratification occurs in the uniform soil.Under the external temperature, the temperature difference at the depth of 25 cm is 20℃-30℃, but the difference is about 1℃ when the depth is more than 25 cm.So the temperature gradient variation gradually decreases with the increase of depth, and becomes zero eventually.The distributions of water and salt first decrease and then increase with the depth in aeolian sand subgrade, and appear hooklike rule.The water-salt migration in aeolian sand subgrade results from the mixing effect of gas-liquid states.The hydrosphere migration is primary within the depth of 10 cm from subgrade top surface under high temperature.However, because the effective access channels of capillary water can not form below 10 cm in aeolian sand composed of fine sand, the moisture mainly migrates in the form of pellicular water.The liquid water with salinity rises under the cooling effect to lead to salt accumulation effect on the top surface of subgrade.
- subgrade engineering /
- aeolian sand subgrade /
- water content /
- salt content /
- model test /
- water-salt migration

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图 1 路面典型病害

Figure 1. Typical diseases of pavement

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图 2 室内模拟试验

Figure 2. Indoor simulation experiment

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图 3 试验模型实体

Figure 3. Experimental model entity

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图 4 覆膜

Figure 4. Film

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图 5 数据采集仪

Figure 5. Data-collecting instrument

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图 6 孔1含水率曲线

Figure 6. Moisture content curves in measuring hole 1

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图 7 孔1电导率曲线

Figure 7. Electrical conductivity curves in measuring hole 1

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图 8 孔2含水率曲线

Figure 8. Moisture content curves in measuring hole 2

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图 9 孔2电导率曲线

Figure 9. Electrical conductivity curves in measuring hole 2

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图 10 孔3含水率曲线

Figure 10. Moisture content curves in measuring hole 3

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图 11 孔3电导率曲线

Figure 11. Electrical conductivity curves in measuring hole 3

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图 12 孔4含水率曲线

Figure 12. Moisture content curves in measuring hole 4

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图 13 孔4电导率曲线

Figure 13. Electrical conductivity curves in measuring hole 4

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图 14 箱1含水率变化曲线

Figure 14. Moisture content curves in measuring box 1

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图 15 箱1硫酸根含量变化曲线

Figure 15. Sulfate content curves in measuring box 1

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图 16 箱2含水率变化曲线

Figure 16. Moisture content curves in measuring box 2

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图 17 箱2硫酸根含量变化曲线

Figure 17. Sulfate content curves in measuring box 2

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图 18 箱1温度曲线

Figure 18. Temperature curves in measuring box 1

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图 19 制冷条件下孔1含水率变化曲线

Figure 19. Moisture content curves in measuring hole 1under refrigeration condition

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图 20 制冷条件下孔2含水率变化曲线

Figure 20. Moisture content curves in measuring hole 2under refrigeration condition

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图 21 盐分在薄膜表面结晶

Figure 21. Salt crystallization on film surface

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图 22 盐分在土体表层结晶

Figure 22. Salt crystallization on soil surface

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表 1 试样中氯离子与硫酸根离子含量之比

Table 1. Content ratios of chlorine ions and sulfate ions in samples

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表 2 土样筛分结果

Table 2. Screening result of soil samples

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