| 非饱和粉土路基内水分迁移规律试验研究 |
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| 引用本文： | 杨志浩,岳祖润,冯怀平.非饱和粉土路基内水分迁移规律试验研究[J].岩土力学,2020,41(7):2241-2251. |
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| 作者姓名： | 杨志浩 岳祖润 冯怀平 |
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| 作者单位： | 1. 石家庄铁道大学 省部共建交通工程结构力学行为与系统安全国家重点实验室，河北 石家庄 050043；2. 石家庄铁道大学 土木工程学院，
河北 石家庄 050043；3. 道路与铁道工程安全保障省部共建教育部重点实验室（石家庄铁道大学），河北 石家庄 050043 |
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| 基金项目： | 河北省自然科学基金项目（No. E2019210137）；中国铁路总公司科技研究开发计划项目（No. 2017G008-G，No. 2017G002-W，No. 2017G008-A）。 |
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| 摘 要： | 动载作用下非饱和粉土路基内部的水分迁移规律，对研究重载铁路在浸水状态下的路基稳定具有重要意义。基于范德堡原理，利用土样的电阻率特性，研制出一套基于GDS动三轴仪的非饱和土样含水率分布规律测试系统。利用该系统开展浸水动三轴试验，并对试验过程中非饱和试样的分层含水率进行连续测试，探究土样的初始压实度、动载的动应力幅值对非饱和土样内部水分迁移的影响规律。结果表明：该测试系统可在动三轴试验过程中对非饱和试样的分层含水率进行实时、无损、连续地测定，测试结果的最大误差为0.7%；非饱和土样在动载作用下随其含水率逐渐增大，土样的初始压实度对电阻率的影响程度减弱，接近饱和含水率时可忽略；土样初始压实度、含水率与土体电阻率具有确定的函数表达式，并具有良好的相关性及唯一性。结合试验结果分析认为：降雨及动荷载共同作用下，路基内水分在某一深度土体积聚，该区域孔隙水压力增大，强度降低，导致翻浆冒泥病害的发生；路基压实度及列车轴重增大，均会抑制路基内水分向下部迁移，有助于路基的稳定，但轴重增加，可能导致路基的失稳，当轴重大于临界动应力时，路基将发生破坏。
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| 关 键 词： | 范德堡法 非饱和土样 动三轴试验 水分迁移 |
| 收稿时间： | 2019-07-02 |
| 修稿时间： | 2020-01-02 |
Experimental study on moisture migration properties in
unsaturated silty subgrade |
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| YANG Zhi-hao,YUE Zu-run,FENG Huai-ping.Experimental study on moisture migration properties in
unsaturated silty subgrade[J].Rock and Soil Mechanics,2020,41(7):2241-2251. |
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| Authors: | YANG Zhi-hao YUE Zu-run FENG Huai-ping |
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| Institution: | 1. State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures, Shijiazhuang Tiedao University, Shijiazhuang, Hebei 050043, China; 2. School of Civil Engineering, Shijiazhuang Tiedao University, Shijiazhuang, Hebei 050043, China; 3. Key Laboratory of Roads and Railway Engineering Safety Control (Shijiazhuang Tiedao University), Ministry of Education, Shijiazhuang, Hebei 050043, China |
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| Abstract: | Moisture migration inside unsaturated silty subgrades under dynamic loading is of great significance for investigating the stability of heavy haul railway subgrades in water immersion conditions. Based on soil electrical properties, a measurement system combined with a GDS cyclic triaxial instrument was developed relying on the van der Pauw principle to measure the water content distribution properties of unsaturated soil specimens. With the use of the aforementioned measurement system, water-supply dynamic triaxial tests were carried out. Moreover, the stratified water content of the unsaturated specimen was continuously measured during the test to explore the influence of the initial compaction degree of the unsaturated specimen and dynamic stress amplitude of dynamic loading on water migration inside the unsaturated specimen. This measurement system which can be used to determine the stratified water content of unsaturated specimens in real time, is able to achieve nondestructive and consecutive testing during dynamic triaxial tests, and the maximum error is only 0.7%. As the water content of the unsaturated soil specimen gradually increases under dynamic loading, the influence of the soil specimen initial compaction degree on resistivity decreases, and the influence can be ignored when the water content is close to saturated water content. A function exists to correlate soil resistivity with soil specimen initial compaction degree and water content, and the function has a high level of correlation and uniqueness. According to the analysis of the testing results, under the combined action of rainfall and cyclic loading, the water inside the subgrade accumulates to a certain depth inside the soil, and the pore water pressure in this area increases. The increase of pore water pressure decreases the strength and leads to the occurrence of mud-pumping disease. Increasing the subgrade compaction degree and the axle weight of the train will inhibit the downward water migration inside the subgrade and contribute to subgrade stability. However, an excessive increase in axle load may result in subgrade instability. When the axle load is greater than the critical dynamic stress, the subgrade will be destroyed. |
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| Keywords: | van der Pauw principle unsaturated soil specimens cyclic triaxial test moisture migration |
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