Abstract
In hot and humid regions of southern China, the volumetric moisture content of the embankment after opening to traffic for a period of time reaches a stable state, and it is higher than the design value. When it was widened, the humidity gradient and exchange were formed due to the difference in moisture content between the existing and new embankment. To reveal the moisture migration of the existing and new embankment and control the rise of volumetric moisture content in new embankment, six frequency domain reflectometry sensors were installed in existing and new embankment to monitor the volumetric moisture content. A finite element model for the embankment was established and verified with the measured data. And seven numerical analyses of transient seepage in the new embankment of the cushion, cover, and partition using capillary barrier by sand were simulated. The results show that the volumetric moisture contents of the new embankment in southern China gradually increase and eventually reach an equilibrium state. The increase in water comes from the slope, the foundation, and the existing embankment. Early in the first 1∼2 years, the water mainly comes from the foundation and the existing embankment. After that, as time goes by, the water comes mostly from the slope infiltration and gradually migrates to the foundation and the existing embankment. Finally, the volumetric moisture content and the water storage gradually reach equilibrium. The volumetric moisture content of the new embankment using capillary barrier by sand at the cushion, the cover, and the partition is maintained as the construction volumetric moisture content. This combination is a very effective method to control the humidity stability of the new embankment in southern China.
Highlights
In the field construction, the embankment soil is generally compacted by the optimum moisture content (OMC) within 2% error [1, 2]
Many expressways need to be widened since the existing expressways cannot meet the demands of the growing traffic during the operation for many years [7]. When these embankments were widened, the new embankment was compacted by the OMC. en, the moisture will migrate between the existing and new embankment owing to their moisture content difference. is is helpful to a series of performance deteriorations of the new embankment, such as a loss of the structural bearing capacity [8, 9], an increase of lateral pressure [10], a reduction of the resilient modulus [11, 12], and an increase of permanent deformation [13, 14]
To investigate the moisture migration and the influence of the cushion, the cover, and the partition using the capillary barrier on the predictions of the volumetric moisture content distributions in the new embankment, a series of finite-element transient seepage were carried out
Summary
The embankment soil is generally compacted by the optimum moisture content (OMC) within 2% error [1, 2]. Due to the hot and humid environment in southern China, the moisture migration between embankment and surrounding atmosphere will appear sharply [3,4,5]. The moisture of embankment will increase gradually from the OMC and reach an equilibrium state. Yao et al [6] found that the equilibrium moisture content of the embankment in southern China will increase to 1.2 times of OMC. Many expressways need to be widened since the existing expressways cannot meet the demands of the growing traffic during the operation for many years [7]. When these embankments were widened, the new embankment was compacted by the OMC. When these embankments were widened, the new embankment was compacted by the OMC. en, the moisture will migrate between the existing and new embankment owing to their moisture content difference. is is helpful to a series of performance deteriorations of the new embankment, such as a loss of the structural bearing capacity [8, 9], an increase of lateral pressure [10], a reduction of the resilient modulus [11, 12], and an increase of permanent deformation [13, 14]
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