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J. Yu
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Civil Engineering, Building, Construction & Architecture Engineering Transportation

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PREDICTION OF SOIL WATER CHARACTERISTIC CURVE USING PHYSICALLY BASED SCALING TECHNIQUE S. Y. Liu; N. Yasufuku; Q. Liu; J. Yu
Lowland Technology International Vol 15 No 1, June (2013)
Publisher : International Association of Lowland Technology

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Abstract

The soil water characteristic curve (SWCC) is an important hydraulic parameter for modeling water flow and contaminant transport in the vadose zone. However, direct measurement of the SWCC is still difficult. The Arya and Paris (AP) model estimates the SWCC from particle-size distribution curve (PSD) based on the shape similarity of the two curves. They introduced an empirical parameter, a, used to scale pore attributes from hypothetical formations to natural structure. Several approaches have been used to derive a. However, the calculation precedures of these approaches are either quite complicated or are developed without paying much attention to the physical significance of the soil properties. In the present paper the physically based scaling technique (PBS) was applied to derive a for the AP model. Fifty soil samples, representing a range of textures that include sand, sandy loam, loam, sit loam, and clay, were selected from UNSODA hydraulic property database for calculating a using PBS approach. In addition, nineteen soil samples with different textures were used to verify effectiveness of proposed a values. The result compared with other approaches show that the PBS technique combine with the AP model is a more useful and easier approach to predict SWCC from PSD.
INVESTIGATION OF SHORT-TERM RUTTING PROCESS OF FLEXIBLE PAVEMENT SYSTEM WITH GEOGRID - REINFORCEMENTS BY HOMOGENIZATION METHOD B. B. Budkowska; J. Yu
Lowland Technology International Vol 4 No 2, Dec (2002)
Publisher : International Association of Lowland Technology

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This paper presents the investigations on short-term rutting that is developed in standard and geogrid-reinforced flexible pavement structure. The main source of the supporting experimental data acquisition on studied type of rutting was provided by laboratory records that had been published in technical literature. The experimental research focused on the development of clear grounds indicating that geogrid-reinforcement is the effective method of reduction of permanent deformations of the pavement system. The comprehensive discussion on the laboratory results showed that the placement of geogrid-reinforcement at various levels of base layer, generated different effects invarious parts of the pavement system. The numerical investigations are focused on determination of modulus of permanent deformation Ep for each layer contributing to the pavement structure. They are considered as being the functions of the number of load repetition N. The constutitutive law incorporated for this purpose is modified 3-D Hooke's law that involves the modulus of permanent deformations. The identification of Ep is-conducted in the framework of homogenization method which assumes the homogenity and isotropy of each layer. The fact of irreversibility of permanent deformations is taken into consideration by geometry's continous updating process. The determination of Ep requires full information on increments of permanent displacements of control points corresponding to each consecutive load repetition. The numerical investigations are performed for axisymetric geometry by means of the finite element analysis (FEA) program ABAQUS (1998). To guarantee the correctness of the results obtained, the problem that was explored was subjected to verivication studies by means of the KENLAYER (1993) program, that was suitably adjusted for this purpose.
Co-Authors B. B. Budkowska N. Yasufuku Q. Liu S. Y. Liu