• Tunnel and Underground Space
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• v.20 no.3
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• pp.153-168
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• 2010

A fifth equation is required to determine the five independent elastic constants of a transversely isotropic rock from compression test of a single specimen. As an approximation proposed by Saint-Venant has been used for long time, it may cause an erroneous result in some cases, especially for specimen with low angle of anisotropy. Three equations were suggested replacing this traditional equation and proved to be applicable by the model analysis in the previous studies. As Saint-Venant's approximation is turned out the same as the first one of them, it has the characteristics that the apparent Young's modulus is monotonously increasing according to the anisotropic angle. The methodology to analyze the elastic constants from four independent strain measurements by uniaxial compressive test of a single standard specimen is concisely described, and the necessity and compatibility of new suggested equations are discussed. Saint-Venant's approximation can determine the elastic constants close to true values and other equations may be unnecessary in specimens with medium to large angle. Nevertheless, they may become applicable because they can produce the almost same amount. For the specimens of small angle of anisotropy, Saint-Venant's approximation may result in out of general ranges or thermodynamic constraints, but other suggested equations can produce the almost true value. Thus they can be applied before other alternative equation is known. The guide map constructed by model study may decide the most compatible one of the three equations.

• Tunnel and Underground Space
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• v.26 no.5
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• pp.363-374
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• 2016

All five independent elastic constants of a transversely isotropic rock sometimes need to be determined from a single specimen. Saint-Venant approximation has been widely used for a long time in the analysis of single specimen test. This paper has proven how this empirical equation can be mathematically transformed into a form of the apparent Young's modulus based on theory of elasticity. The transformed equation is a monotonous function on anisotropic angle and can be useful in the analysis of the in-situ stress measurement in an anisotropic rock mass. The estimations of data in literatures have shown that the measured values of $G^2$ are uniform on anisotropic angles and smaller than that of Saint-Venant's case. This decrement may be caused by sliding of the interface of strata and the decrement rate is inferred to relate well with the combination of bonding condition of strata and strength of rock material. Accumulation of these kinds of studies in the future enables to define the decrement and to determine elastic constants of a transversely isotropic rock from a single specimen from modifying Saint-Venant approximation.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.2 s.25
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• pp.45-52
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• 2007

In this study, the flood inundations of the Nam River catchment running through the Uiryeong and Haman regions have been simulated using the numerical model based on quadtree grids. The nonlinear Saint Venant equation is employed as the governing equation for a numerical model in this study. The governing equations are discretized explicitly with a finite difference leap-frog scheme on adaptive hierarchical quadtree grids. Results from this study are compared with those of established numerical models such as the HEC-RAS and the FLUMEN. A numerical model is also simulated according to the frequency variations of flood event. Obtained numerical results show good agreements with them of commercial models. It is found from this study that the flood inundations in the studied area can be occurred at a 500 year frequency event.

• Water for future
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• v.23 no.2
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• pp.251-263
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• 1990

For surcharge flow in a sewer, the slot technique simulates surcharge flow as open - channel flow using a hypothetical narrow open piezometric slot at the sewer crown. The flow in a sewer is described mathematically using the unsteady open - channel Saint-Venant equations. In this study, the computer simulation model(USS-slot) using slot techniques is develeped to simulate the inlet hydrographs to manholes and the flow under pressure as well as free - surface flow in tree - type sewer networks of circular conduits. The inlet hydrographs are simulated by using the rational method or the ILSD progrm. The Saint-Venant equations for unsteady open - channel flow in seweres are solved by using a four - point implicit difference scheme. The flow equations of the sewers and the junction flow equations are solved simulaneously using a sparse matrix solution technique.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.2
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• pp.159-164
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• 2008

This study simulated the flood inundations of the Nakdong River catchment running through Yangsan, a small city located in the south eastern area of Korea by using the depth averaged two-dimensional hydrodynamic numerical model. The numerical model employs the staggered grid system including moving boundary and a finite different method to solve the Saint-Venant equations. A second order upwind scheme is used to discretize the nonlinear convection terms of the momentum equations, whereas linear terms are discretized by a second order Leap-frog scheme(Cho and Yoon, 1998). The numerical model was applied to a real topography to simulate the flood inundation of the Yangsan basin in Yangsan. The numerical result for urban district was visualization for three dimension. These results can be essentially utilized to construct the three dimensional inundation map after building the GIS-based database in local public organizations in order to protect the life and property safely.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1047-1052
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• 2005

The purpose of this study is developing a coupled model for the flood analysis. Firstly, the model(river model) describing the inundation in a river solves the two-dimensional Saint Venant equations with a finite difference method and it is possible moving boundary treatment. The other model(inland model) in developed based on the ILLUDAS model to describe the conveyance capacity of a stormwater sewer system. Finally, a coupled model is applied to a real situation. The newly developed coupled model simulates reasonably the flood event occurred in a river and a inland simultaneously

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.179-182
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• 2008

This study simulated the flood inundations of the Nakdong River catchment running through Yangsan, a small city located in the south eastern area of Korea by using the depth averaged two-dimensional hydrodynamic numerical model. The numerical model employs the staggered grid system including moving boundary and a finite different method to solve the Saint-Venant equations. A second order upwind scheme is used to discretize the nonlinear convection terms of the momentum equations, whereas linear terms are discretized by a first order leap-frog scheme(Cho and Yoon, 1998). The numerical model was applied to a real topography to simulate the flood inundation of the Yangsan basin. The numerical results for urban district are visualized in three dimension. These results can be essentially utilized to construct the three dimensional inundation map after building the GIS-based database in local public organizations in order to protect the life and property safely.

• Tunnel and Underground Space
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• v.18 no.4
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• pp.252-262
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• 2008

In the uniaxial compressive test of a single specimen of transversely isotropic rock, its 5 independent elastic constants can not be defined since maximum 4 independent strain measurements are available theoretically. In order to solve this problem, one equation proposed by Saint Venant in 19C and confirmed by Lekhnitskii through the test experiences has been used for long time. Accordign to authors' experiences, however, this equation turned out to give erroneous elastic constants in some cases. Three new equations are suggested and their compatibilities are discussed in this paper. As the results of the analyses of the models, Lekhnitskii's suggested equation is effective for the specimen with the high dip angle whereas it results in the large erred output for that with dip angle less than $25{\sim}30$. It was found that the effectivenesses of three suggested equations and their compatibilities are subject to the dip angle and not to the amounts of elastic constants. Guide map to the selection of the compatible one of those suggested equations is presented as a result of the study.

• Spatial Information Research
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• v.15 no.4
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• pp.397-406
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• 2007

2D hydraulic models of urban areas are at the forefront of current research of flood inundation mechanisms, but they are constrained by inadequate parameters of topography and insufficient data. In this paper a numerical model based on DEMs is presented to represent overflow waters due to bank break in urban areas. The surface flow in the building areas is assumed to be properly modeled by solving Saint-Venant equation. In order to represent flooding broken out in Samcheok city, 2002, hydraulic model test using tracer has been carried out and validated. These efforts will serve for making flood hazard map and for estimating economic loss due to inundation of personal properties in urban areas.

• Journal of Korea Water Resources Association
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• v.41 no.8
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• pp.761-772
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• 2008

The object of this study is to develop the model that solves the numerically difficult problems in hydraulic engineering and to demonstrate the applicability of this model by means of various test examples, such as, verification in the gradually varied unsteady condition, three steady flow problems with the change of bottom slope with exact solution, and frictional bed with analytical solution. The governing equation of this model is the integral form of the Saint-Venant equation satisfying the conservation laws, and finite volume method with the Riemann solver is used. The evaluation of the mass and momentum flux with the HLL Riemann approximate solver is executed. MUSCL-Hancock scheme is used to achieve the second order accuracy in space and time. This study introduce the new and simple technique to discretize the source terms of gravity and hydrostatic pressure force due to longitudinal width variation for the balance of quantity between nonlinear flux and source terms. The results show that the developed model's implementation is accurate, robust and highly stable in various flow conditions with source terms, and this model is reliable for one-dimensional applications in hydraulic engineering.