• Title/Summary/Keyword: Parametric Surface

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Critical face pressure and backfill pressure in shield TBM tunneling on soft ground

  • Kim, Kiseok;Oh, Juyoung;Lee, Hyobum;Kim, Dongku;Choi, Hangseok
    • Geomechanics and Engineering
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    • v.15 no.3
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    • pp.823-831
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    • 2018
  • The most important issue during shield TBM tunneling in soft ground formations is to appropriately control ground surface settlement. Among various operational conditions in shield TBM tunneling, the face pressure and backfill pressure should be the most important and immediate measure to restrain surface settlement during excavation. In this paper, a 3-D hydro-mechanical coupled FE model is developed to numerically simulate the entire process of shield TBM tunneling, which is verified by comparing with real field measurements of ground surface settlement. The effect of permeability and stiffness of ground formations on tunneling-induced surface settlement was discussed in the parametric study. An increase in the face pressure and backfill pressure does not always lead to a decrease in surface settlement, but there are the critical face pressure and backfill pressure. In addition, considering the relatively low permeability of ground formations, the surface settlement consists of two parts, i.e., immediate settlement and consolidation settlement, which shows a distinct settlement behavior to each other.

Flow Near a Rotating Disk with Surface Roughness (표면조도를 갖는 회전판 주위의 유동)

  • Park, Jun-Sang;Yoon, Myung-Sup;Hyun, Jae-Min
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.634-639
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    • 2003
  • It has been studied the flow near a rotating disk with surface topography. The system Ekman number is assumed very small, i.e., $E[{\equiv}\frac{\nu}{{\Omega}^{\ast}L^{\ast2}}]<<1$ in which $L^{\ast}$ denotes a disk radius, ${\nu}$ kinematic viscosity of the fluid and ${\Omega}^{\ast}$ angular velocity of the basic state. Disk surface has a sinusoidal topographic variation along radial coordinate, i.e., $z={\delta}cos(2{\pi}{\omega}r)$, where ${\delta}$ and ${\omega}$ are, respectively, nondimensional amplitude and wave number of the disk surface. Analytic solutions, being useful over the parametric ranges of ${\delta}{\sim}O$( $E^{1/2}$ ) and ${\omega}{\leq}O$ ( $E^{1/2}$ ), are secured in a series-function form of Fourier-Bessel type. An asymptotic behavior, when $E{\rightarrow}0$, is clarified as : for a disk with surface roughness, in contrast to the case of a flat disk, the azimuthal velocity increases in magnitude, together with the thickening boundary layer. The radial velocity, however, decreases in magnitude as the amplitude of surface waviness increases. Consequently, the overall Ekman pumping at the edge of the boundary layer remains unchanged, maintaining the constant value equal to that of the flat disk.

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Determination of mass flow rate, jet temperature and heating time in mold surface heating technology using hot jet impingement (고온제트에 의한 금형표면 가열기법에서의 유량, 온도, 가열시간의 결정)

  • Choi, Sung-Ju;Yoo, Young-Eun;Kim, Sun-Kyoung
    • 한국금형공학회:학술대회논문집
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    • 2008.06a
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    • pp.135-139
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    • 2008
  • Development of surface heating technology using hot jet impingement onto mold inner surface for improvement of pattern transcription. This study is focused on how to control the parameters related to hot jet impingement. The mass flow rate, the jet temperature and the duration of the impingement are major parameters. The nozzle design and other geometric configurations also affect the heat transfer to the surface. In terms of heat transfer analysis, the most important number is the heat transfer coefficient, which is influenced by the mass flow rate, nozzle design, distance between the nozzle tip and the surface. In summary, several parametric studies using the developed model are conducted to investigate the effects of mass flow rate, jet temperature and Heating Time in Surface heating technology using hot jet impingement onto mold.

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A new hyperbolic shear deformation plate theory for static analysis of FGM plate based on neutral surface position

  • Merazi, M.;Hadji, L.;Daouadji, T.H.;Tounsi, Abdelouahed;Adda Bedia, E.A.
    • Geomechanics and Engineering
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    • v.8 no.3
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    • pp.305-321
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    • 2015
  • In this paper, a new hyperbolic shear deformation plate theory based on neutral surface position is developed for the static analysis of functionally graded plates (FGPs). The theory accounts for hyperbolic distribution of the transverse shear strains and satisfies the zero traction boundary conditions on the surfaces of the beam without using shear correction factors. The neutral surface position for a functionally graded plate which its material properties vary in the thickness direction is determined. The mechanical properties of the plate are assumed to vary continuously in the thickness direction by a simple power-law distribution in terms of the volume fractions of the constituents. Based on the present new hyperbolic shear deformation plate theory and the neutral surface concept, the governing equations of equilibrium are derived from the principle of virtual displacements. Numerical illustrations concern flexural behavior of FG plates with Metal-Ceramic composition. Parametric studies are performed for varying ceramic volume fraction, volume fraction profiles, aspect ratios and length to thickness ratios. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions.

Static and dynamic behavior of FGM plate using a new first shear deformation plate theory

  • Hadji, Lazreg;Meziane, M. Ait Amar;Abdelhak, Z.;Daouadji, T. Hassaine;Bedia, E.A Adda
    • Structural Engineering and Mechanics
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    • v.57 no.1
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    • pp.127-140
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    • 2016
  • In this paper, a new first shear deformation plate theory based on neutral surface position is developed for the static and the free vibration analysis of functionally graded plates (FGPs). Moreover, the number of unknowns of this theory is the least one comparing with the traditional first-order and the other higher order shear deformation theories. The neutral surface position for a functionally graded plate which its material properties vary in the thickness direction is determined. The mechanical properties of the plate are assumed to vary continuously in the thickness direction by a simple power-law distribution in terms of the volume fractions of the constituents. Based on the present shear deformation plate theory and the neutral surface concept, the governing equations are derived from the principle of Hamilton. There is no stretching-bending coupling effect in the neutral surface based formulation. Numerical illustrations concern flexural and dynamic behavior of FG plates with Metal-Ceramic composition. Parametric studies are performed for varying ceramic volume fraction, length to thickness ratios. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions.

A novel method for predicting the swelling potential of clay-bearing rocks

  • Moosavi, Mahdi;Ghadernejad, Saleh
    • Geomechanics and Engineering
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    • v.27 no.6
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    • pp.615-626
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    • 2021
  • The main objective of this study is to present a fast and reliable approach to predict the swelling potential of clay-bearing rocks. Investigations showed that there is a good correlation between the swelling potential of a rock and its desire to absorb water due to its clay content which could be measured using the "Contact Angle" test as one of the most common ways to determine the wettability. In this test, the angle between a water drop and the flat rock surface on which it rests is measured. The present method is very fast and returns repeatable results and requires minimal sample preparation. Only having a saw-cut surface of a sample with any shape is all one needs to perform this test. The logic behind this approach is that the swelling potential of a rock is a function of its mineral content and molecular structure, which are not only distributed in the bulk of the sample but also reflected on its surface. Therefore, to evaluate swelling behavior, it is not necessary to wait for a sample to get wet all the way to its "internal structure" (which, due to the low permeability of clay-bearing rocks, is very slow and time-consuming). Instead, one can have a good sense of swelling potential by studying its surface. Parametric studies on the effect of moisture content, porosity, and surface roughness on the contact angle measurements showed that using a saw-cut oven-dried sample is a convenient way to evaluate the swelling potential by this method.

Validation of an asymptotic zone conditional expression for turbulent burning velocity against DNS database (영역조건평균에 기초한 난류연소속도의 직접수치해법검증)

  • Kim, Soo-Youb;Huh, Kang-Y.
    • 한국연소학회:학술대회논문집
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    • 2004.11a
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    • pp.62-69
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    • 2004
  • Zone conditional formulations for the Reynolds average reaction progress variable are used to derive an asymptotic expression for turbulent burning velocity. New DNS runs are performed for validation in a statistically one dimensional steady state configuration. Parametric study is performed with respect to turbulent intensity, integral length scale, density ratio and laminar flame speed. Results show good agreement between DNS results and the asymptotic expression in terms of measured maximum flame surface density and estimated turbulent diffusivity in unburned gas.

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Validation of an asymptotic zone conditional expression for turbulent burning velocity against DNS database (영역조건평균에 기초한 난류연소속도의 직접수치해법검증)

  • Kim, Soo-Youb;Huh, Kang-Y.
    • Journal of the Korean Society of Combustion
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    • v.9 no.4
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    • pp.1-8
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    • 2004
  • Zone conditional formulation for the Reynolds average reaction progress variable is used to derive an asymptotic expression for turbulent burning velocity. New DNS runs are performed for validation in a statistically one dimensional steady state configuration. Parametric study is performed with respect to turbulent intensity, integral length scale, density ratio and laminar flame speed. Results show good agreement between DNS results and the asymptotic expression in terms of measured maximum flame surface density and estimated turbulent diffusivity in unburned gas.

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Triangular Mesh Generation on Places or Surfaces by a New Looping Method (새로운 분할법에 의한 평면 및 곡면의 삼각형 요소망 자동생성)

  • 이민철;전만수;임우섭
    • Korean Journal of Computational Design and Engineering
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    • v.4 no.2
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    • pp.79-86
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    • 1999
  • A general approach to automatic generation of triangular meshes on three-dimensional surfaces is presented in this paper. The approach, developed with emphasis on program generality and interface with CAD/CAM systems, is based on the double mapping method and the looping method. The double mapping method is introduced and anew splitting scheme is proposed for the looping method employed for triangular mesh generation on the parametric domain. Several application examples are given.

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Atmospheric Plasma application for dry cleaner, PR ashing & PI rework in the $5^{th}$ generation and beyond LCD production

  • Park, Young-Chun;Lee, Bong-Ju
    • 한국정보디스플레이학회:학술대회논문집
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    • 2003.07a
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    • pp.421-424
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    • 2003
  • An AP plasma technology has been developed for the application of dry cleaner, PR ashing and PI rework in the large glass size. The technology is cost effective, environment friendly, and best fits for coming generation LCD production since the design is easily scalable to bigger size glasses. Surface cleaning results based on the contact angle study has been presented for $5^{th}$ generation LCD bare glass. PR ashing results and various parametric studies have been also presented.

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