• Geomechanics and Engineering
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• v.13 no.6
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• pp.907-928
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• 2017

The effects of seepage force and out-of-plane stress on cavity contracting and tunnel opening was investigated in this study. The generalized Hoek-Brown (H-B) failure criterion and non-associated flow rule were adopted. Because of the complex solution of pore pressure in an arbitrary direction, only the pore pressure through the radial direction was assumed in this paper. In order to investigate the effect of out-of-plane stress and seepage force on the cavity contraction and circular tunnel opening, three cases of the out-of-plane stress being the minor, intermediate, or major principal stress are assumed separately. A method of plane strain problem is adopted to obtain the stress and strain for cavity contracting and circular tunnel opening for three cases, respectively, that incorporated the effects of seepage force. The proposed solutions were validated by the published results and the correction is verified. Several cases were analyzed, and parameter studies were conducted to highlight the effects of seepage force, H-B constants, and out-of-plane stress on stress, displacement, and plastic radius with the numerical method. The proposed method may be used to address the complex problems of cavity contraction and tunnel opening in rock mass.

• KIEAE Journal
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• v.11 no.6
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• pp.37-42
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• 2011

This Paper aims for analyzing the effect of opening types on wind-driven ventilation performance in basement parking lots of apartment. The scale model of basement parking lot was made, wind tunnel tests conducted. Wind pressure of three opening types was measured, wind pressure coefficient calculated. As the result, it showed that the air flow pattern of stack type opening was strongly changed by wind direction, but it was almost not at scuttle vent type. But, as for the difference of wind pressure coefficient, stack type opening was more than the other two types.

• Wind and Structures
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• v.13 no.4
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• pp.363-374
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• 2010

Appropriate scaling methods for wind tunnel modelling of building internal pressures induced through a dominant opening were investigated. In particular, model cavity volume distortion and geometric scaling of the opening details were studied. It was found that while model volume distortion may be used to scale down buildings for wind tunnel studies on internal pressure, the implementation of the added volume must be done with care so as not to create two cavity resonance systems. Incorrect scaling of opening details was also found to generate incorrect internal pressure characteristics. Furthermore, the effective air slug or jet was found to be longer when the opening was near a floor or sidewall as evidenced by somewhat lower Helmholtz frequencies. It is also shown that tangential flow excitation of Helmholtz resonance for off-centre openings in normal flow is also possible.

• Wind and Structures
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• v.32 no.2
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• pp.105-114
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• 2021

This paper describes a wind tunnel test on a 1:25 scale model of TTU building with several adjustable openings in order to comprehensively study the characteristics of fluctuating internal pressures, especially the phenomenon of the increase in fluctuating internal pressures induced by tangential flow over building openings and the mechanism causing that. The effects of several factors, such as wind angle, turbulence intensity, opening location, opening size, opening shape and background porosity on the fluctuating internal pressures at oblique wind angles are also described. It has been found that there is a large increase in the fluctuating internal pressures at certain oblique wind angles (typically around 60° to 80°). These fluctuations are greater than those produced by the flow normal to the opening when the turbulence intensity is low. It is demonstrated that the internal pressure resonances induced by the external pressure fluctuations emanating from flapping shear layers on the sidewall downstream of the windward corner are responsible for the increase in the fluctuating internal pressures. Furthermore, the test results show that apart from the opening shape, all the other factors influence the fluctuating internal pressures and the internal pressure resonances at oblique wind angles to varying degrees.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.6
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• pp.20-28
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• 2021

High enthalpy test facilities, such as a shock tunnel, are to be operated at the specific pressure ratio according to the desired test condition. A metallic diaphragm is machined or a forced rupture device is used to open it at a specific pressure ratio. The diaphragm opening procedure takes several hundred microseconds including rupture and deformation. This process is expected to affect the test conditions. In this study, numerical simulation was performed for different materials, thicknesses, and opening ratios. And the characteristics of shock wave generation and the stagnation condition in the tube are investigated. Results show that the final opening ratio and rupturing procedure directly affect the speed of a shock wave, stagnation pressure, and test time.

• Journal of ILASS-Korea
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• v.21 no.3
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• pp.162-169
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• 2016

When we construct a road near an apartment complex, we consider a soundproof wall. To make residential places quieter, we may consider a soundproof road tunnel. Such a tunnel, however, would become highly concentrated with soot from vehicles whenever a traffic jam might occur. To create an optimum design, this study utilizes the PHOENICS-VR software. The work considers three cases: (1) no openings (2) openings at 30m intervals, and (3) openings at 60m intervals on the upper side of the tunnel. The study finds that in the second case shows CO concentration distributions were 15% less than those without openings. And the CO concentration distributions of the second and third cases are almost the same. The findings suggest that we should make the soundproof tunnel to reduce construction fees.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.111-115
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• 2001

Durability of tunnel drains is important, because the accumulation of groundwater around the tunnel due to clogging of filter or reduction of discharge capacity of drain causes reduction of the life time of tunnel linings. In this paper, clogging and discharge capacity of drain and filter of tunnels are evaluated using a gradient ratio test and filter design criteria. The results of the gradient ratio test showed that gradient ratio(GR) is high when fine content is high in the soil samples and equivalent opening size(EOS) of filter materials is small. Measured GR was less than allowable critical gradinet ratio : 3.0, which is the clogging criteria of U.S. Army Corps of Engineers.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.1059-1064
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• 2002

The behavior of an opening and the performance of support system depend upon the load-deformation characteristics of ground and support as well as of the manner and of timing of support installation. The load-deformation characteristics of ground and support are derived by the interaction between ground and support. The interaction between ground and support is qualitatively illustrated by a ground response curve. The behavior of an opening and the performance of support system depend upon the load-deformation characteristics of ground and support as well as of the manner and of timing of support installation. The interaction between ground and support is qualitatively illustrated by a ground response curve. The convergence-confinement method don't need the basic assumptions for a mathematical model. Also This is applicable to general tunnel. Consequently the stability of tunnel must be qualitatively investigated by a ground response curve and quantitatively adjudged by a numerical analysis for the reasonable design of tunnel.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1990.10a
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• pp.63-68
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• 1990

The nature of fluctuating air pressure inside building was studied by testing a building model in a wind tunnel. The model has a single room and a sin81e window opening. Various opening conditions were tested in both laminar uniform wind and turbulent boundary-layer wind. The RMS and the spectra of the fluctuating internal pressure were measured. The test results support a recent theory which predicts the behavior of internal pressure under high wind based on aerodynamic analysis.

• Wind and Structures
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• v.16 no.1
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• pp.61-91
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• 2013

An analytical model of internal pressure response of a leaky and quasi-statically flexible building with a dominant opening is provided by including the effect of the envelope external pressure fluctuations on the roof, in addition to the fluctuating external pressure at the dominant opening. Wind tunnel experiments involving a flexible roof and different building porosities were carried out to validate the analytical predictions. While the effect of envelope flexibility is shown to lower the Helmholtz frequency of the building volume-opening combination, the lowering of the resonant peak in the internal and net roof pressure coefficient spectra is attributed to the increased damping in the system due to inherent background leakage and envelope flexibility. The extent of the damping effects of "skin" flexibility and background leakage in moderating the internal and net pressure response under high wind conditions is quantified using the linearized admittance functions developed. Analytical examples provided for different combinations of background leakage and envelope flexibility show that alleviation of internal and net pressure fluctuations due to these factors by as much as 40 and 15% respectively is possible compared to that for a nominally sealed rigid building of the same internal volume and opening size.