• Journal of Korean Tunnelling and Underground Space Association
• /
• v.14 no.4
• /
• pp.437-451
• /
• 2012

Application of 3D laser scanner to civil engineering is widely studied in various fields such as tunnel, bridge, calculation of earth volume, construction measurement, observation of rock joint, etc. Some studies on utilization of the 3D laser scanner for calculating the over-break and/or under-break of tunnels have also been carried out. However, in the previous research, the scanning data were usually compared with the 2D CAD blueprint results; although the shape of tunnel structure is relatively simple, for precise calculation of the over-break and/or under-break of tunnels, three-dimensional analysis based on BIM is needed. Therefore, in this paper, a new program that calculates the over-break and/or under-break of tunnels using the 3D laser scanner and the BIM is developed; moreover the effective and rapid process of data treatment is proposed. The accuracy of the developed program was verified by applying the new system to a real tunnels construction field.

• Tunnel and Underground Space
• /
• v.17 no.3 s.68
• /
• pp.216-224
• /
• 2007

Blasting, using shock and dynamic energy of explosive, is very effective tunnel excavation method. But it had serious problem which is the blast vibration and over-break. In recent study, pre-cracked excavation method using notch hole reduced blast vibration and over-break in tunnel, so we performed study about developing notch bit system for making notch hole. In order to make notch hole effectively we had perform drilling experiments changing length and height of notch and in order to improve speed and precision of drilling we had developed notch bit system which consists of drilling bit, notch bit, adapter and notch guide.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.6 no.2 s.21
• /
• pp.45-50
• /
• 2006

When we build the tunnel, occasionally, the blasted section exceed the designed section because of geological properties and the lack of blasting technologies, and the exceed section is remained as over break after the construction of tunnel lining. When the underground water leaks with silt and clay through the cracks of rocks, the large over break cause a structural stability problem in tunnel, and the back charging of over break is very important subject, because the undoing of back charging cause the drop of crashed rocks and serious problem in the stability of tunnel lining. Therefore, the theory of blast is studied and purpose the structural analysis of back charging and propose the safe method about the drop of crashed rocks.

• Journal of Korean Society of Water and Wastewater
• /
• v.16 no.6
• /
• pp.710-716
• /
• 2002

A General Pipe Break Prediction Model that incorporates linear and exponential models in its form is developed. The model is capable of fitting pipe break trends that have linear, exponential or in between of linear and exponential trend by using a weighting factor. The weighting factor is adjusted to obtain a best model that minimizes the sum of squared errors of the model. The model essentially plots a best curve (or a line) passing through "cumulative number of pipe breaks" versus "break times since installation of a pipe" data points. Therefore, it prevents over-predicting future number of pipe breaks compared to the conventional exponential model. The optimal replacement time equation is derived by using the Threshold Break Rate equation by Loganathan et al. (2002).

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.21 no.5
• /
• pp.101-107
• /
• 2017

Over-break, which is excavated larger than planned line at tunnel excavation, is inevitable due to the nature of blasting. But regarding the bottom of the foundation, most of the domestic ordering organizations pay only 10 cm thick filled concrete when pouring concrete due to over-break. In accordance, the construction cost will increase greatly if all the depths of the designed over-break are filled only with concrete. When tunnel excavation occurs, concrete filling of 18 MPa(T = 100 mm) and 150 mm~237 mm auxiliary concrete layer and 240 mm concrete track(TCL) are applied to the upper part. The concrete is installed in an excessive amount of about 600 mm between the lower part of the rail and the tunnel rock bed. Therefore, in this study, it is necessary to analyze the concrete crack structure according to the depth of the existing tunnel and the modified tunnel section, and to evaluate the adequacy of the required thickness of the tunnel floor concrete for securing the crack stability of the concrete.

• Explosives and Blasting
• /
• v.36 no.1
• /
• pp.12-19
• /
• 2018

When an underground limestone mine selects room-and-pillar mining method, in which the stability of mine openings is maintained by leaving safety pillars, the stability of safety pillars is always incompatible with their productivity. Therefore, the engineering decision for stability and productivity is essential. In this study, a progress of excavation faces by conventional blasting pattern has been examined in field for investigating over-break and stereo-photogrammetry method has been applied to this field measurement for improvement of accuracy. Also this result has been reflected instantly to composite blasting pattern by feedback, for minimizing overbreak. Field tests showed the relevant results that $3.5m^2$ in over-break out of $70m^2$ in total excavation face has been decreased, that is 5% of reduction rate in maximum.

• Journal of Korea Water Resources Association
• /
• v.56 no.10
• /
• pp.603-617
• /
• 2023

This study aims to provide a better understanding of the turbulent flow characteristics in swash zone. A double dam-break method is employed to generate the swash zone flow. Comparing with the conventional single dam-break method, a delay between two gate opening can be controlled to reproduce various interactions between uprush and backwash. For numerical simulations, overInterDyMFoam based on OpenFOAM is adopted. Using overInterDyMFoam, interface between two immiscible fluids having different densities (i.e., air and water phases) can be tracked in a moving mesh with multiple layers. Two-dimensional Reynolds-Averaged Navier-Stokes equations are solved with a standard 𝜅-𝜖 turbulence model for momentum and continuity. Numerical model results are validated with laboratory experiment data for the time series of water depth and streamwise velocity. Turbulent kinetic energy distribution is further investigated to identify the turbulence evolution for each flow regime (i.e., uprush, backwash, and swash-swash interaction).

• Explosives and Blasting
• /
• v.36 no.1
• /
• pp.34-38
• /
• 2018

It proceed the trial test by applying blasting system with combination of electronic detonator and non-electric detonator(Supex Blasting Method) for the purpose of preventing the over-break as well as controling the blasting vibration and noisy at the site of Boseong-Imseongri railroad section ${\bigcirc}{\bigcirc}$. As a result of that, the blasting vibration and noisy was measured within the allowable standard of vibration. In conclusion, the combination of electronic detonator and non-electric detonator can not only reduce come construction cost, level of vibration and noisy but also get the prevention effect for Public resentment and minimize the rock-damage through over break control.

• Fisheries and Aquatic Sciences
• /
• v.1 no.1
• /
• pp.48-62
• /
• 1998

Seasonal volume transport on the Texas-Louisiana continental shelf is investigated in terms of objectively fitted transport streamfunction fields based on the current meter data of the Texas­Louisiana Shelf Circulation and Transport Processes Study. Adopted here for the objective mapping is a method employing a two-dimensional truncated Fourier representation of the streamfunction over a domain, with the amplitudes determined by least square fit of the observation. The fitting was done with depth-averaged flow rather than depth-integrated flow to reduce the root-mean-square error. The fitting process filters out $11\%$ of the kinetic energy in the monthly mean transport fields. The shelf-wide pattern of streamfunction fields is similar to that of near-surface velocity fields over the region. The nearshore transport, about 0.1 to 0.3 Sv $(1 Sv= 10^6\;m^3/sec)$, is well correlated with the seasonal signal of along-shelf wind stress. The spring transport is weak compared to other seasons in the inner shelf region. The transport along the shelf break is large and variable. In the southwestern shelf break, transport amounts up to 4.7 Sv, which is associated with the activities of the encroaching of energetic anticyclonic eddies originated in Loop Current of the eastern Gulf of Mexico. The first empirical orthogonal function (EOF) of streamfunction variability contains $67.3\%$ of the variance and shows a simple, shelf-wide, along-shelf pattern of transport. The amplitude evolution of the first EOF is highly correlated (correlation coefficient: 0.88) with the evolution of the along-shelf wind stress. This provides strong evidence that the large portion of seasonal variation of the shelf transport is wind-forced. The second EOF contains $23.7\%$ of the variance and shows eddy activities at the southwestern shelf break. The correlation coefficient between the amplitudes of the second EOF and wind stress is 0.42. We assume that this mode is coupled a periodic inner shelf process with a non-periodic eddy process on the shelf break. The third EOF (accounting for $7.2\% of the variance) shows several cell structures near the shelf break associated with the variability of the Loop Current Eddies. The amplitude time series of the third EOF show little correlation with the along-shelf wind.

• Journal of Bio-Environment Control
• /
• v.11 no.2
• /
• pp.61-66
• /
• 2002

Double cropping system in a year in Kyoho grapes (Vitis labruscana L.) has currently been attempted in the plastic greenhouse. One of the problems in double cropping system is the promotion of bud break in summer season and shoot fertility. Effects of the control of soil moisture tension near the root zone and treatments of bud dormancy breaking agents on bud breaking in summer were examined to promote the bud break for the second fruiting. The lignification of shoots was induced in July or August by the control of soil moisture tension in root zone environment. The first shoot growth was almost the same as that in common plastic greenhouses. The highest bud break value appeared in the plot of cyanamide chemicals mixed with merit blue as over 75% bud break rate. The bud break rate in the discontinuing plot in irrigation showed significantly higher in bud break than that in the continuing plot in irrigation. Despite of the final high bud break rate, the time of bud break was irregular.