• Proceedings of the Korean Geotechical Society Conference
• /
• 2002.10a
• /
• pp.327-333
• /
• 2002

In this study, the effect of tunnel advance rate on the seepage forces acting on the tunnel face was studied. The finite element program to analyze the groundwater flow around a tunnel with the consideration of tunnel advance rate was developed. Using the program, the parametric study for the effect of the tunnel advance rate and hydraulic characteristics of the ground on the seepage forces acting on the tunnel face was studied. From this study, it was concluded that the tunnel advance rate must be taken into consideration as an additional parameter to assess the seepage forces at the tunnel face and a rational design methodology for the assessment of support pressures required for maintaining the stability of the tunnel face was suggested for underwater tunnels.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.5
• /
• pp.221-228
• /
• 2002

The stability of a tunnel face is one of the most important factors in tunnel excavation. Especially, if a tunnel is located under groundwater level, groundwater may flow into the tunnel face and seepage forces acting on the tunnel face due to groundwater flow may affect seriously the stability of the tunnel face. Therefore, the seepage pressure at the tunnel face should be considered fir the proper design and safe construction of a tunnel. In this paper, the effect of tunnel advance rate on the seepage forces acting on the tunnel face was studied. The finite element program to analyze the groundwater flow around a tunnel with the consideration of tunnel advance rate was developed. Using the program, the parametric study for the effect of the tunnel advance rate and hydraulic characteristics of the ground on the seepage forces acting on the tunnel face was made. From this study, it was concluded that the tunnel advance rate must betaken into consideration as an additional parameter to assess the seepage forces at the tunnel face and a rational design methodology fer the assessment of support pressures required for maintaining the stability of the tunnel face was suggested for undetwater tunnels.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.26 no.5
• /
• pp.403-419
• /
• 2024

Advance rate significantly affects both the construction period and cost in tunnel blasting. As such, there has been persistent research dedicated to the development of innovative blasting technique aimed at enhancing the advance rate. This paper aims to provide fundamental insights into the differences in advance rate and the powder factor between two- and three-free-face blasting, laying the groundwork for the advancement of tunnel blasting techniques. Large-scale cement mortar specimens were fabricated, and blasting tests were conducted for both two- and three-free-face blasting. Experimental findings were then compared with those from numerical simulation. Notably, an increase in the number of free faces, under uniform conditions, significantly improved the advance rate while reducing the powder factor. The outcomes of this study serve as crucial groundwork for devising blasting patterns employing three-free-face blasting, characterized by improved advance rates and minimized powder factors. Consequently, the anticipated outcomes include an overall improvement in tunnel advance rates and a reduction in the number of drilling holes and the amounts of explosives.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1997.10a
• /
• pp.171-176
• /
• 1997

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.5 no.3
• /
• pp.241-250
• /
• 2003

Rock mass is very inhomogeneous in nature and data obtained by site investigations and tests are very limited. For this reason, many uncertainties are to be included in the process of constructing structures in rock mass. In the design of a tunnel, support pattern, advance rate, and excavation method, which are important design parameters, must be determined to be optimal. However, it is not easy to determine those parameters. Moreover if those parameters are determined incorrectly, unexpected risk occurs such as decrease in the stability of a tunnel or economic loss due to the excessive supports etc. In this study, how to determine an optimal support pattern and advance rate, which are the important tunnel design parameters, is introduced based on a risk analysis. It can be confirmed quantitatively that the more supported a tunnel is, the larger reliability index becomes and the more stable the tunnel becomes. Also an optimal support pattern and advance rate can be determined quantitatively by performing a risk analysis considering construction cost and the cost of loss which can be occurred due to the collapse of a tunnel.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.6D
• /
• pp.839-848
• /
• 2011

TBM (Tunnel Boring Machine) tunnel should be carry out with the adopted machine until the end of excavation because of impossibility of replacement or modification of machine. Observation of the face of the tunnel is difficult, especially in EPB(Earth Pressure Balance) shield TBM, predict changes in the ground condition with analyzing data, collected during the excavation, and it should be reflected in construction. Until recently, subjects of studies on TBM are mainly the determination of machine and the development of advance rate prediction model, according to the characteristics of ground which is the target of excavation. However, study focused on the estimation of ground conditions and the improvement in operational methods using excavation data of TBM equipment, the principal of the excavation, has been done not so much. This study examine the variances in advance rate depending on changes in operating conditions and evaluate the optimal operating conditions of adopt machine, using working data obtained from EPB shield TBM project. The result of this study is suggested as follows. First, cutter head RPM and total thrust force are biggest influences on advance rate, Second, it is recommended for proper advance rate that total thrust force is controlled while optimum cutter head RPM is kept, Third, according to the increasing trend of total thrust force, the changes in ground conditions can be predicted, the appropriate operating conditions can be determined.

• Tunnel and Underground Space
• /
• v.2 no.1
• /
• pp.177-189
• /
• 1992

As tunnel becomes longer and larger, TBM has become one of the most popular methods of excavatio in rock. This paper describes the degree of operation the degree of availability and penetration rate of TBM and TBE applied in Namsan roadway tunnelling site. Net penetration rate was 1.62m/hr for TBM and 0.72m/hr for TBE. Net penetration rate showed no direct relation to daily advance or penetration time, but the lower bound of penetration rate could be obtained from the relation with daily advance. For both of TBM and TBE, the degree of operation and the degree of availability were 33.8% and 68.6% respectively. Life time of normal cutter was $310m^3$ for TBM and $194m^3$ for TBE, while that of center and gauge cutter was about $50m^3$. When the two machines were compared, TBM showed 80% higher penetration rate, and 40% shorter life time of cutter.

• Explosives and Blasting
• /
• v.31 no.2
• /
• pp.32-39
• /
• 2013

Generally, The way of long hole blasting is carried out in coal-face, basic excavation for dam, mine etc. Recently, this long hole blasting has been implemented in civil engineering for efficiency & economic feasibility. National express no.600 of Pusan outer high-express ${\bigcirc}$ construction site with four lanes of the length of 8km was also a site applied by long hole blasting. But After blasting, tunnel advance rate is less than 75%. As a result of that, Follow-up working time is influenced. Thereby, The total of working process is significantly so increased that planned excavation cannot be implemented many times. For not only improve excavation rate but reduce working process time in job site, we introduce blasting case which apply the ${\phi}36mm$ explosive suited for high desity of charging among long hole blasting in order to overcome mentioned problem.

• Tunnel and Underground Space
• /
• v.13 no.3
• /
• pp.196-206
• /
• 2003

In order to investigate the workability of Raise Boring Machine(RBM) such as utilization, penetration rate and advance rate, a vertical shaft of 98 m in length and 3.05 m in diameter was constructed in the layer of conglomerate by using the RBM in this study. In addition, field data from tow different construction sites including water-pump power plant tunnel, roadway tunnel and mining tunnel by RBM were collected and analyzed. The results show that the average weekly bored length is 19.3 m and its average utilization is between 54.3 % and 75.1 % very higher than that of the TBM(Tunnel Boring Machine). It also turns out that the bit force increases linearly with respect to the increase of the RPM(revolution per minute) of RBM. However, the net penetration rate decreases with the increase of bit force, RPM of RBM and depth of shaft. The findings of this study can be used to provide the useful information for the design of shaft and the selection of RBM.

• Tunnel and Underground Space
• /
• v.13 no.4
• /
• pp.260-269
• /
• 2003

In order to introduce to engineers the suitable calculation techniques of TBM advance rate (ad.) and ultimately promote to understand the designing process, this study was carried out. We analyzed the 17 bored data of TBM which applied to the roadway and water supply tunnels in Korea. From this analysis, it was able to how that the average utilization is 30.83% md the correlation equation of Ad and TBM´s diameter (D) is Ad(m/month) = 506.05ㆍ $e^{-0.1162}$$\times$D than the correlation coefficient ($R^2$) is 0.76. In the object of the W tunnel of Seoul-Busan highspeed railway, the Ad of TBM 5.0mø was analyzed by the variety of empirical models and upper correlation equation. Average Ad of the empirical models was calculated to be larger than one of the upper equations. But considering only the results of 3.0~5.0mø TBM in the 17 bored data, the average Ad by the models belongs to the similar range of bored data. Therefore, when the reliability and representative of parameters are decreased, a reliability test should be carried out through the comparison a variety of empirical models with the upper correlation equation.