• Journal of the Korean Society of Safety
• /
• v.23 no.1
• /
• pp.28-34
• /
• 2008

The corrugated steel plate structures is applied to the construction of mountain tunnel portal part with shallow depth, the tunnel on the outskirts of urban areas and ecology move passage. In this study, A finite element method is used for research the behavior of corrugated steel plate structures due to construction position under declinating earth pressure and excavation depth. A finite element method were performed varying construction position(10, 15, 20 and 25m) from slope and excavation depth from surface. The hoop thrust and moment, displacement of corrugated steel plate subjected to construction position and excavation depth is determined from a finite element method. From results of finite element method, it was found that the increase of thrust and the decrease of displacement as the amount of distance increase from slope with construction position. But the thrust and moment, displacement has not different value with excavation depth.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2001.03a
• /
• pp.113-120
• /
• 2001

A frame slab method has been proved as a possible and profitable construction solution for the urban tunnels with very shallow overburden and the excavation from the surface Is strictly limited. Since this method allows only a small amount of construction activities in the ground surface, the disturbances to the public and the surface traffic can be drastically reduced compared with the ordinary cut-and-cover method. The construction sequences of the method and the some of critical cautions needed are described in detail. Also a comprehensive numerical analysis including 2-D and 3-D analysis have been performed to verify the stability of the ground during the construction. It is revealed from this study that the frame slab method can be a quite successful solution for the shallow overburden tunnelling in urban area.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.4 no.3
• /
• pp.185-193
• /
• 2002

In this paper, deformation behavior of shallow subway tunnel excavated in weathered soil and reinforcement effects of longitudinal support measures are investigated via three dimensional FDM analysis. Two excavation methods, half-face excavation and full-face excavation, are considered in simulation to study the influences of excavation methods on tunnel deformation behavior. In addition, the reinforcing effects of RPUM and fiberglass pipe are compared. Face extrusion, covergence, preconvergence, and sidewall displacement are investigated to analyze tunnel deformation behavior, and surface settlement is used to analyze the effects of excavation methods and longitudinal supports measures. The simulation results show that half-face excavation induces larger convergence, preconvergence, sidewall displacement, surface settlement than full-face excavation, while full-face excavation induces larger extrusion than half-face excavation. In addition, under same excavation method, all displacements are larger when RPUM is only used for longitudinal support than when RPUM is jointly used with fiberglass pipes.

• Geomechanics and Engineering
• /
• v.17 no.6
• /
• pp.573-581
• /
• 2019

Excavation of underground cavern and shaft was proposed for the construction of a ventilation facility in an urban area. A shaft connects the street-level air plenum to an underground cavern, which extends down approximately 46 m below the street surface. At the project site, the rock mass was relatively strong and well-defined joint sets were present. A kinematic block stability analysis was first performed to estimate the required reinforcement system. Then a 3-D discontinuum numerical analysis was conducted to evaluate the capacity of the initial support and the overall stability of the required excavation, followed by a 3-D continuum numerical analysis to complement the calculated result. This paper illustrates the application of detailed numerical analyses to the design of the required initial support system for the stability of underground hard rock mining at a relatively shallow depth.

• Proceedings of the Korean Society for Rock Mechanics Conference
• /
• 2007.03a
• /
• pp.13-28
• /
• 2007

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.19 no.6
• /
• pp.1045-1058
• /
• 2017

This paper is a study on railway tunnel behavior characteristic of shallow overburden under the existing road. In order to understand the behavior characteristics of the ground deformation during tunnel excavation, a horizontal rod extensometers were installed in the passage area of the shallow overburden tunnel under the road, and the measurement and analysis were carried out. To compare the in situ measurement, three dimensional numerical analysis with ground condition and construction step was carried out using MIDAS NX. As a result of the field measurement, large preceding settlement occurred where the poor ground condition with shallow overburden excavation has been conducted. As a result of the numerical analysis, the largest settlement occurred at the shallow overburden point where the ground condition was poor. Therefore, in the shallow overburden section where the soil condition is poor and a sufficient depth can't be secured and the arching effect of the ground around the tunnel can't be expected, careful attention should be paid to the application of stiffness reinforcement measures and to minimize ground loosening.

• Geomechanics and Engineering
• /
• v.2 no.2
• /
• pp.107-123
• /
• 2010

Ground settlements and pore pressure changes were monitored around a shallow tunnel constructed in clay till during the excavation and primary lining installation. The settlements above the tunnel continued to develop for up to 100 days after the primary lining installation. Triaxial compression tests were carried out to estimate the short-term and long-term deformation characteristics of the till. Numerical simulation was conducted to history match the field measurements, and thus, to quantify the settlements induced by ground stress relief, consolidation and creep. It was found that the surface settlements due to ground stress relief, consolidation and creep are 17, 12 and 71% of total settlement (about 44 mm), respectively. In addition, early installation of rigid concrete lining could be an effective means to reduce the settlement due to creep.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.7 no.3
• /
• pp.227-237
• /
• 2005

In this study, the behavior of shallow 2-Arch tunnel due to excavation under horizontal discontinuity plane was verified experimentally. The model tests were carried out by varying the overburden height and the location of the discontinuity plane. The model tests followed exactly the real 2-Arch tunnel construction stages. As a result, it is discovered that stress-transfer mechanism and loosening area around the 2-Arch tunnel depends on the overburden heights and the location of the discontinuity plane. And central pillar load is also dependent on overburden height, location of discontinuity plane and construction stages.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.03a
• /
• pp.1224-1239
• /
• 2008

The earth retaining walls using stabilizing piles can be applied to shallow excavation works without any stiffener. But, It demends a variety of installed composite stiffener on the earth retaining walls when it is installed as deep excavation works. Because, it causes an excessive displacement of walls. This research tried to overcome the problems created by the above issues and intended to apply the composite stiffener. The model test, focused on the effect of installed composite stiffener, measured the bending stress with stabilizing piles and walls, the settlement of earth surface, the displacement of walls for a step excavation and an increase in strip load. With the test results and soil deformation analysis, the reinforcement effect(relating to control displacement and earth presure) was analyzed in a qualitative and quantitative manner. It is expected to overcome a deep excavation works.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.7 no.1
• /
• pp.3-12
• /
• 2005

The behaviors of the ground in crossed zone and the existing upper tunnel in shallow cover due to the excavation of new lower tunnel Rectangularly crossed to that was studied. Model tests were performed in the large scale test pit, the size was '$4.0m(width){\times}3.8m(height){\times}4.1m(length)$'. Test ground was constructed uniformly by sand in middle density. Results of the model tests show that earth pressure and settlement of the ground in crossed zone were redistributed due to the longitudinal arching effect by the excavation of lower tunnel. Upper tunnel blocks stress flow due to the longitudinal arching effect by excavation of lower tunnel.