• Explosives and Blasting
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• v.22 no.3
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• pp.71-78
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• 2004

Explosive blasting, hydaulic power unit and rock splitter are typically utilized for rockmass breakage and cutting in reconstruction of building structures and other construction site. Hydraulic rock cutting method, that can be utilized any weather conditions, has been applied mainly by experience for controling damages caused by vibration, noise and rock cuttings, and reducing damage claim by protecting adjacent structures. However, it is required to understand the characteristics of rockmass to improve operation efficiency. Although every cutting method has its own advantage, but it should be applied by considering site circumstance and rockmass properties in details to maximize the operation efficiency and economic feasibility.

• Journal of the Korean Geotechnical Society
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• v.25 no.11
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• pp.53-60
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• 2009

Construction of a tunnel induces rock masses damage around the tunnel. The degree of damage produced on rock masses will affect on the mechanical and hydraulic behaviors of the rock masses. In this paper, P wave velocity measured by cross-hole test was used to assess rock masses damage around the test tunnel. Initiation of source signal was carried out using mechanical impact at the source installed borehole. In consequence, the generated P wave signal was low noise and apparent wave form, which allows accurate pick-up of first arrival time. From the test, the region where rock damage is expected shows relatively low P wave velocity. In addition, with multiple points of P wave velocity measurement along each cross-hole, two dimensional P wave tomography was obtained. The tomography provides apparent view of the rock damage behind the tunnel. The measured P wave velocity was correlated with features of rock masses, porosity and Q value.

• Tunnel and Underground Space
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• v.29 no.6
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• pp.508-522
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• 2019

Because of the slope failure, not only property damage but also human damage can occur, slope stability analysis should be conducted to predict and reinforce of the slope. This paper, defines the ground areas that can be characterized in terms of slope failure such as Rockmass jointset, Rockmass fault, Soil, Leakage water and Crush zone in sloped images. As a result, it was shown that the deep learning instance segmentation network can be used to recognize and automatically segment the precise shape of the ground region with different characteristics shown in the image. It showed the possibility of supporting the slope mapping work and automatically calculating the ground characteristics information of slopes necessary for decision making such as slope reinforcement.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.584-590
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• 2009

One of the critical design problems involved in deep tunnelling in brittle rock, is the creation of surface spalling damage and breakouts. If weak fault zone is developed in deep tunnel, squeezing problem is added to the problems. According to the results of ground investigation in the study area, hard granitic rockmass and distinguished high angle fault zone are distributed on the tunnel level over 400m depth. To analyse the probability of brittle failure and squeezing, ground characterization with special lab. and field test were carried out. By the results, probability of brittle failures like spalling and rock burst is very low. But squeezing may be probable, if weak fault zone observed surface and drill core is extended to designed tunnel level.

• Geomechanics and Engineering
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• v.24 no.6
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• pp.505-518
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• 2021

The present paper has been carried out to understand the effects of impact loading on the rock tunnels, constructed in different region corresponding to varying unconfined compressive strength (UCS), through finite element method. The UCS of rockmass has substantial role in the stability of rock tunnels under impact loading condition due to falling rocks or other objects. In the present study, Dolomite, Shale, Sandstone, Granite, Basalt, and Quartzite rocks have been taken into consideration for understanding of the effect of UCS that vary from 2.85 MPa to 207.03 MPa. The Mohr-Coulomb constitutive model has been considered in the present study for the nonlinear elastoplastic analysis for all the rocks surrounding the tunnel opening. The geometry and boundary conditions of the model remains constant throughout the analysis and missile has 100 kg of weight. The general hard contact has been assigned to incorporate the interaction between different parts of the model. The present study focuses on studying the deformations in the rock tunnel caused by impacting load due to missile for tunnels having different concrete grade, and steel grade. The broader range of rock strength depicts the strong relationship between the UCS of rock and the extent of damage produced under different impact loading conditions. The energy released during an impact loading simulation shows the variation of safety and serviceability of the rock tunnel.