• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.3
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• pp.393-401
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• 2015

In the construction of a TBM tunnel, it is very important to acquire accurate information of the excavated rock mass for an efficient and safe work. In this study, we developed the prediction system of TBM tunnel face ahead using probe drilling equipment and drilled hole imaging equipment to predict rock mass conditions of the tunnel face ahead. The prediction system consists of the probe drilling equipment, drilled hole imaging equipment and analysis software. The probe drilling equipment has been developed to be applicable to both non-coring and coring. Also the probe drilling equipment can obtain the drilling parameters such as feed pressure, torque pressure, rotation speed, drilling speed and so on. The drilling index is converted to the drilling index RMR through the correlation between a drilling index and core RMR. The developed system verification was carried out through a slope and tunnel field application. From the field application result, the non-coring is four times faster than a coring and the drilling index RMR and core RMR are similar in the distribution range. This system is expected to predict the rock mass conditions of the TBM tunnel face ahead very quickly and efficiently.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.127-133
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• 2008

The electrical resistivity methods have been commonly used for figuring out the ground layers. The purpose of this paper, differently from previous methods, is not only to figure out the layers but also to develope a equipment and a method to analyze ground porosity. Equipment has a shape of cone, which can be coupled with drilling rods. A field penetration test was performed to test application in Incheon Chungla area. Through the field test soil resistances were measured. To calculate soil porosity along the depth, Archie's law is applied. The results show that a new equipment and porosity analysis method using Archie's law can distinguish soil layers and precisely measure soil porosity.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.1
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• pp.135-144
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• 2020

Since the depth of tunneling with tunnel boring machine (TBM) becomes deeper and deeper, the expense for site investigation for coring and geophysical survey increases to obtain the sufficient accuracy. The tunnel ahead prediction methods have been introduced to overcome this limitation in the stage of site investigation. Probe drilling can obtain the core and borehole images from a borehole. However, the space in TBM for the probe drilling equipment is restricted and the core from probe drilling cannot reflect the whole tunnel face. Seismic methods such as tunnel seismic prediction (TSP) can forecast over 100 m ahead from the tunnel face though the signal is usually generated using the explosive which can affect the stability of segments and backfill grout. Electromagnetic methods such as tunnel electrical resistivity prospecting system (TEPS) offer the exact prediction for a conductive zone such as water-bearing zone. However, the number of electrodes installed for exploration is limited in small diameter TBM and finally the reduction of prediction ranges. In this study, the theoretical equations for the electrical resistivity survey whose electrodes are installed in the face and side of TBM to minimize the installed electrodes on face. The experimental tests were conducted to verify the derived equations.