Abstract

For deep tunnel projects, the working conditions of construction personnel and machines must be considered. With rock temperatures reaching 50°C in some tunnels whose overburden exceeds 1,000 meters, it is necessary to predict the thermal conditions in the tunnel in order to design ventilation or tiller systems to combat such temperature increase at the time of construction and thereafter. Hence, a practical heat transfer analysis model for tunnels was developed in order to estimate the requirements for any ventilation and tiller system. It is also necessary to establish a means of setting up appropriate boundary conditions from limited boring data, such as the base rock temperature, the thermodiffusion coefficient, and flow of groundwater. In order to improve this method, we measured the thermal environments in the Pahang-Selangor Raw Water Transfer Tunnel in Malaysia, which is now under construction and has a very high overburden peaking at 1,246 meters with a base rock temperature reaching as much as 55°C. Such measurements of the thermal conditions in the tunnel can be used to verify the analysis model. Various thermometers, hygrometers, and anemometers were installed inside the tunnel in about ten locations. A special 11-meter-deep borehole has been drilled into the tunnel wall at TD8630 of TBM-2, thermocouples were embedded at nine points along the hole, and the rock temperatures were measured. Comparisons of the analytic values and these measurements of the air and rock temperatures demonstrated broad qualitative agreement, and we consider the model sufficiently accurate for practical uses.

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