Investigation of the thermal behavior of crystalline rock mass using an in situ borehole heater test

초록

An in situ borehole heater test was carried out in an underground research tunnel, which is for the validation of high-level radioactive waste disposal system suggested in Korea. For the test at a shallow depth in granite, the thermal and mechanical properties of rock were measured at different conditions. During the test, the heater temperature was increased to 90oC to simulate the thermo-mechanical behavior of crystalline rock under normal underground repository conditions. For simulating an abnormal over heating condition, the heater temperature was increased to 115oC at the end of the test.The air, wall and rock temperatures were measured over a period of several years. The peak temperatures at the observation holes located at 0.3m and 0.6m from the heater hole were approximately 50oC and 37oC, respectively. From the temperature measurements, it was possible to observe thee influence of rock joints and the influence of heat convection through the tunnel wall.