In developing underground rock, it is necessary to understand the hydraulic characteristics of the rock around the facility in order to evaluate safety and performance. The transient pulse method is one of the permeability tests of rock. It is suitable for measuring the permeability of the low-permeability rocks and has the advantage of being able to measure briefly and accurately. In this study, we have developed the apparatus of the transient pulse method based on the previous studies and measured the permeability. The tests were conducted by using two large reservoirs compared with the void volume of the rocks. Then, we also conducted the flow-through permeability tests and the results were compared with those using the transient pulse method so as to examine the validity of the transient pulse method. Both tests were conducted in Toki granite and Berea sandstone. From the data of the transient pulse tests, the permeability of both samples fell in one order. Also, comparing the permeability between the transient pulse method the flow-through procedure, the difference of the permeability by both tests fell in one order. However, the permeability of the transient pulse test was slightly less than that of the flow-through permeability test in Berea sandstone, and further investigation should be necessary.

1. Introduction

Underground rock has various characteristics such as rigidity, durability and shielding properties, and the development of underground space utilizing these features is underway. Especially in the energy field, geological disposal of high-level radioactive waste and underground fuel stockpiling are examples. In developing the underground rock, it is necessary to grasp the hydraulic characteristics of the rock around the facility in order to evaluate the safety and performance. Transient pulse tests are often used for the permeability tests of rocks, and they have the advantage of measuring low-permeable rocks in a short time with high accuracy. Therefore, in this study, transient pulse test device was developed and permeability tests were conducted using the developed apparatus. The effectiveness of the transient pulse test was evaluated by comparing the permeability obtained by the flow-through permeability test.

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