Plain waterjet cutting for concrete plug dismantling in disposal research tunnel

Recently, the Korea Atomic Energy Research Institute adopted and applied waterjet technology for the dismantling of a concrete plug using in situ tests of the thermal-hydraulic-mechanical behavior without disrupting or damaging the test specimen in a disposal tunnel. Successfully dismantling the plug through a combination of waterjet pre-cutting and mechanical breakage in an environment demands novel technical solutions. This study evaluated the performance of waterjet technology and its applicability within a disposal tunnel. Under various conditions of waterjet systems, a maximum cutting depth of 180 mm was achieved. An analysis of the measured results indicate that the standoff distance significantly influences the cutting depth. A multilinear regression model considering the key variables of the waterjet was proposed to simulate the crushing of the cut concrete plug, review the cutting path, and verify the technical feasibility of waterjet technology. Environmental assessments resulting from waterjet use in the disposal tunnel show that the noise levels during pump operation and jetting for cutting were 66.4 and 84.1 dB, respectively, satisfying the regulatory standards in Korea. This research holds significance not only as a challenging field application of waterjet technology, but also because of its unique characteristics associated with disposal tunnel utilization. The findings of this study are expected to serve as fundamental data for predicting cutting depth and guiding future on-site applications.