A study on the vehicles and construction equipments vibration characteristics of Geomunoreum lava tube system, Jeju Island

초록

This study has been conducted to analyze the effect of vibration occurred by vehicles and construction equipments in the area of Geomunoreum Lava Tube system, Jeju Island, South Korea, and to prepare the efficient preservation and management measures for lava tubes. For this purpose, vibration tests with vehicles and construction equipments were performed. Then, the effects of the distance from the vibration sources and velocity changes of them were evaluated. Within the standard for continuous vibration of cultural properties (0.07 cm/sec), the result of vehicle vibration tests shows that passenger vehicles with the weight of about 2 tons do not exceal the influential radius of 1 m at the lower speed than 100 km/h. When the vehicle speed was set to 60 km/h, the influential range of the bus and dump truck were 2.2 m and 2.8 m, respectively. When the vehicle speed was set to 80 km/h, the influential range of the bus and dump truck were evaluated 3.0 in and 3.7 m. Considering that the speed limit of roads surrounding to the Geomunoreum lava tube system is around 60 km/h, it can be concluded that the stability of the cave (passages) in the Geomunoreum lava tube system has been secured against any types of vehicle activities because most of cave passages have sifted below about 3 in at least from the surface. Nevertheless, in the fact that many passages across directly beneath paved roads, long-term stability needs to be considered. As a result of vibration tests on construction equipments, the influential distances of breaker and compaction engineering works were evaluated as 10.9 m and 14.0 m, respectively. For the test result of the vibration velocity that satisfies the restriction standard through the interaction formula of vibration velocity (PPV) and vibration level (dB(V)), the restriction standard was satisfied under 1.525 mm/sec during the daytime and 0.904 mm/sec during nighttime. Furthermore, within the standard of continuous vibration velocity (PPV) for cultural properties (0.7 mm/sec), the maximum permissible vibration level in the lava tube caves was evaluated as 57.6 dB(V).

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