Integrity assessment of rock mass behind the shotcreted slope using thermography: Fid-Bau Portal

Integrity assessment of rock mass behind the shotcreted slope using thermography

Wu, J.H. / Lin, N.M. / Lee, D.H. / Fang, S.C.

Shotcrete is a method commonly employed for preventing landslides or slope failures. By protecting slope from further erosion or weathering, the failure of the shotcrete-treated slope or simply called shotcreted slope may be prevented. This method is frequently emp1oyed to treat the rocky slopes along numerous highways in Taiwan and different parts of the world because of its low construction cost and short project duration. The results of a field study of using thermography to identify the existence of eroded caves behind shotcrete-protected slopes is presented. The temperature variation calculated from the highest and lowest temperatures measured at each point on the shotcrete surface was utilised to evaluate the integrity of the rock mass behind the concrete. In addition, ground penetration radar (GPR) was performed at three selected locations near the toe of the slope of concern, while the necked eye observation and knocking tests were conducted at two of the selected areas. The soils taken out from the rock mass and the abnormal echo, as well as strong GPR reflection patterns, confirmed the existence of eroded caves behind the shotcrete surface. The agreement of the locations that showed both strong GPR reflection and large temperature variation verified the applicability of thermography in evaluating the integrity of rock mass behind the shotcrete surface. More studies are required that will verify the new method in different geological environments and investigate the essential factors that affect the results.