Abstract
Determining the cause of cracks in tunnel linings is important to establish an efficient repair scheme. This study addresses the use of the lining shape obtained using laser scanning for the investigation of the cause of cracks. A tunnel constructed by timbering support method was selected and considered to not be affected by any external force. Profiles of the tunnel lining were measured using a mobile laser scanner with improved accuracy. Curvature radii of the upper section of the tunnel lining were then determined by the proposed method using the three-dimensional point cloud obtained from the laser scanning results. The results showed the characteristic distribution of the curvature radii that were consistent throughout each installation interval of assembly form centering. It is difficult to consider that the distribution of the lining shape resulted from the deformation of the lining owing to an external force in the case when this type of distribution is observed. It is, therefore, concluded that the cracks in the lining were attributed to causes other than an external force, such as deformation of the concrete lining during the curing process.
