Abstract
The current geological sketch in tunnel engineering is mainly based on sketches of workers. However, geological sketch drawn by workers always offers fundamental data purely due to its drawing mode. A novel drawing method for geological sketch has been introduced using multiview photos in this process. The images of tunnel faces are taken from multiple angles, and every two pictures have overlaps. By measuring the distance between the camera and the tunnel face using a laser range finder, the photographic scale of each photo can be confirmed. SpeededUp Robust Features (SURF) is a good practice for detecting feature points, and the sparse point cloud is reconstructed from multiview photos by structure from motion (SFM). However, the sparse point cloud is not suitable for analysis for structural planes due to its sparsity. Therefore, patch-based multiview stereo (PMVS) is used to reconstruct dense point cloud from the sparse point cloud. After 3D reconstruction, the details of the tunnel face are recorded. The proposed technique was applied to multiview photos acquired in the Xiaosanxia railway tunnel and Fengjie tunnel in Chongqing, China. In order to record the geological conditions of the tunnel face quickly and accurately, Chengdu Tianyou Tunnelkey has developed a set of software and hardware integration system called CameraPad. Besides, CameraPad was used to collect the multiview photos of the tunnel face in the No. 1 Xinan railway tunnel in Jilin, China. By comparing with traditional and existing methods, the proposed method offers a more reductive model for geological conditions of the tunnel face.
Highlights
Tunnel engineering is concealed engineering, which is often affected by a variety of adverse geological conditions
Erefore, the geological prospecting during the tunnel construction period will be more meaningful for tunnel engineering. e stratum lithology, geological structure, and structural plane occurrence in the tunnel construction period need to be recorded to provide raw data, which are used for the interpretation and analysis of geotectonic movement and the prediction of long-term stability of rock mass
structure from motion (SFM) is used to extract the sparse point cloud, and the dense reconstruction of the point cloud is performed based on the patch-based multiview stereo algorithm
Summary
Tunnel engineering is concealed engineering, which is often affected by a variety of adverse geological conditions. It is difficult to observe the tunnel face directly when the TBM and shield method are used in recent years, so many scholars have proposed many new techniques for collecting the geological conditions of the tunnel face. It is difficult to obtain the geological conditions during the construction period, so such a method is proposed [1]. Terrestrial laser scanning (TLS) technology is used for the construction of the three-dimensional model of the tunnel face. Wang et al proposed a new method for tunnel digital geological mapping and recording using 3D terrestrial laser scanning (TLS) [4]. Since it takes a long time to perform high-precision modelling of the tunnel face, the proposed image preprocessing scheme can effectively reduce the amount of calculation in the reconstruction process. This article can offer research objectives as follows: 1 a novel method of rapid 3D reconstruction of the tunnel faces automatically; 2 a new device to collect data for fast 3D reconstruction of the tunnel faces; 3 application of the proposed method
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
