Application of 3D-Laser Scanning Technique in Tunnel Engineering

Traditional tunnel’s profile monitoring usually costs a lot of manpower, finance and time, and it utilizes only few, selected and fixed observation points in a single tunnel’s profile to get the desired information. In the advancement of optics’ technique and of the performance of computer recently, the development of a new monitoring technique, which is easy to operate, rapid and inexpensive, for tunnel engineering might be helpful for us to equally understand the deformation tendency in a tunnel. From this, derived results can serve as a reference for future repairing of the support system, or the parameters of back analyzing about the development of plastic zone considering long-term and/or regular monitoring works, and for developing a more complete three-dimensional (3-D) information about tunnel’s profile.
This study was conducted to develop a new non-contact measurement technique which can be applied to tunnel engineering using a two-dimensional laser image and a program to construct the 3-D information in a certain profile. Different from traditional monitoring, this technique can provide a more complete 3-D profile information by first establishing several points whose 3-D information were already known for calibration.
In addition to a small simulative tunnel, a bigger one was constructed in the laboratory to simulate the full-scale tunnel in this study. Based from the results in small tunnel, it was observed that the measurement of deformation behavior from the two successive analyses performed is effective. Also, profiling results from this technique and a total-station-based method were compared and showed that RMSE value can be controlled in about 4 mm in this new technique.
Moreover, this research uses image processing to construct a 3-D tunnel’s profile information, thus, the influence are mostly from images. Therefore, improvement in the image processing method is advised to achieve a more precise result.