The Usability of Terrestrial 3D Laser Scanning Technology for Tunnel Clearance Analysis Application

Abstract

After building underground constructions, spatial parameters monitoring is essential due to safety and statuary reasons. Therefore after completion of work in tunnels often supervision projects follow which include cross sections measurements, as well as ground and secondary wall layer deformations monitoring during consolidation era. Conventional approaches to achieve this type of documentations are different, however their downside is often that they are time consuming and even with combination of independent contractors, collected data is often deficient and corrupted with rough interpolations. Terrestrial 3D laser scanning (TLS) represents alternative approach to conventional monitoring methods [1]. With engineer planning approach, field work and data interpretation, TLS technology allows systematical and fast acquisition of shape and spatial orientation of complex objects and all their components. In case of shorter railway tunnels (up to 360 m) data for clearance analysis in correlation of standard cargo and tunnel surface, was captured with terrestrial 3D laser scanning method. Control of tunnel clearance is usually performed analogously and on conventional low equidistant cross section survey method. Considering that in this article we deal with relative old tunnels, in which there is no constant transversal profile but huge amount of geometric anomalies, simulation verification could be performed only with hi-grid definition survey method. With TLS larger amount of tunnels were measured and clearance analysis simulations for real case of standard cargo profile was made, based on radius and railway inclination of the tunnel. Standard or non-standard cargo transport planning with computer simulation now can be done in relatively short time. In this article is presented integration of TLS in case study of short railway tunnels with focus on clearance analysis applications with interactive and user friendly visualization for data interpretation. Other methods for different spatial parameters interpretations in underground constructions are presented as well.