Development of the georadar observation model for underground infrastructure detection

摘要

The necessity for the implementation of non-destructive methods for recording has arisen from our long term practical experience of extremely wide range of solutions regarding establishment, management and maintenance of the Consolidated Cadastre of Public Infrastructure of the Republic of Slovenia, as well as from our daily work in the field of recording infrastructure consisting of public utilities, energy infrastructure and communication facilities. Similar trends may now also be observed elsewhere in the world. In this thesis, ground-penetrating radar (GPR) observation for monitoring buried utilities based on controlled testing pool environment has been designed and proposed as a three phase process. In the first phase, the kinematic method for positioning GPR is introduced and geophysical and geodetic sets of observation are connected. In the second phase, the systematic latency with images matching (radargrams) is determined. In the final and most important phase of the procedure, the integration of a series of standard processing of GPR signals with the support of advanced algorithms for signal processing results of GPR observations have been interpreted and visualized. The testing pools, into which all of today’s important utilities have been buried, are a good approximation of pavement structures of regional and local roads as well as pedestrian precincts made on the basis of applicable technical specifications for pavement structure planning. Using all known data of the dimensions and buried utilities materials, pavement materials, pavement thickness, sub-base and subgrade, laboratory controlled dielectric, volume percentage of water content, geodetic measurements and considering method used in testing pools as given reference values, accuracy and precision of the proposed model have been analyzed in recording underground utilities infrastructure. The proposed model obtained in testing pools was further on tested in two selected areas of real urban environment. The results have shown that it is possible on the basis of optimum composed model to obtain information on dimensions, depth, inclination and position of ducts, pipes and cables in various demanding circumstances of urban environment subject to thickness and composition of pavement structure and the presence of uncontrolled variables of natural environment such as moisture and permittivity. It is realistic to expect average decimetre position (2D) and height accuracy. Important additional element is also three dimensional visualization of utility infrastructure based on the proposed model. The proposed model of GPR observations and/or research of recording utilities infrastructure, as presented in the thesis, is the first such research carried out in the territory of Slovenia. Moreover, the testing environment with all of its elements of real urban environment in the shape of testing pools has been created for the purpose of the present thesis and is as such unique and one among the few in the world. In the future, more active role in the matter of GPR observations for monitoring and recording utilities infrastructure may be expected.