From the construction made in the “white box” technology, first of all tightness is required - on the structural elements there should not be any cracks or scratches, through which water could penetrate, which in consequence may lead to deformation of structural elements and even loosing of their load-bearing capacity. Among the methods enabling the location of weakened places in watertight concrete, the ground penetrating radar (GPR) method is effective because the local occurrence of water in the structure evokes a clear and unambiguous anomaly on the radargram. In addition, the GPR method allows you to indicate places where water flows without the necessity of excluding the object from use and interference in the construction layers. The designation of such locations will make it possible to undertake technical activities that can facilitate the takeover of water and thus ensure the desired load-bearing capacity and usability of the object. Using the GPR method, you can also designate places that have already been deformed – discontinuities or breaking. The article presents a case study of investigations that determine the causes of leakage of tunnels made in the “white box” technology in: twice within the bottom slab of the tunnel (1 GHz air-coupled and 400 MHz ground-coupled antenna) and once in the case of tunnel walls (1.6 GHz ground-coupled antenna).
GPR method is perfectly suited for recognizing of sedimentary facies diversity in shallowly occurring sediments if there is a contrast of electrical properties between and/or within each layer. The article deals with the issue of the correlation between GPR surveys results and sedimentological analyses. As a result of this correlation a conceptual model of depositional systems of studied areas was developed. Studies were performed in two areas located in central Poland, where glacial deposits formed in the Middle Polish (Saalian) Glaciation are present. The study was based on 49 sediment samples and 21 GPR profiles. Analyses of lithofacies as well as granulometric and mineralogical composition of deposits of collected samples were carried out, showing the diversity of glacial deposits in both study sites. During GPR measurements shielded antenna with a frequency of 500 MHz was used which allowed high-resolution mapping of the internal structure of deposits and to identify four characteristic radar facies. Correlation of GPR profiles with point, one-dimensional sedimentological studies allowed the unambiguous interpretation of the GPR image and draw conclusions about the formation environment of individual units. Geophysical and sedimentological data obtained during study provide a new and detailed insight into selected glacial deposits in central Poland.