No abstract

Durability is one of the most important engineering properties of weak and clay-bearing rocks. Weathering can induce a rapid change in rock material from initial properties to soil-like properties. The sensitivity of a rock type against weatherability is usually described by a durability parameter, such as the slake durability index. However, marl resistance is not detected satisfactorily by the durability indices by using slake durability test as suggested by ISRM for two wetting-drying cycles. The results of this study are obtained from samples of compact or laminated eocene marls from region of Dalmatia, Croatia. The samples were subjected to 4 cycles of slake durability, point load tests, determination of dry density, determination of carbonate content and absorption of water. The scatter of data suggests that strength probably has no influence on the durability of marls. On the other hand a separate group of marl samples have a second-cycle slake durability index higher than approximately 85%, and the durability of these samples is classified as ''medium-high'' to ''high'', although the visual inspection of samples after testing, suggests that they should have ''medium'' to ''low'' durability classification. According to obtained results these samples of marl fulfil the criterions for the durability classification: a carbonate content lower than approximately 65%, a dry density lower than 2.4 Mg/m 3 , and values of water absorption higher than 5%.

No abstract

Recent development of lightweight and small size multi-frequency GNSS receivers allows determination of the precise position of the moving platform and spatial data acquisition without the need for setting up and measuring of ground control points. The main advantage of this approach is a higher operational capacity with reduced time and cost of field measurement. This relates to fieldwork in inaccessible areas with demanding terrain configuration. In this paper development and use of a UAS with direct georeferencing of camera sensor for spatial data acquisition is described, and the possibility of 3D scene reconstruction based on the precise position of the camera with predetermined interior parameters is examined. Modern computer vision-based SfM photogrammetry algorithms are used for determining attitude parameters and reconstruction of the scene. For that purpose, several tests on two different test fields were performed using various system parameters for collecting and analysis of several spatial data sets. The presented results demonstrate a satisfactory accuracy (3.1 cm planar and 6.4 cm spatial) of the system for various applications in geodesy.

Terrestrial laser scanning (TLS) in combination with Unmanned Aircraft System (UAS) and modern computer based photogrammetry is currently the best approach for the acquisition of high-resolution 3D spatial information. Highly realistic 3D spatial data sets are becoming the basis for detailed geological studies, providing a multidisciplinary approach in the study and research of both underground and above ground sites. To emphasize the variety of possible implementations of these state-of-the-art methodologies, four characteristic and yet quite different case studies are presented where such geodetic techniques are successfully employed. The presented case studies demonstrate that TLS and UAS photogrammetry, as non-contact surveying methods, are able to reduce survey time and total project costs. As added value, they provide high-resolution data that can be analyzed in a virtual environment from a sedimentological or structural aspect. Stored digital documentation also allows future multi-temporal spatial data comparison at any timeframe and scale, thus enhancing any target geological data gathering and analyses at the studied sites.