Long-term mass-balance monitoring and evolution of ice in caves through structure from motion–multi-view stereo and ground-penetrating radar techniques

This study investigates the application of a terrestrial structure from motionmulti-view stereo (SfM-MVS) approach combined with ground-penetrating radar (GPR) surveys for monitoring the surface topographic change of two permanent ice deposits in caves located in the Julian Alps (south-eastern European Alps). This method allows accurate calculation of both seasonal and annual mass balance, estimating the amount of ice inside caves. The ground-based SfM approach represents a low-cost workflow with very limited logistical problems of transportation and human resources and a fast acquisition time, all key factors in such extreme environments. Under optimal conditions, SfM-MVS allows sub-centimetric resolution results, comparable to more expensive and logistically demanding surveys such as terrestrial laser scanning (TLS). Fourteen SfM acquisitions were made between the 2017–2020 ablation seasons (i.e. July–October) while 2 GPR surveys were acquired in 2012. The obtained dense point clouds and digital terrain models (DTMs) made possible a reliable calculation of topographic changes and mass balance rates during the analysed period. The integration of SfM-MVS products with GPR surveys provided comprehensive imaging of the ice thickness and the total ice volume present in each of the caves, proving to be a reliable, low cost and multipurpose methodology ideal for long-term monitoring.

Investigation structural settlement by Ground Penetrating Radar (Case study)

Electromagnetic wave is transferred by the GPR (ground penetrating radar), and A geotechnical application may benefit from this non-destructive test. This study is proposed to estimate the type and soil problem location that causes differential settlement of a structure (pumping station) by GPR surveying. The survey is achieved before and after the treatment by cement injection method to identify the locations that took cement injections as a full injection, partial or not at all using two types of antennas (160,450) MHz. The study also will estimate the thickness of the foundation by GPR and comparing it with actually executed. The results showed the creeping soil has occurred in some parts of the soil under the foundation, and after soil treatment, most of these parts were taken injection, and others did not. Also, it was found the relatively high accuracy of GPR for detecting the thickness of the raft foundation.

Mapping Ground Penetrating Radar Amplitudes Using Artificial Neural Network and Multiple Regression Analysis Methods

Bridges are aging and deteriorating. Thus, the development of Bridge Management Systems (BMSs) became imperative nowadays. Condition assessment is one of the most critical and vital components of BMSs. Ground Penetrating Radar (GPR) is one of the non-destructive techniques (NDTs) that are used to evaluate the condition of bridge decks which are subjected to the rebar corrosion. The objective of the proposed method is to develop standardized amplitude scale for bridge decks based on a hybrid optimization-decision making model. Shuffled frog leaping algorithm is employed to compute the optimum thresholds. Then, polynomial regression and artificial neural network models are designed to predict the prioritizing index based on a set of multi-criteria decision-making methods. The weibull distribution is utilized to capture the stochastic nature of deterioration of concrete bridge decks. Lastly, a case study is presented to demonstrate the capabilities of the proposed method.

Condition Assessment Using None Destructive Tests at Montauk Bridge Deck

Ground penetrating radar (GPR) and portable seismic property analyzer (PSPA), was used in concrete structures for monitoring, quantifying, and mapping the deterioration of bridge decks. The Montauk Bridge deck was assessed based on PSPA and GPR data. Based on the analysis of the PSPA data, it was determined that over 65% of bridge conditions were rated serious to poor condition with an average compressive strength of less than 2500 psi; less than 35% of bridge deck conditions were rated fair to good with an average compressive strength over 2500 psi. Based on GPR data, it was determined that 72% of the bridge deck was in serious to poor condition, and only 28% of the bridge deck was in fair to good condition. Additionally, the analyses of the ground penetrating radar data indicated possible rebar corrosion in places. For these reasons, it is recommended that the Montauk bridge’s deck be completely replaced. Keywords: Condition assessment, NDT, GPR, PSPA, bridge deck

The Grouting Process as an Innovative Tool for the Assessment of the State of Preservation and Internal Features of the Holy Aedicule of the Holy Sepulchre

Grouting of historic structures is a common procedure in many restoration projects, as the masonry in many cases requires additional strengthening. However, grouting of complex historic structures can also provide important information regarding the construction phases and the state of preservation of the internal structure of a monument, which may not be visible by the naked eye. This requires an innovative approach in order to reveal these aspects. In the current research, the data recorded from the grouting of the Holy Aedicule are implemented and analyzed, in order to obtain information regarding the construction phases of the complex Holy Aedicule structure, as well as information regarding the state of preservation of the internal structure behind the marble cladding that encloses it. The correlation of detailed grouting data with geospatial information allows for a more detailed analysis, which, coupled with ground-penetrating radar prospections, can provide critical information regarding the features of the internal structure. The results highlight the importance of this correlation to reveal information that may not be obtained through a typical approach. Thus, this study allowed for the development of an evolved interdisciplinary approach for the management of grouting data in a 2.5D environment, which can be applied in other historic structures and buildings.