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Assessment of surveying techniques for analyzing the condition of embankment dams: a case study of R3 Hájecká dam.
Pechar, Jiří ; Jerman, Jan (advisor) ; Špaček, Pavel (referee)
The diploma thesis deals with the evaluation of methods for surveying the construction of dams and for identifying faults in their body. In the beginning of the work, the issue of bulk dams is described with an emphasis on the material composition and structural elements in their bodies. The work also describes the types of dam failures, their characteristics, causes and statistics of their frequency of occurrence. Finally, the text of the thesis describes the monitoring of bulk dams. The practical part is dedicated to the evaluation of the applied engineering geological, hydrogeological and geophysical methods and their suitability for determining the condition of bulk dams. Based on the results, the benefits and limitations of individual methods and the possibility of their combined use to achieve more accurate results are described. For the evaluation of the above methods, the R3 Hájecká earth fill dam was selected, on which water began to seep through the left bank side of the dam body in the course of 2020. Of the safety ones, the water level in the reservoirs was lowered before the field work, which reflects the choice of survey methods carried out.
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Geophysical survey of subsurface voids at locality Letonice
Bartášková, Lucie ; Blecha, Vratislav (advisor) ; Skácelová, Zuzana (referee)
The Větrníky national nature reserve, located in the South Moravian region north of the village of Letonice, is one of the largest steppe reserves in Southern Moravia. This whole area is characterized by the presence of both stable and active landslides, and the occurrence of suffosion sinkholes has been monitored there in the long-term. The aim of the thesis was to investigate whether it was possible to observe subsurface phenomena, caused by the washing out of fine rock particles by ground water, by means of geophysical methods. This phenomenon is known as suffosion. The measurements took place in the areas where the suffosion manifestation was very distinctive, that is around two sinkholes that were visible on the surface. In order to identify the suffosion structural-geological causes and their manifestations at a given location, the gravimetric and electrical resistivity tomography (ERT) methods were used in the first stage of the research. Measured data was further processed and geologically interpreted. The gravimetric method has proved suitable when identifying rocks affected by suffosion, in which case we assume that their density is lower than the density of the surrounding rocks. Using the ERT method, it was possible, in the vertical profile, to distinguish the sandy-gravelly sediments...
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Physical processes leading to failure and entrainment of slightly cohesive material initiated by groundwater seepage
Světlík, Daniel ; Bruthans, Jiří (advisor) ; Mašín, David (referee)
Relatively recently the geomorphologists have realized that beside the overland flow the groundwater flow emerging from porous rock or soil can under specific conditions cause erosion of that material and create land forms. The goal of this theses is to demonstrate the importance of seepage erosion, which on many places on the Earth contributes to the landscape development, and also to describe the physical nature of the erosion processes acting on slightly cohesive material leading to it's entrainment or failure. Special attention is paid to erosion influence of groundwater on stability of streambanks, where in case of suitable hydraulic and geomechanical properties of the material, a perched water table can be developed leading to lateral seepage through a conductive layer and undercutting the bank face.
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