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Papers by Lubomír Petrula
Lecture Notes in Civil Engineering
One of the local defects in soils due to seepage is heave. This may occur at the downstream toe o... more One of the local defects in soils due to seepage is heave. This may occur at the downstream toe of hydraulic structures in the case of upward external seepage where particles of uniform soils are subject to uplift and also upward seepage forces. The phenomena starts with gradual liquefaction of soil grains accompanied by gradual loss of shear strength followed by boiling, heave and possible backward erosion and overall collapse of the structure. The problem of heave has been addressed by numerous authors who have published relationships based on the balance of forces and also on results of laboratory experiments. In this paper the results of extensive systematic experimental research carried on glass beads subjected to upward seepage in the vertical Darcy apparatus are presented. Three glass beads’ diameters 0.2 mm, 0.5 mm and 1.0 mm with uniformity coefficient CU from 1.1 to 1.3 and different porosity n from 0.36 to 0.44 were tested. To enable statistical evaluation of the uncertainty in critical hydraulic gradient 177 individual tests have been performed. The results of measurements were analysed and compared with relationships proposed by various authors. The best agreement was provided by the well-known Terzaghi formula relating the critical gradient to the specific mass of grains and soil porosity. Based on the experimental data the uncertainty in the use of Terzaghi formula was expressed via reliability coefficients recommended for use in technical practice.
Journal of the Croatian Association of Civil Engineers, Jun 1, 2018
The analysis of groundwater contamination at the former military airport, due to fuel tanks leaka... more The analysis of groundwater contamination at the former military airport, due to fuel tanks leakage and other accidental spills, mainly involving polycyclic aromatic hydrocarbons (PAH), is presented in the paper. It was observed by modelling that, after termination of pumping, the contaminant bypasses the slurry wall around its edges and proceeds towards the withdrawal area. The modelling showed that the water contamination hazard is quite low, which is mainly due to pollutant deterioration (decay) and sorption.
Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis
Hydraulic conductivity determination plays an essential role in the investigation of groundwater ... more Hydraulic conductivity determination plays an essential role in the investigation of groundwater flow regime which can then influence many field problems such as pumping capabilities in the area, transport of contaminant or heat and soil internal erosion. Numerous equations based on dimensional analysis or experimental measurements have been published since the end of the 19th century for the determination of hydraulic conductivity. However, not all of these formulae are applicable for every material and all of them bring some uncertainty in the value of hydraulic conductivity. This paper contains a description of experimental research carried out concerning the determination of hydraulic conductivity for four types of sand with different grain size distribution curves and variable porosity. Obtained values of hydraulic conductivity ranged from 1 × 10-4 to 4 × 10-3 according to the sample porosity. The series of experiments consisted of 160 separate tests conducted in order to obtai...
Water
Failures of small dams can pose a serious threat to people and property even if the size of the s... more Failures of small dams can pose a serious threat to people and property even if the size of the schemes is relatively low. In many cases, small dams are situated in a cascade along streams, meaning that the failure of the uppermost dam may cause the dams downstream to fail. In this paper, a cascade of three small reservoirs, Lichnov II (14.6 m high), Lichnov III (10 m high), and Pocheň (8.5 m high), is the subject of the dam break analyses carried out via various methods such as empirical formulae, analogy, and hydraulic modeling. The dam-break flood routing was simulated using a shallow water flow hydraulic model. The simulations confirm that the attenuation effect of the peak discharge is governed by the flood volume, slope, and morphology of the floodplain and increases with the distance from the breached dam following an approximately exponential trend. When estimating peak discharge, empirical formulae derived for a single dam break should be applied carefully as they may under...
Journal of Hydrology and Hydromechanics
Empirical formulae are often used in practice to quickly and cheaply determine the hydraulic cond... more Empirical formulae are often used in practice to quickly and cheaply determine the hydraulic conductivity of soil. Numerous relations based on dimensional analysis and experimental measurements have been published for the determination of hydraulic conductivity since the end of 19th century. In this paper, 20 available empirical formulae are listed, converted and re-arranged into SI units. Experimental research was carried out concerning hydraulic conductivity for three glass bead size (diameters 0.2 mm, 0.5 mm and 1.0 mm) and variable porosity. The series of experiments consisted of 177 separate tests conducted in order to obtain relevant statistical sets. The validity of various published porosity functions and empirical formulae was verified with the use of the experimental data obtained from the glass beads. The best fit was provided by the porosity function n3/(1-n)2. In the case of the estimation of the hydraulic conductivity of uniform glass beads, the best fit was exhibited ...
Lecture Notes in Civil Engineering
One of the local defects in soils due to seepage is heave. This may occur at the downstream toe o... more One of the local defects in soils due to seepage is heave. This may occur at the downstream toe of hydraulic structures in the case of upward external seepage where particles of uniform soils are subject to uplift and also upward seepage forces. The phenomena starts with gradual liquefaction of soil grains accompanied by gradual loss of shear strength followed by boiling, heave and possible backward erosion and overall collapse of the structure. The problem of heave has been addressed by numerous authors who have published relationships based on the balance of forces and also on results of laboratory experiments. In this paper the results of extensive systematic experimental research carried on glass beads subjected to upward seepage in the vertical Darcy apparatus are presented. Three glass beads’ diameters 0.2 mm, 0.5 mm and 1.0 mm with uniformity coefficient CU from 1.1 to 1.3 and different porosity n from 0.36 to 0.44 were tested. To enable statistical evaluation of the uncertainty in critical hydraulic gradient 177 individual tests have been performed. The results of measurements were analysed and compared with relationships proposed by various authors. The best agreement was provided by the well-known Terzaghi formula relating the critical gradient to the specific mass of grains and soil porosity. Based on the experimental data the uncertainty in the use of Terzaghi formula was expressed via reliability coefficients recommended for use in technical practice.
Journal of the Croatian Association of Civil Engineers, Jun 1, 2018
The analysis of groundwater contamination at the former military airport, due to fuel tanks leaka... more The analysis of groundwater contamination at the former military airport, due to fuel tanks leakage and other accidental spills, mainly involving polycyclic aromatic hydrocarbons (PAH), is presented in the paper. It was observed by modelling that, after termination of pumping, the contaminant bypasses the slurry wall around its edges and proceeds towards the withdrawal area. The modelling showed that the water contamination hazard is quite low, which is mainly due to pollutant deterioration (decay) and sorption.
Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis
Hydraulic conductivity determination plays an essential role in the investigation of groundwater ... more Hydraulic conductivity determination plays an essential role in the investigation of groundwater flow regime which can then influence many field problems such as pumping capabilities in the area, transport of contaminant or heat and soil internal erosion. Numerous equations based on dimensional analysis or experimental measurements have been published since the end of the 19th century for the determination of hydraulic conductivity. However, not all of these formulae are applicable for every material and all of them bring some uncertainty in the value of hydraulic conductivity. This paper contains a description of experimental research carried out concerning the determination of hydraulic conductivity for four types of sand with different grain size distribution curves and variable porosity. Obtained values of hydraulic conductivity ranged from 1 × 10-4 to 4 × 10-3 according to the sample porosity. The series of experiments consisted of 160 separate tests conducted in order to obtai...
Water
Failures of small dams can pose a serious threat to people and property even if the size of the s... more Failures of small dams can pose a serious threat to people and property even if the size of the schemes is relatively low. In many cases, small dams are situated in a cascade along streams, meaning that the failure of the uppermost dam may cause the dams downstream to fail. In this paper, a cascade of three small reservoirs, Lichnov II (14.6 m high), Lichnov III (10 m high), and Pocheň (8.5 m high), is the subject of the dam break analyses carried out via various methods such as empirical formulae, analogy, and hydraulic modeling. The dam-break flood routing was simulated using a shallow water flow hydraulic model. The simulations confirm that the attenuation effect of the peak discharge is governed by the flood volume, slope, and morphology of the floodplain and increases with the distance from the breached dam following an approximately exponential trend. When estimating peak discharge, empirical formulae derived for a single dam break should be applied carefully as they may under...
Journal of Hydrology and Hydromechanics
Empirical formulae are often used in practice to quickly and cheaply determine the hydraulic cond... more Empirical formulae are often used in practice to quickly and cheaply determine the hydraulic conductivity of soil. Numerous relations based on dimensional analysis and experimental measurements have been published for the determination of hydraulic conductivity since the end of 19th century. In this paper, 20 available empirical formulae are listed, converted and re-arranged into SI units. Experimental research was carried out concerning hydraulic conductivity for three glass bead size (diameters 0.2 mm, 0.5 mm and 1.0 mm) and variable porosity. The series of experiments consisted of 177 separate tests conducted in order to obtain relevant statistical sets. The validity of various published porosity functions and empirical formulae was verified with the use of the experimental data obtained from the glass beads. The best fit was provided by the porosity function n3/(1-n)2. In the case of the estimation of the hydraulic conductivity of uniform glass beads, the best fit was exhibited ...