Thermal-stress behaviour of RCC gravity dams

Beton zbijen valjanjem ('valjani beton' ili 'RCC' - Roller Compacted Concrete) je vrsta betona sa niskim sadržajem cementa koja se često koristi kod betonskih gravitacionih brana. U radu je razmatran prostorni model za neustaljenu faznu termičko- naponsku analizu brana od valjanog betona. Kalibracija i verifikacija modela uređeni su na osnovu terenskih merenja na brani Platanovrisi. Istraživanje je urađeno uzimajući u obzir stvarnu geometriju brane, dinamiku ugradnje RCC-a i stvarne osobine materijala. Rezultati proračuna pokazuju da razvijeni 3D model omogućava pouzdano predviđanje termičkih napona i određivanje rastojanja između razdelnica kod gravitacionih RCC brana.Roller Compacted Concrete (RCC) is a special concrete mixture with low cement content, frequently used for concrete gravity dams. This paper deals with the 3D finite element model for unsteady phased thermal-stress analysis of RCC dams. Model calibration and verification has been done, based on the in-situ measurements of the Platanovryssi dam. The study has been done using the actual dam shape, RCC time schedule, and material properties. The results prove that the recommended 3D model enables a reliable thermal-stress prediction and transversal joint distance computation for an RCC gravity dam

THE NORTH ATLANTIC OSCILLATION (NAO) AND THE WATER TEMPERATURE OF THE SAVA RIVER IN SERBIA

The data on the water temperature of the Sava in Serbia (hydrological stations Šabac and Belgrade, period 1961–2015) were used for the research, as well as the data on the surface air temperature. The temperature trends were determined and the significance (at p≤0.05 and p≤0.01) was established on the basis of the t-test. The Pearson correlation coefficient (R) was used for the calculation of the correlation. Increasing trends of the water temperature of the Sava were recorded in all cases at both stations. However, in the case of the HS Šabac, the trends for 6 months (February–April and September–November) were not statistically significant. In the case of the HS Belgrade, all the calculations (except for April) showed statistically significant increasing trends, which can be explained by anthropogenic influence. High level of correlation between the surface air temperature and the water temperature was also determined. In this research, the lowest values of R were recorded for October (0.561 for Belgrade), and on the seasonal level, for autumn (0.625 for Šabac). The research on the correlation between the water temperature of the Sava River and the NAO index showed the highest values of R for January (0.512 for HS Šabac and 0.528 for HS Belgrade). On the seasonal level, the highest values were recorded for winter (0.422 for HS Šabac and 0.432 for HS Belgrade)

Predicting phase transition pressure in solids: a semiclassical possibility

This is a short review of the physical ideas,algorithm for calculations and some results of a semiclassical theory of the behaviour of materials under high pressure,proposed by P.Savic and R.Kasanin.The theory has found applications from DAC experiments to studies of planetary interior structure.Comment: PDF file,no figure

Termičko naponsko stanje gravitacionih brana od valjanog betona

Roller Compacted Concrete (RCC) is a special concrete mixture with low cement content, frequently used for concrete gravity dams. This paper deals with the 3D finite element model for unsteady phased thermal-stress analysis of RCC dams. Model calibration and verification has been done, based on the in-situ measurements of the Platanovryssi dam. The study has been done using the actual dam shape, RCC time schedule, and material properties. The results prove that the recommended 3D model enables a reliable thermal-stress prediction and transversal joint distance computation for an RCC gravity dam.Beton zbijen valjanjem ('valjani beton' ili 'RCC' - Roller Compacted Concrete) je vrsta betona sa niskim sadržajem cementa koja se često koristi kod betonskih gravitacionih brana. U radu je razmatran prostorni model za neustaljenu faznu termičko- naponsku analizu brana od valjanog betona. Kalibracija i verifikacija modela uređeni su na osnovu terenskih merenja na brani Platanovrisi. Istraživanje je urađeno uzimajući u obzir stvarnu geometriju brane, dinamiku ugradnje RCC-a i stvarne osobine materijala. Rezultati proračuna pokazuju da razvijeni 3D model omogućava pouzdano predviđanje termičkih napona i određivanje rastojanja između razdelnica kod gravitacionih RCC brana

Statička analiza stepenastog preliva sa odbojnom gredom na pregradi Jelezovac

The concrete gravity dam spillway on the Jelezovac stream is presented. The overflow section of the dam is an original structure, designed as a stepped spillway, with bottom outlets and the modified USBR VI stilling basin with a baffle. The structural design consisted of the general stability computation, and the design of the basin elements was based on the hydrodynamic load, obtained from the hydraulic computations.U radu je prikazana statička analiza prelivne lamele gravitacione betonske pregrade na potoku Jelezovac. Prikazana lamela je originalno rešenje, projektovana kao stepenasti preliv sa propustima i umirujućim bazenom, koji predstavlja modifikovani tip slapišta USBR VI sa odbojnom gredom. Statičkom analizom je obuhvaćena opšta stabilnost pregrade i dimenzionisanje elemenata slapišta, pri čemu su hidrodinamička opterećenja procenjena na osnovu proticaja i brzina dobijenih hidrauličim proračunom

Naponsko stanje u zoni uzvodnog zuba gravitacione betonske brane

Upstream cutoff in the concrete gravity dam foundation is introduced as a general stability measure in the beginning of the 20-th century. It become widely accepted in design practice in the late 50-ties. Nevertheless, very little is done in the stress evaluation in the cutoff zone, so far. The intention of this research is to obtain a reliable assessment of the stresses in this zone, particularly occurrence and distribution of tensile stresses, which may produce cracks. The research is based on a finite-element model, with special features in the foundation zone, and encompassed large range of dam heights, cutoff shapes, and foundation properties.Kao mera opšte stabilnosti kod gravitacionih betonskih brana, uzvodni zub je prvi put primenjen početkom 20. veka, dok se sa njegovom širom primenom otpočelo pedesetak godina kasnije. Međutim, do sada nije posvećena dužna pažnja proceni naponskog stanja u oblasti uzvodnog zuba. Cilj istraživanja je da se dobije pouzdana procena napona u ovoj zoni, sa posebnim osvrtom na napone zatezanja, koji mogu da izazovu prsline u betonu. Istraživanje je zasnovano na metodi konačnih elemenata, sa originalnim rešenjem za temeljnu spojnicu. Parametarskom analizom je obuhvaćen širok opseg visina brana, oblika uzvodnog zuba i karakteristika temelja

Problemi evakuacije velikih voda iz jalovišnih akumulacija

This paper analyzes the problems of flood control for the tailings-dams reservoirs, having in mind the significant rise of the flow and volume of observed flood waves, and increasingly stringent criteria for safety of high dams. Therefore, it is necessary to revise hydrological data and adopt the updated design criteria. The existing flood control facilities are investigated for the case of the tailings reservoir 'Rudnik', indicating a serious lack of capacity. The possibility of reconstruction of the existing structures, as well as various variants of new flood control facilities are considered. For evaluation of proposed variants, all the relevant aspects are taken into account, and a multi-criteria optimization is performed. The most important criteria are: the dam-safety during the entire period of exploitation, the costs, the available reservoir storage capacity, the capability of efficient phase construction, construction duration, the maintenance and operation conditions, and the value of the outflow discharge. As the most effective solutions have been proposed Variant 1 with the Channel spillway, and Variant 2 with Drop inlet spillway. Preference is given to Variant 1, primarily due to higher safety of the channel spillway.U ovom radu analizirani su problemi evakuacije velikih voda iz jalovišnih akumulacija, s obzirom na značajno povećanje proticaja i zapremine talasa merodavnih velikih voda i sve strožije kriterijume sigurnosti visokih brana. Zbog toga je neophodno osavremeniti hidrološke podloge i usvojiti odgovarajuće projektne kriterijume. Na primeru jalovišne akumulacije "Rudnik" analiziran je kapacitet postojećih objekata za evakuaciju velikih voda i pokazan ozbiljan nedostatak propusne moći. Razmatrane su mogućnosti rekonstrukcije postojećeg objekta, kao i razne varijante novih - dodatnih evakuacionih objekata. Prilikom vrednovanja predloženih rešenja uzeti su u obzir svi bitni aspekti, odnosno izvršena je višekriterijumska optimizacija. Najvažniji kriterijumi su: sigurnost brane tokom celog toka ekspolatacije, investiciona vrednost radova, raspoloživa zapremina akumulacije, mogućnost efikasnog faznog izvođenja, trajanje radova, uslovi eksploatacije i održavanja i vrednost izlaznog protoka. Kao najefikasnija rešenja predložene su Varijanta 1 sa Čeonim prelivom i brzotokom i Varijanta 2 sa Modifikovanim šahtnim prelivom, kolektorom i brzotokom. Prednost je data Varijanti 1 pre svega zbog veće sigurnosti rešenja sa čeonim prelivom i brzotokom

Primena valjanog betona u izgradnji brana, IV deo - građenje, kontrola kvaliteta i ekonomski aspekti

The last of the four-paper serial on RCC dams refers to construction, quality-control and economic issues. The first part deals with the most important construction features, such as: concrete preparation, transportation, spreading, compaction, joints, galleries, drainage and concrete care and protection. Follows a section on laboratory and in-situ tests for the RCC concrete quality-control, based on the ACI and USAGE recommendations. The last part addresses economic issues, possible savings, and the RCC cost structure. .Poslednji iz serije od četiri rada posvećenih valjanom betonu odnosi se na građenje, kontrolu kvaliteta i ekonomske aspekte RCC brana. U prvom delu rada obrađena su najvažnija pitanja tehnološkog procesa izgradnje ovog tipa brana, kao što su: spravljanje betona, transport, razastiranje, zbijanje, obrada horizontalnih spojnica, galerije i drenaže, nega i zaštita. Zatim su opisana laboratorijska ispitivanja i terenska merenja u cilju kontrole kvaliteta RCC-a i date preporuke na bazi istraživanja izvršenih u ACI i USACE. U poslednjem poglavlju analizirani su ekonomski aspekti, moguće uštede, struktura i postupak određivanja jedinične cene valjanog betona

Primena valjanog betona u izgradnji brana, IV deo - građenje, kontrola kvaliteta i ekonomski aspekti

The last of the four-paper serial on RCC dams refers to construction, quality-control and economic issues. The first part deals with the most important construction features, such as: concrete preparation, transportation, spreading, compaction, joints, galleries, drainage and concrete care and protection. Follows a section on laboratory and in-situ tests for the RCC concrete quality-control, based on the ACI and USAGE recommendations. The last part addresses economic issues, possible savings, and the RCC cost structure. .Poslednji iz serije od četiri rada posvećenih valjanom betonu odnosi se na građenje, kontrolu kvaliteta i ekonomske aspekte RCC brana. U prvom delu rada obrađena su najvažnija pitanja tehnološkog procesa izgradnje ovog tipa brana, kao što su: spravljanje betona, transport, razastiranje, zbijanje, obrada horizontalnih spojnica, galerije i drenaže, nega i zaštita. Zatim su opisana laboratorijska ispitivanja i terenska merenja u cilju kontrole kvaliteta RCC-a i date preporuke na bazi istraživanja izvršenih u ACI i USACE. U poslednjem poglavlju analizirani su ekonomski aspekti, moguće uštede, struktura i postupak određivanja jedinične cene valjanog betona

Problemi evakuacije velikih voda iz jalovišnih akumulacija

This paper analyzes the problems of flood control for the tailings-dams reservoirs, having in mind the significant rise of the flow and volume of observed flood waves, and increasingly stringent criteria for safety of high dams. Therefore, it is necessary to revise hydrological data and adopt the updated design criteria. The existing flood control facilities are investigated for the case of the tailings reservoir 'Rudnik', indicating a serious lack of capacity. The possibility of reconstruction of the existing structures, as well as various variants of new flood control facilities are considered. For evaluation of proposed variants, all the relevant aspects are taken into account, and a multi-criteria optimization is performed. The most important criteria are: the dam-safety during the entire period of exploitation, the costs, the available reservoir storage capacity, the capability of efficient phase construction, construction duration, the maintenance and operation conditions, and the value of the outflow discharge. As the most effective solutions have been proposed Variant 1 with the Channel spillway, and Variant 2 with Drop inlet spillway. Preference is given to Variant 1, primarily due to higher safety of the channel spillway.U ovom radu analizirani su problemi evakuacije velikih voda iz jalovišnih akumulacija, s obzirom na značajno povećanje proticaja i zapremine talasa merodavnih velikih voda i sve strožije kriterijume sigurnosti visokih brana. Zbog toga je neophodno osavremeniti hidrološke podloge i usvojiti odgovarajuće projektne kriterijume. Na primeru jalovišne akumulacije "Rudnik" analiziran je kapacitet postojećih objekata za evakuaciju velikih voda i pokazan ozbiljan nedostatak propusne moći. Razmatrane su mogućnosti rekonstrukcije postojećeg objekta, kao i razne varijante novih - dodatnih evakuacionih objekata. Prilikom vrednovanja predloženih rešenja uzeti su u obzir svi bitni aspekti, odnosno izvršena je višekriterijumska optimizacija. Najvažniji kriterijumi su: sigurnost brane tokom celog toka ekspolatacije, investiciona vrednost radova, raspoloživa zapremina akumulacije, mogućnost efikasnog faznog izvođenja, trajanje radova, uslovi eksploatacije i održavanja i vrednost izlaznog protoka. Kao najefikasnija rešenja predložene su Varijanta 1 sa Čeonim prelivom i brzotokom i Varijanta 2 sa Modifikovanim šahtnim prelivom, kolektorom i brzotokom. Prednost je data Varijanti 1 pre svega zbog veće sigurnosti rešenja sa čeonim prelivom i brzotokom