Wyniki wyszukiwania - BazTech

1

Bezprzewodowy pomiar ciśnienia wody w porach gruntu w aparacie trójosiowego ściskania

Witowski Marcin

Przegląd Budowlany

|

2023

|

R. 94, nr 7-8

188--192

PL

Aparat trójosiowego ściskania jest jednym z najbardziej rozpowszechnionych w laboratoriach geotechnicznych urządzeń badawczych służących do określania parametrów charakteryzujących zachowanie się gruntów pod względem wytrzymałości i sztywności. Urządzenie to ma możliwość pomiaru szeregu kluczowych parametrów, wśród których zasadniczą rolę odgrywa pomiar siły osiowej, odkształcenia osiowego oraz ciśnienia wody porowej w gruncie. Wskazane w normie europejskiej (Eurokod 7) podejście w zakresie projektowania geotechnicznego i sprawdzania stanów granicznych wymaga korzystania z parametrów efektywnych. Tym samym ich oznaczanie w warunkach laboratoryjnych wymaga prawidłowej (w zakresie procedury nasycania) i poprawnej (w zakresie lokalizacji pomiaru) rejestracji ciśnienia wody w przestrzeni porowej gruntu w trakcie badania. Standardowo pomiar tego ostatniego parametru wykonywany jest w dolnej części próbki lub w bardziej zaawansowanej formie, w połowie wysokości próbki. To drugie podejście jest bardziej miarodajne, ale wprowadza jednak wymóg przerwania ciągłości membrany otaczającej próbkę gruntu, co może prowadzić do niekontrolowanej penetracji wody z komory do wnętrza próbki. Rozwiązaniem tej niedogodności było opracowanie autorskiego projektu czujnika objętego postępowaniem patentowym. Zapewnienie pomiaru bezpośredniego na próbce przy jednoczesnym uniknięciu potencjalnej nieszczelności było możliwe poprzez zastosowanie nowatorskiego czujnika, który mierzy ciśnienie wody w porach gruntu i w sposób bezprzewodowy przesyła wyniki na zewnątrz komory. W artykule przedstawiono opis tego rozwiązania oraz sposób integracji nowego czujnika z rejestratorem i pozostałymi komponentami zestawu aparatu „trójosiowego” ściskania. Skuteczność zaproponowanego rozwiązania wykazano poprzez przeprowadzenie pełnej kalibracji wyników uzyskiwanych z czujnika. Uzyskane wyniki wykazały skuteczności zastosowanego bezprzewodowego czujnika do bezpośredniego pomiaru ciśnienia wody w gruncie.

EN

The triaxial compression apparatus is one of the most popular research devices in geotechnical laboratories used to determine the parameters characterizing the behavior of soils in terms of strength and stiffness. This device has the ability to measure a number of key parameters, among which the measurement of axial force, axial deformation and pore water pressure in the ground plays an essential role. The approach to geotechnical design and limit state verification indicated in the European standard (Eurocode 7) requires the use of effective parameters. Thus, their determination in laboratory conditions requires correct (in terms of the saturation procedure) and correct (in terms of measurement location) recording of water pressure in the soil pore space during the test. As a standard, the measurement of the latter parameter is performed in the lower part of the sample, or in a more advanced form, in the middle of the sample’s height. The latter approach is more reliable, but it introduces a requirement to break the continuity of the membrane surrounding the soil sample, which may lead to uncontrolled penetration of water from the chamber into the sample. The solution to this inconvenience was the development of a proprietary sensor design covered by patent proceedings. Providing direct measurement on the sample while avoiding potential leakage was possible by using an innovative sensor that measures the water pressure in the soil pores and wirelessly sends the results outside the chamber. The article presents a description of this solution and the method of integrating the new sensor with the recorder and other components of the triaxial compression apparatus set. The effectiveness of the proposed solution was demonstrated by carrying out a full calibration of the results obtained from the sensor. Validation of the results was performed on several series of tests carried out on several types of soils with different filtration properties. The obtained results showed the effectiveness of the wireless sensor used for direct measurement of water pressure in the ground.

2

Ocena podatności gruntu sypkiego na upłynnienie w warunkach trójosiowego ściskania pod wpływem małych naprężeń

Mierczyński Jacek, Smyczyński Marcin, Kazimierowicz-Frankowska Krystyna

Inżynieria i Budownictwo

|

2023

|

R. 79, nr 5-6

272--275

PL

Przedstawiono wyniki badań w aparacie trójosiowego ściskania wykonanych na próbkach nawodnionego gruntu niespoistego w warunkach bez odpływu wody z porów. Badano reakcję gruntu na obciążenie cykliczne w zakresie małych naprężeń. Wykonanie tych badań wymagało opracowania opisanej w artykule autorskiej procedury rozszerzającej możliwości pomiarowe standardowego aparatu trójosiowego. Poprawność jej działania zweryfikowano w trakcie wykonanych eksperymentów, określając liczbę cykli obciążeń niezbędnych do upłynnienia próbek gruntu.

EN

The results of tests in the triaxial apparatus performed on samples of non-cohesive soil in undrained conditions are presented. The response of soil to cyclic loading at low stress levels was studied. Performing these tests required the development of a bespoke procedure extending the measurement capabilities of a standard triaxial apparatus, which is described in the article. Its correctness was verified during the experiments, while determining the number of load cycles necessary to liquefy the soil samples.

3

Some remarks on the pore water pressure dissipation patterns from the one-dimensional consolidation test

Olek Bartłomiej Szczepan

Archives of Civil Engineering

|

2022

|

Vol. 68, nr 4

147--162

EN

The pattern of pore water pressure dissipation from the one-dimensional consolidation test significantly affects the calculated value of the coefficient of consolidation. This paper discusses the interpretation methodology for laboratory dissipation data from the oedometer test with the pore water pressure measurements or Rowe cell test. In the analysis, the gradient-based algorithm for finding the optimal value of the coefficient of consolidation is used against experimental results, obtained for various fine-grained soils. The appropriate value of coefficient of consolidation is considered as one with the lowest associated error function, which evaluates fitness between the experimental and theoretical dissipation curves. Based on the experimental results, two different patterns of the pore water pressure dissipation are identified, and the saturation of the specimen was found to be the key factor in describing the change in the patterns. For the monotonically decreasing dissipation curve, an inflection point is identified. The values of degree of dissipation at the inflection point are close to the theoretical value of 53.4%.

PL

W artykule omówiono wzorce rozpraszania ciśnienia wody w porach uzyskane w laboratoryjnym badaniu jednoosiowej konsolidacji. Wzorzec rozpraszania ciśnienia wody w porach istotnie wpływa na obliczoną wartość współczynnika konsolidacji. Zasadniczo istnieją dwa typy krzywych rozpraszania ciśnienia wody w porach w przestrzeni półlogarytmicznej. Typ I charakteryzuje się dylatacyjną odpowiedzią rozpraszania na etapie wzrostu ciśnienia. Czas narastania ciśnienia może być znaczny, a obliczona wartość cv z etapu rozpraszania może nie być wartością rzeczywistą. Krzywa typu II wykazuje monotonicznie zmniejszającą się odpowiedź rozpraszania i charakteryzuje się dobrze zdefiniowanym odwróconym kształtem „S” z obecnością punktu przegięcia. Dla monotonicznie malejącej krzywej dyssypacji wartości stopnia dyssypacji w punkcie przegięcia są zbliżone do wartości teoretycznej Uub = 53.4%. W pracy omówiono metodologię interpretacji laboratoryjnych danych rozpraszania ciśnienia pochodzących z badania komorze Rowe'a. W analizie wykorzystano gradientowy algorytm wyznaczania optymalnej wartości współczynnika konsolidacji w celu porównania rozwiązania teoretycznego z wynikami eksperymentalnymi, uzyskanymi dla różnych gruntów drobnoziarnistych. Optymalną wartość współczynnika konsolidacji powiązano z najniższą wartością funkcji błędu, która ocenia dopasowanie między eksperymentalną i teoretyczną krzywą rozpraszania.

4

Impact of sampling techniques on the concentration of ammonia and sulfide in pore water of marine sediments

Brodecka-Goluch Aleksandra, Siudek Patrycja, Bolałek Jerzy

Oceanological and Hydrobiological Studies

|

2019

|

Vol. 48, No. 2

184--195

EN

Three ex situ pore water sampling procedures (I – rhizon samplers, II – centrifugation of sediment subsamples collected from different sediment depths without core sectioning, III – core sectioning and centrifugation of sediment sections) were compared to indicate factors that may affect concentrations of pore water constituents (ammonia and sulfides). The methods were selected and modified in such a way as to determine how the concentrations are affected by different factors related to sampling procedures, e.g. contact with atmospheric air, filtration and sediment core disturbance. They were tested on nine sediment cores collected at one site in the southern Baltic Sea. The concentration of ammonia in pore water from centrifuged sediment sections was significantly higher compared to pore water extracted by rhizons – probably due to the impact of changing pH. The factor with the greatest impact on the H2S/HS– concentration in the analyzed pore water was the contact with atmospheric air and/or the extrusion of sediments from a core liner. Rhizons proved to be the best option for sampling pore waters analyzed for H2S/HS– and NH4+/NH3. In the case of H2S/HS– we noticed the smallest loss of the analyzed constituents. For ammonia, the centrifugation of the whole sediment sections was likely to cause interferences in the indophenol blue method.

5

Distributions and Fluxes of Nitrogen and Phosphorus Nutrients in Porewater Sediments in the Estuary of Jepara Indonesia

Maslukah Lilik, Wulandari Sri Yulina, Prasetyawan Indra Budi, Zainuri Muhammad

Journal of Ecological Engineering

|

2019

|

Vol. 20, nr 2

58--64

EN

River is a location that is responsible for the main transport of nutrient flow from land to estuary and oceans. The nutrients that are adsorbed by the solid phase can be deposited and stored in the sediment. Sediments in estuaries and beaches have an important role in storing or removing nutrients from or to the water column. The presence of nutrients in porewater interacts with sediment and water column. In general, the nutrients that have a role as limiting factors for life in the waters are nitrogen (N) and phosphorus (P). The release of N and P elements is very important for the estuary and coastal environment, related to the process of regenerating nutrients into the water column. The release mechanism is determined by a diffusion process, based on the difference of concentration between the water column and the porewater. This study aims to determine the concentration of N and P in the porewater and estimate the value of flux. The sediment samples were taken from the Wiso and Serang estuary, Jepara. The components that were analyzed in the porewater are the concentration of N (nitrate, nitrite) and P (phosphate). Nitrite, nitrate and phosphate were determined by using sulphanilamide method and the molybdenum blue method, respectively. Furthermore, the flux value (F) was calculated based on the Fick’s I Law which was corrected by porosity. The results show that the mean concentrations of nitrate (NO3-), nitrite (NO2-) and phosphate (PO42-) in the sediment water of Serang Estuary are 1.96, 1.41, 3.46 μM and in the Wiso estuary are 3.4, 1.85, 8.22 μM. In general, based on the calculation of flux, the sediments in the Serang and Wiso estuaries have a positive flux. Moreover, the sediment in Jepara acts as a source and releases N and P nutrient into the water column. The Wiso estuary has a higher flux than the Serang estuary.

6

Impact of the 2014 Major Baltic Inflow on benthic fluxes of ferrous iron and phosphate below the permanent halocline in the southern Baltic Sea

Brocławik O., Łukawska-Matuszewska K., Bolałek J.

Oceanological and Hydrobiological Studies

|

2018

|

Vol. 47, No. 3

275--287

EN

The impact of 2014 Major Baltic Inflow (MBI) on ferrous iron (FFe(II)) and phosphate (FPO43–) benthic fluxes was investigated. Sampling took place few months after the MBI, in August 2015, and over one year after the inflow, in February 2016. Materials were collected from three sites (depth of 106–108 m) located in the Gdańsk Deep. Total dissolved iron, Fe(II), phosphate, H2S and sulfate were analyzed in bottom and pore water. Benthic fluxes were estimated using Fick’s first law. All fluxes were directed from sediment. FFe(II) ranged from 0.31 × 10–2 to 1.25 × 10–2 μmol m–2 hr–1 and FPO43– from 1.53 to 2.70 μmol m–2 hr–1. At the deepest site, FPO43– was similar in both seasons, while at two other sites fluxes in August 2015 were 40–50% smaller than in February 2016. The increase in bottom water oxygen after the MBI enhanced Fe(oxyhydr)oxides formation. As a consequence, bottom and pore water concentrations of Fe(II) and FFe(II), decreased. Adsorption of phosphate onto Fe(oxyhydr)oxides resulted in binding of P in surface sediment and lower FPO43– in August 2015. This was particularly evident at the shallowest site. The reductive dissolution of Fe(oxyhydr)oxides and desorption of P during the subsequent months resulted in higher FPO43– in February 2016.

7

Deposition, return flux, and burial rates of nitrogen and phosphorus in the sediments of two high-Arctic fjords

Koziorowska K., Kuliński K., Pempkowiak J.

Oceanologia

|

2018

|

No. 60 (4)

431--445

EN

The aim of this study was to determine the burial rates of nitrogen (N) and phosphorus (P) in the sediments of two high-latitude fjords: Hornsund and Kongsfjorden (Spitsbergen). Both deposition to sediments and the return flux from sediments to the water column of the various species of these elements were, therefore, quantified. The burial rate was then calculated as the difference between deposition and return flux. The required concentrations of N and P species were measured in surface sediments, in pore water extracted from the sediments, and in the above-bottom water at sampling stations situated along the axes of the fjords. Annual deposition to sediments ranged between 2.3-8.3 g m−2 for N and 0.9-2.8 g m−2 for P. The nitrogen return fluxes ranged from 0.12 to 1.46 g m−2 y−1. At most stations, the N flux was predominantly of dissolved organic (about 60-70%) rather than inorganic N. The P return flux varied between 0.01 and 0.11 g m−2 y−1, with organic species constituting 60-97%. The N and P burial rates differed between fjords: 2.3-7.9 g N m−2 y−1 and 0.9-2.8 g P m−2 y−1 in Hornsund vs. 0.9-1.3 N g m−2 y−1 and 1.0-1.2 g P m−2 y−1 in Kongsfjorden. This was accompanied by a different efficiency of N and P burial – higher in Hornsund than in Kongsfjorden, in both cases. This suggests differences in the quality and quantity of N and P organic species deposited to sediments and therefore differences in the intensity of their mineralization and/or decomposition.

8

Comparison of the burial rate estimation methods of organic and inorganic carbon and quantification of carbon burial in two high Arctic fjords

Koziorowska K., Kuliński K., Pempkowiak J.

Oceanologia

|

2018

|

No. 60 (3)

405--418

EN

Quantifying the burial of organic carbon (OC) and inorganic carbon (IC) species in marine sediments contribute to a better understanding of carbon cycle. This is especially important in the Arctic, where carbon deposition is relatively high and expected to change with climate warming. This study aimed to quantify the burial rates of OC and IC in the sediments of two high-latitude fjords – Hornsund and Kongsfjorden (European Arctic). Comparison of the results from three methods quantifying carbon burial in marine sediments was carried out. Sediment cores, pore water, and over-bottom water samples were analyzed for OC and IC. The burial rates were established by considering: carbon deposition to sediments minus carbon return flux, carbon deposited to sediments 80-100 years ago and carbon deposited to sediments recently. The radiolead method was employed for sediment dating. Carbon return flux was obtained using dissolved carbon species concentrations in pore water and over-bottom water. Sediment linear and mass accumulation rates in the fjords were 0.12-0.20 cm y−1 and 1160-2330 g m−2y−1. The OC burial rates were 19.3-30.3 g OC m−2 y−1 in Hornsund and 5.7-10.0 g OC m−2y−1 in Kongsfjorden. IC burial was taken as equal to IC deposition and ranged from 10.7 to 20.8 g IC m−2 y−1 in Hornsund and 19.4-45.7 g IC m−2 y−1 in Kongsfjorden. The “return flux” model seems most appropriate for carbon burial rate studies. The data demonstrated that OC burial dominates in Hornsund, while in Kongsfjorden, IC burial is more important.

9

Skład chemiczny wód porowych górnoplejstoceńskiej sekwencji lessowo-glebowej w Zaprężynie (SW Polska)

Skurzyński J., Modelska M., Raczyk J., Staśko S., Jary Z.

Przegląd Geologiczny

|

2017

|

Vol. 65, nr 11/2

1383--1387

EN

The article presents the preliminary results of pore-water chemistry studies of the entire Upper Pleistocene loess-paleosol sequence in Zaprężyn (SW Poland). The pore-water chemical composition provides information about behaviour of the elements in the loess profile during the rock-water interactions. The applied method of ex situ water extraction allows only obtaining slightly bound water, which determines physicochemical parameters of the ground. The considerable variability of the values of pH, EC and concentrations of Al3+, Fe3+, Mn2+, Mg2+, Ca2+, Na+, K+, SO42-, Cl- ions and SiO2 was caused by stratification of sediments. The effect of reduced-permeability barrier on the increased concentrations of some ions was also found.

10

Skład chemiczny wód nadosadowych i roztworów porowych w osadach jeziora Wigry

Zdechlik R., Aleksander-Kwaterczak U.

Przegląd Geologiczny

|

2015

|

Vol. 63, nr 10/2

1145--1149

EN

This research was conducted in the area of Wigry Lake, which is one of the largest and deepest lakes in Poland. It consists of several parts which differ in size, depth, number of islands, chemical composition of water and the nature of shores. To assess variations in chemical composition of the pore water and overlying water, seven research positions were selected. They belong to one of three zones: profundal, littoral and dystrophic. Water characteristics are presented in statistical approach, using the background concentrations determined by the probability method. Chemical composition of the overlying water taken from profundal locations is similar to that from littoral parts of the lake. These are multi-ion waters of HCO3–SO4–Ca, HCO3–SO4–Ca–Mg, HCO3–Ca, HCO3–Ca–Mg type. They have low mineralization (268–552 mg/dm3) and are weakly alkaline (pH from 7.49 to 7.77). The situation is different with the composition of the water taken from the dystrophic lake (SO4–Ca–Mg). These are low mineralization (28 mg/dm3) and acid waters (pH = 5.35). Dominant in pore solutions is multi-ion HCO3–Ca, HCO3–Ca–Mg or HCO3–SO4–Ca–Mg water with mineralization 445–2032 mg/dm3 and pH between 7.39–8.23 (littoral positions), HCO3–Ca–SO4 and HCO3–Ca–Mg water with mineralization 479–762 mg/dm3 and pH from 7.59 to 7.89 (profundal positions). Definitely different chemical compositions have pore water from dystrophic lake: hydrochemical type changes with depth, from the HCO3–SO4–Ca, via HCO3–SO4–Ca–Na and HCO3–SO4–K–Ca, to the HCO3–O4–Na–Ca. Their mineralization is very low (49–69 mg/dm3) and pH changes from 7.25 to 8.01.

11

Spatial distribution of iron and aluminum in pore water and bottom sludge of the meromictic acid lake no 54, Łuk Mużakowski, Poland

Jachimko B.

Civil and Environmental Engineering Reports

|

2013

|

No. 11

67--75

EN

The spatial distribution of iron and aluminum in bottom sludge and pore water of the meromictic acid pit lake no 54 situated in Łuk Mużakowski, Poland were examined. Samples were taken three times from two places located within the meromictic zone and one out of it. Chemical composition of pore water and sludge in vertical profiles were analysed. Two patterns of the distribution of elements between solid and liquid parts depending on the sampling location were found. Samples taken outside meromictic zone had comparable high concentration of iron in the sludge associated with its low amounts in pore water - and on the contrary: low concentration of alum in sludge associated with its high amount in pore water. Samples from the meromictic zone characterized reversed relations.

PL

W publikacji przedstawiono zmiany zawartości żelaza i glinu w wodzie porowej i osadach dennych acidotroficznego zbiornika meromiktycznego nr 54 w Łuku Mużakowskim. Próbki pobierano trzykrotnie z dwóch miejsc w strefie meromiksji i jednego poza nią. Analizowano skład chemiczny osadów i wody porowej w profilu pionowym obranych prób. Stwierdzono dwa wzory rozkładu stężeń badanych pierwiastków między wodą porową i osadami. W próbkach pochodzących spoza strefy meromiksji stosunkowo wysokim stężeniom żelaza w osadach towarzyszyła jego niska zawartość w wodzie porowej, natomiast odwrotną zależność stwierdzono dla glinu, tj. wysokim stężeniom glinu w wodzie porowej towarzyszyła jego niska zawartość w osadach. W próbkach pochodzących ze strefy meromiksji zależności te przebiegały odwrotnie.

12

Makroskopowy model zamarzania i rozmrażania konstrukcji betonowych

Alsabry A.

Przegląd Budowlany

|

2010

|

R. 81, nr 3

30-33

PL

W skali makroskopowej nie ma równowagi termodynamicznej podczas cyklów zamarzania i odmrażania, jak to stwierdzono dla systemów mikroskopowych [Max]. Trwałość konstrukcji betonowych eksploatowanych w warunkach zimowych może być bardzo wysoka lub bardzo niska, przy tych samych lub zbliżonych parametrach jakościowych poszczególnych składników mieszanki betonowej. Konstrukcja betonowa narażona na oddziaływanie wilgoci i mrozu ulega uszkodzeniom. Trudne warunki eksploatacji występują w konstrukcjach narażonych na ciągły kontakt z wodą, takich jak: zapory, przelewy, falochrony, filary mostowe itp. Tematem tego artykułu jest makroskopowy opis procesów zachodzących w betonie na przykładzie dwuskładnikowego materiału porowatego nasyconego wodą.

EN

On a macroscopic scale there is no thermodynamic balance over freezing and thawing cycles, as has been found for microscopic systems [Max]. The durability of concrete structures used in winter conditions may be very high or very low, even when the ingredients of the concrete mix had the same or similar quality parameters. A concrete structure exposed to the action of damp and frost will experience damage. Difficult conditions of use are present in the case of structures which are in constant contact with water, such as dams, overfalls, breakwaters, bridge piers, etc. This paper contains a macroscopic description of processes occurring in concrete, based on the example of a porous material made of two ingredients, saturated with water.

13

Porewater nutrients (phosphate, ammonia and silicate) in the eastern part of the southern Baltic Sea

Graca B., Witek Z., Burska D., Białkowska I., Pawelec A., Bolałek J.

Oceanological and Hydrobiological Studies

|

2006

|

Vol. 35, No.3

237-256

EN

In the present work, results of studies concerning phosphate, ammonia and silicate in porewaters of the eastern part of the southern Baltic sediments are presented. A strong interaction was observed between the investigated compound concentrations and the sea bottom type, defined by means of the sediment water content (W) and loss on ignition (LOI) values. High concentrations and an exponential increase in concentration downwards in the sediment depth profile was observed in regions named here transport/accumulation bottom (LOI?4%, W?50%). Lower concentrations and irregular changes in concentration with depth occurred in regions designated as erosion bottom type (LOI<4, W<50%). Only in areas under strong anthropogenic influence (Vistula river mouth, the vicinity of Gdynia harbour), in the erosion type bottom concentration periodically raised to the level observed in the transport/accumulation bottom areas. The mass of nutrients accumulated in porewaters in the 10 cm thick layer of surface sediments of the Gulf of Gdańsk in September 2000 was estimated to be 910 t P-PO43-, 2780 t N-NH4+ and 5430 t DSi, while in March/April of 2001 estimated values equalled 908 t P-PO43-, 1860 t N-NH4+ and 3080 t DSi. In the erosion bottom areas, approximately 12 t, 210 t and 650 t of P-PO43-, N-NH4+ and DSi, respectively, were flushed out of the sediments during the intensive autumn-winter mixing.