In the past twenty years in Croatia a number of reinforced earth constructions have been built, of which two reinforced earth walls stand out due to their dimensions: Strikići and Sveta Trojica. In ...the building of these walls polyester strips were used as reinforcement elements, whereas as fill material crushed stone aggregate was used. For designing these constructions knowledge about the interaction mechanisms between the polyester strip and the soil is required. So far, most of the published studies have been directed to the determination of the friction interaction coefficient of the polyester strip and the fill material which was sand or gravel, whereas tests on the interaction between the geosynthetic strip and the crushed stone aggregate have not been performed. In order to determine the friction interaction coefficient between the crushed stone aggregate which is commonly used as fill material and the geosynthetic strip pull-out tests of the polyester strip were carried out. Apart from pull-out tests, large direct shear tests were performed to determine shear strength parameters of crushed stone strength. Predictions from the numerical model were compared to a series of pull-out tests, proving that the numerical model provides reasonable predictions of pull-out behavior.
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In the past twenty years in Croatia, a number of reinforced earth constructions have been built, of which two reinforced earth walls stand out due to their dimensions: Strikići and Sveta Trojica. In ...the building of these walls, polyester strips were used as reinforcement elements, whereas as fill material crushed stone aggregate was used. For designing these constructions, knowledge about the interaction mechanisms between the polyester strip and the soil is required. So far, most of the published studies have been directed to the determination of the friction interaction coefficient of the polyester strip and the fill material which was sand or gravel, whereas tests on the interaction between the geosynthetic strip and the crushed stone aggregate have not been performed. In order to determine the friction interaction coefficient between the crushed stone aggregate which is commonly used as fill material and the geosynthetic strip, pull-out tests of the polyester strip were carried out. Apart from pull-out tests, large direct shear tests were performed to determine shear strength parameters of crushed stone strength. Predictions from the numerical model were compared to a series of pull-out tests, proving that the numerical model provides reasonable predictions of pull-out behavior.
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Nuclear power plant (NPP) Krško has a license to operate until 2023, and under the current agreement between the Republic of Slovenia and the Republic of Croatia, countries are bound to dispose one ...half of radioactive waste produced during the operation time and after decommissioning of NPP each. Safe long-term management of high level radioactive waste and spent fuel represents one of the most important issues of the modern world. The best way to provide practical demonstration of repository’s safety, which will be one of convincing arguments in the process of licensing future repository, is developed underground research laboratory (URL). Existence of URL open to international co-operation would certainly improve the international recognition and credibility of Croatian programme, as well as allow dissemination of scientific research results to a broader scientific community (the paper is published in Croatian).
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Poznavanje mehanizma interakcije između tla i elemenata armature ključno je za projektiranje
konstrukcija od armiranog tla, a ovisi o vrsti armaturnih elementa i tlu koje se koristi. U većini
...dosadašnjih istraživanja proučavan je mehanizam interakcije između metalnih traka ili mreža,
te geosintetičkih mreža ili geotekstila i tla, dok je mali broj ispitivanja proveden za određivanje
mehanizma interakcije geosintetičkih traka i tla. U istraživanjima koja su provedena za
određivanje mehanizma interakcije geosintetičkih traka i tla, ispitivanja su provedena za
slučajeve kada je kao materijal ispune korišten pijesak ili rjeđe šljunak, dok za ispitivanja kada
se kao materijal ispune koristio lomljeni kamen ne postoje dostupni podaci u literaturi. Kako je
u Hrvatskoj u izgradnji dva visoka zida od armiranog tla (Strikići i Sv. Trojica) korišten upravo
lomljeni kamen i geosintetičke armaturne trake pojavila se potreba za proučavanjem
mehanizma interakcije između lomljenog kamena i geosintetičke armature. Dosadašnja
istraživanja pokazala su da su koeficijenti interakcije u šljunku veći od onih u pijesku, te je za
očekivati da će koeficijenti interakcije u lomljenom kamenu biti veći od onih koji su određeni
u šljunku. Kako bi se što bolje objasnio mehanizam interakcije između elemenata armature i tla
provode se laboratorijska ispitivanja izravnog posmika i ispitivanja izvlačenja elemenata
armature iz tla. Ispitivanje izravnog posmika slično je ispitivanjima koja se provode za tlo pri
čemu se uzorak armature ugradi u uređaj i smiče, a u ispitivanju se registriraju posmična sila i
pomak. Kod ispitivanja izvlačenja, armatura se ugradi između dva sloja tla, a nakon ugradnje
uzorak armature se izvlači iz sloja tla. U ispitivanju se registriraju sila izvlačenja i pomaci koji
se prate u pojedinim točkama na armaturi. Cilj ispitivanja je da se odredi sila koja je potrebna
za izvlačenje armature ili sila pri kojoj dolazi do sloma armature. Dobivena sila izvlačenja
podijeli se s površinom uzorka armature i dobije se otpor izvlačenju (koeficijent interakcije)
koji se koristi kod projektiranja konstrukcija od armiranog tla. Mehanizam interakcije između
tla i armaturnih elemenata ovisi o vrsti tla koje se koristi i o vrsti armaturnih elemenata, a ovaj
rad je usmjeren na određivanje mehanizma interakcije između istezljive geosintetičke trake i
lomljenog kamena. Kako bi se što bolje objasnio mehanizam interakcije između tla i
geosintetičke trake potrebno je imati podatke o parametrima čvrstoće tla za koje je potrebno
provesti ispitivanja izravnog posmika i parametre o interakciji između elementa tla za koje je
potrebno provesti ispitivanja izvlačenja armature iz tla. U ovom radu promatran je utjecaj
granulometrijskog sastava materijala na koeficijent interakcije između geosintetičke trake i tla.
Ispitivanja su provedena za jednoliko graduirani lomljeni kamen s rasponom frakcija od 30 do
60 mm i dobro graduirani lomljeni kamen s rasponom frakcija od 4 do 60 mm i od 0 do 60 mm.
Parametri čvrstoće lomljenog kamena određeni su u velikom uređaju za izravni posmik koji je
razvijen na Rudarsko-geološko-naftnom fakultetu. Dimenzije uređaja su 300x300x300 mm, a
maksimalni promjer zrna koji je ispitivan u uređaju za izravni posmik je 31 mm. Rezultati ovih
ispitivanja pokazali su da je kut trenja i dilatancije najveći kod jednoliko graduiranog materijala,
dok su najmanji kutovi trenja određeni za dobro graduirani materijal. Koeficijenti interakcije
izmeu geosintetičke trake i lomljenog kamena određeni su u velikom uređaju za ispitivanje
izvlačenja, tip GFOS. Ispitivanja su također provedena za tri različita granulometrijska sastava
materijala: jednoliko graduirani materijal s rasponom frakcija od 30 do 60 mm i dobro
graduirani materijal s rasponom frakcija od 4 do 60 mm i od 0 do 60 mm. Ispitivanja su
provedena za slučaj izvlačenja jedne trake i za slučajeve izvlačenja dvije odvojene i dvije
spojene geosintetičke trake. Ispitivanja izvlačenja jedne trake provedena su s ciljem određivanja
utjecaja granulometrijskog sastava i gustoće materijala na koeficijente interakcije, dok se kod
ispitivanja izvlačenja s dvije trake promatrao utjecaj bočnog trenja na koeficijent interakcije.
Rezultati provedenih istraživanja pokazali su da su najveći kutovi trenja kod dobro graduiranog
materijala od 0 do 60 mm, što je obrnuto od rezultata izravnog posmika gdje su za jednoliko
graduirani materijal određeni najveći kutovi trenja. Ispitivanja s dvije odvojene i dvije spojene
trake pokazala su da bočno trenje doprinosi povećanju koeficijenta interakcije. Uz
laboratorijska ispitivanja određivanja koeficijenata interakcije i parametra koji utječu na
koeficijent interakcije provedene su i povratne analize izvlačenja trake u programu Plaxis 2D.
U povratnim analizama korišteni su parametri materijala određeni izravnim posmikom i
koeficijenti interakcije određeni pokusom izvlačenja.
Knowledge of the mechanism of interaction between the soil and the reinforcement element is
crucial for the design of reinforced soil structures. It depends on the type of the reinforcing
element and the soil that is used. The majority of previous research studied the mechanism of
interaction either between the metal strip or nets, or else geosynthetic nets or geotextile and
soil, while a small number of tests were conducted to determine the mechanism of interaction
between geosynthetic strips and soil. In studies that were conducted to determine the
mechanism of interaction between geosynthetic strip and soil, tests were conducted in cases
when the fill material used was sand or, less frequently, gravel, while there are no available data
in the literature for tests performed with crushed stone as fill material. Since in Croatia broken
rock and geosynthetic reinforcement strip were used in the construction of two high reinforced
earth walls (Strikic and Sveta Trojica), there was a need to study the mechanism of interaction
between the crushed stone and geosynthetic reinforcement. Previous studies have shown that
coefficients of interaction in the gravel are higher than those in the sand. Therefore, it is to be
expected that the coefficients of interaction in crushed stone are to be higher than those for the
gravel. In order to clarify the mechanism of interaction between the elements of reinforcement
and soil, the laboratory direct shear tests and pull-out tests on reinforcement elements and soil
were performed. Direct shear test with reinforcement is similar to usual direct shear test, for
which the reinforcement is incorporated in the device and shear, and the test registers shear
force and displacement. For pull-out test, reinforcement is incorporated between two layers of
the soil, and after emplacement the reinforcement is pulled out from the soil. During the test,
withdrawal forces and displacements are registered at particular points on the reinforcement.
The goal of testing is to determine the force required to pull out the reinforcement or the force
at which the reinforcement broke. The resulting pull-out force is divided with the surface of the
reinforcement material and the obtained value is the draw resistance (coefficient of interaction)
which is used in the design of reinforced soil structures. The mechanism of interaction between
soil and reinforcement depends on the type of soil used and on the type of reinforcement
elements. This thesis is attempting to determine the mechanisms of interaction between
extensible geosynthetic strips and crushed stone. In order to better clarify the mechanism of
interaction between soil and geosynthetic strips, soil strength parameters are necessary (for
which direct shear test is performed), as well as parameters of the interaction between the
elements of the soil (for which pull-out tests are performed). In this study, the effect of particle
size distribution of the material on the coefficient of interaction between geosynthetic strips and
soil was observed. Tests were performed on uniformly graded crushed stone fraction with a
range of 30 to 60 mm and a well graded crushed stone fraction with a range of 4-60 mm, and
from 0 to 60 mm. Strength parameters of the crushed stone are determined in a large direct
shear device developed at the Faculty of Mining, Geology and Petroleum Engineering. Device
dimensions are 300x300x300 mm and the maximum diameter of the grain that was investigated
is 31,5 mm. The results of these tests showed that the friction angle and dilatancy are highest
in uniformly graded material, while the smallest friction angles are specific to well graded
material. Coefficients of interaction between geosynthetic stripe and crushed stone were
determined in a large pull-out test device, GFOS model. These tests were also carried out for
three different granulometric compositions: uniformly graded material with fraction range of
30 to 60 mm and a well-graded material with fraction range of 4-60 mm and from 0 to 60 mm.
Tests were performed in the case of extraction of one strip and for two separated and two
connected geosynthetic strips. One-strip extraction was conducted in order to determine the
influence of particle size distribution and density of material on the interaction coefficient. For
the extraction of the two strips, the effect of side friction on interaction coefficient was
observed. The results of the study show that well graded materials (0-60 mm) show the greatest
angles of friction between soil and strip, which is contrary to the results of direct shear test,
where the uniformly graded material had greatest friction angles. Tests with two separate strips
and two connected strips showed that side friction contributes to the coefficient of the
interaction. In addition to laboratory tests for determining coefficients of interaction and
parameters that affect the coefficient of interaction, feedback analyses have been conducted for
strip pull-out in Plaxis 2D. In feedback analyses, parameters for materials were determi
Urban Mining - a New Concept Kovačević-Zelić, Biljana; Bedeković, Gordan; Gradiški, Karolina ...
Annual of the Croatian Academy of Engineering,
05/2018
21.
Journal Article
U Hrvatskoj je u posljednjih dvadesetak godina izgrađeno više konstrukcija od armiranoga tla, pri čemu se po svojim dimenzijama ističu dva zida od armiranoga tla, Strikići i Sveta Trojica. U gradnji ...tih zidova kao armaturni elementi korištene su poliesterske trake, dok je kao materijal ispune korišten lomljeni kamen. Za projektiranje takvih konstrukcija potrebno je poznavanje mehanizma interakcije između poliesterske trake i tla. Dosadašnja ispitivanja koja su bila usmjerena na određivanje koeficijenta interakcije poliesterske trake i tla provedena su za slučajeve kada je kao materijal ispune korišten pijesak ili šljunak, dok ispitivanja interakcije armaturne trake i lomljenoga kamena nisu provedena. Kako bi se odredili koeficijenti interakcije između lomljenoga kamena i poliesterske trake provedena su ispitivanja izvlačenja poliesterske trake i lomljenoga kamena različitoga granulometrijskog sastava. Uz ispitivanja izvlačenja provedena su i ispitivanja izravnoga smicanja kako bi se odredili parametri čvrstoće lomljenoga kamena, a rezultati laboratorijskih ispitivanja korišteni su za provedbu numeričkih analiza izvlačenja trake iz tla.
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Nuclear power plant (NPP) Krsko has a license to operate until 2023, and under the current agreement between the Republic of Slovenia and the Republic of Croatia, countries are bound to dispose one ...half of radioactive waste produced during the operation time and after decommissioning of NPP each. Safe long-term management of high level radioactive waste and spent fuel represents one of the most important issues of the modern world. The best way to provide practical demonstration of repository's safety, which will be one of convincing arguments in the process of licensing future repository, is developed underground research laboratory (URL). Existence of URL open to international co-operation would certainly improve the international recognition and credibility of Croatian programme, as well as allow dissemination of scientific research results to a broader scientific community. Key words title: underground research laboratory, repository, radioactive waste Nuklearna elektrana Krsko (NEK) ima dozvolu za rad do 2023. godine, a prema postojecim sporazumima izmedu Republike Hrvatske i Republike Slovenije, svaka drzava je duzna zbrinuti polovinu radioaktivnog otpada nastalog tijekom rada i nakon razgradnje NEK. Sigurno trajno zbrinjavanje visokoradioaktivnog otpada i istrosenog goriva predstavlja jedan od najvecih problema suvremene civilizacije. Najbolji nacin za dokazivanje sigurnosti odlagalista, sto ujedno predstavlja i najvazniji argument u procesu ovlascivanja buduceg odlagalista, jest razvijen podzemni istrazivacki laboratorij (PIL). PIL otvoren za medunarodnu suradnju i istrazivanja bi sigurno unaprijedio medunarodnu prepoznatljivost i kredibilitet hrvatskog programa za gospodarenje radioaktivnim otpadom, jednako kao i razmjenu rezultata znanstvenih istrazivanja siroj znanstvenoj zajednici. Kljucne rijeci: podzemni istrazivacki laboratorij, odlagaliste, radioaktivni otpad
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Nuclear power plant (NPP) Krsko has a license to operate until 2023, and under the current agreement between the Republic of Slovenia and the Republic of Croatia, countries are bound to dispose one ...half of radioactive waste produced during the operation time and after decommissioning of NPP each. Safe long-term management of high level radioactive waste and spent fuel represents one of the most important issues of the modern world. The best way to provide practical demonstration of repository's safety, which will be one of convincing arguments in the process of licensing future repository, is developed underground research laboratory (URL). Existence of URL open to international co-operation would certainly improve the international recognition and credibility of Croatian programme, as well as allow dissemination of scientific research results to a broader scientific community.
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Nuklearna elektrana Krško (NEK) ima dozvolu za rad do 2023. godine, a prema postojećim sporazumima između Republike Hrvatske i Republike Slovenije, svaka država je dužna zbrinuti polovinu ...radioaktivnog otpada nastalog tijekom rada i nakon razgradnje NEK. Sigurno trajno zbrinjavanje visokoradioaktivnog otpada i istrošenog goriva predstavlja jedan od najvećih problema suvremene civilizacije. Najbolji način za dokazivanje sigurnosti odlagališta, što ujedno predstavlja i najvažniji argument u procesu ovlašćivanja budućeg odlagališta, jest razvijen podzemni istraživački laboratorij (PIL). PIL otvoren za međunarodnu suradnju i istraživanja bi sigurno unaprijedio međunarodnu prepoznatljivost i kredibilitet hrvatskog programa za gospodarenje radioaktivnim otpadom, jednako kao i razmjenu rezultata znanstvenih istraživanja široj znanstvenoj zajednici.
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