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This paper presents the efforts in rapid evaluation of the probability of liquefaction below the flood protection system in Sisacko – moslavacka county in Croatia, where large-scale liquefaction, occurred after series of earthquakes in December 2020, induced failures of embankments and surrounding soil. The probability of liquefaction is calculated by utilizing data from in-situ CPTU investigations, where the straightforwardness of the probability evaluation methodology was implemented using the custom-made algorithm. The procedure included development of a CPT-based soil profile with respect to the soil classification scheme using the Soil Behaviour Type Index, followed by the calculation of cyclic resistance ratio, cyclic stress ratio and eventually probability of liquefaction. The procedure for evaluation on liquefaction probability is demonstrated for CPTU measurements obtained on the location of flood protection embankment near river Glina. CPTU, as a method that is being increasingly incorporated into the portfolio of investigation methods of geotechnical engineers, has proven as rapid and effective method for evaluation of liquefaction occurrence probability, and this especially useful when assessing linear civil engineering infrastructure.

U radu su prikazani rezultati laboratorijskog ispitivanja uzoraka gline s dva lokaliteta u gradu Zagrebu, pomiješane s letećim pepelom, zgurom i cementom. U laboratorijskim uvjetima su pripremljeni kompozitni uzorci mješavina gline s vezivima koji su u omjerima od 5 %, 10 % i 20 % dodani glini, te ispitani u različitim vremenskim intervalima sazrijevanja od 7, 14 i 28 dana. Ispitan je i analiziran utjecaj različitog tipa i udjela veziva te starosti kompozitnog uzorka na vlažnost i na jednoosnu tlačnu čvrstoću. Dobiveni rezultati pokazuju da se primjenom cementa, letećeg pepela i zgure mogu poboljšati fizikalna i mehanička svojstva zagrebačke gline, u ovisnosti o količini veziva i vremenu sazrijevanja kompozita., The paper presents the results of laboratory testing of clay samples from two localities in the city of Zagreb, mixed with fly ash, slag and cement. Under laboratory conditions, composite samples of clay mixtures with binders were prepared, where the binders are added to the clay in ratios of 5 %, 10 % and 20 %, and tested at different maturation time intervals of 7, 14 and 28 days. The influence of different type and amount of binder and age of the composite sample on moisture and uniaxial compressive strength was examined and analysed. The obtained results show that the utilization of cement, fly ash and slag can improve the physical and mechanical properties of Zagreb clay, depending on the amount of binder and the maturation time of the composite.

U radu se daje prikaz aktivnosti koje se provode u okviru znanstveno-istraživačkog projekta oVERFLOw, financiranog kroz mehanizam civilne zaštite EU. Zajedno sa upraviteljima infrastrukturom i društvima civilne zaštite, konzorcij partnera iz Hrvatske, Slovenije i Nizozemske, implementira novostečena znanja i iskustva na dva pilot područja u Nizozemskoj i u Hrvatskoj. Sveobuhvatan pristup ocjeni ranjivosti nasipa i obaloutvrda, kao ključnih karika u sustavu zaštite od štetnog djelovanja voda, obuhvaća detaljne i inovativne metode ocjene postojećeg stanja koje služe kao ulaz za probabilističke analize evaluacije njihove ranjivosti na niz mehanizama prekoračenja graničnih stanja. Osim toga, projekt analizira i osjetljivost mostova kao ključnih infrastrukturnih elemenata evakuacijskih puteva tijekom poplavnih događaja.

Zbog svoje jedinstvenosti okarakterizirane složenim geološkim i morfološkim, površinskim i podzemnim, značajkama, krš je izuzetno izazovno okruženje za tuneliranje. Postupci numeričkog modeliranja, koji se koriste za predviđanje ponašanja tunela, opterećeni su stoga mnogim nesigurnostima. Ova prezentacija govori o prednostima primjene neuronskih mreža (NN) kao vrlo učinkovitog alata za predviđanje kratkoročnog i dugoročnog ponašanja tunela. Zbog brojnih prednosti u odnosu na tradicionalno korištene statističke i eksperimentalne metode, poput izvanredne sposobnosti obrade informacija koja se odnosi na nelinearnost, visoku paralelnost, toleranciju na smetnje i buku, samoučenje i generalizaciju, mnogi su istraživači koristili neuronske mreže u primjenama vezanim za tunele u stijenskoj masi. Istraživanje dano u prezentaciji provodi se u okviru znanstvenog projekta SAFE 10-T iz programa Obzor 2020. Prezentacija se usredotočuje na primjere gdje su se neuronske mreže pokazale korisnima za probabilističko projektiranje podgradnog sustava krškog tunela, prevladavajući problematiku dugotrajnih numeričkih analiza primjenom Monte-Carlo simulacije (MCS). Drugi primjer, gdje neuronske mreže koriste veliku bazu podataka in-situ monitoringa, predstavlja napore u procjeni najvjerojatnijeg skupa reoloških parametara, omogućujući tako predviđanje dugoročnih deformacija tunela nakon izgradnje. Primjeri dani u radu uključuju dva tunela u Rijeci: cestovni tunel Pećine i željeznički tunel Brajdica koji je nedavno rekonstruiran.

U radu se daje prikaz projektnog rješenja rekonstrukcije uspornih nasipa za obranu od poplava uz rijeku Trnavu. Rekonstrukcija se izvodi zasijecanjem tijela postojećeg nasipa te izvedbom novog nasipa većih dimenzija, sve kako bi se zadovoljili kriteriji osiguranja mehaničke otpornosti i stabilnosti pri mjerodavnim vodostajima. Međutim, uzimajući u obzir prostorna ograničenja, gdje su nagibi pokosa nasipa uvjetovani visinom nasipa i blizinom vodotoka Trnave te činjenicu da su nasipi projektirani prema relevantnim standardima Eurokoda 7, tehničko rješenje rekonstrukcije je obuhvatilo i ugradnju jednoosnih polimernih geomreža, sve u cilju povećanja stabilnosti za relevantne projektne situacije

Maksimalna krutost tla se u geotehnici najčešće izražava modulom smicanja kao odnos između posmičnog naprezanja i male relativne posmične deformacije. Za određivanje maksimalne krutosti tla najpogodnije su geofizičke metode kojima se mjere brzine širenja posmičnih valova. U radu je prikazan razvoj korelacije između maksimalne krutosti tla, dobivene višekanalnom analizom površinskih valova (MASW) i rezultata statičkog penetracijskog pokusa (CPT). Korelacija je razvijena na temelju baze od 128 parova podataka na lokaciji za ispitivanje nosivosti pilota u Nizozemskoj.

This paper presents a case study focused on the Brajdica railway tunnel, which carries the Zagreb-Rijeka railway line into the multi-modal port of Rijeka in Croatia and thus represents a critical node on the TEN-T network. The tunnel is undergoing a major reconstruction project, during which an extensive embedded monitoring system is being installed. The monitoring system includes a large range of equipment including inclinometers, extensometers, micrometers and survey markers which will be supplemented with periodical scanning of the tunnel interior using laser scanners. Measurement profiles will be set along the tunnel bore and the data collected will be used for validation of the geological and structural model and allow updating to be performed in real-time. Finally the performance model will be used for the development of the life cycle management scenarios, which will be used for the optimization of maintenance planning and identification of short and long-term risks. This work is a part of H2020 SAFE-10-T project.

Rad prikazuje sve faze u pisanju aplikacije, evaluacije i provedbe projekta SAFE-10-T Safety of Transport Infrastructure on the TEN-T Network iz programa Obzor 2020.

U radu se daje prikaz važnosti sudjelovanja u europskim znanstvenim projektima koji služe kao podloga za međunarodnu prepoznatljivost.

A paper proposes the framework, which would provide tunnel infrastructure managers with information on life cycle costs for remediation of structural cracks in secondary lining of tunnels. The framework is based on several characteristic phases, where the data between phases is transferred is automatic manner. The continuous, long-term, in-situ monitoring of behavior of tunnel and surrounding rock mass (phase 1) provides input data for the custommade neural network with back propagation algorithm, which is used to determine constitutive model input parameters necessary for numerical modeling (phase 2). In this way, secondary lining internal forces can be foreseen throughout the tunnel service life, with determination of cracking propagation rate in secondary lining (phase 3). Finally, life- cycle costs are determined using software for cost calculations (phase 4), adapted to the specific purpose, where the sole input of crack width gives an detail insight into life-cycle repair costs including man/hour, equipment/hour, material and other costs. The monitoring data will continuously be used to update and calibrate the crack repair costs, giving the tunnel managers real-time information and opportunity for proactive planning of tunnel maintenance, easing the overall decisionmaking process.

Klasična teorija blokova, službeno objavljena 1985. godine s objavom knjige „Block Theory and Its Application to Rock Engineering“ [1], sadrži niz pojednostavljujućih pretpostavki. Takve pretpostavke omogućile su stvaranje jednostavne metode koja uz prihvatljiva ograničenja daje zadovoljavajuće rezultate za inženjerske potrebe. Usprkos tome, tijekom godina se nastojalo unaprijediti klasičnu teoriju, kako bi se mogla akomodirati složenijim problemima, i/ili povećala pouzdanost proračuna realnijim opisivanjem stanja u stijenskoj masi. Cilj ovoga članka je napraviti pregled istraživanja provedenih u cilju unaprjeđenja određenih ograničenja klasične teorije blokova. Na temelju pregleda pretpostavki i ograničenja klasične teorije te dosadašnjih istraživanja, mogu se lakše identificirati područja za daljnji razvoj teorije blokova., Classic block theory, officially established in 1985 with the publishing of the book “Block Theory and Its Application to Rock Engineering” [1], takes a lot of simplifying and restricting assumptions. Such assumptions allowed for a simple method which with acceptable restrictions gave satisfying results for engineering practice. Despite that, there have been many improvements throughout the years which try to accommodate for more complex problems and/or increase the overall reliability of the method. The scope of this paper is to give an overview of said improvements over the classic block theory. Based on the overview of assumptions of the classic theory and on the researches to date, it’s possible to more easily identify areas of further research and improvement.

The presentation compares the protection measures for rockfall events threatening the road infrastructure all over the world.

Georadar (GPR) je geofizička metoda koja se intezivno koristi posljednjih godina u cilju ocjene stanja željezničkih pruga kroz mapiranje niza faktora kao što su debljina i zablaćenost zastorne prizme, varijacije debljina slojeva duž pruge, sadržaj vode te položaj i dubina elemenata kao što su podzemne drenažne cijevi, rovovi ili ostale instalacije. Kao elektromagnetna metoda, oslanja se na frekvenciju i dubinu prodiranja korištenih antena, pa je vrlo važno koristiti optimalnu konfiguraciju za ispitivanje. Predstavljeni su rezultati ispitivanja na više od 180 km željezničkih nasipa u Hrvatskoj, uz prikaz postupaka prikupljanja podataka, analize podataka i njihove interpretacije. Primjena višekanalnog prilagođenog sustava omogućila je ocjenu stanja željezničkih nasipa kategorizacijom u pet razreda, od lošeg do odličnog stanja. Na temelju rezultata kategorizacije, predložen je detaljniji program istražnih radova i monitoringa. Ovi rezultati su vrijedni za HŽ Infrastrukturu kao upravitelja željezničkom infrastrukturom, jer daju početnu informaciju za daljnje korake sanacije. Ranim prepoznavanjem kritičnih lokacija, jeftinije mjere sanacije se mogu implementirati, što rezultira nižim troškovima i izbjegavanjem nepovoljnih situacija. Navedeno predstavlja korak naprijed od dosadašnjeg ‘reaktivnog’ pristupa prema ‘proaktivnom’ pristupu.

Since more than 95% of existing european railway network is older than 100 years, the ageing has unavoidably caused its gradual degradation and there is currently a strong need for risk assessment associated with this type of infrastructure. To increase the safety aspects, as well as to reduce the cost of remediation, railway infrastructure managers need to have more advanced tools on their disposal, since they currently make safety critical investment decisions based on poor data and an over-reliance on visual assessment. As a consequence their estimates of risk are therefore highly questionable and large-scale failures are happening with increasingly regularity. The paper therefore presents the efforts conducted through the some relevant scientific-research projects funded through the Horizon 2020 programme, whose overall goal is to implement and further develop state-of-the-art techniques and tools in field of railway infrastructure safety.

Several emerging technologies and techniques have been in focus of geotechnical community during the past few decades. This paper presents some of them, such as non-destructive testing methods and utilization of industrial waste in sustainable soil improvement. These elements represent a step forward from the classical concept of geotechnical engineering which is mostly based on destructive investigation works and application of standard engineering cement-based materials. Further, perspectives faced by geotechnical engineering in the use of the shallow geothermal energy will also be presented due to more and more prominent needs for the utilization of this valuable renewable energy source. Finally, during the last few years risk management has been implemented in geotechnical engineering, especially when there is a need for a rational decision-making process conducted by the infrastructure managers/owners.

The implementation of Eurocode norms in civil engineering design procedures led to a necessity for certain modification of designer’s mindset. The significance of this design approach comes to fore during design of specific structures such as flood protection embankments. To fulfil Eurocode requirements, a designer must consider series of design situations, which are reasonably expected during the lifetime of an embankment. These design situations, present the core of design using Eurocode 7 and it is crucial to identify them. This paper deals with design procedures starting from proper identification and interpretation of investigation works in order to obtain relevant ground model to analysis of both ultimate limit states (ULS) and serviceability limit state (SLS). Further, an importance of designer’s role in overall project of flood protection embankment is stressed out.

Geotehnika predstavlja spregu između klasične građevine i geoznanosti te kao takva obuvaća širok spektar aktivnosti koje je nužno provesti, sve u cilju izvedbe sigurne, funkcionalne i ekonomične građevine. U posljednje vrijeme se sve veći naglasak stavlja na sanaciju postojećih objekata gdje geotehnički istražni radovi predstavljaju ključni element u postupku ocjene njihovog trenutnog stanja. Činjenica je da su u ocjeni stanja još uvijek dominantno zastupljene razorne metode ispitivanja koje zahtijevaju značajne financijske i vremenske resurse. S druge strane, sve češće svoju primjenu u postupku ocjene stanja nalaze nerazorne metode ispitivanja koje mogu zahvatiti veći volumen ispitivanog medija. Dakako, ove metode su još uvijek opterećene određenim nedostacima koje djelomično ograničavaju njihovu primjenu, ali trend porasta njihove primjene je evidentan. Prednosti primjene nerazornih ispitivanja do izražaja dolaze pri ocjeni stanja strateških infrastrukturnih linijskih objekata kao što su željezničke linije, mreže cesta i autocesta, nasipi za obranu od poplava itd. Svaka vrsta linijskog objekta uvjetuje i kriterije primjene pojedine nerazorne metode. Primjeri ocjene stanja strateških infrastrukturnih linijskih objekata, s nerazornim metodama u fokusu metodologije, dati će se kroz prikaz niza stručnih aktivnosti Zavoda za geotehniku Građevinskog fakulteta u Zagrebu koje za cilj imaju pouzdanu i kvalitetnu ocjenu trenutnog stanja.

The need to assess present condition of flood protection embankments becomes more important in recent years. But besides the standard in-situ and laboratory methods for identification of their condition, some novel methods are entering through a “backdoor” and showing high potential, even though designers and investors are in generally not familiar with their possibilities. One of such methods, which can be useful for assessment of current condition, is usage of Unmanned Aerial System (UAS) also known as ‘drone’ which is characterized by an increasing number of engineering applications. First benefit of this method is in interactive approach for visual assessment of condition where a wider aerial picture can be obtained by having a sole operator on site, while the other participants in design of embankment’s remediation (persons who conduct investigation works, designers, investors etc.) can interactively be involved while not being present on site. Also, large areas which are the case for linear structures such as flood protection embankments, can be surveyed in fast manner, reducing the time necessary for standard visual assessment. However, full potential of this method is in possibility for advanced engineering analysis through the formation of orthophoto maps and 3D models using aerial photogrammetry. From this type of models, a complete spatial characteristics of embankments can be obtained with provisional cross sections extrapolated, thus avoiding a current practice where surveying activities are conducted along several profiles. The paper presents the possibilities of using Unmanned Aerial Systems on flood protection embankments, emphasizing their advantages and shortcomings.

U radu je prikazana primjena rezultata CPT pokusa za klasifikaciju tla prema Jedinstvenoj klasifikaciji tla (USCS) i Europskoj klasifikaciji tla (ESCS) korištenjem računalnog programa KLASIF. Prikazane su korelacije između rezultata CPT pokusa i parametara za klasifikaciju tla. Na primjeru kanala za navodnjavanje Biđ-Bosutskog polja pokazano je relativno uspješno klasificiranje tla pomoću CPT pokusa.

Using geosynthetics as a substitution for natural low permeability materials such as clays and silts have come to fore in last few decades. Numerous advantages in their performance and installation procedure make them popular for use inside flood protection embankments. Geomembrane and geosynthetic clay liner (GCL) are commonly used as hydraulic barriers. However, some limitations of these materials need to be stressed both from hydraulic stability and shear strength point of view. An example of application of GCL for reconstruction of embankment Virje - Otok Brezje, Varaždin County is demonstrated in this paper. The installation of GCL with carefully chosen characteristics proved that man-made materials such as geosynthetics can be successfully applied for ensuring stability of flood protection embankments.