Fuzzy Sets concept for optimization underground gas storage

Risk and Reliability in Geotechnical Engineerin

GEOLAB - Transnational Access project HSRTSUB - Resilient behaviour of stabilized and conventional high-speed's rail track subgrades under different drainage conditions and seat loads

In this study, the shear strength of track ballast material is evaluated by testing different types of track ballast specimens, which was conducted in a Large-scale Triaxial Apparatus at ZAG ) that has a shear area of 40 cm x 40 cm and can accommodate specimens up to 80 cm high. It enable loading of specimens in simple shear mode. The tests, which were conducted within HSRTSUB project, include two different types of ballast, the fouled ballast samples and the clean ballast samples, and two different specimen preparation techniques (with and without compaction). The normal stresses used cover a wide range from 50 to 400 kPa. The European standard EN13450 "Aggregates for railway ballast" was used. This standard specifies the properties of aggregates obtained by processing natural, manufactured or recycled crushed unbound aggregates for use in the construction of the upper layer of railway track. For the purposes of this standard, the aggregate is referred to as track ballast. Tests were conducted under unsaturated conditions with two types of lightweight materials: - fouled ballast aggregates and - clean ballast aggregate

GEOLAB - Transnational Access project LIWEMAT – Deformation characterisation of LIghtWEight foundation MATerials

Proper use of lightweight materials as construction material for various types of infrastructure brings a lot of advantages to European critical infrastructure related to weight reduction and prevention of progressive heating or freezing of its structural elements. Large-scale Triaxial Apparatus was used to perform the loading tests, which enables the characterization of materials at very small strain ranges with a very high accuracy level of load-displacement control. The apparatus has rigid confining aluminum frames with a height of 3 cm and cross-section of 40 x 40 cm, enabling prismatic specimens with a height of up to 80 cm to be tested. This research aims to determine the characteristics of expanded clay and foamed glass aggregates through laboratory testing, performing cyclic loading for the stiffness and damping evaluation, which would be beneficial parameters for numerical simulations. Testing material The foam glass aggregate has a homogeneous microstructure with approximate uniform shape and sizes. Foam glass aggregate is considered one of the best solid isolation materials with several unique properties. It can be widely used in many applications such as basement walls, foundations, floors and roofs, terrace and garden covers, rooftops, and parking areas. The expanded clay aggregate is round shape with different sizes with small, air-filled cavities, with dark brown, reddish, brown-red or gray colors, which depends on the chemical composition of the expanded clay. The lightweight expanded clay aggregate has bulk density from 250 kg/m3 to 710 kg/m3, mostly dependent on the size of the aggregate

Climate Change Adaptation of Geo-Structures in Europe: Emerging Issues and Future Steps

Climate change is already being felt in Europe, unequivocally affecting the regions’ geo-structures. Concern over this is rising, as reflected in the increasing number of studies on the subject. However, the majority of these studies focused only on slopes and on a limited geographical scope. In this paper, we attempted to provide a broader picture of potential climate change impacts on the geo-structures in Europe by gathering the collective view of geo-engineers and geo-scientists in several countries, and by considering different geo-structure types. We also investigated how geo-structural concerns are being addressed in national adaptation plans. We found that specific provisions for geo-structural adaptation are generally lacking and mainly come in the form of strategies for specific problems. In this regard, two common strategies are hazard/risk assessment and monitoring, which are mainly implemented in relation to slope stability. We recommend that in future steps, other geo-structures are likewise given attention, particularly those assessed as also potentially significantly affected by climate change. Countries considered in this study are mainly the member countries of the European Large Geotechnical Institutes Platform (ELGIP)

Climate Change Adaptation of Geo-Structures in Europe: Emerging Issues and Future Steps

Climate change is already being felt in Europe, unequivocally affecting the regions’ geo-structures. Concern over this is rising, as reflected in the increasing number of studies on the subject. However, the majority of these studies focused only on slopes and on a limited geographical scope. In this paper, we attempted to provide a broader picture of potential climate change impacts on the geo-structures in Europe by gathering the collective view of geo-engineers and geo-scientists in several countries, and by considering different geo-structure types. We also investigated how geo-structural concerns are being addressed in national adaptation plans. We found that specific provisions for geo-structural adaptation are generally lacking and mainly come in the form of strategies for specific problems. In this regard, two common strategies are hazard/risk assessment and monitoring, which are mainly implemented in relation to slope stability. We recommend that in future steps, other geo-structures are likewise given attention, particularly those assessed as also potentially significantly affected by climate change. Countries considered in this study are mainly the member countries of the European Large Geotechnical Institutes Platform (ELGIP)

Potencial ciklične likvefakcije jezerske krede in Julijskih alp

This paper presents the liquefaction studies of lacustrine carbonate silt from the Julian Alp landslide Stože. Geological conditions of the region and geomechanical characteristics of the ground were investigated. The research project was performed with the intention to determine the effects of cyclic loading on lacustrine carbonate silt. Investigation with 77 cyclic triaxial tests was performed on universal triaxial apparatus Wykeham Farrance UP 100 TR, in the Laboratory of soil mechanics, Faculty of Civil Engineering, University of Maribor. The essential equipment comprises cylindrical triaxial apparatus with a cell, a press with appurtenant electro-mechanic equipment, measuring equipment, and computer hardware and software equipment. Specimens with dimensions of height = 140 mm and diameter = 70 mm were saturated, then subjected to the arbitrary initial isotropic stress state and consolidated with vertical and radial draining, and then loaded with distortional loading of chosen dynamical axial force (frequency f = 1 Hz). A set of tests with a spectrum of different stress states and cyclic loading were performed. This research showed that lacustrine carbonate silt is a highly sensitive material.The resistance to liquefaction was somewhat higher than that of typical clean sand, but a perceivable excess pore pressure generation, which causes the decrease of strength parameters, was noticed. Test results of cyclic triaxial tests indicate dynamic characteristics of lacustrine carbonate silt and wide applicability of the test method.Prispevek podaja rezultate ciklične triosne preiskave kompozita prodnato peščenega melja jezerske krede iz območja plazu Stože v Julijskih Alpah. Namen preiskave je bil določitev nekaterih statičnih in dinamičnih lastnosti obravnavanega melja pri različnih (izbranih) pogojih in dinamičnih vplivih. Obravnavan je likvifakcijski potencial, t.j. možnost (verjetnost) utekočinjenja materiala zaradi izničenja njegove strižne trdnosti, pri naraščanju pornega vodnega tlaka v zemljini, zaradi ciklične obtežbe. Na območju plazu so bile pred tem opravljene obsežne geološke in geotehnične raziskave. Za določitev dinamičnih lastnosti so bile izvedene terenske preiskave, ki so vsebovale seizmične refrakcijske meritve in meritve hitrosti seizmičnih valov z “down-hole” metodo ter laboratorijske preiskave, ki so med drugim vsebovale tudi resonančni preizkus in ciklično torzijsko preiskavo. Pri preiskovanem materialu je za geotehnične analize ključnega pomena preučevanje fenomena likvifakcije. Namen pričujoče preiskave je bil pripravljene vzorce prodnato peščenega melja pri različnih pogojih privesti do likvifakcije s cikličnim obremenjevanjem, ter iz odziva na dinamične vplive podati zakonitosti likvifakcije. Podani so odnosi med številom ciklov potrebnih za likvifakcijo, začetnim stanjem materiala in pogoji obremenjevanja. V Laboratoriju za mehaniko tal, na Fakulteti za gradbeništvo, Univerze v Mariboru, je bila izvedena preiskava s 77 cikličnimi triosnimi preizkusi. Za preiskavo je bil uporabljen Univerzalni triosni aparat Wykeham Farrance UP 100 TR. Preizkusi so bili izvedeni na valjastih preizkušancih višine 140 mm in premera 70 mm. Vsak preizkušanec je imel enake začetne fizikalne lastnosti, z minimalnim odstopanjem vrednosti. Izvedena je bila saturacija, do stanja popolnega zasičenja (po kriteriju B>0.96). Sledila je faza konsolidacije pri izbranem napetostnem stanju in omogočenem bočnem dreniranju. Naslednji korak je bila izvedba nedreniranega cikličnega preizkusa z izbrano vertikalno ciklično obtežbo, s frekvenco 1 Hz. Med preizkusom so bile merjene časovne spremembe vertikalne napetosti σd(t), vertikalne deformacije εa(t), in porni vodni tlak uw(t). V preiskavi so bili spreminjani naslednji pogoji: začetne efektivne napetosti σ0’, količnik por ec in faktor obremenitve CSR, v naslednjih mejah: σ0’ = 50, 100, 150 in 200 kPa, ec = 0,320 ÷ 0,490 in CSR = 0,15 ÷ 0,30. Rezultati preiskave nakazujejo občutljivost jezerske krede. Odpor na likvifakcijo je sicer višji kot pri tipičnih čistih peskih, vendar so opazni prirastki pornega tlaka in upad parametrov trdnosti

Dinamične lastnosti polžarice iz Ljubljanskega barja

A series of cyclic triaxial tests was performed on snail-soil samples with different porosities. The cyclic loading was performed with a Wykeham Farrance cyclic triaxial system. The investigation was based on a series of tests in which the following conditions were varied: the initial effective pressures (50, 100, and 150 kPa), the void ratio after consolidation (2.0–1.2) and the cyclic loading expressed by the cyclic stress ratio CSR (0.1–1.0). Measurements were made of the stress, the deformation and the pore-water pressure. The results of the tests show that interdependency exists between the geomechanical characteristics and the porosity. These relationships can be expressed as functions of the density, the porosity or the water content. It is evident from the results that the changes in the coefficient of permeability, the coefficient of consolidation, and the coefficient of volume compressibility are non-linear with respect to the changes in the porosity. However, the changes at high porosity are much greater than the changes at low porosity, and the changes of the mechanical parameters, such as the Young’s modulus, Poisson’s ratio, and the friction angle, are indistinct and almost linear at lower changes of porosity, and after that become non-linear. The initial void ratio e is extremely high and the snail soil is liquid after consolidationa volume strain of εvol > 16 % is needed for the plastic limit state. The chemical and mineral composition, the particle size distribution and the remains of micro-organisms in the snail soil are constants. In addition, the specific surface is independent of the porosity and the density or unit weight, the porosity and the volume strain are in the well-known correlation. The performed cyclic triaxial tests show the dynamic characteristics of the snail soil and the influence of the porosity on the cyclic loading strength. The snail soil was recognized as a highly sensitive material. A large strain appears after the initial cycles. The pore pressure, increases already during the first cycle, to the hydrostatic part of the cyclic loading, or more (depending on CSR). The damping ratio increases exponentially with strain, after some cycles it reach its maximum value, and after that it decreases to the asymptotic value. The reason for such behaviour is the large deformation. The maximum and asymptotic values of the damping ratio are a changed minimum with a void ratio. There is obviously no influence of the porosity on the damping ratio. The shear modulus is described in relation to shear strain. The increasing of the pore pressure is independent of the porosity until it reaches some value of the pore-pressure ratio (>0.7). Similarly, the increasing of the shear strain becomes dependent on the void ratio until it reaches some particular value of the shear strain (>3%). The deformation and failure lines for the different porosities are determined from the relationship between the shear stress and the effective stress at some shear strain, after 10 cycles. The relationships between the shear stress and the effective stress at some value of the pore-pressure ratio are expressed in a similar way. Two kinds of criteria were used to determine the triggering of liquefaction during the cyclic triaxial tests: first, when the pore pressure becomes equal to the effective confining pressure, and, second, when the axial strain reaches 5% of the double amplitude.Na vzorcih polžarice iz jugozahodne lokacije Ljubljanskega barja je bila izvedena raziskava njenih dinamičnih lastnosti. Izvedeni so bili ciklični triosni preizkusi. V preiskavi so bili spreminjani pogoji: začetna efektivna napetost (50, 100, 150 kPa), količnik por (2.1 do 1.2) in faktor ciklične obremenitve CSR (med 0.1 in 1). Med posameznim preizkusom so bile merjene časovne spremembe napetosti, deformacij in pornega vodnega tlaka. Parametri fizikalnih lastnosti so podani kot funkcije zgoščenosti polžarice, torej volumenske deformacije, gostote, poroznosti ali vlažnosti. Kemični sestav delcev in mineralna sestava ter zrnatost polžarice se zaradi zgoščevanja ne spremenijo. Delež mikroorganizmov v polžarici je zelo majhen in ga lahko smatramo kot konstanto. Specifična površina je neodvisna od zgoščevanja. Nekateri parametri fizikalnih lastnosti polžarice (prostorninska teža, vlažnost, poroznost) se spreminjajo v odvisnosti od zgostitve, kar lahko izrazimo s splošno znanimi odnosi. Spremembe vodoprepustnosti, konsolidacije in stisljivosti so nelinearno odvisne od sprememb poroznosti, pri začetnem zgoščanju so spremembe očitne, z nadaljnim zgoščanjem se njihove spremembe manjšajo. Spremembe mehanskih parametrov kot so Youngov modul, Poissonov količnik in strižni kot, pa so pri pri začetnih spremembah poroznosti neizrazite in skoraj linearne, pri nadaljnem zgoščanju pa se njihove spremembe večajo. Vpliv zgoščanja na Poissonov količnik je skoraj linearen. Polžarica je kljub židkosti in neugodnim fizikalnim lastnostim ter nizkim parametrom trdnosti dokaj odporna na pojav likvifakcije. Se pa že v začetnih ciklih obremenjevanja pojavijo velike specifične deformacije. Tudi porni vodni tlaki že po nekaj ciklih izrazito narastejo, vendar pri manjših vrednostih CSR praviloma ne dosežejo efektivne celične napetosti. Dušenje narašča eksponentno z deformacijo. Zaradi velikih deformacij pa praviloma že po nekaj ciklih doseže maksimalno vrednost in zatem upade na neko asimptotično vrednost. Maksimalna in asimptotična vrednost dušenja se s spremembo poroznosti polžarice minimalno spremenita. Na strižni modul vpliva zgoščevanje posredno, saj je le ta izražen kot funkcija strižne deformacije. Deformacija je manjša pri gostejšem materialu in večja z večanjem CSR. Za različne vrednosti začetne efektivne napetosti in poroznosti polžarice so določene deformacijske in porušne ovojnice tako, da so podane vrednosti CSR pri katerih je po nekem številu ciklov (npr. 10) dosežena določena deformacija. Kot mejna vrednost je izbrana dvojna amplituta osne deformacije velikosti 5%. Podobno so podane ovojnice za različna stanja pornega tlaka in za mejno stanje, ko razmerje naraščajočega pornega tlaka in efektivne celične napetosti doseže vrednost 1

Analiza trajnih deformacij ciklično obremenjenih Murskih prodov

This contribution presents the results of the analysis of permanent deformations of gravel in the Mura region under repeated loading. The purpose of the analysis is to forecast the development of permanent normalised axial deformations ▫$/epsilon_1^{p*}$▫ regarding the number of loading cycles N and appurtenant stress states during cycling loading. The analysis used the results of tests performed by ZAG Ljubljana and Faculty of Civil Engineering and Geodesy (FGG) of the University of Ljubljana [1]. The analysis considers five types of stonematerials of different quantity of crushed grains in the mixture and of different water contents. Four types of stone materials are mixtures of different portions of crushed grains larger than 2 mm (Dcr = 87.7 %, 58.9 %, 32.6 % in 0 %), and of the water content around w = wopt - 2%. The stone material with portions of crushed grains larger than 2 mm Dcr= 58.9 % is analysed also for water content w = wopt + 0.7 %. The results of the analysis are deformations expressed as a function of the number of loading cycles N, and a spherical component of the repeated loading p and a distortional component of the repeated loading q. The results can be presentedas deformation surfaces in the ▫$/epsilon_1^{p*}$▫ - p - q space for an arbitrary number of cycles N. The relation between the spherical stress component p and the distortional stress component q, at arbitrary values of axial permanent deformations ▫$/epsilon_1^{p*}$▫, gives a failure envelope, and the so called deformation envelopes in the p - q space. The failure envelopes and deformation envelopes are given separately for five types of stone material. The deformation envelopes are low at small values of the axial permanent deformation ▫$/epsilon_1^{p*}$▫ When permanent axial deformations grow, the permanent deformation approaches the failure envelopes. The failure envelopes for individual types of stone material agree with research results performed by [1]. The analysis of permanent deformations also shows their dependence on the portion of crushed material Dcr in the mixture of crushed and uncrushed stone material. The deformation envelope for uncrushed stone material is situated in the lowest position, regarding the portion of crushed material in the mixture. With an increased portion of crushed material in the mixture of crushed and uncrushed stone material, the deformation envelope is also higher, similarly to the lawfulness of failure envelopes. The relation of failure and deformation envelopes is mathematically established as a function of the portion of crushed grains larger than 2 mm. The comparison of stone material results for different water contents shows that a minimal increase of water content above the optimal one essentially increases deformation.Prispevek podaja rezultate analize trajnih deformacij murskih prodov, na podlagi cikličnih triosnih preizkusov, s katerimi je simulirana prometna obtežba. Namen predstavljene analize je podati napoved razvoja normaliziranih osnih trajnih deformacij ▫$/epsilon_1^{p*}$▫ glede na število obtežnih ciklov N in pripadajoče napetostno stanje med cikličnim obremenjevanjem. V analizi so uporabljeni rezultati cikličnih triosnih preizkusov, izvedenih v sklopu raziskovalnega projekta, ki sta ga izvajala ZAG Ljubljana in Fakulteta za gradbeništvo in geodezijo (FGG) Univerze v Ljubljani [1]. Obravnavanih je pet tipov kamnitega materiala, ki so zmesi drobljenega in nedrobljenega murskega proda. Tipi kamnitega materiala so podani glede na količino drobljenih zrn v produ in vlažnost. Štirje tipi kamnitega materiala so zmesi z različnim deležem Dcr drobljenih zrn nad 2 mm (Dcr = 87.7 %, 58.9 %, 32.6 % in 0 %), njihova vlažnost je okoli w = wopt - 2%. Kamniti material Dcr = 58.9 % pa je analiziran še za vlažnost w = wopt + 0.7 %. Rezultat analize so osne trajne deformacije ▫$/epsilon_1^{p*}$▫, ki so izražene kot funkcije števila obtežnih ciklov N, ter sferne komponente ciklične obtežbe p in distorzijske komponente ciklične obtežbe q. Rezultat lahko izrazimo z deformacijskimi ploskvami v ▫$/epsilon_1^{p*}$▫ - p - q prostoru za poljubno število ciklov N. Odnos med sferno in distorzijsko komponento napetosti pri neki vrednosti osne trajne deformacije ▫$/epsilon_1^{p*}$▫, podaja porušno ovojnico in deformacijske ovojnice v p – q prostoru. Porušne ovojnice so mejna stanja možnega razmerja q/p, deformacijske ovojnice pa podajajo razmerja q/p pri neki izbrani velikosti deformacije. Porušne ovojnice in deformacijske ovojnice so podane za vseh pet tipov kamnitega materiala. Porušne ovojnice za posamezne tipe kamnitega materiala se ujemajo z rezultati raziskave, ki sta jo izvajala ZAG in FGG [1]. Deformacijske ovojnice so pri malih vrednostih osne trajne deformacije ▫$/epsilon_1^{p*}$▫ nizke, z večanjem vrednosti osne trajne deformacije pa se približujejo porušnim ovojnicam. Analiza trajnih deformacij murskih prodov je tudi pokazala, da so le te odvisne od deleža drobljenega materiala Dcr v zmesi drobljenega in nedrobljenega kamnitega materiala. Glede na delež drobljenega materiala so deformacijske ovojnice najnižje pri nedrobljenem kamnitem materialu, z večanjem deleža drobljenega materiala v zmesi pa se deformacijske ovojnice višajo, podobna zakonitost velja tudi za porušne ovojnice. Sovisnost porušnih in deformacijskih ovojnic je matematično ovrednotena kot funkcija deleža drobljenih zrn nad 2 mm Dcr. Primerjava deformacij kamnitega materiala različne vlažnosti kaže, da se že z minimalnim povečanjem vlažnosti nad optimalno deformacije bistveno povečajo

Discrete optimization with fuzzy constraints

The primary benefit of fuzzy systems theory is to approximate system behavior where analytic functions or numerical relations do not exist. In this paper, heuristic fuzzy rules were used with the intention of improving the performance of optimization models, introducing experiential rules acquired from experts and utilizing recommendations. The aim of this paper was to define soft constraints using an adaptive network-based fuzzy inference system (ANFIS). This newly-developed soft constraint was applied to discrete optimization for obtaining optimal solutions. Even though the computational model is based on advanced computational technologies including fuzzy logic, neural networks and discrete optimization, it can be used to solve real-world problems of great interest for design engineers. The proposed computational model was used to find the minimum weight solutions for simply-supported laterally-restrained beams

Implementation of climate change effects on slope stability analysis

The objective of this study is to determine the impacts of expected climate change on slope stability. For this purpose, the case study of a slope instability, that was triggered in 2021 was selected. The stability analysis was performed considering the theory of rainfall infiltration and using Geo-Studio’s SEEP/W module for the surface infiltration model of the slope. A parametric stability analysis of the slope was conducted to determine the importance of climate change on slope stability. Conditions for changes in volumetric water content, water permeability, porewater pressure, and groundwater flow are important. When soil permeability is low, the factor of safety decreases during rainfall events and on the days following, while when permeability is higher, safety increases after rainfall events. The effect of lower cohesion is nearly linear, with the factor of safety decreasing by 0.1 for every 1 kPa less cohesion. The increase in net infiltration of water may be the most critical factor for slope instability. The results of the analysis indicate that timely reduction of water net infiltration through planting and proper surface water runoff from the upper road and slope would be a relatively simple and inexpensive measure compared to the cost of remediating the landslide, considering expected climate change. Therefore, it is advisable to analyze all slopes with respect to the expected climate change, taking into account the potential impacts of climate change