NOSIVE PLATFORME ZA PRIJENOS OPTEREĆENJA : USPOREDBA PRORAČUNSKIH METODA

Constructing embankments on compressible foundation soil normally requires soil improvement measures to reduce the amount and duration of settlement. In the most difficult cases, the soil is improved by using pile foundations. When constructing pile foundations, it is necessary to ensure efficient load transfer from the embankment to the piles, which can be achieved using reinforced soil construction with geosynthetics as reinforcement material. In this paper, we compare the calculations of a bearing capacity of such a platform according to the British and the German standards on the example of a level crossing over a railway line. We describe other calculation methods, critically reviewing the fundamental mechanisms of the reinforcement effects in the calculations.Izvedba nasipa na stišljivom temeljnom tlu redovito zahtijeva mjere poboljšanja temeljnog tla kako bi se smanjio iznos i vrijeme slijeganja. Rješenje najtežih slučajeva postiže se upotrebom pilota. U slučaju izvedbe pilota potrebno je osigurati djelotvoran prijenos opterećenja od nasipa na pilote, što se može postići izvedbom platforme od armiranog tla koristeći geosintetike kao armaturu. U radu je prikazan proračun nosivosti ovakvih platformi i usporedba rezultata proračuna po dva standarda: britanskom i njemačkom, na primjeru cestovnog prijelaza preko željezničke pruge. Opisane su i ostale metode proračuna, uz kritički osvrt na način na koji se bitna svojstava korištene armature uvažavaju u proračunu

Vukovar High School Building – investigations and monitoring of a complex geotechnical problem

Na zgradi vukovarske gimnazije, saniranoj od ratnih oštećenja tijekom Domovinskog rata, nedugo nakon početka uporabe počele su se primjećivati pukotine te uočavati znakovi slijeganja temelja. Zgrada koja je tlocrtno razvedena nalazi se na lesnom platou. U podnožju platoa postoje nepodgrađeni “podrumi” kojima su se svodovi počeli zarušavati, što se povezuje s provlaživanjem uslijed neadekvatne površinske odvodnje. Uz lesni plato dijelom su izvedeni stari obložni zidovi od opeke, a dijelom novi potporno-obložni zidovi, dio kojih ima značajke gravitacijskih zidova. Pri gradnji jedne dionice takvog potpornog zida blizu ruba gimnazijske zgrade došlo je do klizanja dijela pokosa u njegovoj pozadini, što je tada sanirano. Navedeni problemi, a posebice problem slijeganja, bili su povod za sanaciju temeljenja najviše oštećenog dijela zgrade, te je 2008. godine ona provedena izvedbom mlazno injektiranih pilota. Pri definiranju uzroka i opsega oštećenja građevine, ali i za ocjenu uspješnosti sanacije, više puta obavljani su geotehnički istražni radovi te mjerenja i opažanja na zgradi i okolišu, što je opisano u okviru ovoga rada.The Vukovar High School building, repaired following war destructions during Homeland War, started to show cracks and signs of foundation settlement already after a short period of use. The building, widely spread and indented in plan, lies on a loess soil plateau. At the bottom of the plateau there are unlined “basements“ whose vaults have started to collapse as a result of moisture due to inadequate surface drainage. Old brick lining walls and new lining and retaining walls, some having properties of gravity walls, actually border on the loess plateau. During construction of one part of such retaining walls, near the high school building, a part of slope was affected by sliding, which was subsequently remedied. All these problems, and the settlement problem in particular, have led to the remedy of foundations at the most damaged part of the building. Thus, in 2008, the remedial work was made by jet-grouted piles. Soil investigation works, measurements and monitoring activities were conducted on several occasions in order to find the causes and the extent of damage to the building, and also to confirm the success of repair activities, as described in the paper

CONSTRUCTED WETLANDS FOR WASTEWATER TREATMENT

Otpadne vode se moraju pročistiti prije ispuštanja u recipijent. Jedan od načina pročišćavanja otpadnih voda je pročišćavanje biljnim uređajima. Biljni uređaji su kompleksni biološki sustavi koji oponašaju procese u prirodi. Jednostavan su, prihvatljiv i ekonomski opravdan način zaštite voda. U radu su opisani biljni uređaji (umjetne močvare) kroz vrste uređaja, njihove prednosti i nedostatke, osnove projektiranja i hidraulički proračun. Posebno je analiziran biljni uređaj Vinogradci.Waste water must be treated prior to discharge into the recipient. One way of treating waste water is constructed wetland for wastewater treatment. Constructed wetlands are complex biological systems that mimic the processes in nature. These systems are simple, acceptable and economically feasible way of water protection. This paper describes the constructed wetlands through device types, their advantages and disadvantages, the basics of design and hydraulics. Especially analyzed constructed wetland Vinogradci

Testing noncohesive geogrid-reinforced soil in triaxial shear apparatus under cyclic loading

U nosivim slojevima kolničke konstrukcije geomreže imaju funkcije ojačanja ili stabilizacije, pri čemu je važna dobra interakcija geomreže i nekoherentnog materijala nosivog sloja. Za ispitivanje interakcije geomreže i materijala nosivih slojeva kolničkih konstrukcija može se primijeniti pokus cikličkim troosnim posmikom. Rad obuhvaća pregled istraživanja primjene cikličkog troosnog posmika posebice tijekom ocjenjivanja utjecaja parametara kao što su krutost, geometrija i veličina otvora, položaj i broj slojeva geomreže na interakciju s materijalom nosivog sloja. Ocjenjuje se da se cikličkim troosnim posmikom može utvrditi doprinos primjene geomreža u nekoherentnim materijalima u vidu smanjenja trajnih deformacija.In road base layers, geogrids assume the reinforcement or stabilization function where good interaction between geogrid and unbound base material is important. The cyclic triaxial test can be used for analysing interaction between geogrid and unbound base material. The paper includes an overview of research where cyclic triaxial test is primarily used for assessing the influence of parameters such as geogrid stiffness, geometry and aperture size, position and number of geogrid layers, on the interaction with the base layer material. The cyclic triaxial test can be used to determine contribution the geogrid application in non-cohesive materials has on the reduction of permanent deformations.In den tragenden Schichten haben die Fahrbahnstrukturen des Geogitters die Funktion der Bewehrung oder Stabilisierung, wobei ein gutes Zusammenspiel des Geogitters und des inkohärenten Materials der tragenden Schicht wichtig ist. Um die Wechselwirkung des Geogitters und des Materials der tragenden Schichten von Fahrbahnstrukturen zu testen, kann ein zyklisches Dreiachsen-Scherexperiment angewendet werden. Diese Arbeit enthält einen Überblick über die Forschung zur Anwendung der zyklischen dreiachsige Scherung, insbesondere während der Bewertung des Einflusses von Parametern wie Steifheit, Geometrie und Größe der Öffnungen, Position und Anzahl der Geogitterschichten auf die Wechselwirkung mit dem Lagerschichtmaterial. Es wird geschätzt, dass der Beitrag der Anwendung von Geogittern in inkohärenten Materialien in Form einer Verringerung dauerhafter Verformungen durch zyklische dreiachsige Scherung bestimmt werden kann

Shear Strength of Reproduced Soil Mixtures Based on Samples from Rammed Earth Walls from Eastern Croatia

Earthen architecture largely supports the concept of sustainable building. In the seismically active area of eastern Croatia, there is a large number of rammed earth houses, many of which are over 100 years old. All these houses were built using empirical knowledge, i.e., without applying national design standards. In order to support the preservation of ethnic villages and traditional rammed earth houses, a field survey was conducted. Parts of the walls of traditional rammed earth houses were collected, and the material was thoroughly analyzed. Samples of rammed earth were reproduced, and tests were carried out with the aim of determining the shear strength to subsequently determine the seismic behavior of Croatian traditional earthen architecture. This paper presents the results of shear strength tests on samples with different particle size distributions, lime content, the straw of different cereals but also hemp fibers. An increase in shear strength was observed with the addition of natural fibers to the samples

Shear Strength of Reproduced Soil Mixtures Based on Samples from Rammed Earth Walls from Eastern Croatia

Earthen architecture largely supports the concept of sustainable building. In the seismically active area of eastern Croatia, there is a large number of rammed earth houses, many of which are over 100 years old. All these houses were built using empirical knowledge, i.e., without applying national design standards. In order to support the preservation of ethnic villages and traditional rammed earth houses, a field survey was conducted. Parts of the walls of traditional rammed earth houses were collected, and the material was thoroughly analyzed. Samples of rammed earth were reproduced, and tests were carried out with the aim of determining the shear strength to subsequently determine the seismic behavior of Croatian traditional earthen architecture. This paper presents the results of shear strength tests on samples with different particle size distributions, lime content, the straw of different cereals but also hemp fibers. An increase in shear strength was observed with the addition of natural fibers to the samples