18 research outputs found
Experimental and theoretical investigation of deep vibro compaction
No full textDeep vibro compaction (vibroflotation) is a soil improvement technique, which was patented by the company Keller in the 1930s and since then it has been continually developed and has been successfully used worldwide for deep compaction of granular soils. The methods for quality control of the compaction works are largely empirical in nature and therefore often unreliable. In a current research project, fundamental experimental investigations on real‐time quality control for the deep vibro compaction were executed. Large‐scale test measurements and numerical simulations were performed to investigate the three‐dimensional vibrator movement during the compaction process. Reliable measurements with measuring instruments on the vibrator tube during the compaction process have been conducted within the current large‐scale field tests. This paper presents the layout of the large‐scale in‐situ tests, moreover, selected test results are shown, and possible indicators of the changing soil conditions are discussed
Development of condition-based tamping process in railway engineering
No full textBallast, rails and sleepers form an elastic track system. This system is subject to elastic deformation as a consequence of tremendous traffic loadings. When the deformations exceed the elastic limit of the system and the track in no longer laying in its correct geometrical position, precautions, e.g. temporary speed restrictions, have to be taken in order to enable a safe and comfortable travel. Maintaining the track in regular intervals helps restore the initial system geometry, thus preventing possible uneconomical effects. Track maintenance includes levelling, lifting, lining and tamping of the track, hence ensuring rehabilitation of ideal track geometry. This is performed by a tamping machine, with a system of non-synchronous, directional constant pressure tamping, where the tamping tines penetrate the ballast and compact it under the sleeper.
For the purpose of this research project, a tamping machine was equipped with a number of strategically positioned sensors in order to perform the in-situ measurements required to describe the interaction of the tamping tines with the ballast and its compaction beneath the sleeper. With a special emphasis on the energy transferred into the ballast and alteration of ballast stiffness during compaction, conclusions concerning efficiency of the tamping process in different ballast conditions are made, and will be presented in this paper
SELECTION OF DESIGN APPROACH FOR DESIGNING SPREAD FOUNDATONS IN OUR REGION ACCORDING TO EUROCODE 7
No full textAbstract. The existing civil engineering standards for designing are to be replaced with a set of Eurocodes. Eurocode 7 is related to a geotechnical design, but its implementation is difficult, due to different geological, geographical and climate conditions which lead to development of different local designing traditions all over Europe. In order to overcome them, Eurocode 7 offers three design approaches and sets of partial factors to be used within. After accepting it, each country has to declare on the selection of design approach according to which designing is going to be performed and to define appropriate partial factors. This paper presents methodology for selection of appropriate design approach for spread foundations in our region where the process of introduction of Eurocodes is still active. The method based on keeping up with the similar designing procedure may also be used for other geotechnical structures.Key words: Eurocode 7, geotechnical design, design approach, spread foundations
Evolving Asteroid Starships: A bio-inspired approach for interstellar space systems
No full textThe hostile and unpredictable environment of deep space requires a new conceptual approach for interstellar flight, one that differs radically from any current design in aerospace. A design solution is proposed in which the starship is attached to a C-type asteroid and whose architecture evolves over time. The starship gradually mines resources of the asteroid, while at the same time using it as a shielding structure against frontal impacts. The extracted raw materials are used for cultivation of the onboard ecosystem and expansion of the starship's architecture, the latter of which is primarily conducted by mobile 3D printers. Within the bounds of its sensing horizon, the spacecraft can detect prospective high-energy particle collisions and radiation events along its upcoming flight path. Subsequently, the starship will adapt itself by changing its interior and exterior morphology. This constant evolution aims to minimize the spacecraft damage and loss of functionality, and handles the inherent unpredictability of the mission. The Delft University of Technology Starship Team (DSTART) simulates this concept using an array of different techniques. The ecosystem dynamics are approached using agent-based modeling, while the evolving architecture of the starship is approached with genetic algorithms. The starship simulation relies on four distinct timelines. A first timeline provides real-time updates on the state of the starship's regenerative ecosystem, with a focus on population sizes, mass fluxes, and radiation impact. ESA's MELiSSA project was used as a conceptual blueprint for the ecosystem. A second timeline deals with the growth of the starship architecture, taking into account material supplies, mining rates, 3D printing speeds and wear of existing structures. The third timeline forecasts the impact of future particle collisions and interstellar radiation as assessed within the sensing horizon. The fourth and final timeline is concerned with the evolution of the starship architecture as a response to this forecast. This is done by comparing the structural integrity and ecosystem health of different variations of the starship's morphology. The first results of this work will be presented, as well as an overview of the implications for space system design.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.System Engineerin
Calibration of the rutting model in HDM 4 on the highway network in Macedonia
No full textThe World Bank HDM 4 model is adopted in many countries worldwide. It is consisted of the developed models for almost all types of deformation on the pavement structures, but it can’t be used as it is developed everywhere in the world without proper adjustments to local conditions such as traffic load, climate, construction specificities, maintenance level etc. This paper presents the results of the researches carried out in Macedonia for determining calibration coefficient of the rutting model in HDM 4
Environmental and stability aspects of excavation in landslide zone at a coal mine "Suvodol" - R.Macedonia
No full textOn a NE part of coal mine "Suvodol", near town Bitola in R.Macedonia, during longer time, a landslide with enormous length and volume exists. Its occurrence is connected with a process of sliding, which happened in several phases, with initial signs of sliding in 1993. The moment of global instability happened on a 27.10.1995. Till now, several phases of reactivation are known. Its volume is about 30 000 000 m3. As a result of mass movements, about 8 000 000 tones of coal is concentrated (blocked) at the toe of the landslide. Upper of the main scarp, spaced about 250
meters, the earth-fill dam with a length of about 1000 meters exists. The ground water artesian effects are also present. At the toe of the landslide, the coal is partially involved in a process of selfburning
and it produces environmental not friendly gases. The stability of the sliding during 2007 was near limit equilibrium. All this aspects shows a very specific combination of natural and manmade elements that control the stability of the environment at this part of coal mine. Having this in mind, the specific approach used in an excavation at the toe of sliding mass, with parallel
supporting (always near limit equilibrium) is shown briefly. The results from the stability tests, with some specific comments, are summarized in this paper
Calibration of the rutting model in HDM 4 on the highway network in Macedonia
No full textThe World Bank HDM 4 model is adopted in many countries worldwide. It is consisted of the developed models for almost all types of deformation on the pavement structures, but it can’t be used as it is developed everywhere in the world without proper adjustments to local conditions such as traffic load, climate, construction specificities, maintenance level etc. This paper presents the results of the researches carried out in Macedonia for determining calibration coefficient of the rutting model in HDM 4.</jats:p
Composite Power System Reliability with Renewables and Customer Flexibility
No full textComposite Power System Reliability is defined as the computational procedure that quantifies the probability that the power system will perform the function of delivering electric power to customers adequately, on a continuous basis and with an acceptable quality. This definition leaves many details undefined and exemplifies the ambiguity in reliability analysis. The increasing deployment of wind and PV creates additional uncertainties that make reliability analysis a rather complex issue. Because of increased uncertainty the need for composite reliability analysis and utilization of results in power system planning is critical. New approaches are emerging for dealing with these problems from the operational point of view, including demand response programs, tapping on customer and distributed resource flexibility and new control approaches. The key question to be addressed is: how the new operational paradigms affect composite power system reliability. This paper presents the ongoing work of the IEEE Composite System Reliability Task Force of the IEEE PES Reliability, Risk, Probability Application (RRPA) Subcommittee.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Intelligent Electrical Power Grid
Stability Aspects of Excavations in Landslide Zone for a Coal mine “Suvodol” - R.Macedonia
No full textThe paper presents some elements of stability aspects and approach used for
excavation at the toe of the large landslide which exists on a NE part of coal mine "Suvodol" in R.Macedonia. Its volume is about 30,000,000 m3. Upper of the main scarp, the earth-fill dam with a length of about 1000 meters exists. As a result of mass movements, about 8,000,000 tonnes of coal is blocked at the toe of the landslide. After a longer time of exposition to the air, the crushed coal is partially involved in a process of self-burning. Specific combination of natural and man-made elements that control the stability of the area and specific methodology used for an excavation at the toe of sliding mass is shortly explained. The results from the stability analyses, risks scenarios, some specific comments and recommendations, are summarized in this paper. Some specific comments are also given
