Böschungs‐, Ufer‐ und Sohlsicherungen aus Naturstein erfreuen sich als naturnahe konstruktive Maßnahmen zunehmender Beliebtheit. Hinsichtlich ihrer Wirkungsweise können Steinkonstruktionen ...unterschieden werden in (1) solche mit stützender Wirkung, welche durch Schlichten oder Setzen errichtet werden, und in (2) Steinkörper und Berollungen, deren Herstellung durch Schütten oder Werfen erfolgt und die rein durch ein Beschweren der Böschung wirken. Bei Steinstützkörpern handelt es sich generell um vergleichsweise flexible Konstruktionen, die Verformungen im Dezimeterbereich aufnehmen können. Dabei erfolgt die Kraftübertragung im unvermörtelten Zustand von Stein zu Stein bzw. bei Versetzen der Steine im Mörtelbett über die Mörtelfuge. Durch die Reibung bzw. Reibungskraft zwischen den Steinen bzw. Mörtel und Stein können Schubkräfte übertragen bzw. aufgenommen werden, die bspw. einem auftretenden Erddruck entgegenwirken.
Für Steinstützkörper gibt es bislang einige bestehende Ansätze für deren Bemessung, es wird jedoch nicht spezifisch auf den Nachweis der inneren Standsicherheit (Gleiten und Kippen in der Lagerfuge, mechanisches Steinversagen) eingegangen. Bei gegenständlichem Forschungsvorhaben wird versucht, Kennwerte für die Bemessung von Steinstützkörpern experimentell zu erfassen, um in einem nächsten Schritt Rückschlüsse auf die innere Standsicherheit von Steinstützkörpern ziehen zu können.
Experimental determination of friction coefficients in the context of natural stone structures
Protection constructions for slopes, banks and riverbeds using natural stones are becoming increasingly popular. When considering their operating principle, (1) natural stone structures with a supporting effect and (2) stone structures, that function solely by their weight, can be distinguished. The former is erected by exact placement of the individual stones, while weight effects can also be achieved by a thrown or dumped stone mass. Nevertheless, natural stone structures show a comparatively flexible design that can endure displacements in the order of some decimeters. Transmission of forces takes place stone to stone in case of non‐mortared construction or via mortar material in case of mortared joints. Friction forces are transferred accordingly between the rocks or rock and mortar and can counteract possibly occurring earth pressure.
There are a few approaches concerning structural design and dimensioning of natural stone structures, specific static analysis and calculations regarding the inner stability (sliding and toppling in the horizontal joint as well as mechanical rock failure) of these structures are missing. In this research project, attempts are made to experimentally deduce characteristic values for the design of natural rock structures and drawing conclusions about the inner stability of rock protection structures in a subsequent step.
Introduction. Existing automated construction inspection technologies do not allow the user to select the level of detail. At the same time, in the context of the use of nanotechnology, there is a ...growing need to expand the capabilities of monitoring and control of construction projects. The aim of the research is to develop, implement software, and validate a technology for controlling the speed and accuracy of constructing three-dimensional models from dense point clouds for automated monitoring of construction works. Materials and methods. The research is based on the methodology of non-binary data trees, including the method of constructing octant trees. An unmanned aerial vehicle with an aerial laser scanner, a ground-based scanning total station, and specialized software were used, including the web application "Management System for Monitoring Construction Works on Objects that have undergone state expertise" developed with the participation of the authors. Results and discussion. In the course of the study, a technology was developed and implemented in software that allows the user to select the required balance between accuracy, degree of detail of monitoring and control data for construction work and time costs and computing power requirements. The comparison is made between a construction project, presented in the form of a building information model, and a three-dimensional model of a real object, obtained from a dense point cloud. The degree of comparison accuracy is set by choosing the level of octrees used. By default, the web application uses level eight. However, in the early stages of construction, when the geometric parameters of a dense point cloud deviate significantly from the design boundaries, the ninth, tenth and other levels can be used. In this case, the accuracy and degree of detail increases. Positive and negative deviations are visualized in red and blue colors, respectively, which allows the user to monitor and control the progress of work at the site. Conclusions. The developed technology can be used by customers and other decision makers to control and monitor work.
Opportunities of storing energy recovered from an electro-hydraulic forklift truck are studied. The lifting system is controlled directly with an electric servo motor drive and a hydraulic pump ...capable of operating also as a hydraulic motor during potential energy recovery. The paper describes some of the energy storage devices available, and the analysis results for the proposed systems are compared from the energy efficiency point of view.
► Effect of energy storage on reuse of energy recovered from a forklift was studied. ► Energy storage was evaluated from an energy point of view. ► The maximum value of 54% from recovered energy can be reused.
The 13.35 km long Wienerwald (Vienna Woods) Tunnel forms a key element of the new railway line between Vienna and St. Pölten. The 11 km long twin‐tube western section of the tunnel was constructed ...using two tunnel boring machines, type TBM‐S, with an excavation diameter of approximately 10.7 m, and a water pressure‐relieved, double shell lining system. A Swiss unsealed, stacked segment lining system was used. In the year 2000, a TBM with these dimensions represented new territory for ÖBB‐Infrastructure AG, so intensive investigations of the technology were undertaken from the feasibility study and permit application phases onwards. Risk analyses in respect of geotechnical engineering, TBM design and segmental tunnel lining, cross‐checking of the construction schedule and costs that were estimated during the tender phases were undertaken. Together with a comprehensive and thorough investigation, this led the client to the conclusion that the tunnelling work in the western section should be tendered with two alternatives (conventional tunnelling and TBM drive). Appropriate tender evaluation criteria allowed an objective comparison of the submitted tenders to be made and resulted in an unproblematic contract with the western section being awarded for the TBM system. The expectations of the client and the contractor with regard to geology and geotechnics, construction schedule and construction process are described. Deviations from these expectations and the actual technical and construction difficulties encountered are explained, along with the corresponding solutions that were used to overcome these problems.
Der 13,35 km lange Wienerwaldtunnel stellt das Kernstück der Neubaustrecke Wien‐St. Pölten dar. Der zweiröhrige Westabschnitt des Tunnels wurde über eine Länge von rd. 11 km mit zwei Tunnelbohrmaschinen TBM‐S, Ausbruchsdurchmesser rd. 10,7 m und druckwasserentlastetem, zweischaligen Ausbau hergestellt. Als Tübbingsystem wurde ein ungedichteter Schweizer Stapeltübbing gewählt. TBM‐Vortriebe in dieser Dimension waren Anfang 2000 für die ÖBB‐Infrastruktur AG Neuland, und so befasste sie sich schon bei den Machbarkeitsstudien und den behördlichen Einreichungen intensiv mit dieser Technologie. Risikoanalysen zu Geotechnik, Maschinentechnik, Tübbingausbau, Bauzeit und Kosten in den Phasen Einreichung und Ausschreibung sowie eine umfangreiche Erkundungskampagne ließen den Auftraggeber zu dem Schluss kommen, die Vortriebsarbeiten im Westabschnitt in zwei Varianten (zyklisch und TBM‐Vortrieb) auszuschreiben. Entsprechend gewählte Zuschlagskriterien ermöglichten einen objektiven Vergleich der Angebote und eine einspruchsfreie Vergabe des Westabschnitts zugunsten der Variante mit TBM‐Vortrieben. Die Erwartungen des Auftraggebers (AG) und des Auftragnehmers (AN) werden hinsichtlich Geologie und Geotechnik, Bauzeit und Bauablauf sowie Vertragsabwicklung dargelegt. Die Abweichungen und tatsächlich aufgetretenen, technischen und bauwirtschaftlichen Schwierigkeiten sowie deren Lösungen werden erläutert.
As part of the Qatar National Vision 2030, the capital of Qatar – Doha – is being expanded into a modern centre for economy, trade and sport. A main part of this plan is the establishment of an ...efficient infrastructure with modern means of transportation.
The Design & Build – Project Green Line Underground was awarded to a Joint Venture (JV) composed of PORR (lead), the Saudi BinLadin Group and the local construction company HBK in summer 2013. It contains the turnkey construction of the underground part of the Green Line with a total length of 2 × 17 km tunnel, six stations, switching areas as well as cross passages and emergency exit shafts. The 34 km of tunnelling, bored by six EPB machines simultaneously, has now been completed. The expectations for the project, especially concerning the TBM tunnelling, are compared to the knowledge gained.
The following topics are highlighted:
– climate and culture,
– personnel of different origins/education,
– working with unskilled/semiskilled workers,
– TBM/logistic concepts,
– performance, wear and tear,
– geological conditions,
– segment design,
– health and safety.
The tunnel drives were completed in 18 months despite all challenges.
Im Rahmen der Qatar National Vision 2030 wird die Hauptstadt Katars – Doha – zu einem modernen Zentrum für Wirtschaft, Handel und Sport ausgebaut. Ein wesentlicher Bestandteil zur Realisierung dieses Ziels ist die Errichtung einer leistungsfähigen Infrastruktur mit modernen Massentransportmitteln.
Das Design & Build‐Projekt Green Line Underground wurde im Sommer 2013 an ein Joint Venture (JV) aus Porr (Federführung), der Saudi BinLadin Group und dem lokalen Bauunternehmen HBK vergeben und beinhaltet die schlüsselfertige Errichtung des unterirdischen Abschnitts der Green Line mit einer Tunnellänge von 2 × 17 km, sechs Stationen, Spurwechsel‐ und Weichenanlagen sowie Querschlägen und Notausstiegsschächten. Die Vortriebe der ca. 34 km langen Tunnel, die mit sechs EPB‐Maschinen hergestellt wurden, sind mittlerweile abgeschlossen. In einem Rückblick werden die Erwartungen an das Projekt, insbesondere an den TVM‐Vortrieb, mit den gemachten Erfahrungen verglichen.
Hier werden speziell folgende Themen beleuchtet:
– klimatisches und kulturelles Umfeld,
– Personal unterschiedlichster Herkunft und Bildung,
– Arbeiten mit ungelerntem/angelerntem Personal,
– Vortriebs‐ und Logistikkonzepte,
– Leistungen, Verschleiß, Schäden,
– geologische Verhältnisse, Vorauserkundung,
– technische Ausführung der Tübbinge, inkl. Dichtung,
– Arbeitssicherheit, Gesundheitsschutz.
Trotz aller Herausforderungen konnten die Vortriebsarbeiten in ca. 18 Monaten abgeschlossen werden.
The implementation of construction projects is fraught with many hazards that are difficult to determine at the stage of the tender procedure. Usually, the identification of these hazards rests with ...the contractors. In many cases this diagnosis is not used due to the lack of access to reliable data and easy-to-use computer programs supporting the risk analysis process.
In order to facilitate the analysis and risk assessment on Polish railway investments, the authors present a proposal for the assessment of potential hazards that may occur during the implementation of these investments with the use of their point assessment. The proposed method is an original attempt to apply a point assessment of risk factors, whose final result is ready investment risk assessment matrices at the design and execution stage of constructionworks. The basis for the development of matrices was questionnaire surveys involving a large group of experts with extensive professional experience. In addition, the project manager can set the partial weights of hazards separately for time and cost hazards depending on the assessment of the planned project. In order to quickly calculate the weights of individual risk factors for any defined time and cost of partial weights, the authors developed the proposed matrices in the form of a calculation sheet. The matrices can be used to assess potential hazards to future infrastructure investments.
► New testing system for tool wear of soft ground shield TBMs has been introduced. ► The procedure for performing the Penn state soil abrasion test has been introduced. ► The initial results related ...to this testing device have been reported.
Primary and secondary wear in soft ground tunneling using various types of shields has a major impact on machine operation, utilization, and tunneling costs. Wear occurs due to interaction between abrasive soils and cutters, as well as other components of the machine which come to contact with the muck. However, lack of a standard or universally accepted test for soil abrasivity in the geotechnical investigations has made the prediction of tool wear a difficult task. This paper introduces a new test device, designed to measure soil abrasion and the result of initial testing at the Pennsylvania State University. The testing system is configured to simulate the working condition of the cutting tools in excavation chamber of pressurized face shields. This includes the high contact stresses between the tool and the soil, maintaining the original soil size distribution, field moisture conditions, and possibility of applying high ambient pressures as well as soil conditioners. The preliminary results of testing on several soil types, moisture conditions, and various tool hardness is presented. The test set up is discussed to provide more detailed information on the testing conditions and potential implications in practical applications.
Open Channel Hydraulics is written for undergraduate and graduate civil engineering students, and practicing engineers.Written in clear and simple language, it introduces and explains all the main ...topics required for courses on open channel flows, using numerous worked examples to illustrate the key points.With coverage of both introduction to flows, practical guidance to the design of open channels, and more advanced topics such as bridge hydraulics and the problem of scour, Professor Akan's book offers an unparalleled user- friendly study of this important subject·Clear and simple style suited for undergraduates and graduates alike ·Many solved problems and worked examples ·Practical and accessible guide to key aspects of open channel flow
AbstractOne-fourth of construction industry fatalities are caused by worker collisions with construction equipment. Nonvisible areas (blind spots) for equipment operators are contributing factors to ...many of these fatalities because equipment operators are unable to see ground personnel at certain locations around their equipment. Presented are the design and validation of a unique technique for measuring blind spots by using laser scanning data. The work demonstrates how the design of construction equipment impacts the visibility of its operator. The contribution of the developed technique to the body of knowledge is that it can precisely evaluate and compare different equipment models and design characteristics. The blind spot measurement data for several similar pieces of equipment provides design suggestions that increase operator visibility. By increasing operator visibility through advanced equipment design, safety can be promoted on construction sites and in any other work environment, particularly with nearby ground workforce equipment.
Kombinierte Spundwände aus Trag‐ und Zwischenbohlen sind eine langjährig bewährte Lösung und werden dann eingesetzt, wenn die Tragfähigkeit oder die Steifigkeit von Wellenspundwänden nicht mehr ...ausreicht. Die Verbindung zwischen Trag‐ und Zwischenbohlen erfolgt über die Spundwandschlösser. Während des Einbringens der Zwischenbohlen kann es zu einem Herauslaufen oder einem Blockieren des verbindenden Spundwandschlosses kommen. Diese sog. Schlosssprengungen sind umgehend zu sanieren, um Erosion des anstehenden Bodens und somit Versackungen hinter der Wand zu verhindern. Im folgenden Beitrag werden mögliche Ursachen für Schlosssprengungen aufgeführt und evaluiert. Die Untersuchungen umfassen neben einer Fallstudie zu ausgeführten kombinierten Spundwänden Labor‐ und Feldversuche, die in Verbindung mit Finite‐Elemente‐Berechnungen die mechanischen und mechanisch‐thermischen Prozesse im Schloss während der Einbringung betrachten. Zur Vermeidung von Schlosssprengungen bei kombinierten Spundwänden werden Lösungsaspekte im Rahmen der Planung, der Herstellung und der Ausführung vorgestellt. Dies erfolgt in Ergänzung zu den bestehenden Empfehlungen des Arbeitsausschusses Ufereinfassungen (EAU).
Interlock declutchings of combined sheet pile walls
Combined sheet pile walls are consisting of king and intermediate piles and are used when the load‐bearing capacity or the rigidity of usual sheet pile walls is no longer sufficient. The connection between the king and intermediate piles is assured by interlocks. During installation of the intermediate piles, the connecting interlock may open or block. These so‐called interlock declutchings are to be repaired immediately to prevent the soil from eroding and causing subsidence behind the wall. In this article the causes for interlock declutchings are evaluated. The investigations include a case study as well as various laboratory and field tests which, in conjunction with finite element calculations, consider the mechanical and mechanical‐thermal processes in the interlock during installation. In order to avoid interlock declutchings in combined sheet pile walls, recommendations are derived in the context of planning, production, installation and monitoring. This is done in addition to the existing recommendations of the Working Committee for Waterfront Structures (EAU).
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