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Rohner R.,TUV Rheinland LGA Bautechnik GmbH | Hoch A.,TUV Rheinland LGA Bautechnik GmbH
Tunnelling and Underground Space Technology | Year: 2010

The development of new production techniques in pipe jacking were the inducement for the improvements of the ATV A-161 (2008). In parallel a new version of the ATV A-125 (2007) came out including the calculation of steerable and non-steerable pipe jacking. The new concept of partial safety factors was also a reason for the revision of the ATV A-161 (2008).One of the modifications and additional topics in the new ATV A-161 (2008) are new materials. The new ATV A-161 (2008) deals also with thermosetting materials like fibre reinforced plastics, and thermoplastics. It is planned that all codes of the ATV will use the same material parameters.Furthermore the standard design loads which occur by using technologies of steerable and non-steerable pipe jacking which are given in ATV A-125 (2007) are described in detail.The theory of silo (diminishment of vertical earth pressure because of arching effects) is used and soil density and consistency are taken into account by the parameters of soil mechanics K (earth pressure coefficient), δ (wall friction angle) and c (cohesion).The new ATV A-161 (2008) gives limiting values for the ratio of wall thickness to radius and includes the calculation of curves and angular deviation due to open loop control, planned bending and angular deviation from production tolerances. The pressure transmitting elements are taken into account. In addition the proofs of stability in axial and longitudinal direction are simplified. For anisotropic materials the effective stresses are verified. The design tables for steel pipes are dropped and for certain boundary conditions the proof of dynamic fatigue for steel pipes can be omitted.The term of this paper is to show the calculation of the forces in longitudinal direction (allowable jacking force) for compression closure pipe connections from new ATV A-161. The structural analysis in axial direction is not performed in this article. © 2009 Elsevier Ltd.

In this contribution, the scientific background of the bearing capacity of the sand-steel interface and of the plastic stress-strain-behaviour of sand soils under cyclic loading is firstly described. Upon this, a nonlinear calculation approach is formulated and implemented by using numerical method for predicting the bearing capacity degradation of driven steel piles in sandy subsoil under cyclic-axial loading condition. In this procedure, three controlling factors namely slip on pile-sand-interface, accumulation of plastic shear strain and the decrease in lateral effective stress of surrounding sand soils are taken into consideration. With the help of a model test reported in literature, the applicability of the developed calculation approach is checked. © 2013 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.

Zenk C.H.,Friedrich - Alexander - University, Erlangen - Nuremberg | Bauer A.,Friedrich - Alexander - University, Erlangen - Nuremberg | Bauer A.,TUV Rheinland LGA Bautechnik GmbH | Goik P.,Friedrich - Alexander - University, Erlangen - Nuremberg | And 3 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2016

The quaternary alloy system Co-Al-W-Ge was investigated and it was found that a continuous (Formula presented.) two-phase field extends between the systems Co-Al-W and Co-Ge-W. All alloys examined comprised cuboidal L1(Formula presented.) precipitates coherently embedded in an A1 matrix. Differential scanning calorimetry measurements revealed that the liquidus, solidus, and (Formula presented.)-solvus temperatures decrease when the Ge content is increased. The lower liquidus temperature and the capability of (Formula presented.)-strengthening in the Ge-rich alloys make them interesting as potential candidates for brazing applications of Co-base superalloys. The (Formula presented.) lattice misfit was determined by high-resolution X-ray diffraction and found to be positive for all alloys investigated, decreasing with increasing Ge content.The mechanical properties of the Al-rich alloys surpass those rich in Ge. © 2016 The Minerals, Metals & Materials Society and ASM International

Henken-Mellies W.-U.,TUV Rheinland LGA Bautechnik GmbH | Schweizer A.,Bavarian Environment Agency
Waste Management and Research | Year: 2011

A comprehensive study was conducted to examine the performance and possible changes in the effectiveness of landfill surface covers. Three different profiles of mineral landfill caps were examined. The results of precipitation and flow measurements show distinct seasonal differences which are typical for middle-European climatic conditions. In the case of the simple landfill cap design consisting of a thick layer of loamy sand, approximately 100-200 L m -2 of annual seepage into the landfill body occurs during winter season. The three-layer systems of the two other test fields performed much better. Most of the water which percolated through the top soil profile drained sideways in the drainage layer. Only 1-3% of precipitation percolated through the sealing layer. The long-term effectiveness of the mineral sealing layer depended on the ability of the top soil layer to protect it from critical loss of soil water/critical increase of suction. In dry summers there was even a loss in soil water content at the base of the 2.0 m thick soil cover. The results of this study demonstrate the importance of the long-term aspect when assessing the effectiveness of landfill covers: The hydraulic conductivity at the time of construction gives only an initial (minimum) value. The hydraulic conductivity of the compacted clay layer or of the geosynthetic clay liner may increase substantially, if there is no long-lasting protection against desiccation (by a thick soil cover or by a geomembrane). This has to be taken into account in landfill cover design. © The Author(s) 2011.

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