Rolf Katzenbach

Rapid flow of dry granular materials down inclined chutes impinging on rigid walls

We performed laboratory experiments of dry granular chute flows impinging an obstructing wall. The chute consists of a 10cm wide rectangular channel, inclined by 50° relative to the horizontal, which, 2m downslope abruptly changes into a horizontal channel of the same width. 15l of quartz chips are released through a gate with the same width as the chute and a gap of 6cm height, respectively. Experiments are conducted for two positions of the obstructing wall, (i) 2m below the exit gate and perpendicular to the inclined chute, and (ii) 0.63m into the horizontal runout and then vertically oriented. Granular material is continuously released by opening the shutter of the silo. The material then moves rapidly down the chute and impinges on the obstructing wall. This leads to a sudden change in the flow regime from a fast moving supercritical thin layer to a stagnant thick heap with variable thickness and a surface dictated by the angle of repose typical for the material. We conducted particle image velocimet...

Avalanching granular flows down curved and twisted channels: Theoretical and experimental results

Depth evolution and final deposits play a crucial role in the description of the dynamics of granular avalanches. This paper presents new and important results on the geometric deformation and measurements of avalanche depositions in laboratory granular flows and their comparisons with theoretical predictions through some benchmark problems for flows down curved and twisted channels merging into a horizontal plane. XY-table and analoglaser sensor are applied to measure geometries of deposited masses in the fanlike open transition and runout zones for different granular materials, different channel lengths, and different channel mouths in the runout zone. The model equations proposed by Pudasaini and Hutter [“Rapid shear flows of dry granular masses down curved and twisted channels,” J. Fluid Mech. 495, 193 (2003)] are used for theoretical prediction. We show that geometric parameters such as curvature, twist and local details of the channel play a crucial role in the description of avalanching debris and ...

The influence of capillarity on multiphase flow within porous media: a new model for interpreting fluid levels in groundwater monitoring wells in dynamic aquifers

A new approach is presented to calculate the volume of oil in the underground at an oil spill site from fluid levels in monitoring wells. The approach includes the effects of hysteresis due to irregular pore geometry and to phase entrapment. It is possible to explain the drastic changes in the oil thickness in a monitoring well due to the decrease and increase in the groundwater table. A correct evaluation of the oil volume infiltrated underground from an oil spill and the effective control of remediation works can only be done by using the newly developed approach with a consideration of the dynamic changes in the groundwater table.

Advanced New Methodology for the Identification of Stiffness and Strength of Weak Rock as Basis for Economic Foundation Design

The most important aspects for the design of any foundation system are safety, optimisation and the sustainability. An optimised and safe design of foundation systems for high-rise structures in difficult soil and groundwater conditions is based on a reduction of construction material used, construction time spent, energy consumed and the adequate consideration of the soil-structure interaction. This is also important for the high-rise structures like skyscrapers and bridge piers in weak rock like in Dubai, UAE. Due to the large loads most of these structures are founded in the Dubai Sandstone and Dubai Siltstone. Up to now the rock mechanical parameters for these rock layers have been defined on the very conservative side which led to over-dimensioned foundations in many cases. In a large research program the bearing behaviour of Dubai Sandstone and Dubai Siltstone has been investigated by field and laboratory tests, by in-situ pile load tests and the numerical back-analysis using the Finite-Element-Method (FEM). The comprehensive research investigations show, that the stiffness of Dubai Sandstone and Dubai Siltstone is more than 20 times higher as it is assumed up to now. The paper presents the scope of research, the epoch-making results and the significance for the engineering practice.

Potentials of sustainable energy management in buildings

How to achieve an efficient energy use and sustainable resource management has become more active than it has been before. This paper aims to shed light on the current situation of energy consumption patterns in residential buildings, above of all, in social housing buildings in Germany, and discusses the potential of energy conservation and resource management in building systems with respect to the risks and benefits for different stakeholders being involved in building operation and maintenance as well as building occupation. Strategies for a sustainable development in building systems are to be introduced based on a comprehensive consideration including analysis on technical improvement in building construction with the benefit of Retro-commissioning methodology, the economic assessment like cost-benefit-analysis as well with consideration of environmental impacts. As a conclusion this paper suggests a systematic approach which aims to optimize the residential building energy operation with a sustainable way.

Prozessorientierte Vernetzung von Ingenieurplanungen am Beispiel der Geotechnik

Im Rahmen der Fachplanung von Projekten im Bauwesen ist ein hohes Mas an Kooperation zwischen den Planungsbeteiligten notwendig. Dies resultiert aus der fall- und projektbezogenen Arbeitsteilung zwischen den Planern, wobei der einzelne Fachplaner oft nicht in der Lage ist, die Auswirkung seiner Planungsent-scheidungen in den Kontext der Gesamtplanung einordnen zu konnen, da ihm der vollstandige Uberblick uber die Zusammenhange der Planungsprozesse fehlt.