Bugnion L.,Swiss Federal Institute of forest |
McArdell B.W.,Swiss Federal Institute of forest |
Bartelt P.,Swiss Federal Institute of forest |
Wendeler C.,Geobrugg AG
Landslides | Year: 2012
We present measurements of hillslope debris flow impact pressures on small obstacles. Two impact sensors have been installed in a real-scale experimental site where 50 m 3 of water-saturated soil material are released from rest. Impact velocities vary between 2 and 13 m/s; flow heights between 0. 3 and 1. 0 m. The maximum impact pressures measured over 15 events represent between 2 and 50 times the equivalent static pressures. The measurements reveal that quadratic velocity-dependent formulas can be used to estimate impact pressures. Impact coefficients C are constant from front to tail and range between 0. 4 < C < 0. 8 according to the individual events. The pressure fluctuations to depend on the sensor size and are between 20% and 60% of the mean pressure values. Our results suggest that hazard guidelines for hillslope debris flows should be based on quadratic velocity-dependent formulas. © 2011 Springer-Verlag.
Buzzi O.,University of Newcastle |
Leonarduzzi E.,Geobrugg AG |
Krummenacher B.,Swiss Federal Institute of forest |
Volkwein A.,Swiss Federal Institute of forest |
Giacomini A.,University of Newcastle
Rock Mechanics and Rock Engineering | Year: 2015
In rockfall science, the bullet effect refers to the perforation of a rockfall mesh by a small block traveling at high speed. To date, there is still no comprehensive experimental data set investigating the underlying mechanisms of such effect. The bullet effect illustrates the fact that the capacity of a rockfall mesh depends on the size and speed of the impacting block. This paper presents the results of an experimental study on the effect of block size and mesh geometry (aperture and wire diameter) on the mesh performance. The results clearly show that the amount of energy required to perforate the mesh drops as the blocks get smaller. They also suggest that the mesh performance reaches a maximum and reduces to zero when the mesh cannot sustain the static load imposed by very large blocks. The outcome of the first series validates an analytical model for mesh perforation, making it the first simple model capturing the bullet effect. A second series of tests focused on the effect of mesh geometry and it was found that decreasing the mesh aperture by 19 % improves the performance by 50 % while only an extra 30 % could be gained by increasing the wire diameter by 33 %. The outcomes of the second series were used to discuss and redefine a dimensionless geometrical parameter G* and to validate a simple power type equation relating the mesh characteristics and the mesh performance. © 2014, Springer-Verlag Wien.
Louis B.,Swiss Federal Institute of forest |
Corinna W.,Geobrugg AG
Landslide Science and Practice: Early Warning, Instrumentation and Monitoring | Year: 2013
We reproduce shallow landslides by releasing 50 m3 of debris mixture down a 40 m long and 30° steep slope. The slope is instrumented in order to measure front and surface velocities, flow height and impact pressure on small obstacles. The mixture properties are determined from analysis of material samples. The impact process is investigated on the basis of the undisturbed flow properties 4 m upstream of the obstacles. Impact coefficients relating mixture density and surface velocity to the impact pressure are computed from the front to the tail of the flow. © Springer-Verlag Berlin Heidelberg 2013.
PubMed | Institute of Forensic Medicine, Swiss Federal Institute of forest and Geobrugg AG
Type: Journal Article | Journal: Sensors (Basel, Switzerland) | Year: 2016
Rockfall protection barriers are connected to the ground using steel cables fixed with anchors and foundations for the steel posts. It is common practice to measure the forces in the cables, while to date measurements of forces in the foundations have been inadequately resolved. An overview is presented of existing methods to measure the loads on the post foundations of rockfall protection barriers. Addressing some of the inadequacies of existing approaches, a novel sensor unit is presented that is able to capture the forces acting on post foundations in all six degrees of freedom. The sensor unit consists of four triaxial force sensors placed between two steel plates. To correctly convert the measurements into the directional forces acting on the foundation a special in-situ calibration procedure is proposed that delivers a corresponding conversion matrix.
Wendeler C.,Geobrugg AG |
Deana M.L.,Geobrugg Italia SRL
Landslides and Engineered Slopes. Experience, Theory and Practice | Year: 2016
A number of different gravity driven hazards (shallow landslide, rockfall, snow slides), threaten the safety of people and infrastructure. Combined shallow landslide and rockfall hazards are a common situation for unstable slopes: the steep flanks of landslide slopes are often sources of rockfalls. Moreover, the erosive action of a shallow landslide can remove soil and vegetation cover down to the underlying bedrock, exposing further potential for rockfall events. In this contribution we discuss the challenges in designing protection measures that can cope with both shallow landslides and rockfalls, each one characterized by different load cases. Shallow landslides impact with spreading pressures that load gradually, while rockfalls impact punctually with high velocities. We discuss the findings of number of full scale experiments investigating different load case; a finite element simulation software FARO used in the design of flexible wire protection systems will be presented. © 2016 Associazione Geotecnica Italiana, Rome, Italy.
Flum D.,RueggerFlum AG |
Roduner A.,Geobrugg AG
Rock Mechanics in Civil and Environmental Engineering - Proceedings of the European Rock Mechanics Symposium, EUROCK 2010 | Year: 2010
Flexible rope nets have been used in alpine regions for some decades for protecting rock slopes against unstable boulders or critical rock masses. The configuration of the protection measure was often based on the years' of experience of individual specialists. There was a lack of adequate dimensioning concepts or extremely simplified models were used. To better understand the supporting behavior of flexible rope nets and their interaction with nails or extruded piles, to thoroughly analyze the force distribution and investigate the influence of dynamic influences, comprehensive large scale field tests were carried out in Felsberg near Chur, Switzerland. This paper summarizes the information gained and conclusions drawn for the practical application of flexible rope nets anchored by nails or rock anchors. © 2010 Taylor & Francis Group.
Geobrugg AG | Date: 2015-10-12
A protective device for animal breeding, such as the breeding of fish, mussels or molluscs, includes at least an inner cage that can be positioned in a body of water and which is formed from a net. This cage is dimensioned here with a mesh width such that the animals to be bred are retained within the net. It is preferably totally surrounded by at least one outer cage spaced apart from the latter and which is produced from a net made of thin wires and/or strands. The mesh width of the outer cage is greater than that of the inner cage, and it is thus guaranteed that predators cannot damage the net of the inner cage from the outside.
Geobrugg Ag | Date: 2013-07-12
A net is particularly suitable for a basket for pisciculture, which may be placed in sea or fresh water. The net is made of a wire material, producible from individual spiral or similarly bent longitudinal elements, wherein adjacent threads are woven together. The net is simple and economical to produce, for example, by threading each longitudinal element into engagement with another longitudinal element while it has a shape of a spiral or screw to thereby provide it with a cylindrical form, and compressing each longitudinal element, when having the cylindrical form and after being threaded into engagement with the another longitudinal element, to provide the longitudinal element with substantially straight wire sections. The threading and compression steps are repeated to form a net after compression of several longitudinal elements threaded to one another.
Geobrugg Ag | Date: 2010-01-08
An unrollable safety system has a box (15) accommodating a net (11) which contains a device with a rotatable shaft on which the net (11) can be rolled up and out. One or more supports (12, 25) can be positioned specific distances away from the box (15). Moreover, at least one longitudinal element (16), preferably a rope, that can be pulled out of the box (15) and can be held by the positioned supports (12, 25) is provided on which the net (11) is rolled out and held like a curtain by means of brackets (21). The net (11), as meshwork, is flexible, and so designed to be able to roll up, it being produced from a plurality of wires, ropes and/or cords bent in coil shapes. The wires (13), ropes and/or cords bend in coil shapes are preferably aligned perpendicularly to the direction of pulling out the net (11) so that the net can be rolled up on the shaft. A mobile or stationary barrier over shorter or longer distances, with a high degree of stability and with simple and rapid assembly and dismantling has thus been produced.
Geobrugg AG | Date: 2013-02-22
A net, in particular for protection, safety, water-rearing or architectural purposes, is braided together from individual helically curved longitudinal elements (3) to form a braided structure. Individual longitudinal elements (3) curved into a cylinder or screw shape are twisted one inside the other with adjacent ones and compressed such that the braided structure is in more or less planar sheet-like form and the longitudinal elements (3) here each form more or less rectilinear limbs (8a, 8b; 9a, 9b) and curves (10a, 10b; 11a, 11b) therebetween. The curves (10a, 10b; 11a, 1b) between elongate limbs (8a, 8b; 9a, 9b) are inflected in kink form. This gives a net design with unexpectedly high strength values.