Pressure of Snow Avalanches against Buildings

2011 ◽  
Vol 82 ◽  
pp. 392-397 ◽  
Author(s):  
Eloise Bovet ◽  
Bernardino Chiaia ◽  
Valerio De Biagi ◽  
Barbara Frigo
Keyword(s):  
Lower Bound ◽  
Physical Properties ◽  
Structural Investigation ◽  
Back Analysis ◽  
Impact Pressure ◽  
Snow Avalanche ◽  
Snow Avalanches ◽  
Avalanche Behavior ◽  
Qualitative Measure

The paper aims to analyse the e ects of topography and building position on themagnitude of pressure exerted by snow avalanches against buildings, through a structural backanalysis and numerical uid-dynamics. Studying a real snow avalanche impact occurred in2008 which destroyed a village in Valsavarenche (Aosta Valley - IT), the attention is focused onthe avalanche ow deviation caused by the destructive interaction with a rst building, whichprotected part of a second building beyond it. By means of photographical and in situ survey,a detailed description of avalanche geometrical, dynamical and physical properties is outlined.A structural investigation, based both on debris arrangement and on measurements on theundamaged parts of buildings is also carried out.Thus, a back analysis is carried out in order to de ne collapse dynamics and to estimate theupper and the lower bound of impact pressure. Afterwards, numerical uid-dynamical analysesare performed to simulate di erent impact scenarios and to understand the e ects of obstacleson avalanche behavior: a qualitative measure of the interactions among buildings, which maymutually protect one another, is obtained.

scholarly journals Physical vulnerability of reinforced concrete buildings impacted by snow avalanches

2010 ◽  
Vol 10 (7) ◽  
pp. 1531-1545 ◽  
Author(s):  
D. Bertrand ◽  
M. Naaim ◽  
M. Brun
Keyword(s):  
Reinforced Concrete ◽  
Numerical Simulations ◽  
Damage Index ◽  
Impact Pressure ◽  
Snow Avalanche ◽  
Reference Structure ◽  
Snow Avalanches ◽  
Physical Vulnerability ◽  
Engineering Structures ◽  
The Impact

Abstract. This paper deals with the assessment of physical vulnerability of civil engineering structures to snow avalanche loadings. In this case, the vulnerability of the element at risk is defined by its damage level expressed on a scale from 0 (no damage) to 1 (total destruction). The vulnerability of a building depends on its structure and flow features (geometry, mechanical properties, type of avalanche, topography, etc.). This makes it difficult to obtain vulnerability relations. Most existing vulnerability relations have been built from field observations. This approach suffers from the scarcity of well documented events. Moreover, the back analysis is based on both rough descriptions of the avalanche and the structure. To overcome this problem, numerical simulations of reinforced concrete structures loaded by snow avalanches are carried out. Numerical simulations allow to study, in controlled conditions, the structure behavior under snow avalanche loading. The structure is modeled in 3-D by the finite element method (FEM). The elasto-plasticity framework is used to represent the mechanical behavior of both materials (concrete and steel bars) and the transient feature of the avalanche loading is taken into account in the simulation. Considering a reference structure, several simulation campaigns are conducted in order to assess its snow avalanches vulnerability. Thus, a damage index is defined and is based on global and local parameters of the structure. The influence of the geometrical features of the structure, the compressive strength of the concrete, the density of steel inside the composite material and the maximum impact pressure on the damage index are studied and analyzed. These simulations allow establishing the vulnerability as a function of the impact pressure and the structure features. The derived vulnerability functions could be used for risk analysis in a snow avalanche context.

Risk-based definition of zones for land-use planning in snow avalanche terrain

2005 ◽  
Vol 42 (4) ◽  
pp. 1030-1038 ◽  
Author(s):  
D M McClung
Keyword(s):  
Land Use ◽  
Return Period ◽  
Land Use Planning ◽  
Impact Pressure ◽  
Snow Avalanche ◽  
Snow Avalanches ◽  
Definition Of

For avalanche applications, the definition of zones for land-use planning typically involves estimates of both return period and impact pressures as functions of position in the runout zone. Since return period is related to expected avalanche frequency and impact pressure is related to consequences if structures are hit, zone specifications imply a risk-based approach. In this paper, the schemes for definition of zones from three countries (Switzerland, Canada, and Austria) are presented and compared from a mathematical, risk-based framework. The comparison reveals that the Swiss standard is the least conservative and the Austrian standard is the most conservative.Key words: risk, snow avalanches, zoning, return period.

scholarly journals Microstructural Characteristics of Frazil Particles and the Physical Properties of Frazil Ice in the Yellow River, China

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 617
Author(s):  
Yaodan Zhang ◽  
Zhijun Li ◽  
Yuanren Xiu ◽  
Chunjiang Li ◽  
Baosen Zhang ◽  
...  
Keyword(s):  
Physical Properties ◽  
Yellow River ◽  
The Yellow River ◽  
Ice Crystal ◽  
Microstructural Characteristics ◽  
Air Bubble ◽  
Frazil Ice ◽  
Sediment Content ◽  
Crystal Diameter

Frazil particles, ice crystals or slushy granules that form in turbulent water, change the freezing properties of ice to create “frazil ice”. To understand the microstructural characteristics of these particles and the physical properties of frazil ice in greater depth, an in situ sampler was designed to collect frazil particles in the Yellow River. The ice crystal microstructural characteristics of the frazil particles (morphology, size, air bubble, and sediment) were observed under a microscope, and their nucleation mechanism was analyzed according to its microstructure. The physical properties of frazil ice (ice crystal microstructure, air bubble, ice density, and sediment content) were also observed. The results showed that these microstructures of frazil particles can be divided into four types: granular, dendritic, needle-like, and serrated. The size of the measured frazil particles ranged from 0.1 to 25 mm. Compared with columnar ice, the crystal microstructure of frazil ice is irregular, with a mean crystal diameter less than 5 mm extending in all directions. The crystal grain size and ice density of frazil ice are smaller than columnar ice, but the bubble and sediment content are larger.

In Situ Stress Measurement and Inversion in Deep Roadway

2013 ◽  
Vol 734-737 ◽  
pp. 759-763 ◽  
Author(s):  
Yong Li ◽  
Yun Yi Zhang ◽  
Ren Jie Gao ◽  
Shuai Tao Xie
Keyword(s):  
Field Measurement ◽  
Stress Measurement ◽  
Measurement Data ◽  
Back Analysis ◽  
In Situ Stress ◽  
Deep Mine ◽  
Accuracy Requirement ◽  
Initial Stress Field ◽  
In Situ Stress Measurement

Jixi mine area is one of the early mined areas in China and it's a typical deep mine. Because of large deformation of underground roadway and dynamic disasters occurred frequently in this mine, five measurement points of in-situ stress in this mine was measured and then analyzed with inversion. Based on these in-situ stress measurement data, numerical model of 3D in-situ stress back analysis was established. According to different stress fields, related analytical samples of neural network were given with FLAC program. Through the determination of hidden layers, hidden nodes and the setting of parameters, the network was optimized and trained. Then according to field measurement of in-situ stress, back analysis of initial stress field was conducted. Compared with field measurement, with accuracy requirement satisfied, it shows that the in-situ stress of rock mass obtained is basically reasonable. Meanwhile, it proves that the measurement of in-situ stress can provide deep mines with effective and rapid means, and also provide reliable data to optimization of deep roadway layout and supporting design.

Back Analysis Methods in Geotechnical Engineering

2014 ◽  
Vol 1020 ◽  
pp. 423-428 ◽  
Author(s):  
Eva Hrubesova ◽  
Marek Mohyla
Keyword(s):  
Rock Mass ◽  
Geotechnical Engineering ◽  
Back Analysis ◽  
Rheological Parameters ◽  
Analysis Method ◽  
Direct Optimization ◽  
Initial Stress State ◽  
Analytical Functions ◽  
Is Evaluation

The paper deals with the back analysis method in geotechnical engineering, that goal is evaluation the more objective and reliable parameters of the rock mass on the basis of in-situ measurements. Stress, deformational, strength and rheological parameters of the rock mass are usually determined by some inaccuracies and errors arising from the complexity and variability of the rock mass. This higher or lower degree of imprecision is reflected in the reliability of the mathematical modelling results. The paper presents the utilization of direct optimization back analysis method, based on the theory of analytical functions of complex variable and Kolosov-Muschelischvili relations, to the evaluation of initial stress state inside the rock massif.

In situ polymerized poly(butylene succinate)/silica nanocomposites: Physical properties and biodegradation

2008 ◽  
Vol 93 (5) ◽  
pp. 889-895 ◽  
Author(s):  
Sang-Il Han ◽  
Jung Seop Lim ◽  
Dong Kook Kim ◽  
Mal Nam Kim ◽  
Seung Soon Im
Keyword(s):  
Physical Properties ◽  
Butylene Succinate ◽  
Silica Nanocomposites

scholarly journals Flow-law hypotheses for ice-sheet modeling

1992 ◽  
Vol 38 (129) ◽  
pp. 245-256 ◽  
Author(s):  
Richard B. Alley
Keyword(s):  
Physical Properties ◽  
Ice Sheets ◽  
Diffusion Control ◽  
Ice Streams ◽  
Ice Shelves ◽  
Dislocation Glide ◽  
Ice Sheet Modeling ◽  
Flow Law ◽  
Power Law Creep

AbstractIce-flow modeling requires a flow law relating strain rates to stresses in situ, but a flow law cannot be measured directly in ice sheets. Microscopic processes such as dislocation glide and boundary diffusion control both the flow law for ice and the development of physical properties such as grain-size andc-axis fabric. These microscopic processes can be inferred from observations of the physical properties, and the flow law can then be estimated from the microscopic processes.A review of available literature shows that this approach can be imperfectly successful. Interior regions of large ice sheets probably have depth-varying flow-law “constants”, with the stress exponent,n, for power-law creep less than 3 in upper regions and equal to 3 only in deep ice;nprobably equals 3 through most of the thickness of ice shelves and ice streams.

Study on Deformation and Damage of Rock Mass Subject to High In Situ Stress by Using a Elastoplastic Damage Model and Considering the Impact of Weak Planes

2013 ◽  
Vol 838-841 ◽  
pp. 705-709
Author(s):  
Yun Hao Yang ◽  
Ren Kun Wang
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Damage Model ◽  
Back Analysis ◽  
In Situ Stress ◽  
Surrounding Rock ◽  
High In Situ Stress ◽  
Underground Caverns ◽  
The Impact

Large scale underground caverns are under construction in high in-situ stress field at Houziyan hydropower station. To investigate deformation and damage of surrounding rock mass, a elastoplastic orthotropic damage model capable of describing induced orthotropic damage and post-peak behavior of hard rock is used, together with a effective approach accounting for the presence of weak planes. Then a displacement based back analysis was conducted by using the measured deformation data from extensometers. The computed displacements are in good agreement with the measured ones at most of measurement points, which confirm the validities of constitutive model and numerical simulation model. The result of simulation shows that damage of surrounding rock mass is mainly dominated by the high in-situ stress rather than the weak planes and heavy damage occur at the cavern shoulders and side walls.

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