Avalanches (anglais)

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AVALANCHES

RUFFAUT Martin - PRIHSE3
CHASTAING Alexandre - 3I3
POLYTECH’ GRENOBLE
Le 23/04/2010
Table of Contents

The sun is shining, the snow is perfect. You practice the off piste and suddenly the snow out from under your ski ... You are caught in an avalanche!

Abstract…………………………………………………..…..3
Introduction………………………………………………......4

I -Avalanche………………………………………………….........5

1) Definition............................................................................5
2) What does trigger it ? ……………………………….........5
3) The different type...........................................................….5
4) The risks and dangers………………………………..…....6

II - The prevention and protection……………………………..…..6

1) Figures…………………………………………...……......6
2) Protection of sensitiveareas………………….….….....….7
3) Prevention and protection in mountain……………......….8

III – Rescue systems……………………...…………………....…10

1) The ARVA system………………………………….…….10
11) transmitter function….….….……………….….....10
12) Receiver function…………………………………11
2) The Recco system………………………………………..12
21) Reflector…………………………………………..12
22) Detector…………...………………………………12

Conclusion………………………………………………….13Bibliography………………………………………………..14

Even if the mountain remains a place of relaxation and fun, everyone have to be careful and respect the rules in order to avoid any disaster.
Abstract

Every winter, we often learn that many groups of skiers are dead, or for the luckiest of them have survived of an avalanche. Despite the preventions and prohibitions, some do not hesitate to brave thedangers and play with their lives in the off-piste. Thus it’s interesting to better understand avalanches and what trigger it to study the effectiveness of the devices used to counter their starting or their effects which can be devastating. Besides there are also various equipments used to increase the chances of survival and rescue a burial person as quickly as possible. Thus, although some peopleact unconsciously, various safety equipments combined with « paravalanche » devices are a great way of survival for any victims.

Introduction

This year, the French ski resort is the busiest in the world, with about 58 million skier-days recorded. These great results are due to a good weather but also thanks to the French skiers who represent 75% of the attendance areas. Indeed eachwinter, about 30% of French population enjoys the mountain including nearly five million which down the slopes of Alps and Pyrenees resorts. Thus the French stations are in good health because they get about 1200 million euros in turnover. But this money won’t be too much because it enables them to finance the 26,500 hectares of slopes, the 3000 kilometers of ski lifts and also all ways of preventionand protection against avalanches. It’s a fact, the mountain is deadly. Last year, 35 people in France died because of an avalanche and 51 came out injured. Ten years ago, a terrible avalanche in Chamonix Montroc destroyed nearly twenty chalets and 12 people lost their lives. To prevent such accidents from happening again, we are going to study the systems and technologies in place to ensure thesafety of skiers. To begin, we will see avalanches in general, what does trigger it and the risks and dangers. After that we will speak about the prevention and the protection. Finally we will study two ways of rescue: the ARVA and the Recco systems.

I - Avalanches

I-1) Definition:

An avalanche is a rapid flow of a large mass of snow or ice. It takes place after the break of thesnowpack.

I-2) What does trigger it ?

The snowpack is rarely homogeneous. Because of the change of climatic conditions, namely the temperature, the wind, humidity, layers of snow that form it have different physical characteristics. The density of snow can vary from 50kg/m3 of snow cold and dry to 500kg/m3 for the hard snow.
Thus the snowpack is more or...
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