CableHelp: A numerical tool to optimize the set-up of a ... - Newfor

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CableHelp: A numerical tool to optimize the set-up of a standing skyline and improve cable yarding planning Sylvain DUPIRE, Franck BOURRIER, Frédéric BERGER Irstea - UR EMGR - Centre de Grenoble, France Contact: [email protected]

IUFRO World Congress 2014 – Salt Lake City (USA)

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Mountain forests and cable yarding operations in France A point of history 1st part of the 20th century: long cable (“tri-câble”) period

2nd part of the 20th century: Ground-based system period

Return of cable systems: mobile cable towers

2014

1995

1960 Cable roads in the Pyrenees in 1960 Intermediate station

Ma in ca b

Skidder

Proportion of the annual total harvested volume extracted by cable yarding in 2010

F.BERGER

Storage places

le ro ad

Intermediate station

Intermediate station

n ai M

e bl ca

ad ro

Source : Bartoli 2008, Brändli 2010) Start station

1 km

Source : Bartoli 2007

CableHelp a new numerical tool to optimize the set-up of a standing skyline and improve cable yarding planning Sylvain Dupire – Irstea – IUFRO World Congress 2014 – [email protected]

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Questions and objectives of this work How to improve specific skills of the forest managers and operators involved in cable yarding activities? Objective n°1: Create an user-friendly model  Adaptable to different configurations (uphill/downhill yarding, single/multiple span, classical or self-motorized carriages)  Allowing to optimize the set-up of a cable road

Can we efficiently apply complex mechanical approach to cable yarding operations? Objective n°2: Create a model that uses non linear analysis of cable structure  That allows predicting load path and skyline tensile force  With fast computational time

How to evaluate the accuracy of the model? Objective n°3: Compare real field data with model prediction

CableHelp a new numerical tool to optimize the set-up of a standing skyline and improve cable yarding planning Sylvain Dupire – Irstea – IUFRO World Congress 2014 – [email protected]

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Limitation to the standing skyline cable systems T < TMc

Mobile cable tower Skyline Intermediate support Jack Carriage

Forest road S. Dupire 2007

Mainline

Tail tree

H < Hmin Load Anchors Ground

CableHelp a new numerical tool to optimize the set-up of a standing skyline and improve cable yarding planning Sylvain Dupire – Irstea – IUFRO World Congress 2014 – [email protected]

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Model development: operational data as inputs Terrain profile: 2 possible options  Use spatial inputs (DTM + shp of cable road)  Use field data collected for a cable project

Cable roads Forest roads

Cable parameters

Modeling parameters: 2 possible scenarios  Model an existing configuration (initial skyline tensile force T0 and carriage position sc)  Optimize the layout of a particular cable road (respecting standing skyline condition)

CableHelp a new numerical tool to optimize the set-up of a standing skyline and improve cable yarding planning Sylvain Dupire – Irstea – IUFRO World Congress 2014 – [email protected]

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Model development: cable mechanical response to a load The tension T(s) in any point of the cable and the load path (x(s),y(s)) are functions of a single variable: the curvilinear abscissa s. Irvine (1981)

Tensile force T(sF) x

A e ap Sh t of

These functions describe catenary shape of the skyline

he ble ca

z

the

d de loa sF at

Curvilinear abscissa of the load (sF) Load Shap e

All the load positions = load trajectory or load path

of an un loaded cable

B

Curvilinear abscissa s

Cartesian coordinates (xsF, zsF) of the load

CableHelp a new numerical tool to optimize the set-up of a standing skyline and improve cable yarding planning Sylvain Dupire – Irstea – IUFRO World Congress 2014 – [email protected]

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Model development: basic and complete process Simple process of calculation (no mainline, no friction at intermediate support): 1. Iterative method to find the unstrained (= unstretched) length of the skyline L0 that respects the modeling scenario: Model a real case knowing the initial configuration (T0, sc,…) or Optimize a cable road according to TMc, Hmin… 2. Calculate the load path and the skyline tensile force moving the carriage from s=0 to s=L0 while respecting L0

Complete process . Possibility to account for the effects of mainline and haulback line . Possibility to account for the friction at intermediate support Language of programming All programming done with open source materials: Python 2.7, GDAL, Numpy, Matplotlib CableHelp a new numerical tool to optimize the set-up of a standing skyline and improve cable yarding planning Sylvain Dupire – Irstea – IUFRO World Congress 2014 – [email protected]

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Model development: multiple span analysis Ground Chord Load path without intermediate support Load path with intermediate support

CableHelp a new numerical tool to optimize the set-up of a standing skyline and improve cable yarding planning Sylvain Dupire – Irstea – IUFRO World Congress 2014 – [email protected]

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Model validation: follow up of a real cable operation Partnership: FERBOIS enterprise National forest of Gargas French Alps, Isère UTM Long 5°55’17” Lat 44°52’37”

D1 = 24 m, H1 = 15 m D2 = 197 m, H2 = 113 m D3 = 40 m, H3 = 25 m

Load cell

{x(s), z(s)}

Theodolite measurement. Isère. France

For each carriage position on SPAN 2 we measured: •

Skyline tension T(s) with a cell load positioned at the anchorage

•

Carriage position {x(s),z(s)} with a theodolite positioned at the top of the line CableHelp a new numerical tool to optimize the set-up of a standing skyline and improve cable yarding planning Sylvain Dupire – Irstea – IUFRO World Congress 2014 – [email protected]

T(s)

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Tool validation: model prediction vs field measurements Load path

Basic: mainline and friction not considered Complete: mainline and friction considered

Average value

Average value

1 configuration tested for 30 different carriage positions

Basic application:

precision of load path prediction ~ 0.4 meters (< 0.1%)

Complete application: precision of load path prediction ~ 0.2 meters (< 0.3%)

CableHelp a new numerical tool to optimize the set-up of a standing skyline and improve cable yarding planning Sylvain Dupire – Irstea – IUFRO World Congress 2014 – [email protected]

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Tool validation: model prediction vs field measurements Skyline tensile force Basic: mainline and friction not considered Complete: mainline and friction considered

Average value

1 configuration tested for 30 different carriage positions

Basic application:

precision of skyline tension prediction ~ 1.9 kN (2.6%)

Complete application:

precision of skyline tension prediction ~ 0.8 kN (1.1%) + Better local prediction CableHelp a new numerical tool to optimize the set-up of a standing skyline and improve cable yarding planning Sylvain Dupire – Irstea – IUFRO World Congress 2014 – [email protected]

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Example of application of the model Cable road n°1

Haulback Tension (kN)

GIS interfacing

Spatial inputs (DTM, cable road shapefile, forest area, raster of volume) are taken into the model which optimizes the layout and returns: • A graphical view of the profile • A summary of the cable road CableHelp a new numerical tool to optimize the set-up of a standing skyline and improve cable yarding planning Sylvain Dupire – Irstea – IUFRO World Congress 2014 – [email protected]

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Conclusion/discussion CableHelp: a tool corresponding to the needs of forest managers and operators     

Developed with an operational point of view Adapted to several configurations and materials: Developed with open source language Precision range of predicted values known Fast computational time: about 5 ms per cable road (2.5 m resolution)

CableHelp: shortcomings    

Specific to standing skyline configuration Limited to full suspension of the logs Mainline tension calculation perfectible Only one field experiment

Perspectives  Toward a database for the follow-up of cable yarding operations ?  Open source distribution of the model ? CableHelp a new numerical tool to optimize the set-up of a standing skyline and improve cable yarding planning Sylvain Dupire – Irstea – IUFRO World Congress 2014 – [email protected]

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THANK YOU FOR YOUR ATTENTION Contact: [email protected]