Utveckling av expertsystem för bedömning av bergmaterialens mekaniska egenskaper: komplement till VTI rapport 715

Eva Johansson
Karel Miskovsky
Magnus Bergknut

On behalf of the Swedish Transport Administration, Luleå University of Technology (LTU)/Envix North Ltd and the Swedish National Road and Transport Research Institute (VTI) developed the expert system for evaluation of rock materials' mechanical properties, i.e. an evaluation system based on petrographic parameters. The project aimed to provide a prompt documented evaluation of rock mass quality and its practical use as aggregate, even when rock is covered by drift material. The project's primary outcome has been published in VTI rapport 715. The present project was carried out by analysis of selected samples, multivariate evaluation, and improvement of the expert system's classification keys for granitoids and gabbroids. The system is currently based on 43 selectively chosen rock materials. The multivariate evaluation used PCA and PLS. The correlation (PLS evaluation) between petrographic and mechanical properties shows that for both granitoids and gabbroids, there are generally the same petrographic parameters that affect mechanical properties. The petrographic parameter for the granitoids having the greatest impact on the mechanical properties are: grain size, grain size distribution and mica content. The analysis also indicated a strong correlation between mica content and degree of foliation, which in turn results in a clear difference between magmatic and metamorphic granitoids. Concerning the gabbroids, it was frequency of micro fractures, mica content, grain size, and grain size distribution that had the greatest impact on the mechanical properties. The analysis indicated that the degree of metamorphism affects the resistance to abrasion from studded tires. Low metamorphic gabbroids show generally “lower” (better) Nordic ball mill values, compared to rocks of “higher” degree of metamorphism. Mica in gabbroids generally has a positive effect (more competent) on mechanical properties. Rock samples with “higher” mica content (5–-15%) generally have better mechanical properties than those with lower (>5%) mica content. The multivariate evaluation has proven to be a suitable tool to verify the mechanical properties' dependence on petrographic parameters.



Open seminar with Mistra SAMS international scientific advisory...

Mistra SAMS international scientific advisory panel (ISAP) is visiting Stockholm, and the program will host an open seminar where the panel members will give talks in their area of expertise.

ERPUG 2017

The five year anniversary of  European Road Profile Users' Group (ERPUG) Forum will take place at Ramboll head quarter, Copenhagen, Denmark October 19-20, 2017. 



Vehicle Driver Monitoring: sleepiness and cognitive load

To prevent road crashes it is important to understand driver related contributing factors, which have been suggested to be the critical reason in 94 per cent of crashes. The overall aim of the project Vehicle Driver Monitoring has been to advance the...


Tomas Svensson new director-general

Tomas Svensson was today appointed Director-General of VTI. Tomas has been acting Director-General since January 2017. 


Crash testing bicycles at VTI

For the first time single bicycle crashes have been simulated at the VTI crash safety laboratory.


A case study exploring firefighters’ and municipal officials’ preparedness for electrical vehicles

A VTI-study presents a social perspective on new vehicle technology. It explores the self-reported preparedness of the fire departments (i.e., rescue services) in Sweden’s three largest cities regarding rescue operations involving electrical vehicles (EVs).


Pioneering research on and about bicycles at VTI

Under what circumstances might cyclists lose tyre grip? What actions could then be taken to prevent a crash? VTI is currently developing a theoretical model of the behaviour of bicycle tyres during braking and steering in different situations and on different...


Virtual pedestrians create efficient stations

If more people are to choose sustainable travel, then the public transport stations of the future must be designed so that pedestrians can get where they are going quickly, without congestion or queues. The Swedish Road and Transport Research Institute (VTI)...