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Volume 44 (2022): Edition 4 (December 2022)

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Special Edition: Underground Infrastructure of Urban Areas

Volume 42 (2020): Edition 4 (December 2020)

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Volume 41 (2019): Edition 4 (December 2019)

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Volume 40 (2018): Edition 4 (December 2018)

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Volume 40 (2018): Edition 2 (October 2018)

Volume 40 (2018): Edition 1 (July 2018)

Volume 39 (2017): Edition 4 (December 2017)

Volume 39 (2017): Edition 3 (September 2017)

Volume 39 (2017): Edition 2 (June 2017)

Volume 39 (2017): Edition 1 (March 2017)

Volume 38 (2016): Edition 4 (December 2016)

Volume 38 (2016): Edition 3 (September 2016)

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Volume 37 (2015): Edition 4 (December 2015)

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Volume 37 (2015): Edition 2 (June 2015)

Volume 37 (2015): Edition 1 (March 2015)

Volume 36 (2014): Edition 4 (December 2014)

Volume 36 (2014): Edition 3 (September 2014)

Volume 36 (2014): Edition 2 (June 2014)

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Volume 35 (2013): Edition 4 (December 2013)

Volume 35 (2013): Edition 3 (September 2013)

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Volume 34 (2012): Edition 4 (December 2012)

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Volume 34 (2012): Edition 2 (June 2012)

Volume 34 (2012): Edition 1 (March 2012)

Détails du magazine
Format
Magazine
eISSN
2083-831X
Première publication
09 Nov 2012
Période de publication
4 fois par an
Langues
Anglais

Chercher

Volume 44 (2022): Edition 3 (September 2022)

Détails du magazine
Format
Magazine
eISSN
2083-831X
Première publication
09 Nov 2012
Période de publication
4 fois par an
Langues
Anglais

Chercher

6 Articles

Original Study

Accès libre

Effect of suction on the mechanical behaviour of unsaturated compacted clay–sand mixtures

Publié en ligne: 09 Sep 2022
Pages: 175 - 189

Résumé

Abstract

In this work, a series of unconfined compression tests at different water contents were performed to investigate the mechanical behaviour of clay–sand mixtures compacted in standard Proctor conditions. For studying the effect of water content and suction on unconfined compressive strength (UCS) and on strain secant modulus (E50 modulus) of these mixtures, drying–wetting paths were defined by measuring the soil–water characteristic curves (SWCCs) using osmotic and salt solution techniques and filter paper method. The results highlighted that an increase in sand content of the mixture leads to an increase in the maximum dry densities and a decrease in the optimum water content of the materials. However, at the given state, when clay is mixed with 25% of sand, the UCS and E50 modulus increase to 37% and 70%, respectively, compared to those of clayey samples. But when clay is mixed with 50% of sand, the UCS and E50 modulus decrease to 38% and 46%, respectively, compared to those of clayey samples. The results also indicate that the UCS and E50 increase with a decrease in the water content and an increase in suction, irrespective of the sand content.

Mots clés

  • Suction
  • Unsaturated soil
  • Clay–sand mixture
  • Unconfined compression strength
  • Strain secant modulus
  • Wetting–drying path
Accès libre

Case studies on Q-slope method use for slope stability analyses

Publié en ligne: 27 Jul 2022
Pages: 190 - 197

Résumé

Abstract

The use of the Q-slope value is a relatively new approach for the stability investigations of rock slopes. In this study, four different slopes in Giresun and Ordu cities of Turkey were investigated to assess whether the Q-slope approach is usable for varying slope heights, or not. A back analysis was carried out for a landslide in a case study quarry located in Kovanlik municipality of Giresun city. Carrying out detailed investigations on the geotechnical drill cores and the field studies, the Q-slope value of the rock mass of the Kovanlik quarry was determined as 0.58. According to the Q-slope approach, the slope which had a landslide under the case of 49° general slope angle and 225 m height should have been stable at a general slope angle of 59°. It has been found that the Q-slope approach is not favorable for a high slope with the height of 225 m. Two roadway excavations with steep slope angles and low heights smaller than 25 m were also investigated within this study. According to the Q-slope value, the roadway slopes which are stable for more than 3 years are estimated to be unstable. Therefore, the Q-slope approach was found also misleading for slopes with low heights like those under 25 m. On the other hand, the Q-slope method usability is confirmed obtaining parallel results with the observations from another case study slope with a height of 78 m. Although it has become a popular empirical method in the recent years, it is recommended to revise the Q-slope approach or limit its use depending on the slope height parameter.

Mots clés

  • Slope stability
  • Rock mass stability
  • Empirical methods in rock engineering
  • Q-slope
Accès libre

Effect of Time History on Long-Term Deformation of Gypseous Soils

Publié en ligne: 09 Sep 2022
Pages: 198 - 210

Résumé

Abstract

The time-dependent behavior of three gypseous soils was investigated. The soils had gypsum content of 66%, 44%, and 14.8%. The mineralogical and chemical properties of the soils were determined. Two series of tests were performed. In the first, collapsibility characteristics were investigated for a long period (60 days) by conducting single and double oedometer tests. In the second series, the effect of relative density on collapse with time was investigated. The samples were compacted to 40%, 50%, and 60% relative density and then tested. The results of collapse tests showed that the relationship between the strain and logarithm of effective stress has two vertical lines. The first one represents the collapse settlement taking place within 24 h, while the second one represents the long-term collapse. The collapse potential (CP) in both single and double oedometer tests increases when the gypsum content increases from 14.8% to 66% and when the initial void ratio increases.

The CP–logarithm of time relationship for soaked samples prepared at different relative densities under 800 kPa indicated that the CP increased with time for the soil sample compacted at 60% relative density and the increase was higher than those compacted at 40% and 50% relative density. The curves started with a straight line and then a concave downward curve was observed with a high strain. For samples compacted at 40% and 50% relative densities, the curves were interrupted by little soil collapses, while the third curve exhibited smooth relation following the collapse.

Mots clés

  • Gypseous soil
  • creep
  • collapse
  • time history
  • relative density
Accès libre

Does water lubrication affect friction differently for rocks and soils? Evidence and open questions

Publié en ligne: 27 Jul 2022
Pages: 211 - 223

Résumé

Abstract

The present paper focuses on the shear strength exhibited by rocks and soils when sliding along dry and wet surfaces, with this mechanism of failure being strongly related to the water lubrication phenomenon. It is well known that the frictional behaviour of geomaterials requires multiscale investigation. Under this perspective, experimental evidence of both friction at the grain scale (i.e. interparticle friction) and friction along sliding surfaces of rock and granular soil samples (i.e. surface friction) are analysed by using data from the literature. The review is addressed at linking different scales, stating the differences between rocks and soils in terms of frictional response to sliding and trying to point out still open problems for the research.

Mots clés

  • Water lubrication
  • friction scale
  • fractures
  • sliding
  • roughness
Accès libre

Behavior of Vertically Confined Square Footing on Reinforced Sand under Centric Inclined Loading

Publié en ligne: 27 Jul 2022
Pages: 224 - 238

Résumé

Abstract

This study presents the behavior of vertically confined square footing on geogrid-reinforced sand under centric inclined loading through a series of experimental tests. The load was applied at 5°, 10° and 20° angles of inclination with the vertical. The tests were conducted on surface footing, footing with confiner and footing with confiner and horizontal reinforcement configurations subjected to inclined loading. Parametric variations like depth of the confiner (d=1B, 1.5B, 2B), number of geogrid layers (N; varies with variation in depth of confiner), and spacing between horizontal reinforcements (Y=0.25B, 0.5B, 0.75B, 1B) have been investigated at the top surface dimension of confiner (D) as 1.0B, 1.5B and 2.0B (where B is the width of the model footing). Results show that combined effect of confiner and horizontal reinforcement increases the ultimate bearing capacity of footing significantly compared to only confiner for all angle of inclinations. It can also be observed that load bearing capacities decrease with increase in angles of inclination and record the minimum improvement at 20° angle of inclination. Improvement in bearing capacities and reduction in settlement of footing analyzed in terms of bearing capacity ratio (BCR) and settlement reduction factor (SRF) are compared for all footing configurations. To summarize, the test results showed that confiner along with reinforcement can be considered as an economic ground improvement technique for shallow foundations to counter against heavily inclined loading.

Mots clés

  • Centric inclined loading
  • load intensity
  • settlement
  • geogrid
  • sand
  • square footing
Accès libre

Observation Method in the Control of Stacker Capacity Under Landslide Hazard – A Case Study

Publié en ligne: 27 Jul 2022
Pages: 239 - 251

Résumé

Abstract

The article presents both an application and the purpose of the observation method in the control of stacker capacity. It lists the types of the measured (observed) quantities, which serve as a basis for the observation method. It also describes the procedure of the method and discusses its individual steps. It further provides examples of applying the method in defining the capacity levels of a stacking machine ZGOT-11500, based on the recorded surface and subsurface soil displacement values. The article also offers the increment values and speeds for the individual parameters, which serve as a warning against deterioration of the geotechnical condition of the soil. Knowledge of the relationships between the parameters that describe soil deformation and the required defined stacker capacity may serve as a basis for further research and experiments on the observation method, which may increase the safety of stacking operations. The analysis was based on the results of geotechnical and geodetic measurements, as well as on the operating parameters of the stacker, acquired over a period of 5 months.

Mots clés

  • open-cast mine
  • mine spoils
  • observation method
  • geotechnical hazard
6 Articles

Original Study

Accès libre

Effect of suction on the mechanical behaviour of unsaturated compacted clay–sand mixtures

Publié en ligne: 09 Sep 2022
Pages: 175 - 189

Résumé

Abstract

In this work, a series of unconfined compression tests at different water contents were performed to investigate the mechanical behaviour of clay–sand mixtures compacted in standard Proctor conditions. For studying the effect of water content and suction on unconfined compressive strength (UCS) and on strain secant modulus (E50 modulus) of these mixtures, drying–wetting paths were defined by measuring the soil–water characteristic curves (SWCCs) using osmotic and salt solution techniques and filter paper method. The results highlighted that an increase in sand content of the mixture leads to an increase in the maximum dry densities and a decrease in the optimum water content of the materials. However, at the given state, when clay is mixed with 25% of sand, the UCS and E50 modulus increase to 37% and 70%, respectively, compared to those of clayey samples. But when clay is mixed with 50% of sand, the UCS and E50 modulus decrease to 38% and 46%, respectively, compared to those of clayey samples. The results also indicate that the UCS and E50 increase with a decrease in the water content and an increase in suction, irrespective of the sand content.

Mots clés

  • Suction
  • Unsaturated soil
  • Clay–sand mixture
  • Unconfined compression strength
  • Strain secant modulus
  • Wetting–drying path
Accès libre

Case studies on Q-slope method use for slope stability analyses

Publié en ligne: 27 Jul 2022
Pages: 190 - 197

Résumé

Abstract

The use of the Q-slope value is a relatively new approach for the stability investigations of rock slopes. In this study, four different slopes in Giresun and Ordu cities of Turkey were investigated to assess whether the Q-slope approach is usable for varying slope heights, or not. A back analysis was carried out for a landslide in a case study quarry located in Kovanlik municipality of Giresun city. Carrying out detailed investigations on the geotechnical drill cores and the field studies, the Q-slope value of the rock mass of the Kovanlik quarry was determined as 0.58. According to the Q-slope approach, the slope which had a landslide under the case of 49° general slope angle and 225 m height should have been stable at a general slope angle of 59°. It has been found that the Q-slope approach is not favorable for a high slope with the height of 225 m. Two roadway excavations with steep slope angles and low heights smaller than 25 m were also investigated within this study. According to the Q-slope value, the roadway slopes which are stable for more than 3 years are estimated to be unstable. Therefore, the Q-slope approach was found also misleading for slopes with low heights like those under 25 m. On the other hand, the Q-slope method usability is confirmed obtaining parallel results with the observations from another case study slope with a height of 78 m. Although it has become a popular empirical method in the recent years, it is recommended to revise the Q-slope approach or limit its use depending on the slope height parameter.

Mots clés

  • Slope stability
  • Rock mass stability
  • Empirical methods in rock engineering
  • Q-slope
Accès libre

Effect of Time History on Long-Term Deformation of Gypseous Soils

Publié en ligne: 09 Sep 2022
Pages: 198 - 210

Résumé

Abstract

The time-dependent behavior of three gypseous soils was investigated. The soils had gypsum content of 66%, 44%, and 14.8%. The mineralogical and chemical properties of the soils were determined. Two series of tests were performed. In the first, collapsibility characteristics were investigated for a long period (60 days) by conducting single and double oedometer tests. In the second series, the effect of relative density on collapse with time was investigated. The samples were compacted to 40%, 50%, and 60% relative density and then tested. The results of collapse tests showed that the relationship between the strain and logarithm of effective stress has two vertical lines. The first one represents the collapse settlement taking place within 24 h, while the second one represents the long-term collapse. The collapse potential (CP) in both single and double oedometer tests increases when the gypsum content increases from 14.8% to 66% and when the initial void ratio increases.

The CP–logarithm of time relationship for soaked samples prepared at different relative densities under 800 kPa indicated that the CP increased with time for the soil sample compacted at 60% relative density and the increase was higher than those compacted at 40% and 50% relative density. The curves started with a straight line and then a concave downward curve was observed with a high strain. For samples compacted at 40% and 50% relative densities, the curves were interrupted by little soil collapses, while the third curve exhibited smooth relation following the collapse.

Mots clés

  • Gypseous soil
  • creep
  • collapse
  • time history
  • relative density
Accès libre

Does water lubrication affect friction differently for rocks and soils? Evidence and open questions

Publié en ligne: 27 Jul 2022
Pages: 211 - 223

Résumé

Abstract

The present paper focuses on the shear strength exhibited by rocks and soils when sliding along dry and wet surfaces, with this mechanism of failure being strongly related to the water lubrication phenomenon. It is well known that the frictional behaviour of geomaterials requires multiscale investigation. Under this perspective, experimental evidence of both friction at the grain scale (i.e. interparticle friction) and friction along sliding surfaces of rock and granular soil samples (i.e. surface friction) are analysed by using data from the literature. The review is addressed at linking different scales, stating the differences between rocks and soils in terms of frictional response to sliding and trying to point out still open problems for the research.

Mots clés

  • Water lubrication
  • friction scale
  • fractures
  • sliding
  • roughness
Accès libre

Behavior of Vertically Confined Square Footing on Reinforced Sand under Centric Inclined Loading

Publié en ligne: 27 Jul 2022
Pages: 224 - 238

Résumé

Abstract

This study presents the behavior of vertically confined square footing on geogrid-reinforced sand under centric inclined loading through a series of experimental tests. The load was applied at 5°, 10° and 20° angles of inclination with the vertical. The tests were conducted on surface footing, footing with confiner and footing with confiner and horizontal reinforcement configurations subjected to inclined loading. Parametric variations like depth of the confiner (d=1B, 1.5B, 2B), number of geogrid layers (N; varies with variation in depth of confiner), and spacing between horizontal reinforcements (Y=0.25B, 0.5B, 0.75B, 1B) have been investigated at the top surface dimension of confiner (D) as 1.0B, 1.5B and 2.0B (where B is the width of the model footing). Results show that combined effect of confiner and horizontal reinforcement increases the ultimate bearing capacity of footing significantly compared to only confiner for all angle of inclinations. It can also be observed that load bearing capacities decrease with increase in angles of inclination and record the minimum improvement at 20° angle of inclination. Improvement in bearing capacities and reduction in settlement of footing analyzed in terms of bearing capacity ratio (BCR) and settlement reduction factor (SRF) are compared for all footing configurations. To summarize, the test results showed that confiner along with reinforcement can be considered as an economic ground improvement technique for shallow foundations to counter against heavily inclined loading.

Mots clés

  • Centric inclined loading
  • load intensity
  • settlement
  • geogrid
  • sand
  • square footing
Accès libre

Observation Method in the Control of Stacker Capacity Under Landslide Hazard – A Case Study

Publié en ligne: 27 Jul 2022
Pages: 239 - 251

Résumé

Abstract

The article presents both an application and the purpose of the observation method in the control of stacker capacity. It lists the types of the measured (observed) quantities, which serve as a basis for the observation method. It also describes the procedure of the method and discusses its individual steps. It further provides examples of applying the method in defining the capacity levels of a stacking machine ZGOT-11500, based on the recorded surface and subsurface soil displacement values. The article also offers the increment values and speeds for the individual parameters, which serve as a warning against deterioration of the geotechnical condition of the soil. Knowledge of the relationships between the parameters that describe soil deformation and the required defined stacker capacity may serve as a basis for further research and experiments on the observation method, which may increase the safety of stacking operations. The analysis was based on the results of geotechnical and geodetic measurements, as well as on the operating parameters of the stacker, acquired over a period of 5 months.

Mots clés

  • open-cast mine
  • mine spoils
  • observation method
  • geotechnical hazard

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