PSI - Issue 45

Ali et al. / Structural Integrity Procedia 00 (2023) 000 – 000 Ali et al. / Structural Integrity Procedia 00 (2023) 000 – 000 Ali et al. / Structural Integrity Procedia 00 (2023) 000 – 000

Zulfiqar Ali et al. / Procedia Structural Integrity 45 (2023) 60 – 65 the load frame and subjecting them to two cycles of uniaxial compression after incorporating delays of 1 hour, 6 hours, 24 hours, 72 hours and 1-week time. the load frame and subjecting them to two cycles of uniaxial compression after incorporating delays of 1 hour, 6 hours, 24 hours, 72 hours and 1-week time. the load frame and subjecting them to two cycles of uniaxial compression after incorporating delays of 1 hour, 6 hours, 24 hours, 72 hours and 1-week time. Ali et al. / Structural Integrity Procedia 00 (2023) 000 – 000 the load frame and subjecting them to two cycles of uniaxial compression after incorporating delays of 1 hour, 6 hours, 24 hours, 72 hours and 1-week time.

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Two Cycles Two Cycles Two Cycles Two Cycles

Two Cycles Two Cycles Two Cycles Two Cycles

Stress Stress Stress Stress

Stress Stress Stress Stress

Pre-load Pre-load Pre-load Pre-load

Pre-load Pre-load Pre-load Pre-load

Time Time Time Time

Time Time

Fig. 2 Schematic of the loading scheme showing preload and two cycle compression with and without time delay. Fig. 2 Schematic of the loading scheme showing preload and two cycle compression with and without time delay. Fig. 2 Schematic of the loading scheme showing preload and two cycle compression with and without time delay. Time 3. Results All the rock specimens were preloaded, and two cycles of uniaxial compression were applied with and without incorporating time delays. The applied stresses were then estimated using the conventional TMM technique and their ratio to the applied stress, which is referred to as the felicity ratio (FR), was determined. Fig. 3 shows the characteristic TMM curves for a granite specimen tested without time delay and a time delay of 1 week. A distinct separation point is evident between the two cycles at the prestress levels when the specimen is reloaded without any time delay. However, the effect of time delay is apparent in the specimen after a one-week time delay, resulting in non-overlapping curves and indicating a limitation in the technique. 3. Results All the rock specimens were preloaded, and two cycles of uniaxial compression were applied with and without incorporating time delays. The applied stresses were then estimated using the conventional TMM technique and their ratio to the applied stress, which is referred to as the felicity ratio (FR), was determined. Fig. 3 shows the characteristic TMM curves for a granite specimen tested without time delay and a time delay of 1 week. A distinct separation point is evident between the two cycles at the prestress levels when the specimen is reloaded without any time delay. However, the effect of time delay is apparent in the specimen after a one-week time delay, resulting in non-overlapping curves and indicating a limitation in the technique. 3. Results All the rock specimens were preloaded, and two cycles of uniaxial compression were applied with and without incorporating time delays. The applied stresses were then estimated using the conventional TMM technique and their ratio to the applied stress, which is referred to as the felicity ratio (FR), was determined. Fig. 3 shows the characteristic TMM curves for a granite specimen tested without time delay and a time delay of 1 week. A distinct separation point is evident between the two cycles at the prestress levels when the specimen is reloaded without any time delay. However, the effect of time delay is apparent in the specimen after a one-week time delay, resulting in non-overlapping curves and indicating a limitation in the technique. Fig. 2 Schematic of the loading scheme showing preload and two cycle compression with and without time delay. 3. Results All the rock specimens were preloaded, and two cycles of uniaxial compression were applied with and without incorporating time delays. The applied stresses were then estimated using the conventional TMM technique and their ratio to the applied stress, which is referred to as the felicity ratio (FR), was determined. Fig. 3 shows the characteristic TMM curves for a granite specimen tested without time delay and a time delay of 1 week. A distinct separation point is evident between the two cycles at the prestress levels when the specimen is reloaded without any time delay. However, the effect of time delay is apparent in the specimen after a one-week time delay, resulting in non-overlapping curves and indicating a limitation in the technique. Time

Granite Granite Granite

Granite Granite Granite

Granite

Granite

No Time Delay No Time Delay No Time Delay

1 Week Time Delay 1 Week Time Delay 1 Week Time Delay

No Time Delay

1 Week Time Delay

Fig. 3. TMM curves of granite specimen without time delay and after a delay of 1 week Fig. 3. TMM curves of granite specimen without time delay and after a delay of 1 week Fig. 3. TMM curves of granite specimen without time delay and after a delay of 1 week

We found that the TMM is effective for a certain range of time delay only and beyond 24 hours a considerable drop in the FR is seen. This observation in consistent in all the rock types but are more pronounced in the soft and porous rocks like sandstone and limestone. We believe that this is due to stress relaxation and hysteresis loops, which cause non-overlapping curves as the time delay is increased. When the specimen is unloaded and allowed to relax, the cracks reopen, and the grains readjust until an equilibrium is achieved. Reloading the specimen after a certain time delay produces in inelastic strains due to crack closure and sliding resulting in an increase in the tangent modulus and non-overlapping curves, thus leading to lower FR. We found that the TMM is effective for a certain range of time delay only and beyond 24 hours a considerable drop in the FR is seen. This observation in consistent in all the rock types but are more pronounced in the soft and porous rocks like sandstone and limestone. We believe that this is due to stress relaxation and hysteresis loops, which cause non-overlapping curves as the time delay is increased. When the specimen is unloaded and allowed to relax, the cracks reopen, and the grains readjust until an equilibrium is achieved. Reloading the specimen after a certain time delay produces in inelastic strains due to crack closure and sliding resulting in an increase in the tangent modulus and non-overlapping curves, thus leading to lower FR. We found that the TMM is effective for a certain range of time delay only and beyond 24 hours a considerable drop in the FR is seen. This observation in consistent in all the rock types but are more pronounced in the soft and porous rocks like sandstone and limestone. We believe that this is due to stress relaxation and hysteresis loops, which cause non-overlapping curves as the time delay is increased. When the specimen is unloaded and allowed to relax, the cracks reopen, and the grains readjust until an equilibrium is achieved. Reloading the specimen after a certain time delay produces in inelastic strains due to crack closure and sliding resulting in an increase in the tangent modulus and non-overlapping curves, thus leading to lower FR. Fig. 3. TMM curves of granite specimen without time delay and after a delay of 1 week We found that the TMM is effective for a certain range of time delay only and beyond 24 hours a considerable drop in the FR is seen. This observation in consistent in all the rock types but are more pronounced in the soft and porous rocks like sandstone and limestone. We believe that this is due to stress relaxation and hysteresis loops, which cause non-overlapping curves as the time delay is increased. When the specimen is unloaded and allowed to relax, the cracks reopen, and the grains readjust until an equilibrium is achieved. Reloading the specimen after a certain time delay produces in inelastic strains due to crack closure and sliding resulting in an increase in the