The fight-bank slope of the Dagangshan hydropower station located in Southwest China is a highly unloaded rock slope. Moreover, large-scale natural faults were detected in the slope body; some excavation-induced unloa...The fight-bank slope of the Dagangshan hydropower station located in Southwest China is a highly unloaded rock slope. Moreover, large-scale natural faults were detected in the slope body; some excavation-induced unloading fractures were discovered at elevations between lo75m and 1146m. Because of poor tectonic stability, the excavation work was suspended in September 2009, and six large- scale anti-shear galleries were employed to replace the weak zone in the slope body to reinforce the fight- bank slope. In this study, based on microseismic- monitoring technology and a numerical-simulation method, the stabilities of the slope with and without the reinforcement are analysed. An in-situ microseismic-monitofing system is used to obtain quantitative information about the damage location, extent, energy, and magnitude of the rocks. Thus, any potential sliding block in the fight-bank slope can be identified. By incorporating the numerical results along with the microseismic-monitoring data, the stress concentration is found to largely occur aroundthe anti-shear galleries, and the seismic deformation near the anti-shear galleries is apparent, particularly at elevations of 121o, 118o, 115o, and 112om. To understand the interaction mechanism between the anti-shear gallery and the surrounding rock, a 2D simulation of the potential damage process occurring in an anti-shear gallery is performed. The numerical simulation helps in obtaining additional information about the stress distribution and failure-induced stress re-distribution in the vicinity of the anti-shear galleries that cannot be directly observed in the field. Finally, the potential sliding surface of the right-bank slope is numerically obtained, which generally agrees with the spatial distribution of the in-situ monitored microseismic events. The safety factor of the slope reinforced with the anti-shear gallery increases by approximately 36.2%. Both the numerical results and microseismic data show that the anti-shear galleries have a good reinforcement effect.展开更多
It is extremely important to study and understand the deformation behavior and strength characteristics of rocks under thermal-mechanical （TM） coupling effects. Failure behavior and strength characteristics of Pingd...It is extremely important to study and understand the deformation behavior and strength characteristics of rocks under thermal-mechanical （TM） coupling effects. Failure behavior and strength characteristics of Pingdingshan sandstone were investigated at room temperatures up to 300℃ in an internally heated apparatus and tensile load through meso-scale laboratory experiments in this work. 33 experiments have successfully been conducted for Pingdingshan sandstone. Experimental results indicated that the tensile strength increased slowly with temperatures from 25℃ to 100℃, and then sharply jumped from 100℃ to 150℃, and finally decreased slightly with temperatures from 150℃ to 300℃. And about 150℃ is the threshold temperature of strength and thermal cracking. At low temperatures （25℃-150℃）, sandstone strength is determined by relatively weak clay cement. However, at higher temperatures （150℃-300℃）, because of the strength enhancement of clay cement, sandstone strength is controlled by both mineral particles and clay cement. The effects of cement clay, micro-cracks closing, and thermal cracking were the possible reasons for our detailed analysis. In addition, the typical fracture position maps and nominal stress-strain curves indicated that the temperature had strong effects on the failure mechanism of sandstone. The fractograph implied that the dominant fracture mechanism tended to transform from brittle at low temperatures to ductile at high temperatures.展开更多
基金jointly supported by grants from the National Key Research and Development Program(Grant No.2016YFC0801607,2016YFC0801602)the National Natural Science Foundation of China(Grant No.51279024)the National Basic Research Program of China(Grant No.2014CB047103)
文摘The fight-bank slope of the Dagangshan hydropower station located in Southwest China is a highly unloaded rock slope. Moreover, large-scale natural faults were detected in the slope body; some excavation-induced unloading fractures were discovered at elevations between lo75m and 1146m. Because of poor tectonic stability, the excavation work was suspended in September 2009, and six large- scale anti-shear galleries were employed to replace the weak zone in the slope body to reinforce the fight- bank slope. In this study, based on microseismic- monitoring technology and a numerical-simulation method, the stabilities of the slope with and without the reinforcement are analysed. An in-situ microseismic-monitofing system is used to obtain quantitative information about the damage location, extent, energy, and magnitude of the rocks. Thus, any potential sliding block in the fight-bank slope can be identified. By incorporating the numerical results along with the microseismic-monitoring data, the stress concentration is found to largely occur aroundthe anti-shear galleries, and the seismic deformation near the anti-shear galleries is apparent, particularly at elevations of 121o, 118o, 115o, and 112om. To understand the interaction mechanism between the anti-shear gallery and the surrounding rock, a 2D simulation of the potential damage process occurring in an anti-shear gallery is performed. The numerical simulation helps in obtaining additional information about the stress distribution and failure-induced stress re-distribution in the vicinity of the anti-shear galleries that cannot be directly observed in the field. Finally, the potential sliding surface of the right-bank slope is numerically obtained, which generally agrees with the spatial distribution of the in-situ monitored microseismic events. The safety factor of the slope reinforced with the anti-shear gallery increases by approximately 36.2%. Both the numerical results and microseismic data show that the anti-shear galleries have a good reinforcement effect.
基金supported by the National Natural Science Foundation of China(Grant No.11102225)the Special Funds for Major State Basic Research Project(Grant Nos. 2010CB732002 and 2011CB201201)+2 种基金the National Excellent Doctoral Dissertation of China(Grant No.201030)the Beijing Nova Program (Grant No.2010B062)the New Century Excellent Talents in University(Grant No.NCET-09-0726)
文摘It is extremely important to study and understand the deformation behavior and strength characteristics of rocks under thermal-mechanical （TM） coupling effects. Failure behavior and strength characteristics of Pingdingshan sandstone were investigated at room temperatures up to 300℃ in an internally heated apparatus and tensile load through meso-scale laboratory experiments in this work. 33 experiments have successfully been conducted for Pingdingshan sandstone. Experimental results indicated that the tensile strength increased slowly with temperatures from 25℃ to 100℃, and then sharply jumped from 100℃ to 150℃, and finally decreased slightly with temperatures from 150℃ to 300℃. And about 150℃ is the threshold temperature of strength and thermal cracking. At low temperatures （25℃-150℃）, sandstone strength is determined by relatively weak clay cement. However, at higher temperatures （150℃-300℃）, because of the strength enhancement of clay cement, sandstone strength is controlled by both mineral particles and clay cement. The effects of cement clay, micro-cracks closing, and thermal cracking were the possible reasons for our detailed analysis. In addition, the typical fracture position maps and nominal stress-strain curves indicated that the temperature had strong effects on the failure mechanism of sandstone. The fractograph implied that the dominant fracture mechanism tended to transform from brittle at low temperatures to ductile at high temperatures.
