Based on water inrush accident of 1841 working face of Desheng Coal Mine in Wu'an, Hebei province, China, an evaluation model of hydrodynamic characteristics of the project is set up and simulated using Matlab. It...Based on water inrush accident of 1841 working face of Desheng Coal Mine in Wu'an, Hebei province, China, an evaluation model of hydrodynamic characteristics of the project is set up and simulated using Matlab. It is assumed that the pipe flow would transform into seepage flow when the aggregates are plugged into the water inrush channel and the seepage flow would disappear along with grouting process. The simulation results show that the flow velocity will increase with an increase in height of aggregates accumulation body during the aggregates filling process; the maximum seepage velocity occurs on the top of plugging zone; and the water flow decreases with increasing plugging height of water inrush channel. Finally, the field construction results show that the water inrush channel can be plugged effectively by the compacted body prepared with aggregate and cement slurry.展开更多
According to site-specific environments such as high water pressures, high in-situ stresses and strong rockbursts, the design scheme of the long and deep diversion tunnels at Jinping II hydropower station was optimize...According to site-specific environments such as high water pressures, high in-situ stresses and strong rockbursts, the design scheme of the long and deep diversion tunnels at Jinping II hydropower station was optimized to ensure construction safety. New drainage tunnels were considered. Furthermore, lining structures and grouting pressures were modified during the excavation of tunnels. The construction scheme was updated dynamically based on the complex geological conditions. For instances, the diversion tunnels were first excavated by drilling and blasting method at the first stage of construction, and then by the combination method of tunnel boring machine (TBM) and drilling and blasting, and finally by drilling and blasting method. Through optimized scheme and updated construction scheme, the excavation of diversion tunnel #1 was successfully completed in June, 2011. This paper summarizes the key issues in rock mechanics associated with the construction of the long and deep diversion tunnels at Jinping II hydropower station. The experiences of design and construction obtained from this project could provide reference to similar projects.展开更多
On-site monitoring and numerical simulation have been combined to analyze the stability of the jointed surrounding rock and the stress inside the lining structure of a sample deeply buried hydraulic tunnel.We show tha...On-site monitoring and numerical simulation have been combined to analyze the stability of the jointed surrounding rock and the stress inside the lining structure of a sample deeply buried hydraulic tunnel.We show that the deformation around the tunnel was mainly concentrated in the range 51.37 mm∼66.73 mm,the tunnel circumference was dominated by shear failure,and the maximum plastic zone was about 3.90 m.When the shotcrete treatment was performed immediately after the excavation,the deformation of the surrounding rock was reduced by 58.94%∼76.31%,and the extension of the plastic zone was relatively limited,thereby leading to improvements in terms of the stability of surrounding rock.When the support was provided at different time points,the stress of the surrounding rock in the shallow part of the tunnel was improved everywhere.In the tunnel section with high ground stress and joint development,when 10 cm steel fiber concrete spray layer and 40 cm C25 concrete secondary lining were used,the maximum tensile stress on the lining structure was 0.89 MPa,i.e.,it was less than the tensile strength of concrete,which indicates that the internal force of the lining can meet the overall requirements.展开更多
The columnar jointed rock mass(CJR), composed of polygonal cross-sectional columns cut by several groups of joints in various directions, was exposed during the excavations of the Baihetan hydropower station, China. I...The columnar jointed rock mass(CJR), composed of polygonal cross-sectional columns cut by several groups of joints in various directions, was exposed during the excavations of the Baihetan hydropower station, China. In order to investigate the unloading performances and the stability conditions during excavation of the columns, an experimental field study was performed. Firstly, on-site investigations indicated that the geotechnical problems, including rock relaxation, cracking and collapse, were the most prominent for the CJR Class I that contains intensive joint network and the smallest column sizes.Comprehensive field tests, including deformation measurement by multi-point extensometers, ultrasonic wave testing, borehole television observation and stress monitoring of rock anchors, revealed that the time-dependent relaxation of the CJRs was marked. The practical excavation experiences for the Baihetan columnar jointed rock masses, such as blasting scheme, supporting time of shotcrete and rock bolts, were presented in the excavations of the diversion tunnels. These detailed investigations and practical construction experiences can provide helpful information for similar geotechnical works in jointed rock mass.展开更多
A 3-D temperature model for diversion tunnel was developed by combining k-εmodel and energy transport e-quation. The actual geometry data of the tunnel was used to construct athree-dimensional computational domain in...A 3-D temperature model for diversion tunnel was developed by combining k-εmodel and energy transport e-quation. The actual geometry data of the tunnel was used to construct athree-dimensional computational domain including the concrete lining. As the interaction betweentemperature and velocity fields can be taken into account, the model can be employed to accuratelysimulate the temperature and velocity field. The model was validated with the field data observed inthe diversion tunnel of the Nanya River. The water temperature of the diversion tunnel of theSecond Jinping Cascade Hy-dropower Station to be built was predicted. It is shown that thetemperature increase is not observable due to the large diameter of the tunnel, the big flow rateand the short contact time, The result can provide scientific foundation or reference for the designof hydropower station, and protection strategy of aquatic organisms and aquatic ecosystem.展开更多
基金Financial support for this work, provided by the National Natural Science Foundation of China (Nos. 41072031, 40172119)the Natural Science Foundation of Hebei Province of China(No. D2012402008)
文摘Based on water inrush accident of 1841 working face of Desheng Coal Mine in Wu'an, Hebei province, China, an evaluation model of hydrodynamic characteristics of the project is set up and simulated using Matlab. It is assumed that the pipe flow would transform into seepage flow when the aggregates are plugged into the water inrush channel and the seepage flow would disappear along with grouting process. The simulation results show that the flow velocity will increase with an increase in height of aggregates accumulation body during the aggregates filling process; the maximum seepage velocity occurs on the top of plugging zone; and the water flow decreases with increasing plugging height of water inrush channel. Finally, the field construction results show that the water inrush channel can be plugged effectively by the compacted body prepared with aggregate and cement slurry.
文摘According to site-specific environments such as high water pressures, high in-situ stresses and strong rockbursts, the design scheme of the long and deep diversion tunnels at Jinping II hydropower station was optimized to ensure construction safety. New drainage tunnels were considered. Furthermore, lining structures and grouting pressures were modified during the excavation of tunnels. The construction scheme was updated dynamically based on the complex geological conditions. For instances, the diversion tunnels were first excavated by drilling and blasting method at the first stage of construction, and then by the combination method of tunnel boring machine (TBM) and drilling and blasting, and finally by drilling and blasting method. Through optimized scheme and updated construction scheme, the excavation of diversion tunnel #1 was successfully completed in June, 2011. This paper summarizes the key issues in rock mechanics associated with the construction of the long and deep diversion tunnels at Jinping II hydropower station. The experiences of design and construction obtained from this project could provide reference to similar projects.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.51769031)Regional Innovation Guidance Plan Project of the XPCC(Grant No.2021BB004).
文摘On-site monitoring and numerical simulation have been combined to analyze the stability of the jointed surrounding rock and the stress inside the lining structure of a sample deeply buried hydraulic tunnel.We show that the deformation around the tunnel was mainly concentrated in the range 51.37 mm∼66.73 mm,the tunnel circumference was dominated by shear failure,and the maximum plastic zone was about 3.90 m.When the shotcrete treatment was performed immediately after the excavation,the deformation of the surrounding rock was reduced by 58.94%∼76.31%,and the extension of the plastic zone was relatively limited,thereby leading to improvements in terms of the stability of surrounding rock.When the support was provided at different time points,the stress of the surrounding rock in the shallow part of the tunnel was improved everywhere.In the tunnel section with high ground stress and joint development,when 10 cm steel fiber concrete spray layer and 40 cm C25 concrete secondary lining were used,the maximum tensile stress on the lining structure was 0.89 MPa,i.e.,it was less than the tensile strength of concrete,which indicates that the internal force of the lining can meet the overall requirements.
基金the financial support from the International Partnership Program of Chinese Academy of Sciences(Grant No.115242KYSB20160017)the Key Project of Natural Science Foundation of China(Grant No.11232014)National Natural Science Foundation of China(Grant No.51379202)
文摘The columnar jointed rock mass(CJR), composed of polygonal cross-sectional columns cut by several groups of joints in various directions, was exposed during the excavations of the Baihetan hydropower station, China. In order to investigate the unloading performances and the stability conditions during excavation of the columns, an experimental field study was performed. Firstly, on-site investigations indicated that the geotechnical problems, including rock relaxation, cracking and collapse, were the most prominent for the CJR Class I that contains intensive joint network and the smallest column sizes.Comprehensive field tests, including deformation measurement by multi-point extensometers, ultrasonic wave testing, borehole television observation and stress monitoring of rock anchors, revealed that the time-dependent relaxation of the CJRs was marked. The practical excavation experiences for the Baihetan columnar jointed rock masses, such as blasting scheme, supporting time of shotcrete and rock bolts, were presented in the excavations of the diversion tunnels. These detailed investigations and practical construction experiences can provide helpful information for similar geotechnical works in jointed rock mass.
文摘A 3-D temperature model for diversion tunnel was developed by combining k-εmodel and energy transport e-quation. The actual geometry data of the tunnel was used to construct athree-dimensional computational domain including the concrete lining. As the interaction betweentemperature and velocity fields can be taken into account, the model can be employed to accuratelysimulate the temperature and velocity field. The model was validated with the field data observed inthe diversion tunnel of the Nanya River. The water temperature of the diversion tunnel of theSecond Jinping Cascade Hy-dropower Station to be built was predicted. It is shown that thetemperature increase is not observable due to the large diameter of the tunnel, the big flow rateand the short contact time, The result can provide scientific foundation or reference for the designof hydropower station, and protection strategy of aquatic organisms and aquatic ecosystem.