Reducing the blasting vibration is important for blasting excavation in subway tunnel construction.Taking the 3rd bid section of Line 3 of Qingdao subway project as an example,the distance between tunnel vault and gro...Reducing the blasting vibration is important for blasting excavation in subway tunnel construction.Taking the 3rd bid section of Line 3 of Qingdao subway project as an example,the distance between tunnel vault and ground is 5 ~ 8 m.In order to insure the safety of the upper buildings,technologies of parallel cut with large diameter empty hole,one-time initiation and delay by parts,and multiple shallow holes were adopted in the project.The results showed that the maximum value of vertical vibration was limited in the criterion allowance,and the upper buildings were not damaged.Besides,problems were solved that the number of nonel detonator was difficult to meet the requirements of excavating a large cross-section tunnel by blasting,multiple cross-section could’t be initiated simultaneously,and construction efficiency was low,which ensure the construction safety and schedule.展开更多
This work studied the effect of increasing degree of metamorphism on the properties of rocks.The properties investigated are the physical,mechanical and dynamic parameters.They are important inputs in the design of ma...This work studied the effect of increasing degree of metamorphism on the properties of rocks.The properties investigated are the physical,mechanical and dynamic parameters.They are important inputs in the design of many mining and civil engineering techniques such as in tunnelling,slope stability and dynamic activities associated with seismicity and fragmentation.This work compared the degree of metamorphism examined through petrographic studies of the Transvaal Sequence in South Africa with the properties of the rocks.The study shows that as the effect metamorphism increases,the state of stress,compaction of grains,cementation and the brittleness of the rocks increases.In addition,increase in the metamorphic effect increases the value of the rock property.The degree of metamorphism of an outcrop is the key factor influencing its property value.Therefore the metamorphism effect of an outcrop may act as a guide to its engineering properties.展开更多
Nuclear engineering belongs to significant project;there is higher requirement on sitings.The study has discussed basic factors of selecting sites,anti-seismic research on sitings including the seismic ground motion,p...Nuclear engineering belongs to significant project;there is higher requirement on sitings.The study has discussed basic factors of selecting sites,anti-seismic research on sitings including the seismic ground motion,probability methods of seismic hazard analysis as well as interaction about structure and foundation,meanwhile provide the reason for nuclear engineering selecting sites.展开更多
A physical random function model of ground motions for engineering purposes is presented with verification of sample level. Firstly,we derive the Fourier spectral transfer form of the solution to the definition proble...A physical random function model of ground motions for engineering purposes is presented with verification of sample level. Firstly,we derive the Fourier spectral transfer form of the solution to the definition problem,which describes the one-dimensional seismic wave field. Then based on the special models of the source,path and local site,the physical random function model of ground motions is obtained whose physical parameters are random variables. The superposition method of narrow-band harmonic wave groups is improved to synthesize ground motion samples. Finally,an application of this model to simulate ground motion records in 1995 Kobe earthquake is described. The resulting accelerograms have the frequencydomain and non-stationary characteristics that are in full agreement with the realistic ground motion records.展开更多
Reservoir-induced earthquakes related with the construction of the Three Gorges Project have attracted great concerns of the public. Since the first water impoundment on May 25, 2003, a number of earthquakes have occu...Reservoir-induced earthquakes related with the construction of the Three Gorges Project have attracted great concerns of the public. Since the first water impoundment on May 25, 2003, a number of earthquakes have occurred during the water storage stages, in which the largest was the Badong M5.1 earthquake on December 16, 2013. In this paper, the relationships between seismic activities, b value, seismic parameters, and reservoir water level fluctuations are studied. In addition, based on the digital seismic waveform data obtained since 2000, the focal depth changes and focal mechanism characteristics before and after the water impoundment are studied as well. These provide us important information to understand the earthquake mechanisms. The results show that these earthquakes are typical reservoir-induced earthquakes, which are closely related to water infiltration, pore pressure, and water level fluctuations.The majority of the micro and small earthquakes are caused by karst collapse, mine collapse, bank reformation, superficial unloading, and so on. The larger earthquakes are related to the fault structures to some extent. Due to the persistent effects of water impoundment on the seismic and geological environments around the reservoir and water infiltration into the rocks, the influences on the crustal deformation field, gravity field, seepage field, and fault medium-softening action may vary gradually from a higher strength to a weaker one. Therefore, it is possible that small earthquakes and few medium earthquakes(M≤5.5) will occur in the reservoir area in the future.展开更多
文摘Reducing the blasting vibration is important for blasting excavation in subway tunnel construction.Taking the 3rd bid section of Line 3 of Qingdao subway project as an example,the distance between tunnel vault and ground is 5 ~ 8 m.In order to insure the safety of the upper buildings,technologies of parallel cut with large diameter empty hole,one-time initiation and delay by parts,and multiple shallow holes were adopted in the project.The results showed that the maximum value of vertical vibration was limited in the criterion allowance,and the upper buildings were not damaged.Besides,problems were solved that the number of nonel detonator was difficult to meet the requirements of excavating a large cross-section tunnel by blasting,multiple cross-section could’t be initiated simultaneously,and construction efficiency was low,which ensure the construction safety and schedule.
基金The School of Mining Engineering,University of the Witwatersrand South Africa is acknowledged for providing support towards the success of this researchSpecifically the Centennial Trust Fund for Rock Engineering is appreciated for funding part of this research
文摘This work studied the effect of increasing degree of metamorphism on the properties of rocks.The properties investigated are the physical,mechanical and dynamic parameters.They are important inputs in the design of many mining and civil engineering techniques such as in tunnelling,slope stability and dynamic activities associated with seismicity and fragmentation.This work compared the degree of metamorphism examined through petrographic studies of the Transvaal Sequence in South Africa with the properties of the rocks.The study shows that as the effect metamorphism increases,the state of stress,compaction of grains,cementation and the brittleness of the rocks increases.In addition,increase in the metamorphic effect increases the value of the rock property.The degree of metamorphism of an outcrop is the key factor influencing its property value.Therefore the metamorphism effect of an outcrop may act as a guide to its engineering properties.
文摘Nuclear engineering belongs to significant project;there is higher requirement on sitings.The study has discussed basic factors of selecting sites,anti-seismic research on sitings including the seismic ground motion,probability methods of seismic hazard analysis as well as interaction about structure and foundation,meanwhile provide the reason for nuclear engineering selecting sites.
基金supported by the Funds for Creative Research Groups of China (Grant No.50621062)
文摘A physical random function model of ground motions for engineering purposes is presented with verification of sample level. Firstly,we derive the Fourier spectral transfer form of the solution to the definition problem,which describes the one-dimensional seismic wave field. Then based on the special models of the source,path and local site,the physical random function model of ground motions is obtained whose physical parameters are random variables. The superposition method of narrow-band harmonic wave groups is improved to synthesize ground motion samples. Finally,an application of this model to simulate ground motion records in 1995 Kobe earthquake is described. The resulting accelerograms have the frequencydomain and non-stationary characteristics that are in full agreement with the realistic ground motion records.
基金supported by the National Natural Science Foundation of China (41572354)the Key Foundation of the Institute of Seismology (IS201616254)
文摘Reservoir-induced earthquakes related with the construction of the Three Gorges Project have attracted great concerns of the public. Since the first water impoundment on May 25, 2003, a number of earthquakes have occurred during the water storage stages, in which the largest was the Badong M5.1 earthquake on December 16, 2013. In this paper, the relationships between seismic activities, b value, seismic parameters, and reservoir water level fluctuations are studied. In addition, based on the digital seismic waveform data obtained since 2000, the focal depth changes and focal mechanism characteristics before and after the water impoundment are studied as well. These provide us important information to understand the earthquake mechanisms. The results show that these earthquakes are typical reservoir-induced earthquakes, which are closely related to water infiltration, pore pressure, and water level fluctuations.The majority of the micro and small earthquakes are caused by karst collapse, mine collapse, bank reformation, superficial unloading, and so on. The larger earthquakes are related to the fault structures to some extent. Due to the persistent effects of water impoundment on the seismic and geological environments around the reservoir and water infiltration into the rocks, the influences on the crustal deformation field, gravity field, seepage field, and fault medium-softening action may vary gradually from a higher strength to a weaker one. Therefore, it is possible that small earthquakes and few medium earthquakes(M≤5.5) will occur in the reservoir area in the future.
