The Three Gorges Reservoir is a good site for the further researches on reservoir induced seismicity due to decades' seismic monitoring. After the first water impounding in 2003, seismic activity becomes more frequen...The Three Gorges Reservoir is a good site for the further researches on reservoir induced seismicity due to decades' seismic monitoring. After the first water impounding in 2003, seismic activity becomes more frequent than that before water impoundment. In order to quantitatively study, the relationship between the water level fluctuation and earthquakes in TGR, we introduced statistical methods to attain the goal. First of all, we relocated the earthquakes in TGR region with double difference method and divided the earthquakes into 5 clusters with clustering analysis method. Secondly, to examine the impacts of water level fluctuation in different water filling stages on the seismic activity in the 5 clusters, a series of statistical analyses are applied. Pearson correlation results show that only the 175 m water level fluc- tuation has significantly positive impacts on the seismic activity in clusters I, II, III and V with correlation coefficients of 0.44, 0.38, 0.66 and 0.63. Cross-correlation analysis demonstrates that 0, ], 0 and 0 month time delay separately for the clusters I, II, III and V exists. It illustrated the influences of the water loading and pore pressure diffusion on induced earthquakes. Cointegration tests and impulse response analysis denoted that the 175 m water level only had long term and significant effects just on the seismic events in the intersection region of the Fairy Mount Fault and Nine-brook Fault. One standard deviation shock to 175 m water level increased the seismic activity in cluster V for the first 3 months, and then the negative influence was shown. After 7 months, the negative impulse response becomes stable. The long-term effect of the 175 m water impoundment also proved the important role of pore pressure diffusion in RIS with time.展开更多
As one of the most important urban lifeline systems,a water distribution system can be damaged under a strong earthquake,and the damage cannot easily be located,especially immediately after the event.This often causes...As one of the most important urban lifeline systems,a water distribution system can be damaged under a strong earthquake,and the damage cannot easily be located,especially immediately after the event.This often causes tremendous difficulties to post-earthquake emergency response and recovery activities.This paper proposes a methodology to locate seismic damage to a water distribution system by monitoring water head online at some nodes in the water distribution system.An artificial neural network-based inverse analysis method is developed to estimate the water head variations at all nodes that are not monitored based on the water head variations at the nodes that are monitored.The methodology provides a quick,effective,and practical way to locate seismic damage to a water distribution system.展开更多
Passive seismic interferometry takes advantage of natural ambient seismic noise generated by the wind, the storms and the human activities (e.g. cars, trains and hereafter pumps) to recover the slight variations of th...Passive seismic interferometry takes advantage of natural ambient seismic noise generated by the wind, the storms and the human activities (e.g. cars, trains and hereafter pumps) to recover the slight variations of the seismic wave velocity induced by changes in the groundwater level. Here we compare the seismic measurements with actual piezometric data acquired on the Crépieux-Charmy (Lyon, France) groundwater exploitation field. We show the excellent correspondance between variations in the groundwater level and seismic velocity variations. We present hereafter the time and space monitoring of an hydraulic dome formed to prevent biological and chemical pollutions to enter the exploitation field. The horizontal resolution is solely limited by the number of seismic stations used, and is about 30 m in the present study. The vertical resolution of seismic measurement is impaired by spurious artifacts linked to the intermittent sources of noise. In average, the sensitivity of the seismic velocity change corresponds to a 50 cm change of waterlevel. This study confirms the possibility of groundwater monitoring in an industrial context with ambient seismic noise.展开更多
We study the feature of media changes beneath the Zipingpu reservoir and discuss the process of permeation with the water level rise and fall of the reservoir from January 2005 to January 2008 from ambient noise cross...We study the feature of media changes beneath the Zipingpu reservoir and discuss the process of permeation with the water level rise and fall of the reservoir from January 2005 to January 2008 from ambient noise cross correlation by using continuous seismic data recorded by the stations of Zipingpu seismic network and YZP station. A moving-window cross-spectrum technique has been used to calculate the relative seismic velocity changes between station pairs. Results revealed an obvious relationship between relative seismic velocity, and the water level changes with a time delay that may be caused by permeation during three main impoundments and two large scale disemboguements. Impoundment generates a fast and large impact on the superficial layer, and the changes of seismic velocity is the result of increased pressure and permeation during the impoundment. At the first impoundment, the main effect factor is pressure. During the next two process of impoundment, permeation becomes the main effect factor, affecting the fault at a depth of about 8kin.展开更多
The effect of water compressibility on the seismic responses of arch dams is not well understood.In this paper,a numerical model is developed with rigorous representation of the dynamic interaction between arch dam-wa...The effect of water compressibility on the seismic responses of arch dams is not well understood.In this paper,a numerical model is developed with rigorous representation of the dynamic interaction between arch dam-water- rock foundation.The model is applied to the seismic response analysis of an arch dam with a height of 292m designed to a seismic intensity of IX.It is shown that consideration of the water compressibility clearly decreases the stress responses at key positions of the dam,while the added mass model gives a conservative estimate.展开更多
An approach to analyze the seismic reliability of water distribution networks by combining a hydraulic analysis with a first-order reliability method (FORM), is proposed in this paper. The hydraulic analysis method ...An approach to analyze the seismic reliability of water distribution networks by combining a hydraulic analysis with a first-order reliability method (FORM), is proposed in this paper. The hydraulic analysis method for normal conditions is modified to accommodate the special conditions necessary to perform a seismic hydraulic analysis. In order to calculate the leakage area and leaking flow of the pipelines in the hydraulic analysis method, a new leakage model established from the seismic response analysis of buried pipelines is presented. To validate the proposed approach, a network with 17 nodes and 24 pipelines is investigated in detail. The approach is also applied to an actual project consisting of 463 nodes and 767 pipelines. The results show that the proposed approach achieves satisfactory results in analyzing the seismic reliability of large-scale water distribution networks.展开更多
This paper describes a systematic study on the fundamental features of seismic soil pressure on underground tunnels, in terms of its magnitude and distribution, and further identifi es the dominant factors that signif...This paper describes a systematic study on the fundamental features of seismic soil pressure on underground tunnels, in terms of its magnitude and distribution, and further identifi es the dominant factors that signifi cantly infl uence the seismic soil pressure. A tunnel embedded in water-saturated poroelastic half-space is considered, with a large variety of model and excitation parameters. The primary features of both the total soil pressure and the pore pressure are investigated. Taking a circular tunnel as an example, the results are presented using a fi nite element-indirect boundary element(FE-IBE) method, which can account for dynamic soil-tunnel interaction and solid frame-pore water coupling. The effects of tunnel stiffness, tunnel buried depth and input motions on the seismic soil pressure and pore pressure are also examined. It is shown that the most crucial factors that dominate the magnitude and distribution of the soil pressure are the tunnel stiffness and dynamic soil-tunnel interaction. Moreover, the solid frame-pore water coupling has a prominent infl uence on the magnitude of the pore pressure. The fi ndings are benefi cial to obtain insight into the seismic soil pressure on underground tunnels, thus facilitating more accurate estimation of the seismic soil pressure.展开更多
Hydrological and marine seismic data, collected in the Gulf of Cadiz (respectively in July 1999, 2000, 2001 and 2002, and in April 2000 and 2001) are analysed to reveal the various structures of Mediterranean Water (M...Hydrological and marine seismic data, collected in the Gulf of Cadiz (respectively in July 1999, 2000, 2001 and 2002, and in April 2000 and 2001) are analysed to reveal the various structures of Mediterranean Water (MW). Both the hydrological and seismic data clearly identify the MW undercurrents on the Iberian slope, detached MW eddies (meddies and a cyclone) and smaller fragments of MW (filaments and small eddies). Seismic reflectivity and synthetic reflectivity computed from hydrology, indicate that strong acoustic reflectors, associated with 8 - 64 m thick homogeneous water layers, are found above and below meddies and filaments, around the MW undercurrents, but mostly in the lower part of cyclones and below submesoscale eddies. Reflectors are also observed in the near surface layers where thermohaline contrasts are quite pronounced. The successful use of seismic data to locate submesoscale MW structures, superior to that of hydrology, is related to the improved horizontal resolution.展开更多
There is a global trend for seismic response improvement of new buildings to reduce cost and future damage. It is also important to improve existing structures that are designed without consideration of seismic load o...There is a global trend for seismic response improvement of new buildings to reduce cost and future damage. It is also important to improve existing structures that are designed without consideration of seismic load or using old provisions that cannot meet the new one. The objective of this paper is to draw attention to evaluate existing reinforced concrete school buildings, then to present a proposed methodology to improve the behaviour of such schools with low cost especially in a developing country. The proposed method uses overhead water tanks as a tuned mass damper. A pushover analysis has been performed to evaluate the existing schools and perform a feasibility study to select the best solution to achieve seismic response improvement of the existing structure. Of course, the proposed methodology can be applied easily to other existing structures.展开更多
基金financially supported by the fund of the institute of seismology,China Earthquake Administration(IS201616254)National Natural Science Foundation of China(41572354,41304046)
文摘The Three Gorges Reservoir is a good site for the further researches on reservoir induced seismicity due to decades' seismic monitoring. After the first water impounding in 2003, seismic activity becomes more frequent than that before water impoundment. In order to quantitatively study, the relationship between the water level fluctuation and earthquakes in TGR, we introduced statistical methods to attain the goal. First of all, we relocated the earthquakes in TGR region with double difference method and divided the earthquakes into 5 clusters with clustering analysis method. Secondly, to examine the impacts of water level fluctuation in different water filling stages on the seismic activity in the 5 clusters, a series of statistical analyses are applied. Pearson correlation results show that only the 175 m water level fluc- tuation has significantly positive impacts on the seismic activity in clusters I, II, III and V with correlation coefficients of 0.44, 0.38, 0.66 and 0.63. Cross-correlation analysis demonstrates that 0, ], 0 and 0 month time delay separately for the clusters I, II, III and V exists. It illustrated the influences of the water loading and pore pressure diffusion on induced earthquakes. Cointegration tests and impulse response analysis denoted that the 175 m water level only had long term and significant effects just on the seismic events in the intersection region of the Fairy Mount Fault and Nine-brook Fault. One standard deviation shock to 175 m water level increased the seismic activity in cluster V for the first 3 months, and then the negative influence was shown. After 7 months, the negative impulse response becomes stable. The long-term effect of the 175 m water impoundment also proved the important role of pore pressure diffusion in RIS with time.
基金National Natural Science Foundation of China under Grant No.59878032
文摘As one of the most important urban lifeline systems,a water distribution system can be damaged under a strong earthquake,and the damage cannot easily be located,especially immediately after the event.This often causes tremendous difficulties to post-earthquake emergency response and recovery activities.This paper proposes a methodology to locate seismic damage to a water distribution system by monitoring water head online at some nodes in the water distribution system.An artificial neural network-based inverse analysis method is developed to estimate the water head variations at all nodes that are not monitored based on the water head variations at the nodes that are monitored.The methodology provides a quick,effective,and practical way to locate seismic damage to a water distribution system.
文摘Passive seismic interferometry takes advantage of natural ambient seismic noise generated by the wind, the storms and the human activities (e.g. cars, trains and hereafter pumps) to recover the slight variations of the seismic wave velocity induced by changes in the groundwater level. Here we compare the seismic measurements with actual piezometric data acquired on the Crépieux-Charmy (Lyon, France) groundwater exploitation field. We show the excellent correspondance between variations in the groundwater level and seismic velocity variations. We present hereafter the time and space monitoring of an hydraulic dome formed to prevent biological and chemical pollutions to enter the exploitation field. The horizontal resolution is solely limited by the number of seismic stations used, and is about 30 m in the present study. The vertical resolution of seismic measurement is impaired by spurious artifacts linked to the intermittent sources of noise. In average, the sensitivity of the seismic velocity change corresponds to a 50 cm change of waterlevel. This study confirms the possibility of groundwater monitoring in an industrial context with ambient seismic noise.
基金sponsored by the National Natural Science Foundation of China (2012BAK1902)
文摘We study the feature of media changes beneath the Zipingpu reservoir and discuss the process of permeation with the water level rise and fall of the reservoir from January 2005 to January 2008 from ambient noise cross correlation by using continuous seismic data recorded by the stations of Zipingpu seismic network and YZP station. A moving-window cross-spectrum technique has been used to calculate the relative seismic velocity changes between station pairs. Results revealed an obvious relationship between relative seismic velocity, and the water level changes with a time delay that may be caused by permeation during three main impoundments and two large scale disemboguements. Impoundment generates a fast and large impact on the superficial layer, and the changes of seismic velocity is the result of increased pressure and permeation during the impoundment. At the first impoundment, the main effect factor is pressure. During the next two process of impoundment, permeation becomes the main effect factor, affecting the fault at a depth of about 8kin.
基金National Natural Science Foundation of China for Distinguished Young Scholar of China Under Grant No.50325826National Natural Science Foundation of China Under Grant No.50309005Science & Technology Development Project of Education Committee of Beijing Under Grant No.KM200310005017
文摘The effect of water compressibility on the seismic responses of arch dams is not well understood.In this paper,a numerical model is developed with rigorous representation of the dynamic interaction between arch dam-water- rock foundation.The model is applied to the seismic response analysis of an arch dam with a height of 292m designed to a seismic intensity of IX.It is shown that consideration of the water compressibility clearly decreases the stress responses at key positions of the dam,while the added mass model gives a conservative estimate.
基金Natural Science Funds for the Innovative ResearchGroup of China Under Grant No.50321803
文摘An approach to analyze the seismic reliability of water distribution networks by combining a hydraulic analysis with a first-order reliability method (FORM), is proposed in this paper. The hydraulic analysis method for normal conditions is modified to accommodate the special conditions necessary to perform a seismic hydraulic analysis. In order to calculate the leakage area and leaking flow of the pipelines in the hydraulic analysis method, a new leakage model established from the seismic response analysis of buried pipelines is presented. To validate the proposed approach, a network with 17 nodes and 24 pipelines is investigated in detail. The approach is also applied to an actual project consisting of 463 nodes and 767 pipelines. The results show that the proposed approach achieves satisfactory results in analyzing the seismic reliability of large-scale water distribution networks.
基金Supported by:National Natural Science Foundation of China under Grant No.51978462
文摘This paper describes a systematic study on the fundamental features of seismic soil pressure on underground tunnels, in terms of its magnitude and distribution, and further identifi es the dominant factors that signifi cantly infl uence the seismic soil pressure. A tunnel embedded in water-saturated poroelastic half-space is considered, with a large variety of model and excitation parameters. The primary features of both the total soil pressure and the pore pressure are investigated. Taking a circular tunnel as an example, the results are presented using a fi nite element-indirect boundary element(FE-IBE) method, which can account for dynamic soil-tunnel interaction and solid frame-pore water coupling. The effects of tunnel stiffness, tunnel buried depth and input motions on the seismic soil pressure and pore pressure are also examined. It is shown that the most crucial factors that dominate the magnitude and distribution of the soil pressure are the tunnel stiffness and dynamic soil-tunnel interaction. Moreover, the solid frame-pore water coupling has a prominent infl uence on the magnitude of the pore pressure. The fi ndings are benefi cial to obtain insight into the seismic soil pressure on underground tunnels, thus facilitating more accurate estimation of the seismic soil pressure.
文摘Hydrological and marine seismic data, collected in the Gulf of Cadiz (respectively in July 1999, 2000, 2001 and 2002, and in April 2000 and 2001) are analysed to reveal the various structures of Mediterranean Water (MW). Both the hydrological and seismic data clearly identify the MW undercurrents on the Iberian slope, detached MW eddies (meddies and a cyclone) and smaller fragments of MW (filaments and small eddies). Seismic reflectivity and synthetic reflectivity computed from hydrology, indicate that strong acoustic reflectors, associated with 8 - 64 m thick homogeneous water layers, are found above and below meddies and filaments, around the MW undercurrents, but mostly in the lower part of cyclones and below submesoscale eddies. Reflectors are also observed in the near surface layers where thermohaline contrasts are quite pronounced. The successful use of seismic data to locate submesoscale MW structures, superior to that of hydrology, is related to the improved horizontal resolution.
文摘There is a global trend for seismic response improvement of new buildings to reduce cost and future damage. It is also important to improve existing structures that are designed without consideration of seismic load or using old provisions that cannot meet the new one. The objective of this paper is to draw attention to evaluate existing reinforced concrete school buildings, then to present a proposed methodology to improve the behaviour of such schools with low cost especially in a developing country. The proposed method uses overhead water tanks as a tuned mass damper. A pushover analysis has been performed to evaluate the existing schools and perform a feasibility study to select the best solution to achieve seismic response improvement of the existing structure. Of course, the proposed methodology can be applied easily to other existing structures.