Objective:To analyze the existing risks in breast milk management at the neonatal department and provide corresponding countermeasures.Methods:22 risk events were identified in 7 risk links in the process of bottle-fe...Objective:To analyze the existing risks in breast milk management at the neonatal department and provide corresponding countermeasures.Methods:22 risk events were identified in 7 risk links in the process of bottle-feeding of breast milk.Hazard Vulnerability Analysis based on the Kaiser model was applied to investigate and evaluate the risk events.Results:High-risk events include breast milk quality inspection,hand hygiene during collection,disinfection of collectors,cold chain management,hand hygiene during the reception,breast milk closed-loop management,and post-collection disposal.Root cause analysis of high-risk events was conducted and breast milk management strategies outside the hospital and within the neonatal department were proposed.Conclusion:Hazard Vulnerability Analysis based on the Kaiser model can identify and assess neonatal breast milk management risks effectively,which helps improve the management of neonatal breast milk.It is conducive to the safe development and promotion of bottle feeding of breast milk for neonates,ensuring the quality of medical services and the safety of children.展开更多
A comprehensive evaluation method is proposed to analyze dust pollution generated in the production process of mines.The method employs an optimized image-processing and deep learning framework to characterize the gra...A comprehensive evaluation method is proposed to analyze dust pollution generated in the production process of mines.The method employs an optimized image-processing and deep learning framework to characterize the gray and fractal features in dust images.The research reveals both linear and logarithmic correlations between the gray features,fractal dimension,and dust mass,while employing Chauvenel criteria and arithmetic averaging to minimize data discreteness.An integrated hazardous index is developed,including a logarithmic correlation between the index and dust mass,and a four-category dataset is subsequently prepared for the deep learning framework.Based on the range of the hazardous index,the dust images are divided into four categories.Subsequently,a dust risk classifcation system is established using the deep learning model,which exhibits a high degree of performance after the training process.Notably,the model achieves a testing accuracy of 95.3%,indicating its efectiveness in classifying diferent levels of dust pollution,and the precision,recall,and F1-score of the system confrm its reliability in analyzing dust pollution.Overall,the proposed method provides a reliable and efcient way to monitor and analyze dust pollution in mines.展开更多
The authors study the structure, functions and data organization for the hazard analysis system of urban post-earthquake fire on the platform of GIS. A general hazard analysis model of the post-earthquake fire is pres...The authors study the structure, functions and data organization for the hazard analysis system of urban post-earthquake fire on the platform of GIS. A general hazard analysis model of the post-earthquake fire is presented. Taking Shanghai central district as background, a system for hazard analysis of the post-earthquake fire and auxiliary decision-against fire is developed.展开更多
In this study, we present a PSHA(Probabilistic Seismic Hazard Analysis) for the city of San Juan, which is located in the central-western region of Argentina(30°S-35.5°S; 66.5°W-71°W). In addit...In this study, we present a PSHA(Probabilistic Seismic Hazard Analysis) for the city of San Juan, which is located in the central-western region of Argentina(30°S-35.5°S; 66.5°W-71°W). In addition to crustal earthquakes provided by catalogues, recent paleoseismological and neotectonic investigations have permitted to consider events which occurred during the last 400 years.Four seismogenic sources that could cause damages to the studied site corresponding to Precordillera,Western Sierras Pampeanas, Basement of the Cuyana Basin and Cordillera Principal were identified.Based on the evaluation of the contribution of these sources,maximum moment magnitudes above 7.5(Mw) are expected.High values of SA(spectral acceleration)(0.2 and 1 s periods) and PGA(peak ground acceleration) were found in the city of San Juan, which suggests that it is located in a zone of high seismic hazard.Finally, the obtained SA spectra were compared with the seismic-resistant construction standards of Argentina INPRES-CIRSOC 103 [1]. Results suggest that for the city of San Juan and for a return period of475 years, it covers the seismic requirements of the structures.展开更多
A mature mathematical technique called copula joint function is introduced in this paper, which is commonly used in the financial risk analysis to estimate uncertainty. The joint function is generalized to the n-dimen...A mature mathematical technique called copula joint function is introduced in this paper, which is commonly used in the financial risk analysis to estimate uncertainty. The joint function is generalized to the n-dimensional Frank’s copula. In addition, we adopt two attenuation models proposed by YU and Boore et al, respectively, and construct a two-dimensional copula joint probabilistic function as an example to illustrate the uncertainty treatment at low probability. The results show that copula joint function gives us a better prediction of peak ground motion than that resultant from the simple linear weight technique which is commonly used in the traditional logic-tree treatment of model uncertainties. In light of widespread application in the risk analysis from financial investment to insurance assessment, we believe that the copula-based technique will have a potential application in the seismic hazard analysis.展开更多
Potential sources are simplified as point sources or linear sources in current probabilistic seismic hazard analysis (PSHA) methods. Focus size of large earthquakes is considerable, and fault rupture attitudes may h...Potential sources are simplified as point sources or linear sources in current probabilistic seismic hazard analysis (PSHA) methods. Focus size of large earthquakes is considerable, and fault rupture attitudes may have great influence upon the seismic hazard of a site which is near the source. Under this circumstance, it is unreasonable to use the simplified potential source models in the PSHA, so a potential rupture surface model is proposed in this paper. Adopting this model, we analyze the seismic hazard near the Chelungpu fault that generated the Chi-Chi (Jiji) earthquake with magnitude 7.6 and the following conclusions are reached. (1) This model is reasonable on the base of focal mechanism, especially for sites near potential earthquakes with large magnitude; (2) The attitudes of potential rupture surfaces have great influence on the results of probabilistic seismic hazard analysis and seismic zoning.展开更多
This paper presents an effective means of analyzing the safety of a tunnel under dynamic loading in areas<span style="font-family:Verdana;"> </span><span style="font-family:Verdana;"...This paper presents an effective means of analyzing the safety of a tunnel under dynamic loading in areas<span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">with seismic records. A particular case of the railway tunnel in the earthquake-prone regions of the escarpment seismic zone of Ethiopia was the specific focus area of the research. Probabilistic seismic hazard analysis (PSHA) and deaggregation have been conducted to determine the design earthquake required as an input for the dynamic analysis. The PSHA</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">performed by considering the operating design earthquake with conservative assumptions of the local geological features resulted in a peak ground acceleration of 0.36. Two pairs of design earthquake have been obtained from the deaggregation process, which were used to filter acceleration time histories for the selected design earthquake from the ground motion database of Pacific Earthquake Engineering Research Center. Finally, full dynamic analyses of the tunnel have been performed by applying the scaled acceleration time histories corresponding to the structure in the specific site. It was demonstrated how to prove the stability of the tunnel located in difficult ground conditions by performing plane strain analyses with the possible minimum computational efforts.</span>展开更多
This study aims to utilize the Small Baseline Subset Interferometric Synthetic Aperture Radar(SBAS-In SAR)technique and Google Earth optical remote sensing images to analyze the area within 20 km around the epicenter ...This study aims to utilize the Small Baseline Subset Interferometric Synthetic Aperture Radar(SBAS-In SAR)technique and Google Earth optical remote sensing images to analyze the area within 20 km around the epicenter of a M 3.9, earthquake that occurred in Tanchang County, Gansu Province, on December 28, 2020. The objective is to identify potential earthquake-induced landslides, assess their scale, and determine their impact range. The study results reveal the successful identification of two potential landslides in the 20 km radius around the epicenter. Through time-series deformation analysis, it was observed that these potential landslides were significantly influenced by both the earthquake and rainfall. Further estimation of these potential landslides indicates maximum depths of 7.4 m and 14.1 m for the failure surfaces, with volumes of 9.02 × 10~4m~3and 25.5 ×10~4m~3, respectively. Finally, based on the simulation analysis of Massflow software, the maximum thickness of soil accumulation in the final accumulation area after sliding of the potential landslide in Shangyaai is 12 m, the area of the final accumulation area is 1.75 × 10~4m~2, and the farthest movement distance is 1124 m. The maximum thickness of soil accumulation in the final accumulation area after sliding of the potential landslide in Wangshancun is 8 m, the area of the final accumulation area is 7.89 × 10~4m~2, and the farthest movement distance is 742 m.展开更多
Fault parameters are important in earthquake hazard analysis.In this paper,theoretical relationships between moment magnitude and fault parameters including subsurface rupture length,downdip rupture width,rupture area...Fault parameters are important in earthquake hazard analysis.In this paper,theoretical relationships between moment magnitude and fault parameters including subsurface rupture length,downdip rupture width,rupture area,and average slip over the fault surface are deduced based on seismological theory.These theoretical relationships are further simplified by applying similarity conditions and an unique form is established.Then,combining the simplified theoretical relationships between moment magnitude and fault parameters with seismic source data selected in this study,a practical semi-empirical relationship is established.The seismic source data selected is also to used to derive empirical relationships between moment magnitude and fault parameters by the ordinary least square regression method.Comparisons between semi-empirical relationships and empirical relationships show that the former depict distribution trends of data better than the latter.It is also observed that downdip rupture widths of strike slip faults are saturated when moment magnitude is more than 7.0,but downdip rupture widths of dip slip faults are not saturated in the molnent magnitude rangcs of this study.展开更多
This paper presents probabilistic assessment of seismically-induced slope displacements considering uncertainties of seismic ground motions and soil properties.A stochastic ground motion model representing both the te...This paper presents probabilistic assessment of seismically-induced slope displacements considering uncertainties of seismic ground motions and soil properties.A stochastic ground motion model representing both the temporal and spectral non-stationarity of earthquake shakings and a three-dimensional rotational failure mechanism are integrated to assess Newmark-type slope displacements.A new probabilistic approach that incorporates machine learning in metamodeling technique is proposed,by combining relevance vector machine with polynomial chaos expansions(RVM-PCE).Compared with other PCE methods,the proposed RVM-PCE is shown to be more effective in estimating failure probabilities.The sensitivity and relative influence of each random input parameter to the slope displacements are discussed.Finally,the fragility curves for slope displacements are established for sitespecific soil conditions and earthquake hazard levels.The results indicate that the slope displacement is more sensitive to the intensities and strong shaking durations of seismic ground motions than the frequency contents,and a critical Arias intensity that leads to the maximum annual failure probabilities can be identified by the proposed approach.展开更多
In this study, we adopt an improved Bayesian approach based on free-knot B-spline bases to study the spatial and temporal distribution of the b-value. Synthetic tests show that the improved Bayesian approach has a sup...In this study, we adopt an improved Bayesian approach based on free-knot B-spline bases to study the spatial and temporal distribution of the b-value. Synthetic tests show that the improved Bayesian approach has a superior performance compared to the Bayesian approach as well as the widely used maximum likelihood estimation (MLE) method in fitting the real variation of b-values. We then apply the improved Bayesian approach to North China and find that the b-value has a clear relevance to seismicity. Temporal changes of b-values are also investigated in two specific areas of North China. We interpret sharp decreases in the b-values as useful messages in earthquake hazard analysis.展开更多
It is pointed out in this paper that the concept of scenario earthquake, expectant earthquake or proposed earthquake suggested by Kameda Nojima (1988) is not probability consistent due to unfit understanding for the ...It is pointed out in this paper that the concept of scenario earthquake, expectant earthquake or proposed earthquake suggested by Kameda Nojima (1988) is not probability consistent due to unfit understanding for the aseismic design standard of probabilistic method. The corresponding concept proposed by QI FENG LUO meets the meaning of probability consistent, but it is still in a meaning of average so the result is not good enough. On the basis of above analysis, a concept of probability consistent conservative earthquakes is suggested. And a new method selecting aseismic objective earthquake with physical meaning is proposed on the basis of probabilistic method. After seismic hazard is analysed by certain control parameters, such as peak acceleration, we can determine the aseismic standard according to certain probabilistic level. Based on the attenuation law and the potential sources, we can find out some earthquakes or their combinations of magnitudes and distances. Such earthquakes or combinations are probability consistent for this control parameter. Based on above parameter, we suggest considering the destructive effects of other parameters (such as response spectrum), and selecting conservative earthquakes to replace the average earthquake and meet the requirements of aseismic design better.展开更多
The computation of the representative ground motions,to be used as input for the dynamic analyses of a struc- ture at a particular site,can be approached by several methods.The choice of the approach depends on two fa...The computation of the representative ground motions,to be used as input for the dynamic analyses of a struc- ture at a particular site,can be approached by several methods.The choice of the approach depends on two factors:the da- ta available and the type of problem to be solved.This paper reports the experience of the authors in approaching a specific case study:the Southern Memnon Colossus,located in Luxor,Egypt.The results are of interest when the hazard analysis estimation in developing countries and the safeguard of cultural heritage are concerned.Monuments have to be treated as important structures,due to their historical and economical value.Hence,standard procedures of probabilistic seismic haz- ard analysis for the seismic classification of common buildings have to be disregarded.On the other hand,the consequences of the collapse of a monument are not comparable to those related to structures such as nuclear power plants and large dams, for which the deterministic seismic hazard analysis provides a straightforward framework for evaluation of the worst case ground motions.An'intermediate'approach,which requites a lower amount of input data with respect to the deterministic one,is adopted.Its stochastic component can eapture significant eharacteristics of earthquakes,primarily the frequency contents which depend on the magnitude(often referred to as the earthquake scaling law).展开更多
In this study, a composite source model has been used to calculate the realistic strong ground motions in Beijing area, caused by 1679 Ms8.0 earthquake in Sanhe-Pinggu. The results could provide us the useful physical...In this study, a composite source model has been used to calculate the realistic strong ground motions in Beijing area, caused by 1679 Ms8.0 earthquake in Sanhe-Pinggu. The results could provide us the useful physical parameters for the future seismic hazard analysis in this area. Considering the regional geological/geophysical background, we simulated the scenario earthquake with an associated ground motions in the area ranging from 39.3°N to 41. 1°N in latitude and from 115.35°E to 117.55°E in longitude. Some of the key factors which could influence the characteristics of strong ground motion have been discussed, and the resultant peak ground acceleration (PGA) distribution and the peak ground velocity (PGV) distribution around Beijing area also have been made as well. A comparison of the simulated result with the results derived from the attenuation relation has been made, and a sufficient discussion about the advantages and disadvantages of composite source model also has been given in this study. The numerical results, such as the PGA, PGV, peak ground displacement (PGD), and the three-component time-histories developed for Beijing area, have a potential application in earthquake engineering field and building code design, especially for the evaluation of critical constructions, government decision making and the seismic hazard assessment by financial/insurance companies.展开更多
Based on the modern earthquake catalogue,the incomplete centroidal voronoi tessellation(ICVT)method was used in this study to estimate the seismic hazard in Sichuan-Yunnan region of China.We calculated spatial distrib...Based on the modern earthquake catalogue,the incomplete centroidal voronoi tessellation(ICVT)method was used in this study to estimate the seismic hazard in Sichuan-Yunnan region of China.We calculated spatial distributions of the total seismic hazard and background seismic hazard in this area.The Bayesian delaunay tessellation smoothing method put forward by Ogata was used to calculate the spatial distributions of b-value.The results show that seismic hazards in Sichuan-Yunan region are high,and areas with relatively high hazard values are distributed along the main faults,while seismic hazards in Sichuan basin are relatively low.展开更多
The seismic hazard of research area is evaluated by probabilistic analysis method for three different seismic statis-tical zone scenarios. The influence of uncertainty in seismic statistical zone delimiting on the eva...The seismic hazard of research area is evaluated by probabilistic analysis method for three different seismic statis-tical zone scenarios. The influence of uncertainty in seismic statistical zone delimiting on the evaluation result is discussed too. It can be seen that for those local sites along zone's border or within areas with vast change of upper bound magnitude among different scenarios the influence on seismic hazard result should not be neglected.展开更多
This paper makes a summary of status of delimitation of seismic zones and belts of China firstly in aspects of studying history, purpose, usage, delimiting principles, various presenting forms and main specialties. Th...This paper makes a summary of status of delimitation of seismic zones and belts of China firstly in aspects of studying history, purpose, usage, delimiting principles, various presenting forms and main specialties. Then the viewpoints are emphasized, making geographical divisions by seismicity is just the most important purpose of delimiting seismic belts and the concept of seismic belt is also quite different from that of seismic statistical zone used in CPSHA method. The concept of seismic statistical zone and its history of evolvement are introduced too. Large differences between these rwo concepts exist separately in their statistical property, actual meaning, gradation, required scale, and property of refusing to overlap each other, aim and usage of delimitation. But in current engineering practice, these two concepts are confused. On the one hand, it causes no fit theory for delimiting seismic statistical zone in PSHA to be set up; on the other hand, researches about delimitation of seismic belts with purposes of seismicity zoning and studying on structural environment, mechanism of earthquake generating also pause to go ahead. Major conclusions are given in the end of this paper, that seismic statistical zone bases on the result of seismic belt delimiting, it only arises in and can be used in the especial PSHA method of China with considering spatially and temporally inhomogeneous seismic activities, and its concept should be clearly differentiated from the concept of seismic belt.展开更多
The proposed site of the Diamer Bhasha Dam in northern Pakistan is situated in an active tectonic zone with intensive seismicity,which makes it necessary for seismic hazard analysis(SHA).Deterministic and probabilisti...The proposed site of the Diamer Bhasha Dam in northern Pakistan is situated in an active tectonic zone with intensive seismicity,which makes it necessary for seismic hazard analysis(SHA).Deterministic and probabilistic approaches have been used for SHA of the dam site.The Main Mantle Thrust(MMT),Main Karakaram Thrust(MKT),Raikot-Sassi Fault(RKSF)and Kohistan Fault(KF)have been considered as major seismic sources,all of which can create maximum ground shaking with maximum potential earthquake(MPE).Deterministically estimated MPE for magnitudes of 7.8,7.7,7.6,and 7.1 can be produced from MMT,MKT,RKSF and KF,respectively.The corresponding peak ground accelerations(PGA)of 0.07,0.11,0.13 and 0.05 g can also be generated from these earthquakes,respectively.The deterministic analysis predicts a so-called floating earthquake as a MPE of magnitude=7.1 as close as 10 km away from the site.The corresponding PGA was computed as 0.38 g for a maximum design earthquake at the project site.However,the probabilistic analysis revealed that the PGA with 50%probability of exceedance in 100 years is 0.18 g.Thus,this PGA value related to the operational basis earthquake(OBE)is suggested for the design of this project with shear wave velocity(V_(s30))equal to 760 m/s under dense soil and soft rock conditions.展开更多
Many destructive earthquakes happened in Tehran, Iran in the last centuries. The existence of active faults like the North Tehran is the main cause of seismicity in this city. According to past investigations, it is e...Many destructive earthquakes happened in Tehran, Iran in the last centuries. The existence of active faults like the North Tehran is the main cause of seismicity in this city. According to past investigations, it is estimated that in the scenario of activation of the North Tehran fault, many structures in Tehran will collapse. Therefore, it is necessary to incorporate the near field rupture directivity effects of this fault into the seismic hazard assessment of important sites in Tehran. In this study, using calculations coded in MATLAB, Probabilistic Seismic Hazard Analysis (PSHA) is conducted for an important site in Tehran. Following that, deaggregation technique is performed on PSHA and the contribution of seis- mic scenarios to hazard is obtained in the range of distance and magnitude. After identifying the North Tehran fault as the most hazardous source affecting the site in 10000-year return period, rupture directivity effects of this fault is incorporated into the seismic hazard assessment using Somerville et al. (1997) model with broadband approach and Shahi and Baker (2011) model with narrowband approach. The results show that the narrowband approach caused a 27% increase in the peak of response spectrum in 10000-year return period compared with the conventional PSHA. Therefore, it is necessary to incorporate the near fault rupture directivity effects into the higher levels of seismic hazard assessment attributed to important sites.展开更多
文摘Objective:To analyze the existing risks in breast milk management at the neonatal department and provide corresponding countermeasures.Methods:22 risk events were identified in 7 risk links in the process of bottle-feeding of breast milk.Hazard Vulnerability Analysis based on the Kaiser model was applied to investigate and evaluate the risk events.Results:High-risk events include breast milk quality inspection,hand hygiene during collection,disinfection of collectors,cold chain management,hand hygiene during the reception,breast milk closed-loop management,and post-collection disposal.Root cause analysis of high-risk events was conducted and breast milk management strategies outside the hospital and within the neonatal department were proposed.Conclusion:Hazard Vulnerability Analysis based on the Kaiser model can identify and assess neonatal breast milk management risks effectively,which helps improve the management of neonatal breast milk.It is conducive to the safe development and promotion of bottle feeding of breast milk for neonates,ensuring the quality of medical services and the safety of children.
基金supported by the National Natural Science Foundation of China(52174099)the Natural Science Foundation of Liaoning Province(2021-KF-23-01)the Fundamental Research Funds for the Central Universities of Central South University(2022ZZTS0510).
文摘A comprehensive evaluation method is proposed to analyze dust pollution generated in the production process of mines.The method employs an optimized image-processing and deep learning framework to characterize the gray and fractal features in dust images.The research reveals both linear and logarithmic correlations between the gray features,fractal dimension,and dust mass,while employing Chauvenel criteria and arithmetic averaging to minimize data discreteness.An integrated hazardous index is developed,including a logarithmic correlation between the index and dust mass,and a four-category dataset is subsequently prepared for the deep learning framework.Based on the range of the hazardous index,the dust images are divided into four categories.Subsequently,a dust risk classifcation system is established using the deep learning model,which exhibits a high degree of performance after the training process.Notably,the model achieves a testing accuracy of 95.3%,indicating its efectiveness in classifying diferent levels of dust pollution,and the precision,recall,and F1-score of the system confrm its reliability in analyzing dust pollution.Overall,the proposed method provides a reliable and efcient way to monitor and analyze dust pollution in mines.
基金National Outstanding Youth Science Foundation (59825105).
文摘The authors study the structure, functions and data organization for the hazard analysis system of urban post-earthquake fire on the platform of GIS. A general hazard analysis model of the post-earthquake fire is presented. Taking Shanghai central district as background, a system for hazard analysis of the post-earthquake fire and auxiliary decision-against fire is developed.
文摘In this study, we present a PSHA(Probabilistic Seismic Hazard Analysis) for the city of San Juan, which is located in the central-western region of Argentina(30°S-35.5°S; 66.5°W-71°W). In addition to crustal earthquakes provided by catalogues, recent paleoseismological and neotectonic investigations have permitted to consider events which occurred during the last 400 years.Four seismogenic sources that could cause damages to the studied site corresponding to Precordillera,Western Sierras Pampeanas, Basement of the Cuyana Basin and Cordillera Principal were identified.Based on the evaluation of the contribution of these sources,maximum moment magnitudes above 7.5(Mw) are expected.High values of SA(spectral acceleration)(0.2 and 1 s periods) and PGA(peak ground acceleration) were found in the city of San Juan, which suggests that it is located in a zone of high seismic hazard.Finally, the obtained SA spectra were compared with the seismic-resistant construction standards of Argentina INPRES-CIRSOC 103 [1]. Results suggest that for the city of San Juan and for a return period of475 years, it covers the seismic requirements of the structures.
基金Project of Institute of Crustal Dynamics, China Earthquake Administration (ZDJ2007-1)One Hundred Individual Program of Chinese Academy of Sciences (99M2009M02) National Natural Science Foundation of China (40574022)
文摘A mature mathematical technique called copula joint function is introduced in this paper, which is commonly used in the financial risk analysis to estimate uncertainty. The joint function is generalized to the n-dimensional Frank’s copula. In addition, we adopt two attenuation models proposed by YU and Boore et al, respectively, and construct a two-dimensional copula joint probabilistic function as an example to illustrate the uncertainty treatment at low probability. The results show that copula joint function gives us a better prediction of peak ground motion than that resultant from the simple linear weight technique which is commonly used in the traditional logic-tree treatment of model uncertainties. In light of widespread application in the risk analysis from financial investment to insurance assessment, we believe that the copula-based technique will have a potential application in the seismic hazard analysis.
基金Foundation item: Joint Seismological Science Foundation of China (104065)Social Public Welfare Special Foundation of the Na-tional Research Institutes (2005DIB3J119).
文摘Potential sources are simplified as point sources or linear sources in current probabilistic seismic hazard analysis (PSHA) methods. Focus size of large earthquakes is considerable, and fault rupture attitudes may have great influence upon the seismic hazard of a site which is near the source. Under this circumstance, it is unreasonable to use the simplified potential source models in the PSHA, so a potential rupture surface model is proposed in this paper. Adopting this model, we analyze the seismic hazard near the Chelungpu fault that generated the Chi-Chi (Jiji) earthquake with magnitude 7.6 and the following conclusions are reached. (1) This model is reasonable on the base of focal mechanism, especially for sites near potential earthquakes with large magnitude; (2) The attitudes of potential rupture surfaces have great influence on the results of probabilistic seismic hazard analysis and seismic zoning.
文摘This paper presents an effective means of analyzing the safety of a tunnel under dynamic loading in areas<span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">with seismic records. A particular case of the railway tunnel in the earthquake-prone regions of the escarpment seismic zone of Ethiopia was the specific focus area of the research. Probabilistic seismic hazard analysis (PSHA) and deaggregation have been conducted to determine the design earthquake required as an input for the dynamic analysis. The PSHA</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">performed by considering the operating design earthquake with conservative assumptions of the local geological features resulted in a peak ground acceleration of 0.36. Two pairs of design earthquake have been obtained from the deaggregation process, which were used to filter acceleration time histories for the selected design earthquake from the ground motion database of Pacific Earthquake Engineering Research Center. Finally, full dynamic analyses of the tunnel have been performed by applying the scaled acceleration time histories corresponding to the structure in the specific site. It was demonstrated how to prove the stability of the tunnel located in difficult ground conditions by performing plane strain analyses with the possible minimum computational efforts.</span>
基金supported by the Natural Science Foundation of Gansu Province (22JR5RA326)The geological disaster prevention projects of Gansu Provincial Bureau of Geology and Mineral Resources (2023-2-9)。
文摘This study aims to utilize the Small Baseline Subset Interferometric Synthetic Aperture Radar(SBAS-In SAR)technique and Google Earth optical remote sensing images to analyze the area within 20 km around the epicenter of a M 3.9, earthquake that occurred in Tanchang County, Gansu Province, on December 28, 2020. The objective is to identify potential earthquake-induced landslides, assess their scale, and determine their impact range. The study results reveal the successful identification of two potential landslides in the 20 km radius around the epicenter. Through time-series deformation analysis, it was observed that these potential landslides were significantly influenced by both the earthquake and rainfall. Further estimation of these potential landslides indicates maximum depths of 7.4 m and 14.1 m for the failure surfaces, with volumes of 9.02 × 10~4m~3and 25.5 ×10~4m~3, respectively. Finally, based on the simulation analysis of Massflow software, the maximum thickness of soil accumulation in the final accumulation area after sliding of the potential landslide in Shangyaai is 12 m, the area of the final accumulation area is 1.75 × 10~4m~2, and the farthest movement distance is 1124 m. The maximum thickness of soil accumulation in the final accumulation area after sliding of the potential landslide in Wangshancun is 8 m, the area of the final accumulation area is 7.89 × 10~4m~2, and the farthest movement distance is 742 m.
基金Ministry of Science and Technology of China(Grant No.2002DIB30076)China Seismological Bureau(Grant No.201009)
文摘Fault parameters are important in earthquake hazard analysis.In this paper,theoretical relationships between moment magnitude and fault parameters including subsurface rupture length,downdip rupture width,rupture area,and average slip over the fault surface are deduced based on seismological theory.These theoretical relationships are further simplified by applying similarity conditions and an unique form is established.Then,combining the simplified theoretical relationships between moment magnitude and fault parameters with seismic source data selected in this study,a practical semi-empirical relationship is established.The seismic source data selected is also to used to derive empirical relationships between moment magnitude and fault parameters by the ordinary least square regression method.Comparisons between semi-empirical relationships and empirical relationships show that the former depict distribution trends of data better than the latter.It is also observed that downdip rupture widths of strike slip faults are saturated when moment magnitude is more than 7.0,but downdip rupture widths of dip slip faults are not saturated in the molnent magnitude rangcs of this study.
基金financially supported by the Research Grants Council of the Hong Kong Special Administrative Region(Project No.15212418)。
文摘This paper presents probabilistic assessment of seismically-induced slope displacements considering uncertainties of seismic ground motions and soil properties.A stochastic ground motion model representing both the temporal and spectral non-stationarity of earthquake shakings and a three-dimensional rotational failure mechanism are integrated to assess Newmark-type slope displacements.A new probabilistic approach that incorporates machine learning in metamodeling technique is proposed,by combining relevance vector machine with polynomial chaos expansions(RVM-PCE).Compared with other PCE methods,the proposed RVM-PCE is shown to be more effective in estimating failure probabilities.The sensitivity and relative influence of each random input parameter to the slope displacements are discussed.Finally,the fragility curves for slope displacements are established for sitespecific soil conditions and earthquake hazard levels.The results indicate that the slope displacement is more sensitive to the intensities and strong shaking durations of seismic ground motions than the frequency contents,and a critical Arias intensity that leads to the maximum annual failure probabilities can be identified by the proposed approach.
基金jointly funded by the National Natural Science Foundation of China (Grant No.41274052)the Seismological Research Project of China (Grant No.201208009)financially supported by Peking University President’s Research Funding for undergraduate students (2012–2013)
文摘In this study, we adopt an improved Bayesian approach based on free-knot B-spline bases to study the spatial and temporal distribution of the b-value. Synthetic tests show that the improved Bayesian approach has a superior performance compared to the Bayesian approach as well as the widely used maximum likelihood estimation (MLE) method in fitting the real variation of b-values. We then apply the improved Bayesian approach to North China and find that the b-value has a clear relevance to seismicity. Temporal changes of b-values are also investigated in two specific areas of North China. We interpret sharp decreases in the b-values as useful messages in earthquake hazard analysis.
文摘It is pointed out in this paper that the concept of scenario earthquake, expectant earthquake or proposed earthquake suggested by Kameda Nojima (1988) is not probability consistent due to unfit understanding for the aseismic design standard of probabilistic method. The corresponding concept proposed by QI FENG LUO meets the meaning of probability consistent, but it is still in a meaning of average so the result is not good enough. On the basis of above analysis, a concept of probability consistent conservative earthquakes is suggested. And a new method selecting aseismic objective earthquake with physical meaning is proposed on the basis of probabilistic method. After seismic hazard is analysed by certain control parameters, such as peak acceleration, we can determine the aseismic standard according to certain probabilistic level. Based on the attenuation law and the potential sources, we can find out some earthquakes or their combinations of magnitudes and distances. Such earthquakes or combinations are probability consistent for this control parameter. Based on above parameter, we suggest considering the destructive effects of other parameters (such as response spectrum), and selecting conservative earthquakes to replace the average earthquake and meet the requirements of aseismic design better.
文摘The computation of the representative ground motions,to be used as input for the dynamic analyses of a struc- ture at a particular site,can be approached by several methods.The choice of the approach depends on two factors:the da- ta available and the type of problem to be solved.This paper reports the experience of the authors in approaching a specific case study:the Southern Memnon Colossus,located in Luxor,Egypt.The results are of interest when the hazard analysis estimation in developing countries and the safeguard of cultural heritage are concerned.Monuments have to be treated as important structures,due to their historical and economical value.Hence,standard procedures of probabilistic seismic haz- ard analysis for the seismic classification of common buildings have to be disregarded.On the other hand,the consequences of the collapse of a monument are not comparable to those related to structures such as nuclear power plants and large dams, for which the deterministic seismic hazard analysis provides a straightforward framework for evaluation of the worst case ground motions.An'intermediate'approach,which requites a lower amount of input data with respect to the deterministic one,is adopted.Its stochastic component can eapture significant eharacteristics of earthquakes,primarily the frequency contents which depend on the magnitude(often referred to as the earthquake scaling law).
基金The One Hundred Individual Program of Chinese Academy of Sciences and National Natural Science Foundation of China (40574022).
文摘In this study, a composite source model has been used to calculate the realistic strong ground motions in Beijing area, caused by 1679 Ms8.0 earthquake in Sanhe-Pinggu. The results could provide us the useful physical parameters for the future seismic hazard analysis in this area. Considering the regional geological/geophysical background, we simulated the scenario earthquake with an associated ground motions in the area ranging from 39.3°N to 41. 1°N in latitude and from 115.35°E to 117.55°E in longitude. Some of the key factors which could influence the characteristics of strong ground motion have been discussed, and the resultant peak ground acceleration (PGA) distribution and the peak ground velocity (PGV) distribution around Beijing area also have been made as well. A comparison of the simulated result with the results derived from the attenuation relation has been made, and a sufficient discussion about the advantages and disadvantages of composite source model also has been given in this study. The numerical results, such as the PGA, PGV, peak ground displacement (PGD), and the three-component time-histories developed for Beijing area, have a potential application in earthquake engineering field and building code design, especially for the evaluation of critical constructions, government decision making and the seismic hazard assessment by financial/insurance companies.
基金Ningxia Hui Autonomous Region Key R&D Plan East West cooperation Project(No.2018BFG02011)National Natural Science Foundation of China(No.41674047)China Earthquake Science Experiment Site Project,CEA(Nos.2019CSES0105 and 2019CSES0106).
文摘Based on the modern earthquake catalogue,the incomplete centroidal voronoi tessellation(ICVT)method was used in this study to estimate the seismic hazard in Sichuan-Yunnan region of China.We calculated spatial distributions of the total seismic hazard and background seismic hazard in this area.The Bayesian delaunay tessellation smoothing method put forward by Ogata was used to calculate the spatial distributions of b-value.The results show that seismic hazards in Sichuan-Yunan region are high,and areas with relatively high hazard values are distributed along the main faults,while seismic hazards in Sichuan basin are relatively low.
基金Chinese Joint Seismological Science Foundation (100110).
文摘The seismic hazard of research area is evaluated by probabilistic analysis method for three different seismic statis-tical zone scenarios. The influence of uncertainty in seismic statistical zone delimiting on the evaluation result is discussed too. It can be seen that for those local sites along zone's border or within areas with vast change of upper bound magnitude among different scenarios the influence on seismic hazard result should not be neglected.
文摘This paper makes a summary of status of delimitation of seismic zones and belts of China firstly in aspects of studying history, purpose, usage, delimiting principles, various presenting forms and main specialties. Then the viewpoints are emphasized, making geographical divisions by seismicity is just the most important purpose of delimiting seismic belts and the concept of seismic belt is also quite different from that of seismic statistical zone used in CPSHA method. The concept of seismic statistical zone and its history of evolvement are introduced too. Large differences between these rwo concepts exist separately in their statistical property, actual meaning, gradation, required scale, and property of refusing to overlap each other, aim and usage of delimitation. But in current engineering practice, these two concepts are confused. On the one hand, it causes no fit theory for delimiting seismic statistical zone in PSHA to be set up; on the other hand, researches about delimitation of seismic belts with purposes of seismicity zoning and studying on structural environment, mechanism of earthquake generating also pause to go ahead. Major conclusions are given in the end of this paper, that seismic statistical zone bases on the result of seismic belt delimiting, it only arises in and can be used in the especial PSHA method of China with considering spatially and temporally inhomogeneous seismic activities, and its concept should be clearly differentiated from the concept of seismic belt.
文摘The proposed site of the Diamer Bhasha Dam in northern Pakistan is situated in an active tectonic zone with intensive seismicity,which makes it necessary for seismic hazard analysis(SHA).Deterministic and probabilistic approaches have been used for SHA of the dam site.The Main Mantle Thrust(MMT),Main Karakaram Thrust(MKT),Raikot-Sassi Fault(RKSF)and Kohistan Fault(KF)have been considered as major seismic sources,all of which can create maximum ground shaking with maximum potential earthquake(MPE).Deterministically estimated MPE for magnitudes of 7.8,7.7,7.6,and 7.1 can be produced from MMT,MKT,RKSF and KF,respectively.The corresponding peak ground accelerations(PGA)of 0.07,0.11,0.13 and 0.05 g can also be generated from these earthquakes,respectively.The deterministic analysis predicts a so-called floating earthquake as a MPE of magnitude=7.1 as close as 10 km away from the site.The corresponding PGA was computed as 0.38 g for a maximum design earthquake at the project site.However,the probabilistic analysis revealed that the PGA with 50%probability of exceedance in 100 years is 0.18 g.Thus,this PGA value related to the operational basis earthquake(OBE)is suggested for the design of this project with shear wave velocity(V_(s30))equal to 760 m/s under dense soil and soft rock conditions.
文摘Many destructive earthquakes happened in Tehran, Iran in the last centuries. The existence of active faults like the North Tehran is the main cause of seismicity in this city. According to past investigations, it is estimated that in the scenario of activation of the North Tehran fault, many structures in Tehran will collapse. Therefore, it is necessary to incorporate the near field rupture directivity effects of this fault into the seismic hazard assessment of important sites in Tehran. In this study, using calculations coded in MATLAB, Probabilistic Seismic Hazard Analysis (PSHA) is conducted for an important site in Tehran. Following that, deaggregation technique is performed on PSHA and the contribution of seis- mic scenarios to hazard is obtained in the range of distance and magnitude. After identifying the North Tehran fault as the most hazardous source affecting the site in 10000-year return period, rupture directivity effects of this fault is incorporated into the seismic hazard assessment using Somerville et al. (1997) model with broadband approach and Shahi and Baker (2011) model with narrowband approach. The results show that the narrowband approach caused a 27% increase in the peak of response spectrum in 10000-year return period compared with the conventional PSHA. Therefore, it is necessary to incorporate the near fault rupture directivity effects into the higher levels of seismic hazard assessment attributed to important sites.