It is assumed that a pipeline is laid through a vertical fault fracture zone, and is excited by seismic ground motion modelled as stationary stochastic process. For horizontal incidence of waves, the cross-PSD （Power...It is assumed that a pipeline is laid through a vertical fault fracture zone, and is excited by seismic ground motion modelled as stationary stochastic process. For horizontal incidence of waves, the cross-PSD （Power Spectral Density） function is developed using wave propagation theory, while for vertical incidence of waves the cross-PSD function is composed by auto-PSD model, coherence model and site response model. As the seismic input, the eross-PSD function is used to calculate the the axial and lateral seismic responses of underground pipeline through the fracture zone. The results show that the incident directions of seismic waves, width and soil property of the fracture zone have great influence on underground pipeline. It is suggested that the flexible joints with appropriate stiffness should be added into the pipeline near the interfaces between the fracture zone and the surrounded media.展开更多
Observational results of underground water regime (water level and flow) in some strong earthquakes and moderate earthquakes (in this paper we also call them by 'strong earthquakes')in Chinese mainland are stu...Observational results of underground water regime (water level and flow) in some strong earthquakes and moderate earthquakes (in this paper we also call them by 'strong earthquakes')in Chinese mainland are studied and the following conclusions are obtained. For one strong earthquake, the spatial distributions of the anomalies which include medium term anomalies of one year scale, short term anomalies and imminent anomalies, and underground water stations without the anomalies were mainly related to the causative mechanism and active master faults (active abyssal faults or strongly active faults) around the focal region; The spatial distribution of the anomalies coincided with the specific relation among the anomalies, the focal site, the causative mechanism and active master faults. Finally, the mechanism of the relation was briefly discussed, and the importance about the research result in this paper was set forth.展开更多
Underground lifeline engineering (ULE for short) in modern city demands the appreciation of an active fault in buried bedrock . Generally speaking , a large number of urban geological textures of a basement may all be...Underground lifeline engineering (ULE for short) in modern city demands the appreciation of an active fault in buried bedrock . Generally speaking , a large number of urban geological textures of a basement may all be simplified into a dual geological texture model , i. e., the upper part of the basement consists of loose covering layer and the lower part consists of bedrock . The study of an active fault should include three parts of contents , i . e ., to determine the lower time limit of activity of the fault , and the time limit must be recognized by both of designing engineers and geologists ; on the basis of the studies of repetition periods of earthquake occurrence to deter mine whether the fault moves or not during the allowed time of efficacy of buildings and constructions ; for the sake of engineering practice , the active rate of the fault must be given . The fault with different active mechanism has different effects on the ULE . The authors studied the effect of lateral non-uniform overburden site on the ULE by means of the supersonic earthquake modelling . Owing to the lateral non - uniformity of the covering sediments , there occurs an obvious jump of amplitude of the seismic wave propagation near the contact surface between two different sedi ments . In addition , from the modelling experiment curves it may be seen that the different focus mechanisms and different medium characters may also exert an effect in different degrees .展开更多
文摘It is assumed that a pipeline is laid through a vertical fault fracture zone, and is excited by seismic ground motion modelled as stationary stochastic process. For horizontal incidence of waves, the cross-PSD （Power Spectral Density） function is developed using wave propagation theory, while for vertical incidence of waves the cross-PSD function is composed by auto-PSD model, coherence model and site response model. As the seismic input, the eross-PSD function is used to calculate the the axial and lateral seismic responses of underground pipeline through the fracture zone. The results show that the incident directions of seismic waves, width and soil property of the fracture zone have great influence on underground pipeline. It is suggested that the flexible joints with appropriate stiffness should be added into the pipeline near the interfaces between the fracture zone and the surrounded media.
文摘Observational results of underground water regime (water level and flow) in some strong earthquakes and moderate earthquakes (in this paper we also call them by 'strong earthquakes')in Chinese mainland are studied and the following conclusions are obtained. For one strong earthquake, the spatial distributions of the anomalies which include medium term anomalies of one year scale, short term anomalies and imminent anomalies, and underground water stations without the anomalies were mainly related to the causative mechanism and active master faults (active abyssal faults or strongly active faults) around the focal region; The spatial distribution of the anomalies coincided with the specific relation among the anomalies, the focal site, the causative mechanism and active master faults. Finally, the mechanism of the relation was briefly discussed, and the importance about the research result in this paper was set forth.
基金The paper is one Part of a project supported by National Education Commitce Funds for Doctoral Faculty
文摘Underground lifeline engineering (ULE for short) in modern city demands the appreciation of an active fault in buried bedrock . Generally speaking , a large number of urban geological textures of a basement may all be simplified into a dual geological texture model , i. e., the upper part of the basement consists of loose covering layer and the lower part consists of bedrock . The study of an active fault should include three parts of contents , i . e ., to determine the lower time limit of activity of the fault , and the time limit must be recognized by both of designing engineers and geologists ; on the basis of the studies of repetition periods of earthquake occurrence to deter mine whether the fault moves or not during the allowed time of efficacy of buildings and constructions ; for the sake of engineering practice , the active rate of the fault must be given . The fault with different active mechanism has different effects on the ULE . The authors studied the effect of lateral non-uniform overburden site on the ULE by means of the supersonic earthquake modelling . Owing to the lateral non - uniformity of the covering sediments , there occurs an obvious jump of amplitude of the seismic wave propagation near the contact surface between two different sedi ments . In addition , from the modelling experiment curves it may be seen that the different focus mechanisms and different medium characters may also exert an effect in different degrees .
