This study explores the significance,current research landscape,and conceptualization of sports safety promotion.Safety in sports is fundamental to youth physical activities,and an excessive focus on or neglect of saf...This study explores the significance,current research landscape,and conceptualization of sports safety promotion.Safety in sports is fundamental to youth physical activities,and an excessive focus on or neglect of safety is unwarranted.Globally,numerous countries have extensively researched sports safety promotion and implemented diverse strategies.Drawing from KABP(Knowledge,Attitude,Behavior,Practice)theory and 4M(Man,Machine,Medium,Management)management,this paper presents a conceptual framework for sports safety promotion.It integrates these theories to devise a comprehensive accident prevention model within a sports safety promotion system.The framework prioritizes enhancing students’safety literacy and underscores the practical application of safety knowledge and skills in simulated sports settings following structured safety education.It aims to enhance students’competency and proficiency in averting sports-related injuries.展开更多
Based on the tunnel shape, span and depth, the previous elliptical plate model and clamped beam model were modified.The modified model was applied to different situations. For the elliptical plate model, the water eff...Based on the tunnel shape, span and depth, the previous elliptical plate model and clamped beam model were modified.The modified model was applied to different situations. For the elliptical plate model, the water effects were considered. For the clamped beam model, water and horizontal stress were considered. Corresponding potential functions and cusp catastrophe models of rock system were established based on the catastrophe theory. The expressions of critical safety thickness were derived with necessary and sufficient conditions. The method was applied to the practical engineering. Some parameters related to the stability were discussed. The results show that elastic modulus and thickness are advantageous to the floor stability, and that the load, span,horizontal stress and water are disadvantageous to the floor stability.展开更多
In this study, based on the analysis of the catastrophic risk of rural drinking water, with the representative villages in Ya’an as study objects and setting the four evaluation standards: water quality, water quanti...In this study, based on the analysis of the catastrophic risk of rural drinking water, with the representative villages in Ya’an as study objects and setting the four evaluation standards: water quality, water quantity, the Guarantee Probability for water Supply and the Convenience Level of the Access to Water Supply as the ba- sic framework, a Rural Drinking Water Safety Assessment was developed (RDWSA). Research showed that Catastrophe Theory was applicable in the RDWSA. Adding RDWSA based on Catastrophe Theory to the supportive system for decision-making in Ecological Hydrographic Management Decision Support System of Ya’an helped obtain the rank and results of RDWSE by the automatic calculation of programs, which could assist the risk assessment and risk management associated with rural drinking water in Ya’an.展开更多
Background: The modern intensive care unit (ICU) is a complex and high-risk environment, and even small adverse events and changes may deteriorate the patient’s conditions and eventually cause harm. Many factors can ...Background: The modern intensive care unit (ICU) is a complex and high-risk environment, and even small adverse events and changes may deteriorate the patient’s conditions and eventually cause harm. Many factors can potentially be associated within an increased amount of errors, leading to adverse events. Nurses, nurse managers, and other leaders all play important roles in establishing patient safety. Aim: This study aimed to obtain a deeper understanding of leaders’ and nurses’ main concerns in establishing patient safety in Swedish intensive care units. Method: A grounded theory methodology was used. Data from 15 interviews with leaders and nurses involved in critical care in Sweden were collected, analysed and constant compared. Findings: The main concern in establishing patient safety was promoting quality of care, work engagement, and staffs well-being in strained ICUs. The core category building trust explained how the leaders’ and nurses’ strove for quality of care and wished a healthy, safe work environment. This is further explained in the categories “Being an accessible and able leader”, “Creating knowledge and understanding”, and “Establishing collaborative practice”. Conclusion: Establishing patient safety in the ICU requires that staffs enjoy going to work, have good work relations, are committed and want to stay at the unit. A healthy, salutogenetic unit with a work environment marked by trust provides a better opportunity to establish patient safety, and various leaders have potential to achieve this.展开更多
The strata deformation in mining area was monitored in Dabaoshan copper-iron mine,and an analytical method of strata energy release was put forward.On the basis of chaotic theory,by reconstructing the phase space for ...The strata deformation in mining area was monitored in Dabaoshan copper-iron mine,and an analytical method of strata energy release was put forward.On the basis of chaotic theory,by reconstructing the phase space for time series data of strata energy release,the saturated embedding dimension and the correlation dimension of the dynamic system were obtained to be 4 and 1.212 8,respectively,and the evolution laws of distances between phase points of strata energy release in the phase space were revealed.With grey theory,a prediction model of strata energy release was set up,the maximum error of which was less than 6.7%.The results show that there are chaotic characters in strata energy release during mining;after reconstructing phase space,the subtle changing characteristics of energy release can be magnified,and the internal rules can be fully demonstrated.According to the laws,a warning system for strata stability in mining area was established to provide a technical safeguard for safe mining.展开更多
Accident causation analysis is of great importance for accident prevention.In order to improve the aviation safety,a new analysis method of aviation accident causation based on complex network theory is proposed in th...Accident causation analysis is of great importance for accident prevention.In order to improve the aviation safety,a new analysis method of aviation accident causation based on complex network theory is proposed in this paper.Through selecting 257 accident investigation reports,45 causative factors and nine accident types are obtained by the three-level coding process of the grounded theory,and the interaction of these factors is analyzed based on the“2-4”model.Accordingly,the aviation accident causation network is constructed based on complex network theory which has scale-free characteristics and small-world properties,the characteristics of causative factors are analyzed by the topology of the network,and the key causative factors of the accidents are identified by the technique for order of preference by similarity to ideal solution(TOPSIS)method.The comparison results show that the method proposed in this paper has the advantages of independent of expert experience,quantitative analysis of accident causative factors and statistical analysis of a lot of accident data,and it has better applicability and advancement.展开更多
The complexity of flight safety system is usually affected by a variety of uncertainties.The uncertainty of overall security situation of flight safety system are hardly determined.In this work,flight safety assessmen...The complexity of flight safety system is usually affected by a variety of uncertainties.The uncertainty of overall security situation of flight safety system are hardly determined.In this work,flight safety assessment index system is firstly established based on software hardware environment liveware management(SHELM)model.And flight safety assessment is also carried out with matter-element theory algorithm to obtain safety state.According to correlation degree values of each evaluation index,key indexes affected flight safety are obtained.Under the assumption that the flight safety system is a linear dynamic system and combining the above evaluation analysis,Kalman filter algorithm is used to carry out prediction analysis on security situation.A simulation analysis is carried out based on an actual flight safety situation of an airline.The results show that the security state of airline flight safety system in a short period of time can be obtained,and main factors affecting flight safety are found out.This provides a viable way for airlines to further strengthen flight safety management.展开更多
Quantified risk assessment(QRA) needs mathematicization of risk theory.However,attention has been paid almost exclusively to applications of assessment methods,which has led to neglect of research into fundamental the...Quantified risk assessment(QRA) needs mathematicization of risk theory.However,attention has been paid almost exclusively to applications of assessment methods,which has led to neglect of research into fundamental theories,such as the relationships among risk,safety,danger,and so on.In order to solve this problem,as a first step,fundamental theoretical relationships about risk and risk management were analyzed for this paper in the light of mathematics,and then illustrated with some charts.Second,man-machine-environment-management(MMEM) theory was introduced into risk theory to analyze some properties of risk.On the basis of this,a three-dimensional model of risk management was established that includes:a goal dimension;a management dimension;an operation dimension.This goal management operation(GMO) model was explained and then emphasis was laid on the discussion of the risk flowchart(operation dimension),which lays the groundwork for further study of risk management and qualitative and quantitative assessment.Next,the relationship between Formal Safety Assessment(FSA) and Risk Management was researched.This revealed that the FSA method,which the international maritime organization(IMO) is actively spreading,comes from Risk Management theory.Finally,conclusion were made about how to apply this risk management method to concrete fields efficiently and conveniently,as well as areas where further research is required.展开更多
The possibility of pressure control with the structural change of a safety valve is investigated Safety valve is commonly used as safety devices for numerous applications which include boilers,ships,industrial plant...The possibility of pressure control with the structural change of a safety valve is investigated Safety valve is commonly used as safety devices for numerous applications which include boilers,ships,industrial plants,and piping Setting and stopping pressures of a safety valve, p set and p sto ,are traditionally adjusted with a fine tuning of seat ring and valve ring heights, h sr and h vr However, it is not easy to achieve the proper setting and stopping pressures of a safety valve in practice The depth of inside and outside grooves in a valve, d i and d o are modified and their effects on setting and stopping pressures of a safety vlave are tested The most appropriate values appear 1 0 mm in d i and 0 5~1 0 mm in d o,respectively The valve ring height, h vr ,shows that the best results can be achieved at 2 3 mm for setting pressures of 0 1~0 4 MPa and 1 0 mm for setting pressures of 0 5~1 0 MPa The stopping pressures increases with the increase of seat ring height, h sr , upto certain h sr value and then becomes independent to the seat ring height This implies that there exists the optimum h sr ,which provides the largest flow rate and the proper stopping pressure Stopping pressures of a safety valve are adjusted with the seat ring and valve ring heights This study,however,demonstrated that the modification of value grooves also changes setting and stopping pressures of a safety valve Therefore,the proper selection in dimensions of the inside and outside grooves should be considered for the safety valve design展开更多
Advancing the application of safety and health(S&H)technologies is likely to remain a value in the mining industry.However,any information that technologies generate must be translated from the organization to the...Advancing the application of safety and health(S&H)technologies is likely to remain a value in the mining industry.However,any information that technologies generate must be translated from the organization to the workforce in a targeted way to result in sustainable change.Using a case study approach with continuous personal dust monitors(CPDMs),this paper argues for an organizational focus on technology integration.Although CPDMs provide mineworkers with near real-time feedback about their respirable coal dust exposure,they do not ensure that workers or the organization will continuously use the information to learn about and reduce exposure sources.This study used self-determination theory(SDT)to help three mines manage and communicate about information learned from the CPDM technology.Specifically,35 mineworkers participated in two mixed-method data collection efforts to discuss why they do or do not use CPDMs to engage in dust-reducing practices.Subsequently,the data was analyzed to better understand how organizations can improve the integration of technology through their management systems.Results indicate that using the CPDM to reduce sources of dust exposure is consistent with mineworkers’self-values to protect their health and not necessarily because of compliance to a manager or mine.展开更多
In underground mining,there has been an increasing use of"cemented paste"for the backfilling of stopes.As this cemented paste backfill(CPB)enters the stope as a fluid,shotcrete barricades are often used to r...In underground mining,there has been an increasing use of"cemented paste"for the backfilling of stopes.As this cemented paste backfill(CPB)enters the stope as a fluid,shotcrete barricades are often used to retain the fill material during and after the filling operations.However,failures of barricades have been reported around the world in recent years.This paper presents an analytical solution based on the elastic thin plate theory for calibrating the design of shotcrete barricades in underground mines using CPB.This solution was used to determine the quantitative relationships between the lateral loading from the paste and the barricade response during the backfilling process.The results show that the proposed solution agrees well with in situ data.According to the actual barricade responses,the acceptable tensile stress and an analysis method of cracks development are proposed.The proposed solution has practical significance for underground mines.展开更多
In order to study the mechanism of water inrush from a concealed, confined karst cave, we established a fluid–solid coupling model of water inrush from a concealed karst cave ahead of a roadway and a strength reducti...In order to study the mechanism of water inrush from a concealed, confined karst cave, we established a fluid–solid coupling model of water inrush from a concealed karst cave ahead of a roadway and a strength reduction method in a rock pillar for preventing water inrush based on catastrophic theory. Fluid–solid coupling effects and safety margins in a rock pillar were studied. Analysis shows that rock pillar instability, exerted by disturbance stress and seepage stress, is the process of rock pillar catastrophic destabilization induced by nonlinear extension of plastic zones in the rock pillar. Seepage flow emerges in the rock pillar for preventing water inrush, accompanied by mechanical instability of the rock pillar. Taking the accident of a confined karst cave water-inrush of Qiyi Mine as an example, by studying the safety factor of the rock pillar and the relationship between karst cave water pressure and thickness of the rock pillar,it is proposed that rock pillar thickness with a safety factor equal to 1.5 is regarded as the calculated safety thickness of the rock pillar, which should be equal to the sum of the blasthole depth, blasting disturbance depth and the calculated safety thickness of the rock pillar. The cause of the karst water inrush at Qiyi Mine is that the rock pillar was so small that it did not possess a safety margin. Combining fluid–solid coupling theory, catastrophic theory and strength reduction method to study the nonlinear mechanical response of complicated rock engineering, new avenues for quantitative analysis of rock engineering stability evaluation should be forthcoming.展开更多
According to the main characters of overlapping underground chambers, the roof (floor) of two adjacent underground chambers is simplified to the mechanical model that is the beam with build-in ends. And vibration load...According to the main characters of overlapping underground chambers, the roof (floor) of two adjacent underground chambers is simplified to the mechanical model that is the beam with build-in ends. And vibration load due to blasting is simplified to harmonic wave. The catastrophic model of double cusp for underground chambers destabilization induced by blasting vibration has been established under the circumstances of considering deadweight of the beam, and the condition of destabilization has been worked out. The critical safety thickness of the roof (floor) of underground chambers has been confirmed according to the destabilization condition. The influence of amplitude and frequency of blasting vibration load on the critical safety thickness has been analyzed, and the quantitative relation between velocity, frequency of blasting vibration and critical safety thickness has been determined. Research results show that the destabilization of underground chambers is not only dependent on the amplitude and frequency of blasting vibration load, but also related to deadweight load and intrinsic attribute. It is accordant to testing results and some related latest research results of blasting seismic effect. With increasing amplitude, the critical safety thickness of underground chambers decreases gradually. And the possibility of underground chambers destabilization increases. When the frequency of blasting vibration is equal to or very close to the frequency of beam, resonance effect will take place in the system. Then the critical safety thickness will turn to zero, underground chambers will be damaged severely, and its loading capacity will lose on the whole.展开更多
Due to a combination of the sea erosion,the ship collision,the change of ground condition,the effect of alternative static and dynamic load and the material deterioration,the structure of high-pile wharf is easily dam...Due to a combination of the sea erosion,the ship collision,the change of ground condition,the effect of alternative static and dynamic load and the material deterioration,the structure of high-pile wharf is easily damaged.Once the structure of high-pile wharf destroyed,it is bound to be a great threat to the safety of various facilities and personnel in the port.Given all of that,the multi-level comprehensive evaluation method based on the extension theory is proposed in this paper.Using this method to assess the safety of high-pile wharf structure,the reasonable advice on its maintenance and reinforcement can be given in time.What’s more,the method is simple and can give more objective result of the evaluation.展开更多
文摘This study explores the significance,current research landscape,and conceptualization of sports safety promotion.Safety in sports is fundamental to youth physical activities,and an excessive focus on or neglect of safety is unwarranted.Globally,numerous countries have extensively researched sports safety promotion and implemented diverse strategies.Drawing from KABP(Knowledge,Attitude,Behavior,Practice)theory and 4M(Man,Machine,Medium,Management)management,this paper presents a conceptual framework for sports safety promotion.It integrates these theories to devise a comprehensive accident prevention model within a sports safety promotion system.The framework prioritizes enhancing students’safety literacy and underscores the practical application of safety knowledge and skills in simulated sports settings following structured safety education.It aims to enhance students’competency and proficiency in averting sports-related injuries.
基金Project(2013CB036004)supported by the National Basic Research Program of ChinaProject(51378510)supported by the National Natural Science Foundation of China
文摘Based on the tunnel shape, span and depth, the previous elliptical plate model and clamped beam model were modified.The modified model was applied to different situations. For the elliptical plate model, the water effects were considered. For the clamped beam model, water and horizontal stress were considered. Corresponding potential functions and cusp catastrophe models of rock system were established based on the catastrophe theory. The expressions of critical safety thickness were derived with necessary and sufficient conditions. The method was applied to the practical engineering. Some parameters related to the stability were discussed. The results show that elastic modulus and thickness are advantageous to the floor stability, and that the load, span,horizontal stress and water are disadvantageous to the floor stability.
文摘In this study, based on the analysis of the catastrophic risk of rural drinking water, with the representative villages in Ya’an as study objects and setting the four evaluation standards: water quality, water quantity, the Guarantee Probability for water Supply and the Convenience Level of the Access to Water Supply as the ba- sic framework, a Rural Drinking Water Safety Assessment was developed (RDWSA). Research showed that Catastrophe Theory was applicable in the RDWSA. Adding RDWSA based on Catastrophe Theory to the supportive system for decision-making in Ecological Hydrographic Management Decision Support System of Ya’an helped obtain the rank and results of RDWSE by the automatic calculation of programs, which could assist the risk assessment and risk management associated with rural drinking water in Ya’an.
文摘Background: The modern intensive care unit (ICU) is a complex and high-risk environment, and even small adverse events and changes may deteriorate the patient’s conditions and eventually cause harm. Many factors can potentially be associated within an increased amount of errors, leading to adverse events. Nurses, nurse managers, and other leaders all play important roles in establishing patient safety. Aim: This study aimed to obtain a deeper understanding of leaders’ and nurses’ main concerns in establishing patient safety in Swedish intensive care units. Method: A grounded theory methodology was used. Data from 15 interviews with leaders and nurses involved in critical care in Sweden were collected, analysed and constant compared. Findings: The main concern in establishing patient safety was promoting quality of care, work engagement, and staffs well-being in strained ICUs. The core category building trust explained how the leaders’ and nurses’ strove for quality of care and wished a healthy, safe work environment. This is further explained in the categories “Being an accessible and able leader”, “Creating knowledge and understanding”, and “Establishing collaborative practice”. Conclusion: Establishing patient safety in the ICU requires that staffs enjoy going to work, have good work relations, are committed and want to stay at the unit. A healthy, salutogenetic unit with a work environment marked by trust provides a better opportunity to establish patient safety, and various leaders have potential to achieve this.
基金Project (2010CB732004) supported by the National Basic Research Program of ChinaProject (51074177) supported by the Joint Funding of National Natural Science Foundation and Shanghai Baosteel Group Corporation,China
文摘The strata deformation in mining area was monitored in Dabaoshan copper-iron mine,and an analytical method of strata energy release was put forward.On the basis of chaotic theory,by reconstructing the phase space for time series data of strata energy release,the saturated embedding dimension and the correlation dimension of the dynamic system were obtained to be 4 and 1.212 8,respectively,and the evolution laws of distances between phase points of strata energy release in the phase space were revealed.With grey theory,a prediction model of strata energy release was set up,the maximum error of which was less than 6.7%.The results show that there are chaotic characters in strata energy release during mining;after reconstructing phase space,the subtle changing characteristics of energy release can be magnified,and the internal rules can be fully demonstrated.According to the laws,a warning system for strata stability in mining area was established to provide a technical safeguard for safe mining.
基金supported by the Civil Aviation Joint Fund of National Natural Science Foundation of China(No.U1533112)。
文摘Accident causation analysis is of great importance for accident prevention.In order to improve the aviation safety,a new analysis method of aviation accident causation based on complex network theory is proposed in this paper.Through selecting 257 accident investigation reports,45 causative factors and nine accident types are obtained by the three-level coding process of the grounded theory,and the interaction of these factors is analyzed based on the“2-4”model.Accordingly,the aviation accident causation network is constructed based on complex network theory which has scale-free characteristics and small-world properties,the characteristics of causative factors are analyzed by the topology of the network,and the key causative factors of the accidents are identified by the technique for order of preference by similarity to ideal solution(TOPSIS)method.The comparison results show that the method proposed in this paper has the advantages of independent of expert experience,quantitative analysis of accident causative factors and statistical analysis of a lot of accident data,and it has better applicability and advancement.
文摘The complexity of flight safety system is usually affected by a variety of uncertainties.The uncertainty of overall security situation of flight safety system are hardly determined.In this work,flight safety assessment index system is firstly established based on software hardware environment liveware management(SHELM)model.And flight safety assessment is also carried out with matter-element theory algorithm to obtain safety state.According to correlation degree values of each evaluation index,key indexes affected flight safety are obtained.Under the assumption that the flight safety system is a linear dynamic system and combining the above evaluation analysis,Kalman filter algorithm is used to carry out prediction analysis on security situation.A simulation analysis is carried out based on an actual flight safety situation of an airline.The results show that the security state of airline flight safety system in a short period of time can be obtained,and main factors affecting flight safety are found out.This provides a viable way for airlines to further strengthen flight safety management.
基金Supported by the Shanghai Leading Academic Discipline Project Foundation under Grant No.T0602Supported by the Shanghai Education Commission Project Foundation under Grant No.05FZ10
文摘Quantified risk assessment(QRA) needs mathematicization of risk theory.However,attention has been paid almost exclusively to applications of assessment methods,which has led to neglect of research into fundamental theories,such as the relationships among risk,safety,danger,and so on.In order to solve this problem,as a first step,fundamental theoretical relationships about risk and risk management were analyzed for this paper in the light of mathematics,and then illustrated with some charts.Second,man-machine-environment-management(MMEM) theory was introduced into risk theory to analyze some properties of risk.On the basis of this,a three-dimensional model of risk management was established that includes:a goal dimension;a management dimension;an operation dimension.This goal management operation(GMO) model was explained and then emphasis was laid on the discussion of the risk flowchart(operation dimension),which lays the groundwork for further study of risk management and qualitative and quantitative assessment.Next,the relationship between Formal Safety Assessment(FSA) and Risk Management was researched.This revealed that the FSA method,which the international maritime organization(IMO) is actively spreading,comes from Risk Management theory.Finally,conclusion were made about how to apply this risk management method to concrete fields efficiently and conveniently,as well as areas where further research is required.
文摘The possibility of pressure control with the structural change of a safety valve is investigated Safety valve is commonly used as safety devices for numerous applications which include boilers,ships,industrial plants,and piping Setting and stopping pressures of a safety valve, p set and p sto ,are traditionally adjusted with a fine tuning of seat ring and valve ring heights, h sr and h vr However, it is not easy to achieve the proper setting and stopping pressures of a safety valve in practice The depth of inside and outside grooves in a valve, d i and d o are modified and their effects on setting and stopping pressures of a safety vlave are tested The most appropriate values appear 1 0 mm in d i and 0 5~1 0 mm in d o,respectively The valve ring height, h vr ,shows that the best results can be achieved at 2 3 mm for setting pressures of 0 1~0 4 MPa and 1 0 mm for setting pressures of 0 5~1 0 MPa The stopping pressures increases with the increase of seat ring height, h sr , upto certain h sr value and then becomes independent to the seat ring height This implies that there exists the optimum h sr ,which provides the largest flow rate and the proper stopping pressure Stopping pressures of a safety valve are adjusted with the seat ring and valve ring heights This study,however,demonstrated that the modification of value grooves also changes setting and stopping pressures of a safety valve Therefore,the proper selection in dimensions of the inside and outside grooves should be considered for the safety valve design
文摘Advancing the application of safety and health(S&H)technologies is likely to remain a value in the mining industry.However,any information that technologies generate must be translated from the organization to the workforce in a targeted way to result in sustainable change.Using a case study approach with continuous personal dust monitors(CPDMs),this paper argues for an organizational focus on technology integration.Although CPDMs provide mineworkers with near real-time feedback about their respirable coal dust exposure,they do not ensure that workers or the organization will continuously use the information to learn about and reduce exposure sources.This study used self-determination theory(SDT)to help three mines manage and communicate about information learned from the CPDM technology.Specifically,35 mineworkers participated in two mixed-method data collection efforts to discuss why they do or do not use CPDMs to engage in dust-reducing practices.Subsequently,the data was analyzed to better understand how organizations can improve the integration of technology through their management systems.Results indicate that using the CPDM to reduce sources of dust exposure is consistent with mineworkers’self-values to protect their health and not necessarily because of compliance to a manager or mine.
基金financially supported by the China Scholarship Council(No.201506420049)。
文摘In underground mining,there has been an increasing use of"cemented paste"for the backfilling of stopes.As this cemented paste backfill(CPB)enters the stope as a fluid,shotcrete barricades are often used to retain the fill material during and after the filling operations.However,failures of barricades have been reported around the world in recent years.This paper presents an analytical solution based on the elastic thin plate theory for calibrating the design of shotcrete barricades in underground mines using CPB.This solution was used to determine the quantitative relationships between the lateral loading from the paste and the barricade response during the backfilling process.The results show that the proposed solution agrees well with in situ data.According to the actual barricade responses,the acceptable tensile stress and an analysis method of cracks development are proposed.The proposed solution has practical significance for underground mines.
基金Financial supports for this work, provided by the National Natural Science Foundation of China (No. 51274097)the Scientific Research Fund of Hunan Provincial Education Department of China (No. 13A020)the Open Projects of State Key Laboratory of Coal Resources and Safe Mining, CUMT (No. 13KF03)
文摘In order to study the mechanism of water inrush from a concealed, confined karst cave, we established a fluid–solid coupling model of water inrush from a concealed karst cave ahead of a roadway and a strength reduction method in a rock pillar for preventing water inrush based on catastrophic theory. Fluid–solid coupling effects and safety margins in a rock pillar were studied. Analysis shows that rock pillar instability, exerted by disturbance stress and seepage stress, is the process of rock pillar catastrophic destabilization induced by nonlinear extension of plastic zones in the rock pillar. Seepage flow emerges in the rock pillar for preventing water inrush, accompanied by mechanical instability of the rock pillar. Taking the accident of a confined karst cave water-inrush of Qiyi Mine as an example, by studying the safety factor of the rock pillar and the relationship between karst cave water pressure and thickness of the rock pillar,it is proposed that rock pillar thickness with a safety factor equal to 1.5 is regarded as the calculated safety thickness of the rock pillar, which should be equal to the sum of the blasthole depth, blasting disturbance depth and the calculated safety thickness of the rock pillar. The cause of the karst water inrush at Qiyi Mine is that the rock pillar was so small that it did not possess a safety margin. Combining fluid–solid coupling theory, catastrophic theory and strength reduction method to study the nonlinear mechanical response of complicated rock engineering, new avenues for quantitative analysis of rock engineering stability evaluation should be forthcoming.
基金Project(50490272) supported by the National Natural Science Foundation of China Project(040109) supported by the Doctor Degree Paper Innovation Engineering of Central South University
文摘According to the main characters of overlapping underground chambers, the roof (floor) of two adjacent underground chambers is simplified to the mechanical model that is the beam with build-in ends. And vibration load due to blasting is simplified to harmonic wave. The catastrophic model of double cusp for underground chambers destabilization induced by blasting vibration has been established under the circumstances of considering deadweight of the beam, and the condition of destabilization has been worked out. The critical safety thickness of the roof (floor) of underground chambers has been confirmed according to the destabilization condition. The influence of amplitude and frequency of blasting vibration load on the critical safety thickness has been analyzed, and the quantitative relation between velocity, frequency of blasting vibration and critical safety thickness has been determined. Research results show that the destabilization of underground chambers is not only dependent on the amplitude and frequency of blasting vibration load, but also related to deadweight load and intrinsic attribute. It is accordant to testing results and some related latest research results of blasting seismic effect. With increasing amplitude, the critical safety thickness of underground chambers decreases gradually. And the possibility of underground chambers destabilization increases. When the frequency of blasting vibration is equal to or very close to the frequency of beam, resonance effect will take place in the system. Then the critical safety thickness will turn to zero, underground chambers will be damaged severely, and its loading capacity will lose on the whole.
文摘Due to a combination of the sea erosion,the ship collision,the change of ground condition,the effect of alternative static and dynamic load and the material deterioration,the structure of high-pile wharf is easily damaged.Once the structure of high-pile wharf destroyed,it is bound to be a great threat to the safety of various facilities and personnel in the port.Given all of that,the multi-level comprehensive evaluation method based on the extension theory is proposed in this paper.Using this method to assess the safety of high-pile wharf structure,the reasonable advice on its maintenance and reinforcement can be given in time.What’s more,the method is simple and can give more objective result of the evaluation.