This paper puts forward using high-pressure water jet technology to control rock burst in roadway, and analyzes the theory of controlling rock burst in roadway by the weak structure zone model. The weak structure zone...This paper puts forward using high-pressure water jet technology to control rock burst in roadway, and analyzes the theory of controlling rock burst in roadway by the weak structure zone model. The weak structure zone is formed by using high-pressure water jet to cut the coal wall in a continuous and rotational way. In order to study the influence law of weak structure zone in surrounding rock, this paper numerically analyzed the influence law of weak structure zone, and the disturbance law of coal wall and floor under dynamic and static combined load. The results show that when the distance between high-pressure water jet drillings is 3 m and the diameter of drilling is 300 mm, continuous stress superposition zone can be formed. The weak structure zone can transfer and reduce the concentrated static load in surrounding rock, and then form distressed zone. The longer the high-pressure water jet drilling is, the larger the distressed zone is. The stress change and displacement change of non-distressed zone in coal wall and floor are significantly greater than that of distressed zone under dynamic and static combined load. And it shows that the distressed zone can effectively control rock burst in roadway under dynamic and static combined load. High-pressure water jet technology was applied in the haulage gate of 250203 working face in Yanbei Coal Mine, and had gained good effect. The study conclusions provide theoretical foundation and a new guidance for controlling rock burst in roadway.展开更多
The descaling level of pipelines can directly affect the safety and stability of pipelines during operation. With the accelerating social and economic development, the application scope of pipelines in various fields ...The descaling level of pipelines can directly affect the safety and stability of pipelines during operation. With the accelerating social and economic development, the application scope of pipelines in various fields of production and construction is expanding day by day, and the types of technologies applied in pipeline descaling are richer. Compared with other descaling technologies, the high-pressure water jet cleaning technology has more remarkable cleaning effect and wide practical application range. Aiming at this, this paper takes the principle of high-pressure water jet cleaning technology as the breakthrough point, and puts forward the application advantages of high-pressure water jet cleaning technology. This paper analyzes the cleaning equipment and cleaning methods in the current high-pressure water jet cleaning technology, and finally puts forward the application benefit of high-pressure water jet cleaning technology in pipe descaling, for reference.展开更多
High-pressure jet grouting construction technology is widely used in water conservancy and hydropower projects at present. The application of this construction technology can not only improve the bearing capacity of t...High-pressure jet grouting construction technology is widely used in water conservancy and hydropower projects at present. The application of this construction technology can not only improve the bearing capacity of the foundation and strengthen the foundation, but also can be applied in anti-seepage construction. Because of its obvious application advantages in water conservancy and hydropower projects, it is highly recognized by construction personnel. The author explores and analyzes the construction technology and technical principle of high-pressure jet grouting, and puts forward the specific application of this construction technology, hoping to help improve the construction level of water conservancy and hydropower projects.展开更多
Self-propelled nozzle is a critical component of the radial jet drilling technology.Its backward orifice structure has a crucial influence on the propulsive force and the drilling performance.To improve the working pe...Self-propelled nozzle is a critical component of the radial jet drilling technology.Its backward orifice structure has a crucial influence on the propulsive force and the drilling performance.To improve the working performance of the nozzle,the numerical simulation model is built and verified by the experimental results of propulsive force.Then the theoretical model of the energy efficiency and energy coefficient of the nozzle is built to reveal the influence of the structural parameters on the jet performance of the nozzle.The results show that the energy efficiency and energy coefficient of the backward orifice increase first and then decrease with the angle increases.The energy coefficient of forward orifice is almost constant with the angle increases.With the increase in the number and diameter,energy efficiency and energy coefficient of the forward orifice gradually decrease,but the backward orifice energy coefficient first increases and then decreases.Finally,it is obtained that the nozzle has better jet performance when the angle of backward orifice is 30°,the number of backward orifice is 6,and the value range of diameter is 2-2.2 mm.This study provides a reference for the design of efficiently self-propelled nozzle for radial jet drilling technology.展开更多
Water inrush and mud gushing are one of the biggest hazards in tunnel construction. Unfavorable geological sections can be observed in almost all railway tunnels under construction or to be constructed, and vary in ex...Water inrush and mud gushing are one of the biggest hazards in tunnel construction. Unfavorable geological sections can be observed in almost all railway tunnels under construction or to be constructed, and vary in extent. Furthermore, due to the different heights of mountains and the lengths of tunnels, the locations of the unfavorable geological sections cannot be fully determined before construction, which increases the risk of water inrush and mud gushing. Based on numerous cases of water inrush and mud gushing in railway tunnels, the paper tries to classify water inrush and mud gushing in railway tunnels in view of the conditions of the surrounding rocks and meteorological factors associated with tunnel excavation. In addition, the causes of water inrush and mud gushing in combination of macroand micromechanisms are summarized, and site-specifc treatment method is put forward. The treatment methods include choosing a method of advance geological forecast according to risk degrees of different sections in the tunnel, determining the items of predictions, and choosing the appropriate methods, i.e. draining-oriented method, blocking-oriented method or draining-and-blocking method. The treatment technologies of railway water inrush and mud gushing are also summarized, including energy relief and pressure relief technology, advance grouting technology, and advance jet grouting technology associated with their key technical features and applicable conditions. The results in terms of treatment methods can provide reference to the prevention and treatment of tunnel water inrush and mud gushing.展开更多
Aim:The aim was to study the role of jet force technology(JFT)in wound management.Methods:This is a retrospective analysis of 18 cases of chronic nonhealing wounds in which JFT was used.Chronic wounds which had alread...Aim:The aim was to study the role of jet force technology(JFT)in wound management.Methods:This is a retrospective analysis of 18 cases of chronic nonhealing wounds in which JFT was used.Chronic wounds which had already undergone surgical debridement but which were not ready for reconstruction(skin graft/flap)secondary to a persistent bacterial load or infection(tissue culture positive)were included in the study.Patients were divided into two groups.Group 1 included those patients who were poor candidates for anesthesia or who refused for reconstruction and were managed with JFT only.Group 2 included those patients who were cleared for anesthesia and who were and who were managed with JFT and skin graft or flap coverage.The time to negative wound cultures after JFT and the total duration of healing were noted.Results:In both the groups,all tissue culture positive chronic wounds became negative after 2±1 weeks and were ready for reconstruction.In Group 1(6 patients),the wounds completely healed in 5-6 weeks with JFT only.In Group 2(12 patients),the wounds completely healed in 3-4 weeks with JFT and skin graft/flap.Conclusion:Hydrotherapy with JFT helps in the removal of contaminants,debris,and microbial colonization of the wound leading to spontaneous wound healing and facilitating wound bed preparation for wound coverage by a skin graft or flap.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 51574243, 51404269)the Fundamental Research Funds for the Central Universities of China (No. 2014XT01)+1 种基金Guizhou Science and Technology Foundation of China (No. 20152072)the Priority Academic Program Development of Jiangsu Higher Education Institutions, China (No. SZBF2011-6B35)
文摘This paper puts forward using high-pressure water jet technology to control rock burst in roadway, and analyzes the theory of controlling rock burst in roadway by the weak structure zone model. The weak structure zone is formed by using high-pressure water jet to cut the coal wall in a continuous and rotational way. In order to study the influence law of weak structure zone in surrounding rock, this paper numerically analyzed the influence law of weak structure zone, and the disturbance law of coal wall and floor under dynamic and static combined load. The results show that when the distance between high-pressure water jet drillings is 3 m and the diameter of drilling is 300 mm, continuous stress superposition zone can be formed. The weak structure zone can transfer and reduce the concentrated static load in surrounding rock, and then form distressed zone. The longer the high-pressure water jet drilling is, the larger the distressed zone is. The stress change and displacement change of non-distressed zone in coal wall and floor are significantly greater than that of distressed zone under dynamic and static combined load. And it shows that the distressed zone can effectively control rock burst in roadway under dynamic and static combined load. High-pressure water jet technology was applied in the haulage gate of 250203 working face in Yanbei Coal Mine, and had gained good effect. The study conclusions provide theoretical foundation and a new guidance for controlling rock burst in roadway.
文摘The descaling level of pipelines can directly affect the safety and stability of pipelines during operation. With the accelerating social and economic development, the application scope of pipelines in various fields of production and construction is expanding day by day, and the types of technologies applied in pipeline descaling are richer. Compared with other descaling technologies, the high-pressure water jet cleaning technology has more remarkable cleaning effect and wide practical application range. Aiming at this, this paper takes the principle of high-pressure water jet cleaning technology as the breakthrough point, and puts forward the application advantages of high-pressure water jet cleaning technology. This paper analyzes the cleaning equipment and cleaning methods in the current high-pressure water jet cleaning technology, and finally puts forward the application benefit of high-pressure water jet cleaning technology in pipe descaling, for reference.
文摘High-pressure jet grouting construction technology is widely used in water conservancy and hydropower projects at present. The application of this construction technology can not only improve the bearing capacity of the foundation and strengthen the foundation, but also can be applied in anti-seepage construction. Because of its obvious application advantages in water conservancy and hydropower projects, it is highly recognized by construction personnel. The author explores and analyzes the construction technology and technical principle of high-pressure jet grouting, and puts forward the specific application of this construction technology, hoping to help improve the construction level of water conservancy and hydropower projects.
基金the paper was supported by the Natural Science Foundation of China(No.51974036 and No.51604039)the Yangtze Fund for Youth Teams of Science and Technology Innovation(No.2016cqt01)。
文摘Self-propelled nozzle is a critical component of the radial jet drilling technology.Its backward orifice structure has a crucial influence on the propulsive force and the drilling performance.To improve the working performance of the nozzle,the numerical simulation model is built and verified by the experimental results of propulsive force.Then the theoretical model of the energy efficiency and energy coefficient of the nozzle is built to reveal the influence of the structural parameters on the jet performance of the nozzle.The results show that the energy efficiency and energy coefficient of the backward orifice increase first and then decrease with the angle increases.The energy coefficient of forward orifice is almost constant with the angle increases.With the increase in the number and diameter,energy efficiency and energy coefficient of the forward orifice gradually decrease,but the backward orifice energy coefficient first increases and then decreases.Finally,it is obtained that the nozzle has better jet performance when the angle of backward orifice is 30°,the number of backward orifice is 6,and the value range of diameter is 2-2.2 mm.This study provides a reference for the design of efficiently self-propelled nozzle for radial jet drilling technology.
文摘Water inrush and mud gushing are one of the biggest hazards in tunnel construction. Unfavorable geological sections can be observed in almost all railway tunnels under construction or to be constructed, and vary in extent. Furthermore, due to the different heights of mountains and the lengths of tunnels, the locations of the unfavorable geological sections cannot be fully determined before construction, which increases the risk of water inrush and mud gushing. Based on numerous cases of water inrush and mud gushing in railway tunnels, the paper tries to classify water inrush and mud gushing in railway tunnels in view of the conditions of the surrounding rocks and meteorological factors associated with tunnel excavation. In addition, the causes of water inrush and mud gushing in combination of macroand micromechanisms are summarized, and site-specifc treatment method is put forward. The treatment methods include choosing a method of advance geological forecast according to risk degrees of different sections in the tunnel, determining the items of predictions, and choosing the appropriate methods, i.e. draining-oriented method, blocking-oriented method or draining-and-blocking method. The treatment technologies of railway water inrush and mud gushing are also summarized, including energy relief and pressure relief technology, advance grouting technology, and advance jet grouting technology associated with their key technical features and applicable conditions. The results in terms of treatment methods can provide reference to the prevention and treatment of tunnel water inrush and mud gushing.
文摘Aim:The aim was to study the role of jet force technology(JFT)in wound management.Methods:This is a retrospective analysis of 18 cases of chronic nonhealing wounds in which JFT was used.Chronic wounds which had already undergone surgical debridement but which were not ready for reconstruction(skin graft/flap)secondary to a persistent bacterial load or infection(tissue culture positive)were included in the study.Patients were divided into two groups.Group 1 included those patients who were poor candidates for anesthesia or who refused for reconstruction and were managed with JFT only.Group 2 included those patients who were cleared for anesthesia and who were and who were managed with JFT and skin graft or flap coverage.The time to negative wound cultures after JFT and the total duration of healing were noted.Results:In both the groups,all tissue culture positive chronic wounds became negative after 2±1 weeks and were ready for reconstruction.In Group 1(6 patients),the wounds completely healed in 5-6 weeks with JFT only.In Group 2(12 patients),the wounds completely healed in 3-4 weeks with JFT and skin graft/flap.Conclusion:Hydrotherapy with JFT helps in the removal of contaminants,debris,and microbial colonization of the wound leading to spontaneous wound healing and facilitating wound bed preparation for wound coverage by a skin graft or flap.
