The surrounding rock is prone to large-scale loosening and failure after the excavation of shallow large-span caverns because of the thin overlying strata and large cross-section span.The rational design of bolt suppo...The surrounding rock is prone to large-scale loosening and failure after the excavation of shallow large-span caverns because of the thin overlying strata and large cross-section span.The rational design of bolt support is very important to the safety control of surrounding rock as a common support means.The control mechanism and design method of bolt support for shallow-buried large-span caverns is carried out.The calculation method of bolt prestress and length based on arched failure and collapsed failure mode is established.The influence mechanism of different influencing factors on the bolt prestress and length is clarified.At the same time,the constant resistance energy-absorbing bolt with high strength and high toughness is developed,and the comparative test of mechanical properties is carried out.On this basis,the design method of high prestressed bolt support for shallow-buried large-span caverns is put forward,and the field test is carried out in Qingdao metro station in China.The monitoring results show that the maximum roof settlement is 6.8 mm after the new design method is adopted,and the effective control of the shallow-buried large-span caverns is realized.The research results can provide theoretical and technical support for the safety control of shallow-buried large-span caverns.展开更多
To investigate the stability of rock mass in high geostress underground powerhouse caverns subjected to excavation,a microseismic(MS)monitoring system was established and the discrete element method(DEM)-based numeric...To investigate the stability of rock mass in high geostress underground powerhouse caverns subjected to excavation,a microseismic(MS)monitoring system was established and the discrete element method(DEM)-based numerical simulation was carried out.The tempo-spatial damage characteristics of rock mass were analyzed.The evolution laws of MS source parameters during the formation of a rock collapse controlled by high geostress and geological structure were investigated.Additionally,a three-dimensional DEM model of the underground powerhouse caverns was built to reveal the deformation characteristics of rock mass.The results indicated that the MS events induced by excavation of high geostress underground powerhouse caverns occurred frequently.The large-stake crown of the main powerhouse was the main damage area.Prior to the rock collapse,the MS event count and accumulated energy release increased rapidly,while the apparent stress sharply increased and then decreased.The amount and proportion of shear and mixed MS events remarkably increased.The maximum displacement was generally located near the spandrel areas.The MS monitoring data and numerical simulation were in good agreement,which can provide significant references for damage evaluation and disaster forecasting in high geostress underground powerhouse caverns.展开更多
Rock mass large deformation in underground powerhouse caverns has been a severe hazard in hydropower engineering in Southwest China.During the development of rock mass large deformation,a sequence of fractures was gen...Rock mass large deformation in underground powerhouse caverns has been a severe hazard in hydropower engineering in Southwest China.During the development of rock mass large deformation,a sequence of fractures was generated that can be monitored using microseismic(MS)monitoring techniques.Two MS monitoring systems were established in two typical underground powerhouse caverns featuring distinct geostress levels.The MS b-values associated with rock mass large deformation and their temporal variation are analysed.The results showed that the MS bvalue in course of rock mass deformation was less than 1.0 in the underground powerhouse caverns at a high stress level while larger than 1.5 at a low stress level.Prior to the rock mass deformation,the MS b-values derived from both the high-stress and low-stress underground powerhouse caverns show an incremental decrease over 10%within 10 d.The results contribute to understanding the fracturing characteristics of MS sources associated with rock mass large deformation and provide a reference for early warning of rock mass large deformation in underground powerhouse caverns.展开更多
Underground energy and resource development,deep underground energy storage and other projects involve the global stability of multiple interconnected cavern groups under internal and external dynamic disturbances.An ...Underground energy and resource development,deep underground energy storage and other projects involve the global stability of multiple interconnected cavern groups under internal and external dynamic disturbances.An evaluation method of the global stability coefficient of underground caverns based on static overload and dynamic overload was proposed.Firstly,the global failure criterion for caverns was defined based on its band connection of plastic-strain between multi-caverns.Then,overloading calculation of the boundary geostress and seismic intensity on the caverns model was carried out,and the critical unstable state of multi-caverns can be identified,if the plastic-strain band appeared between caverns during these overloading processes.Thus,the global stability coefficient for the multi-caverns under static loading and earthquake was obtained based on the corresponding overloading coefficient.Practical analysis for the Yingliangbao(YLB)hydraulic caverns indicated that this method can not only effectively obtain the global stability coefficient of caverns under static and dynamic earthquake conditions,but also identify the caverns’high-risk zone of local instability through localized plastic strain of surrounding rock.This study can provide some reference for the layout design and seismic optimization of underground cavern group.展开更多
The collapse of rock masses in fault-developed zones poses significant safety challenges during the excavation of high-stress underground caverns. This study investigates the spatiotemporal evolution of the collapse m...The collapse of rock masses in fault-developed zones poses significant safety challenges during the excavation of high-stress underground caverns. This study investigates the spatiotemporal evolution of the collapse mechanisms of the cavern in the Yebatan Hydropower Station through using microseismic (MS) monitoring and displacement measurements. We developed a multi-parameter deformation early warning model that integrates three critical indicators: deformation rate, rate increment, and tangential angle of the deformation time curve. The results of the early warning model show a significant and abrupt increase in the deformation of the rock mass during the collapse process. The safety and stability of the local cavern in the face of excavation-induced disturbances are meticulously assessed utilizing MS data. Spatiotemporal analysis of the MS monitoring indicates a high frequency of MS events during the blasting phase, with a notable clustering of these events in the vicinity of the fault. These research results provide a valuable reference for risk warnings and stability assessments in the fault development zones of analogous caverns.展开更多
A simplified method was proposed for the design of concrete lining in underground rock cavern/tunnel against shock loading. The loading may result from the detonation of explosives on ground surface or ground penetrat...A simplified method was proposed for the design of concrete lining in underground rock cavern/tunnel against shock loading. The loading may result from the detonation of explosives on ground surface or ground penetration projectiles exploding adjacent to the cavern/tunnel. The resulting problem necessitates the solution of the dynamics of a beam loaded by a transient pressure uniformly distributed over the span. According to mechanical characteristics of the system with rock bolt and shotcrete, a dynamic support design method based on equivalent single degree of freedom （SDOF） was put forward. The SDOF method was applied to obtaining the maximum displacement at the mid-span of the beam, which is often the controlling factor in the blast-resistant design. In the formulation of the problem, the proposed method combines the phenomena of spalling and structural dynamics theory. An example is provided to demonstrate the applicability of this simplified method.展开更多
Regarding excavation-damaged zone （EDZ） around underground opening as non-homogeneous rockmass with spatial deterioration effect on stuffiness and strength, a parametric model of EDZ using radius-displacement-depend...Regarding excavation-damaged zone （EDZ） around underground opening as non-homogeneous rockmass with spatial deterioration effect on stuffiness and strength, a parametric model of EDZ using radius-displacement-dependent deformation modulus （RDDM） was proposed. Considering the nonlinearity characteristic of deformation and locality otherness of surrounding rock, deterioration parameter field of deformation modulus of rockmass around opening was quantitatively calculated through a given function. Applicability for multi-cavern condition and parameter sensibility of the model was analyzed by numerical experiments using synthetic data. Furthermore, the model was applied to identify EDZ of underground caverns of Pubugou hydropower station by calculating deterioration parameter field. Based on the parametric analysis of spatial effect and geological investigation, it is recognized that large radial deformation of deep fractured rock at the spandrel position and insufficient supporting bolts mainly result in great deformation pressure to act on the shotcrete and cause partial crack and spalling. It is shown that deterioration parameter field along the longitudinal axis of main powerhouse is evidently non-homogeneous in space and distributes exponentially along the radius from the opening. The model provides a simple and convenient way to identify the EDZ in the working state for rapid construction feedback analysis and support optimization of underground cavem from quantitative point of view and also aids in interpreting monitoring displacements and estimating support requirements.展开更多
According to the characteristics of large underground caverns, by using the safety factor of surrounding rock mass point as the control standard of cavern stability, RandWPSO-LSSVM optimization feedback method and flo...According to the characteristics of large underground caverns, by using the safety factor of surrounding rock mass point as the control standard of cavern stability, RandWPSO-LSSVM optimization feedback method and flow process of large underground cavern anchor parameters were established. By applying the optimization feedback method to actual project, the best anchor parameters of large surge shaft five-tunnel area underground cavern of the Nuozhadu hydropower station were obtained through optimization. The results show that the predicted effect of LSSVM prediction model obtained through RandWPSO optimization is good, reasonable and reliable. Combination of the best anchor parameters obtained is 114131312, that is, the locked anchor bar spacing is 1 m x 1 m, pre-stress is 100 kN, elevation 580.45-586.50 m section anchor bar diameter is 36.00 mm, length is 4.50 m, spacing is 1.5 m × 2.5 m; anchor bar diameter at the five-tunnel area side wall is 25.00 mm, length is 7.50 m, spacing is 1 m× 1.5 m, and the shotcrete thickness is 0.15 m. The feedback analyses show that the optimization feedback method of large underground cavern anchor parameters is reasonable and reliable, which has important guiding significance for ensuring the stability of large underground caverns and for saving project investment.展开更多
Objective BACKGROUND Spontaneous closure of direct traumatic carotid cavernous fistulas (TCCFs) is rare. A few cases have been reported in literature to be related to diagnostic cerebral angiography and orbital venogr...Objective BACKGROUND Spontaneous closure of direct traumatic carotid cavernous fistulas (TCCFs) is rare. A few cases have been reported in literature to be related to diagnostic cerebral angiography and orbital venography. Several mechanisms have been postulated, including irritation of the vessels from contrast media, compression of the carotid artery and reduced blood pressure from general anesthesia. In our own series of about 400 patients at Ramathibodi Hospital, the incidence is approximately 1.75%.CASE PRESENTATION We present a case, which spontaneous closure occurred during attempted endovascular embolization. A 45-year-old woman with left TCCF was referred to our hospital for endovascular treatment. Cerebral angiogram revealed a small-hole fistula at the posterosuperior wall of C2-3 segment of the LICA. Transarterial balloon failed due to the small size of the fistula and acute retroangulation of the balloon attached microcatheter. Transarterial GDC coil placement into the first venous pouch was then attempted for two times, but was unsuccessful. During repositioning of the microcatheter for a third attempt, spontaneous closure of the fistula was observed and confirmed by control angiogram. CONCLUSION Spontaneous closure of direct traumatic carotid cavernous fistulas may occur during endovascular procedures, which can be caused by dissection of the venous pouch by the microcatheter or coils during manipulation, irritation of the vascular walls from the contrast media and decreased blood pressure from general anesthesia.展开更多
An intersecting cavern is a common structural form used in underground engineering,and its safety and stability performance directly control the service performance of the whole project.The dynamic responses of the th...An intersecting cavern is a common structural form used in underground engineering,and its safety and stability performance directly control the service performance of the whole project.The dynamic responses of the three kinds of crossing type(+-shaped,T-shaped,L-shaped)caverns subjected to ground shock were studied by numerical simulation.The velocity plus force mode boundary setting method was proposed in the coupled static and dynamic analysis of a deep underground cavern.The results show that,among the three types of crossing caverns,the+-shaped cavern is the most significantly affected by the dynamic action,followed by T-shaped,and then L-shaped caverns.The vault settlement,straight wall deformation,vault peak particle velocity,effective plastic strain of surrounding rock,and maximum principal stress and strain at the bottom of the lining of the straight wall increase with the increase of cavern span.The vault settlement,straight wall deformation,effective plastic strain of surrounding rock,and the maximum principal stress and strain at the bottom of lining to the straight wall decrease with the increase of lateral pressure coefficient,and the peak particle velocity at the vault increases.The variation is small compared with the change of cavern span.The influence range of the underground cavern intersection is two cavern diameters from the intersection centre.The bottom of the straight wall at the intersection is the weak part.It is suggested to thicken the support locally to improve the stability of the cavern.展开更多
OBJECTIVE Our previous studies demonstrated that various ingredients from the traditional Chinese medicine(TCM)for promoting blood circulation and removing blood stasis,as exemplified by cryptotanshinone and salvianol...OBJECTIVE Our previous studies demonstrated that various ingredients from the traditional Chinese medicine(TCM)for promoting blood circulation and removing blood stasis,as exemplified by cryptotanshinone and salvianolic acid B,exerted striking effects on modulating angiogenesis and vascular permeability,which suggests that they may be effective in treating vascular leak-driven diseases(e.g.tumor,cerebral cavernous malformation and diabetic retinopathy).However,the lack of reliable and advanced technologies and models sets up difficult hurdles for better understanding the role of TCM for promoting blood circulation and removing blood stasis.To this end,this study is to outline numerous cutting-edge platforms that can be utilized for exploring the function of TCM for promoting blood circulation and removing blood stasis in vascular leak-driven diseases.METHODS Two-photon laser scanning fluorescence microscopy was used to observe the interactions between neutrophils and blood vessels in a real-time manner.Dynamic flow system was employed to mimic the in vivo behaviors of neutrophils.RIP1-Tag5 spontaneous pancreatic cancer model was used to study the function of tumor blood vessels.CCM2ECKO(deletion of CCM2 in endothelial cells)mice were employed to establish the cerebral cavernous malformation(CCM)animal model.Micro-computed tomography(micro-CT)was utilized to assess the CCM lesion.Müller cell-knockout mouse model was used to study the progression of diabetic retinopathy.Vascular permeability in this model was assessed by fluorescein angiography.RESULTS The interactions between neutrophils and endothelial cells involve a series of complicated processes,including rolling,adhesion,intraluminal crawling and transmigration,which were all monitored in vivo by two-photon laser scanning fluorescence microscopy in a real-time manner.Dynamic flow system was capable of recapitulating the biological behaviors of neutrophils in vitro.Tumor vascular function in particular vascular perfusion could be assessed in the RIP1-Tag5 spontaneous pancreatic cancer model.In terms of CCM studies,specific deletion of CCM2 in endothelial cells resulted in the initiation of CCM lesion.The size and number of CCM lesions could be visualized and quantified by micro-CT.Furthermore,the Müller cell-knockout mouse model was able to precisely reflect the clinical symptoms of diabetic retinopathy.Vascular leak could be monitored at different time points using fluorescein angiography.CONCLUSION An array of high technologies and animal models can be used in investigating the occurrence and progression of multiple vascular leak-driven diseases.The pre-clinical and clinical studies of TCM for promoting blood circulation and removing blood stasis provide fundamental support for the application of the above-mentioned platforms,with the purpose of uncovering the scientific basis of TCM for promoting blood circulation and removing blood stasis.展开更多
Objective Introduction When we perform transvenous embolization of carotid cavernous fistula, we selectively occluded the venous outflow to the retrograde cortical venous drainage and retrograde ophthalmic venous drai...Objective Introduction When we perform transvenous embolization of carotid cavernous fistula, we selectively occluded the venous outflow to the retrograde cortical venous drainage and retrograde ophthalmic venous drainage as the initial steps before the rest of the cavernous sinus. The rationale is to prevent re-diversion of flow into the ophthalmic veins and cortical veins in a subtotally occluded carotid cavernous fistula.Method From 1997 to 2004, a total of 46 patients with carotid cavernous fistula were treated by transvenous embolization using the proposed selective occlusion strategy. There were 6 direct and 40 dural cartoid cavernous fistulae. The embolic agents were Guglielmi detachable coils and fibered platinum coils. Transvenous embolization routes included inferior petrosal sinus (IPS) alone (32 patients), IPS and intercavernous sinus (9 patients), and superior ophthalmic vein (5 patients).Result The follow-up period ranged from 4 months to 7 years. One patient developed retinal hemorrhage due to ophthalic vein thrombosis one week after the embolization procedure. Two patients had transient ophthalmoplegia and 2 patients had symptomatic recurrence of the carotid cavernous fistula during the follow-up. Clinical cure was achieved in 44 patients (96%).Conclusion The sequential occlusion strategy offers a safe and effective method in the transvenous embolization of carotid cavernous fistula.展开更多
基金Project(2023YFC3805700) supported by the National Key Research and Development Program of ChinaProjects(42477166,42277174) supported by the National Natural Science Foundation of China+2 种基金Project(2024JCCXSB01) supported by the Fundamental Research Funds for the Central Universities,ChinaProject(KFJJ24-01M) supported by the State Key Laboratory of Explosion Science and Safety Protection,Beijing Institute of Technology,ChinaProject(HLCX-2024-04) supported by the Open Foundation of Collaborative Innovation Center of Green Development and Ecological Restoration of Mineral Resources,China。
文摘The surrounding rock is prone to large-scale loosening and failure after the excavation of shallow large-span caverns because of the thin overlying strata and large cross-section span.The rational design of bolt support is very important to the safety control of surrounding rock as a common support means.The control mechanism and design method of bolt support for shallow-buried large-span caverns is carried out.The calculation method of bolt prestress and length based on arched failure and collapsed failure mode is established.The influence mechanism of different influencing factors on the bolt prestress and length is clarified.At the same time,the constant resistance energy-absorbing bolt with high strength and high toughness is developed,and the comparative test of mechanical properties is carried out.On this basis,the design method of high prestressed bolt support for shallow-buried large-span caverns is put forward,and the field test is carried out in Qingdao metro station in China.The monitoring results show that the maximum roof settlement is 6.8 mm after the new design method is adopted,and the effective control of the shallow-buried large-span caverns is realized.The research results can provide theoretical and technical support for the safety control of shallow-buried large-span caverns.
基金Project(2017YFC1501100)supported by the National Key R&D Program of ChinaProjects(51809221,51679158)supported by the National Natural Science Foundation of China。
文摘To investigate the stability of rock mass in high geostress underground powerhouse caverns subjected to excavation,a microseismic(MS)monitoring system was established and the discrete element method(DEM)-based numerical simulation was carried out.The tempo-spatial damage characteristics of rock mass were analyzed.The evolution laws of MS source parameters during the formation of a rock collapse controlled by high geostress and geological structure were investigated.Additionally,a three-dimensional DEM model of the underground powerhouse caverns was built to reveal the deformation characteristics of rock mass.The results indicated that the MS events induced by excavation of high geostress underground powerhouse caverns occurred frequently.The large-stake crown of the main powerhouse was the main damage area.Prior to the rock collapse,the MS event count and accumulated energy release increased rapidly,while the apparent stress sharply increased and then decreased.The amount and proportion of shear and mixed MS events remarkably increased.The maximum displacement was generally located near the spandrel areas.The MS monitoring data and numerical simulation were in good agreement,which can provide significant references for damage evaluation and disaster forecasting in high geostress underground powerhouse caverns.
基金Projects(51809221,51679158)supported by the National Natural Science Foundation of ChinaProject(KFJJ20-06M)supported by the State Key Laboratory of Explosion Science and Technology(Beijing Institute of Technology),China。
文摘Rock mass large deformation in underground powerhouse caverns has been a severe hazard in hydropower engineering in Southwest China.During the development of rock mass large deformation,a sequence of fractures was generated that can be monitored using microseismic(MS)monitoring techniques.Two MS monitoring systems were established in two typical underground powerhouse caverns featuring distinct geostress levels.The MS b-values associated with rock mass large deformation and their temporal variation are analysed.The results showed that the MS bvalue in course of rock mass deformation was less than 1.0 in the underground powerhouse caverns at a high stress level while larger than 1.5 at a low stress level.Prior to the rock mass deformation,the MS b-values derived from both the high-stress and low-stress underground powerhouse caverns show an incremental decrease over 10%within 10 d.The results contribute to understanding the fracturing characteristics of MS sources associated with rock mass large deformation and provide a reference for early warning of rock mass large deformation in underground powerhouse caverns.
基金Project(2023YFC2907204)supported by the National Key Research and Development Program of ChinaProject(52325905)supported by the National Natural Science Foundation of ChinaProject(DJ-HXGG-2023-16)supported by the Key Technology Research Projects of Power China。
文摘Underground energy and resource development,deep underground energy storage and other projects involve the global stability of multiple interconnected cavern groups under internal and external dynamic disturbances.An evaluation method of the global stability coefficient of underground caverns based on static overload and dynamic overload was proposed.Firstly,the global failure criterion for caverns was defined based on its band connection of plastic-strain between multi-caverns.Then,overloading calculation of the boundary geostress and seismic intensity on the caverns model was carried out,and the critical unstable state of multi-caverns can be identified,if the plastic-strain band appeared between caverns during these overloading processes.Thus,the global stability coefficient for the multi-caverns under static loading and earthquake was obtained based on the corresponding overloading coefficient.Practical analysis for the Yingliangbao(YLB)hydraulic caverns indicated that this method can not only effectively obtain the global stability coefficient of caverns under static and dynamic earthquake conditions,but also identify the caverns’high-risk zone of local instability through localized plastic strain of surrounding rock.This study can provide some reference for the layout design and seismic optimization of underground cavern group.
基金Projects(52209132, 52309156) supported by the National Natural Science Foundation of ChinaProject(BK20251905) supported by the Natural Science Foundation of Jiangsu Province,China+2 种基金Project(252102320037) supported by the Henan Province Science and Technology Research,ChinaProject(CKWV20231173/KY) supported by the CRSRI Open Research Program,ChinaProject(2023KSD15) supported by the Open Research Fund of Hubei Provincial Key Laboratory of Construction and Management in Hydropower Engineering,China。
文摘The collapse of rock masses in fault-developed zones poses significant safety challenges during the excavation of high-stress underground caverns. This study investigates the spatiotemporal evolution of the collapse mechanisms of the cavern in the Yebatan Hydropower Station through using microseismic (MS) monitoring and displacement measurements. We developed a multi-parameter deformation early warning model that integrates three critical indicators: deformation rate, rate increment, and tangential angle of the deformation time curve. The results of the early warning model show a significant and abrupt increase in the deformation of the rock mass during the collapse process. The safety and stability of the local cavern in the face of excavation-induced disturbances are meticulously assessed utilizing MS data. Spatiotemporal analysis of the MS monitoring indicates a high frequency of MS events during the blasting phase, with a notable clustering of these events in the vicinity of the fault. These research results provide a valuable reference for risk warnings and stability assessments in the fault development zones of analogous caverns.
基金Projects（50934006, 50904079） supported by the National Natural Science Foundation of China Project（2010CB732004） supported by the National Basic Research Program of China
文摘A simplified method was proposed for the design of concrete lining in underground rock cavern/tunnel against shock loading. The loading may result from the detonation of explosives on ground surface or ground penetration projectiles exploding adjacent to the cavern/tunnel. The resulting problem necessitates the solution of the dynamics of a beam loaded by a transient pressure uniformly distributed over the span. According to mechanical characteristics of the system with rock bolt and shotcrete, a dynamic support design method based on equivalent single degree of freedom （SDOF） was put forward. The SDOF method was applied to obtaining the maximum displacement at the mid-span of the beam, which is often the controlling factor in the blast-resistant design. In the formulation of the problem, the proposed method combines the phenomena of spalling and structural dynamics theory. An example is provided to demonstrate the applicability of this simplified method.
基金Project(2010CB732005) supported by the National Basic Research Program of ChinaProjects(51279136, 51209164) supported by the National Natural Science Foundation of China
文摘Regarding excavation-damaged zone （EDZ） around underground opening as non-homogeneous rockmass with spatial deterioration effect on stuffiness and strength, a parametric model of EDZ using radius-displacement-dependent deformation modulus （RDDM） was proposed. Considering the nonlinearity characteristic of deformation and locality otherness of surrounding rock, deterioration parameter field of deformation modulus of rockmass around opening was quantitatively calculated through a given function. Applicability for multi-cavern condition and parameter sensibility of the model was analyzed by numerical experiments using synthetic data. Furthermore, the model was applied to identify EDZ of underground caverns of Pubugou hydropower station by calculating deterioration parameter field. Based on the parametric analysis of spatial effect and geological investigation, it is recognized that large radial deformation of deep fractured rock at the spandrel position and insufficient supporting bolts mainly result in great deformation pressure to act on the shotcrete and cause partial crack and spalling. It is shown that deterioration parameter field along the longitudinal axis of main powerhouse is evidently non-homogeneous in space and distributes exponentially along the radius from the opening. The model provides a simple and convenient way to identify the EDZ in the working state for rapid construction feedback analysis and support optimization of underground cavem from quantitative point of view and also aids in interpreting monitoring displacements and estimating support requirements.
基金Project(50911130366) supported by the National Natural Science Foundation of China
文摘According to the characteristics of large underground caverns, by using the safety factor of surrounding rock mass point as the control standard of cavern stability, RandWPSO-LSSVM optimization feedback method and flow process of large underground cavern anchor parameters were established. By applying the optimization feedback method to actual project, the best anchor parameters of large surge shaft five-tunnel area underground cavern of the Nuozhadu hydropower station were obtained through optimization. The results show that the predicted effect of LSSVM prediction model obtained through RandWPSO optimization is good, reasonable and reliable. Combination of the best anchor parameters obtained is 114131312, that is, the locked anchor bar spacing is 1 m x 1 m, pre-stress is 100 kN, elevation 580.45-586.50 m section anchor bar diameter is 36.00 mm, length is 4.50 m, spacing is 1.5 m × 2.5 m; anchor bar diameter at the five-tunnel area side wall is 25.00 mm, length is 7.50 m, spacing is 1 m× 1.5 m, and the shotcrete thickness is 0.15 m. The feedback analyses show that the optimization feedback method of large underground cavern anchor parameters is reasonable and reliable, which has important guiding significance for ensuring the stability of large underground caverns and for saving project investment.
文摘Objective BACKGROUND Spontaneous closure of direct traumatic carotid cavernous fistulas (TCCFs) is rare. A few cases have been reported in literature to be related to diagnostic cerebral angiography and orbital venography. Several mechanisms have been postulated, including irritation of the vessels from contrast media, compression of the carotid artery and reduced blood pressure from general anesthesia. In our own series of about 400 patients at Ramathibodi Hospital, the incidence is approximately 1.75%.CASE PRESENTATION We present a case, which spontaneous closure occurred during attempted endovascular embolization. A 45-year-old woman with left TCCF was referred to our hospital for endovascular treatment. Cerebral angiogram revealed a small-hole fistula at the posterosuperior wall of C2-3 segment of the LICA. Transarterial balloon failed due to the small size of the fistula and acute retroangulation of the balloon attached microcatheter. Transarterial GDC coil placement into the first venous pouch was then attempted for two times, but was unsuccessful. During repositioning of the microcatheter for a third attempt, spontaneous closure of the fistula was observed and confirmed by control angiogram. CONCLUSION Spontaneous closure of direct traumatic carotid cavernous fistulas may occur during endovascular procedures, which can be caused by dissection of the venous pouch by the microcatheter or coils during manipulation, irritation of the vascular walls from the contrast media and decreased blood pressure from general anesthesia.
基金This research is funded by the National Natural Science Foundation of China(No.51478469).
文摘An intersecting cavern is a common structural form used in underground engineering,and its safety and stability performance directly control the service performance of the whole project.The dynamic responses of the three kinds of crossing type(+-shaped,T-shaped,L-shaped)caverns subjected to ground shock were studied by numerical simulation.The velocity plus force mode boundary setting method was proposed in the coupled static and dynamic analysis of a deep underground cavern.The results show that,among the three types of crossing caverns,the+-shaped cavern is the most significantly affected by the dynamic action,followed by T-shaped,and then L-shaped caverns.The vault settlement,straight wall deformation,vault peak particle velocity,effective plastic strain of surrounding rock,and maximum principal stress and strain at the bottom of the lining of the straight wall increase with the increase of cavern span.The vault settlement,straight wall deformation,effective plastic strain of surrounding rock,and the maximum principal stress and strain at the bottom of lining to the straight wall decrease with the increase of lateral pressure coefficient,and the peak particle velocity at the vault increases.The variation is small compared with the change of cavern span.The influence range of the underground cavern intersection is two cavern diameters from the intersection centre.The bottom of the straight wall at the intersection is the weak part.It is suggested to thicken the support locally to improve the stability of the cavern.
文摘OBJECTIVE Our previous studies demonstrated that various ingredients from the traditional Chinese medicine(TCM)for promoting blood circulation and removing blood stasis,as exemplified by cryptotanshinone and salvianolic acid B,exerted striking effects on modulating angiogenesis and vascular permeability,which suggests that they may be effective in treating vascular leak-driven diseases(e.g.tumor,cerebral cavernous malformation and diabetic retinopathy).However,the lack of reliable and advanced technologies and models sets up difficult hurdles for better understanding the role of TCM for promoting blood circulation and removing blood stasis.To this end,this study is to outline numerous cutting-edge platforms that can be utilized for exploring the function of TCM for promoting blood circulation and removing blood stasis in vascular leak-driven diseases.METHODS Two-photon laser scanning fluorescence microscopy was used to observe the interactions between neutrophils and blood vessels in a real-time manner.Dynamic flow system was employed to mimic the in vivo behaviors of neutrophils.RIP1-Tag5 spontaneous pancreatic cancer model was used to study the function of tumor blood vessels.CCM2ECKO(deletion of CCM2 in endothelial cells)mice were employed to establish the cerebral cavernous malformation(CCM)animal model.Micro-computed tomography(micro-CT)was utilized to assess the CCM lesion.Müller cell-knockout mouse model was used to study the progression of diabetic retinopathy.Vascular permeability in this model was assessed by fluorescein angiography.RESULTS The interactions between neutrophils and endothelial cells involve a series of complicated processes,including rolling,adhesion,intraluminal crawling and transmigration,which were all monitored in vivo by two-photon laser scanning fluorescence microscopy in a real-time manner.Dynamic flow system was capable of recapitulating the biological behaviors of neutrophils in vitro.Tumor vascular function in particular vascular perfusion could be assessed in the RIP1-Tag5 spontaneous pancreatic cancer model.In terms of CCM studies,specific deletion of CCM2 in endothelial cells resulted in the initiation of CCM lesion.The size and number of CCM lesions could be visualized and quantified by micro-CT.Furthermore,the Müller cell-knockout mouse model was able to precisely reflect the clinical symptoms of diabetic retinopathy.Vascular leak could be monitored at different time points using fluorescein angiography.CONCLUSION An array of high technologies and animal models can be used in investigating the occurrence and progression of multiple vascular leak-driven diseases.The pre-clinical and clinical studies of TCM for promoting blood circulation and removing blood stasis provide fundamental support for the application of the above-mentioned platforms,with the purpose of uncovering the scientific basis of TCM for promoting blood circulation and removing blood stasis.
文摘Objective Introduction When we perform transvenous embolization of carotid cavernous fistula, we selectively occluded the venous outflow to the retrograde cortical venous drainage and retrograde ophthalmic venous drainage as the initial steps before the rest of the cavernous sinus. The rationale is to prevent re-diversion of flow into the ophthalmic veins and cortical veins in a subtotally occluded carotid cavernous fistula.Method From 1997 to 2004, a total of 46 patients with carotid cavernous fistula were treated by transvenous embolization using the proposed selective occlusion strategy. There were 6 direct and 40 dural cartoid cavernous fistulae. The embolic agents were Guglielmi detachable coils and fibered platinum coils. Transvenous embolization routes included inferior petrosal sinus (IPS) alone (32 patients), IPS and intercavernous sinus (9 patients), and superior ophthalmic vein (5 patients).Result The follow-up period ranged from 4 months to 7 years. One patient developed retinal hemorrhage due to ophthalic vein thrombosis one week after the embolization procedure. Two patients had transient ophthalmoplegia and 2 patients had symptomatic recurrence of the carotid cavernous fistula during the follow-up. Clinical cure was achieved in 44 patients (96%).Conclusion The sequential occlusion strategy offers a safe and effective method in the transvenous embolization of carotid cavernous fistula.
