Prediction of water inflow into a tunnel is a crucial prerequisite for the waterproof and drainage design of mountain tunnels in water-rich areas.Based on the proposed Baiyun Mountain Tunnel project in Guangzhou,a num...Prediction of water inflow into a tunnel is a crucial prerequisite for the waterproof and drainage design of mountain tunnels in water-rich areas.Based on the proposed Baiyun Mountain Tunnel project in Guangzhou,a numerical percolation model of random fractured rock of a tunnel underpassing a water reservoir is established to study the seepage characteristics of surrounding rock,the law of water inflow,and the change of lining water pressure,considering the local artificial boundary conditions for seepage in large rock mass,.In addition,the influences of rock permeability,fracture aperture,grouting circle thickness,and penetration are analyzed.The results show that:(1)Only fractures with aperture wider than 0.1 mm can play a significant role in water conduction in rocks with the permeability lower than 10^(-11)m^(2);(2)The greater the permeability difference between the fractures and rocks,the more remarkable the effects of fractures on the surrounding rock seepage field and cavern water inflow;(3)The sensitivity of grouting waterproof function to grouting circle thickness,grouting ring penetration,and rock permeability is significantly higher than that of tunnel buried depth and fracture aperture;(4)The lining water head is much more sensitive to the grouting circle thickness and penetration than to the tunnel buried depth;(5)With the grouting range enlarging,the impact of grouting circle permeability on the precipitation pressure role of the grouting ring increases;(6)For the interesting tunnel designed to be built at the depth of 70 m,the grouting circle with the thickness of 0.5 m and permeability of 10-^(14)m^(2)is recommended.展开更多
Water inflow into mountain tunnels exhibits high variability and nonlinear seepage behavior,leading to significant prediction inaccuracies and poor pattern recognition when conventional analytical methods are applied....Water inflow into mountain tunnels exhibits high variability and nonlinear seepage behavior,leading to significant prediction inaccuracies and poor pattern recognition when conventional analytical methods are applied.This study proposes a dynamic water inflow prediction method specifically designed for mountain tunnels.The method is based on groundwater dynamics theory,employing nonDarcian law as the governing equation and deriving analytical solutions applicable to both confined and phreatic aquifer conditions.The method incorporates spatiotemporal variations along the tunnel alignment,enabling both short-term and long-term dynamic predictions of water inflow.The study examines the nonlinear characteristics of the seepage field during tunnel water inrush.The research findings indicate that the predictive results are consistent with the hypothesized two-stage water inflow pattern,with relative errors for key parameters,such as maximum water inflow,normal water inflow,and duration of water inflow,remaining within 10%.The magnitude of water inflow is positively correlated with the permeability coefficient,head height;it is negatively correlated with the axial distance to the tunnel face and the non-Darcian influence coefficient.Both water inflow and water pressure are subject to non-Darcian effects within a defined influence zone extending approximately 1.3 times the tunnel diameter.Comparisons with established predictive methods,numerical simulations,and data from existing tunnel projects confirm the effectiveness of the proposed method.Moreover,the method was successfully applied to a mountain tunnel in the Tibet Plateau region in southwestern China,where it achieved prediction errors within 3%to 8%,demonstrating high reliability.展开更多
We present the existence/non-existence criteria for large-amplitude boundary layer solutions to the inflow problem of the one-dimensional(1D)full compressible NavierStokes equations on a half line R_+.Instead of the c...We present the existence/non-existence criteria for large-amplitude boundary layer solutions to the inflow problem of the one-dimensional(1D)full compressible NavierStokes equations on a half line R_+.Instead of the classical center manifold approach for the existence of small-amplitude boundary layer solutions in the previous results,the delicate global phase plane analysis,based on the qualitative theory of ODEs,is utilized to obtain the sufficient and necessary conditions for the existence/non-existence of large boundary layer solutions to the half-space inflow problem when the right end state belongs to the supersonic,transonic,and subsonic regions,respectively,which completely answers the existence/nonexistence of boundary layer solutions to the half-space inflow problem of 1D full compressible Navier-Stokes equations.展开更多
Accurate prediction of the hydrographs of outburst floods induced by landslide dam overtopping failure is necessary for hazard prevention and mitigation. In this study, flume model tests on the breaching of landslide ...Accurate prediction of the hydrographs of outburst floods induced by landslide dam overtopping failure is necessary for hazard prevention and mitigation. In this study, flume model tests on the breaching of landslide dams were conducted. Unconsolidated soil materials with wide grain size distributions were used to construct the dam. The effects of different upstream inflow discharges and downstream bed soil erosion on the outburst peak discharge were investigated. Experimental results reveal that the whole hydrodynamic process of landslide dam breaching can be divided into three stages as defined by clear inflection points and peak discharges. The larger the inflow discharge, the shorter the time it takes to reach the peak discharge, and the larger the outburst flood peak discharge. The scale of the outburst floods was found to be amplified by the presence of an erodible bed located downstream of the landslide dam. This amplification decreases with the increase of upstream inflow. In addition, the results show that the existence of an erodible bed increases the density of the outburst flow, increasing its probability of transforming from a sediment flow to a debris flow.展开更多
This article proposes a tandem cascade constructed to tackle the thorny problem of designing the high-loaded stator with a supersonic inflow and a large turning angle. The front cascade adopts a supersonic profile to ...This article proposes a tandem cascade constructed to tackle the thorny problem of designing the high-loaded stator with a supersonic inflow and a large turning angle. The front cascade adopts a supersonic profile to reduce the shock wave intensity turning the flow into subsonic,while the rear cascade adopts a subsonic profile with a large camber offering the flow a large turning angle. It is disclosed that the losses would be minimized if the leading edge of the rear cas- cade lies close to the pressure side of the front cascade at a distance of 20% pitch in pitch-wise direction without either axial spacing or overlapping in axial direction. The 2D numerical test results show that,with the inflow Mach number of 1.25 and the turning angle of 52° ,the total pressure loss coefficient of the tandem cascade reaches 0. 106 ,and the diffusion factor 0. 745. Finally,this article has designed and simulated a high-loaded fan stage with the proposed tandem stator,which has the pressure ratio of 3.15 and the efficiency of 86.32% at the rotor tip speed of 495.32 m/s.展开更多
AIM:To investigate the clinical significance of hepatic blood inflow occlusion without hemihepatic artery control (BIOwHAC) in the treatment of hepatocellular carcinoma (HCC).METHODS:Fifty-nine patients with HCC were ...AIM:To investigate the clinical significance of hepatic blood inflow occlusion without hemihepatic artery control (BIOwHAC) in the treatment of hepatocellular carcinoma (HCC).METHODS:Fifty-nine patients with HCC were divided into 3 groups based on the technique used for achieving hepatic vascular occlusion:group 1,vascular occlusion was achieved by the Pringle maneuver (n=20);group 2,by hemihepatic vascular occlusion (HVO) (n=20);and group 3,by BIOwHAC (n=19).We compared the procedures among the three groups in term of operation time,intraoperative bleeding,postoperative liver function,postoperative complications,and length of hospital stay.RESULTS:There were no statistically significant differences (P > 0.05) in age,sex,pathological diagnosis,preoperative Child's disease grade,hepatic function,and tumor size among the three groups.No intraoperative complications or deaths occurrred,and there were no significant intergroup differences (P > 0.05) in intraoperative bleeding,hepatic function change 3 and 7 d after operation,the incidence of complications,and length of hospital stay.BIOwHAC and Pringle maneuver required a significantly shorter operation time than HVO;the difference in the serum alanine aminotransferase or aspartate aminotransferase levels before and 1 d after operation was more significant in the BIOwHAC and HVO groups than in the Pringle maneuver group (P < 0.05).CONCLUSION:BIOwHAC is convenient and safe;this technique causes slight hepatic ischemia-reperfusion injury similar to HVO.展开更多
BACKGROUND:Survival of the partial graft after living donor liver transplantation owes much to its tremendous regenerative ability.With excellent venous outflow capacity,a graft within a wide range of graft-to-standar...BACKGROUND:Survival of the partial graft after living donor liver transplantation owes much to its tremendous regenerative ability.With excellent venous outflow capacity,a graft within a wide range of graft-to-standard-liver-volume ratios can cope with portal hypertension that is common in liver transplant recipients.However,when the ratio range is exceeded,modulation of graft vascular inflow becomes necessary for graft survival.The interplay between graft-to-standard-liver-volume ratio and portal pressure,in the presence of portosystemic shunt or otherwise,requires individualized modulation of graft portal and arterial inflows.Boosting of portal inflow by shunt ligation can be guided by transonic flowmetry,whereas muting of portal inflow by splenic artery ligation can be monitored by portal electronic manometry.METHOD:We describe four cases to illustrate the above.RESULTS:One patient had hepatic artery thrombosis resulting from splenic artery steal syndrome which was the sequela of small-for-size syndrome.Emergency splenic artery ligation and re-anastomosis of the hepatic artery successfully muted the portal inflow and boosted the hepatic arterial inflow.Another patient with portal vein thrombosis underwent thrombendvenectomy.Portal inflow was boosted with ligation of portosystemic shunt,which is often present in these patients with portal hypertension.The coexistence of splenic aneurysm and splenorenal shunt required ligation of both in the third patient.The fourth patient,with portal pressure and flow monitoring,avoided ligation of a coronary vein which became a main portal inflow after portal thrombendvenectomy.CONCLUSION:Management of graft inflow modulation guided selectively by transonic flowmetry or portal manometry was described.展开更多
AIM： To evaluate the clinical outcomes of patients undergoing hepatectomy with hemihepatic vascular occlusion （HHO） compared with total hepatic inflow occlusion （THO）. METHODS： Randomized controlled trials （RCT...AIM： To evaluate the clinical outcomes of patients undergoing hepatectomy with hemihepatic vascular occlusion （HHO） compared with total hepatic inflow occlusion （THO）. METHODS： Randomized controlled trials （RCTs） co- mparing hemihepatic vascular occlusion and total he- patic inflow occlusion were included by a systematic literature search. Two authors independently assessed the trials for inclusion and extracted the data. A meta- analysis was conducted to estimate blood loss, transfu- sion requirement, and liver injury based on the levels of aspartate aminotransferase （AST） and alanine arni- notransferase （ALT）. Either the fixed effects model or random effects model was used. RESULTS- Four RCTs including 338 patients met the predefined inclusion criteria. A total of 167 patients were treated with THO and 171 with HHO. Metaanalysis of AST levels on postoperative day 1 indicated higher levels in the THO group with weighted mean dif- ference （WMD） 342.27; 95% confidence intervals （CI） 217.28-467.26; P = 0.00001; I2 = 16%. Meta-analysis showed no significant difference between THO group and HHO group on blood loss, transfusion requirement, mortality, morbidity, operating time, ischemic duration, hospital stay, ALT levels on postoperative day 1, 3 and 7 and AST levels on postoperative day 3 and 7. CONCLUSION： Hemihepatic vascular occlusion does not offer satisfying benefit to the patients undergoing hepatic resection. However, they have less liver injury after liver resections.展开更多
Objective: To evaluate the tolerance limit of rats tonormothermic hepatic inflow occlusion under portalblood bypass.Methods: A new rat model of normothermic hepaticinflow occlusion under portal blood bypass was estab-...Objective: To evaluate the tolerance limit of rats tonormothermic hepatic inflow occlusion under portalblood bypass.Methods: A new rat model of normothermic hepaticinflow occlusion under portal blood bypass was estab-lished by clamping temporarily the pedicles of all liverlobes while the caudal lobe was kept as a passage ofthe portal blood flow. After hepatic blood flow re-stored, the caudal lobe was cut off. On the 7th postop-erative day, survival rate, hepatic morphological changes,and the severity and reversibility of the injured energymetabolism of the liver were investigated.Results: All rats that had been subjected to 30, 60 and90 minutes of hepatic inflow occlusion under portalblood bypass survived on the 7th postoperativeday. Ischemia-reperfusion injury of the liver was re-versible and compensatory in rats with hepatic inflowocclusion within 90minutes. However, the survivalrates of rats with 100, 110 and 120 minutes of hepaticinflow occlusion were 50%, 30% and 20% respective-ly. Liver injury of rats with 120 minutes of hepatic in-flow occlusion was severe and irreversible.Conclusions: The tolerance limit of rats to normother-mic hepatic inflow occlusion is enhanced significantlyunder portal blood bypass and the upper limit is 90minutes.展开更多
文摘Prediction of water inflow into a tunnel is a crucial prerequisite for the waterproof and drainage design of mountain tunnels in water-rich areas.Based on the proposed Baiyun Mountain Tunnel project in Guangzhou,a numerical percolation model of random fractured rock of a tunnel underpassing a water reservoir is established to study the seepage characteristics of surrounding rock,the law of water inflow,and the change of lining water pressure,considering the local artificial boundary conditions for seepage in large rock mass,.In addition,the influences of rock permeability,fracture aperture,grouting circle thickness,and penetration are analyzed.The results show that:(1)Only fractures with aperture wider than 0.1 mm can play a significant role in water conduction in rocks with the permeability lower than 10^(-11)m^(2);(2)The greater the permeability difference between the fractures and rocks,the more remarkable the effects of fractures on the surrounding rock seepage field and cavern water inflow;(3)The sensitivity of grouting waterproof function to grouting circle thickness,grouting ring penetration,and rock permeability is significantly higher than that of tunnel buried depth and fracture aperture;(4)The lining water head is much more sensitive to the grouting circle thickness and penetration than to the tunnel buried depth;(5)With the grouting range enlarging,the impact of grouting circle permeability on the precipitation pressure role of the grouting ring increases;(6)For the interesting tunnel designed to be built at the depth of 70 m,the grouting circle with the thickness of 0.5 m and permeability of 10-^(14)m^(2)is recommended.
基金the financial support provided by the Key Laboratory of Urban Underground Engineering of Ministry of Education,Beijing Jiaotong University(Grant Nos.TUL2024-05)。
文摘Water inflow into mountain tunnels exhibits high variability and nonlinear seepage behavior,leading to significant prediction inaccuracies and poor pattern recognition when conventional analytical methods are applied.This study proposes a dynamic water inflow prediction method specifically designed for mountain tunnels.The method is based on groundwater dynamics theory,employing nonDarcian law as the governing equation and deriving analytical solutions applicable to both confined and phreatic aquifer conditions.The method incorporates spatiotemporal variations along the tunnel alignment,enabling both short-term and long-term dynamic predictions of water inflow.The study examines the nonlinear characteristics of the seepage field during tunnel water inrush.The research findings indicate that the predictive results are consistent with the hypothesized two-stage water inflow pattern,with relative errors for key parameters,such as maximum water inflow,normal water inflow,and duration of water inflow,remaining within 10%.The magnitude of water inflow is positively correlated with the permeability coefficient,head height;it is negatively correlated with the axial distance to the tunnel face and the non-Darcian influence coefficient.Both water inflow and water pressure are subject to non-Darcian effects within a defined influence zone extending approximately 1.3 times the tunnel diameter.Comparisons with established predictive methods,numerical simulations,and data from existing tunnel projects confirm the effectiveness of the proposed method.Moreover,the method was successfully applied to a mountain tunnel in the Tibet Plateau region in southwestern China,where it achieved prediction errors within 3%to 8%,demonstrating high reliability.
基金partially supported by the NSFC(12171459,12288201,12090014,12421001)CAS Project for Young Scientists in Basic Research(YSBR-031)。
文摘We present the existence/non-existence criteria for large-amplitude boundary layer solutions to the inflow problem of the one-dimensional(1D)full compressible NavierStokes equations on a half line R_+.Instead of the classical center manifold approach for the existence of small-amplitude boundary layer solutions in the previous results,the delicate global phase plane analysis,based on the qualitative theory of ODEs,is utilized to obtain the sufficient and necessary conditions for the existence/non-existence of large boundary layer solutions to the half-space inflow problem when the right end state belongs to the supersonic,transonic,and subsonic regions,respectively,which completely answers the existence/nonexistence of boundary layer solutions to the half-space inflow problem of 1D full compressible Navier-Stokes equations.
基金the financial support from the National Natural Science Foundation of China (Grant No. 41731283)the Key Research Program of Frontier Sciences, Chinese Academy of Sciences (CAS) (Grant No. QYZDB-SSW-DQC010)the Youth Innovation Promotion Association, Chinese Academy of Sciences (CAS)
文摘Accurate prediction of the hydrographs of outburst floods induced by landslide dam overtopping failure is necessary for hazard prevention and mitigation. In this study, flume model tests on the breaching of landslide dams were conducted. Unconsolidated soil materials with wide grain size distributions were used to construct the dam. The effects of different upstream inflow discharges and downstream bed soil erosion on the outburst peak discharge were investigated. Experimental results reveal that the whole hydrodynamic process of landslide dam breaching can be divided into three stages as defined by clear inflection points and peak discharges. The larger the inflow discharge, the shorter the time it takes to reach the peak discharge, and the larger the outburst flood peak discharge. The scale of the outburst floods was found to be amplified by the presence of an erodible bed located downstream of the landslide dam. This amplification decreases with the increase of upstream inflow. In addition, the results show that the existence of an erodible bed increases the density of the outburst flow, increasing its probability of transforming from a sediment flow to a debris flow.
基金National Natural Science Foundation of China(10577002)Innovation Foundation of BUAA for PhD Graduates
文摘This article proposes a tandem cascade constructed to tackle the thorny problem of designing the high-loaded stator with a supersonic inflow and a large turning angle. The front cascade adopts a supersonic profile to reduce the shock wave intensity turning the flow into subsonic,while the rear cascade adopts a subsonic profile with a large camber offering the flow a large turning angle. It is disclosed that the losses would be minimized if the leading edge of the rear cas- cade lies close to the pressure side of the front cascade at a distance of 20% pitch in pitch-wise direction without either axial spacing or overlapping in axial direction. The 2D numerical test results show that,with the inflow Mach number of 1.25 and the turning angle of 52° ,the total pressure loss coefficient of the tandem cascade reaches 0. 106 ,and the diffusion factor 0. 745. Finally,this article has designed and simulated a high-loaded fan stage with the proposed tandem stator,which has the pressure ratio of 3.15 and the efficiency of 86.32% at the rotor tip speed of 495.32 m/s.
基金Supported by The Inner Mongolia Science Foundation,Grant No.2009BS1103
文摘AIM:To investigate the clinical significance of hepatic blood inflow occlusion without hemihepatic artery control (BIOwHAC) in the treatment of hepatocellular carcinoma (HCC).METHODS:Fifty-nine patients with HCC were divided into 3 groups based on the technique used for achieving hepatic vascular occlusion:group 1,vascular occlusion was achieved by the Pringle maneuver (n=20);group 2,by hemihepatic vascular occlusion (HVO) (n=20);and group 3,by BIOwHAC (n=19).We compared the procedures among the three groups in term of operation time,intraoperative bleeding,postoperative liver function,postoperative complications,and length of hospital stay.RESULTS:There were no statistically significant differences (P > 0.05) in age,sex,pathological diagnosis,preoperative Child's disease grade,hepatic function,and tumor size among the three groups.No intraoperative complications or deaths occurrred,and there were no significant intergroup differences (P > 0.05) in intraoperative bleeding,hepatic function change 3 and 7 d after operation,the incidence of complications,and length of hospital stay.BIOwHAC and Pringle maneuver required a significantly shorter operation time than HVO;the difference in the serum alanine aminotransferase or aspartate aminotransferase levels before and 1 d after operation was more significant in the BIOwHAC and HVO groups than in the Pringle maneuver group (P < 0.05).CONCLUSION:BIOwHAC is convenient and safe;this technique causes slight hepatic ischemia-reperfusion injury similar to HVO.
文摘BACKGROUND:Survival of the partial graft after living donor liver transplantation owes much to its tremendous regenerative ability.With excellent venous outflow capacity,a graft within a wide range of graft-to-standard-liver-volume ratios can cope with portal hypertension that is common in liver transplant recipients.However,when the ratio range is exceeded,modulation of graft vascular inflow becomes necessary for graft survival.The interplay between graft-to-standard-liver-volume ratio and portal pressure,in the presence of portosystemic shunt or otherwise,requires individualized modulation of graft portal and arterial inflows.Boosting of portal inflow by shunt ligation can be guided by transonic flowmetry,whereas muting of portal inflow by splenic artery ligation can be monitored by portal electronic manometry.METHOD:We describe four cases to illustrate the above.RESULTS:One patient had hepatic artery thrombosis resulting from splenic artery steal syndrome which was the sequela of small-for-size syndrome.Emergency splenic artery ligation and re-anastomosis of the hepatic artery successfully muted the portal inflow and boosted the hepatic arterial inflow.Another patient with portal vein thrombosis underwent thrombendvenectomy.Portal inflow was boosted with ligation of portosystemic shunt,which is often present in these patients with portal hypertension.The coexistence of splenic aneurysm and splenorenal shunt required ligation of both in the third patient.The fourth patient,with portal pressure and flow monitoring,avoided ligation of a coronary vein which became a main portal inflow after portal thrombendvenectomy.CONCLUSION:Management of graft inflow modulation guided selectively by transonic flowmetry or portal manometry was described.
文摘AIM： To evaluate the clinical outcomes of patients undergoing hepatectomy with hemihepatic vascular occlusion （HHO） compared with total hepatic inflow occlusion （THO）. METHODS： Randomized controlled trials （RCTs） co- mparing hemihepatic vascular occlusion and total he- patic inflow occlusion were included by a systematic literature search. Two authors independently assessed the trials for inclusion and extracted the data. A meta- analysis was conducted to estimate blood loss, transfu- sion requirement, and liver injury based on the levels of aspartate aminotransferase （AST） and alanine arni- notransferase （ALT）. Either the fixed effects model or random effects model was used. RESULTS- Four RCTs including 338 patients met the predefined inclusion criteria. A total of 167 patients were treated with THO and 171 with HHO. Metaanalysis of AST levels on postoperative day 1 indicated higher levels in the THO group with weighted mean dif- ference （WMD） 342.27; 95% confidence intervals （CI） 217.28-467.26; P = 0.00001; I2 = 16%. Meta-analysis showed no significant difference between THO group and HHO group on blood loss, transfusion requirement, mortality, morbidity, operating time, ischemic duration, hospital stay, ALT levels on postoperative day 1, 3 and 7 and AST levels on postoperative day 3 and 7. CONCLUSION： Hemihepatic vascular occlusion does not offer satisfying benefit to the patients undergoing hepatic resection. However, they have less liver injury after liver resections.
文摘Objective: To evaluate the tolerance limit of rats tonormothermic hepatic inflow occlusion under portalblood bypass.Methods: A new rat model of normothermic hepaticinflow occlusion under portal blood bypass was estab-lished by clamping temporarily the pedicles of all liverlobes while the caudal lobe was kept as a passage ofthe portal blood flow. After hepatic blood flow re-stored, the caudal lobe was cut off. On the 7th postop-erative day, survival rate, hepatic morphological changes,and the severity and reversibility of the injured energymetabolism of the liver were investigated.Results: All rats that had been subjected to 30, 60 and90 minutes of hepatic inflow occlusion under portalblood bypass survived on the 7th postoperativeday. Ischemia-reperfusion injury of the liver was re-versible and compensatory in rats with hepatic inflowocclusion within 90minutes. However, the survivalrates of rats with 100, 110 and 120 minutes of hepaticinflow occlusion were 50%, 30% and 20% respective-ly. Liver injury of rats with 120 minutes of hepatic in-flow occlusion was severe and irreversible.Conclusions: The tolerance limit of rats to normother-mic hepatic inflow occlusion is enhanced significantlyunder portal blood bypass and the upper limit is 90minutes.
