The tunnel subjected to strike-slip fault dislocation exhibits severe and catastrophic damage.The existing analysis models frequently assume uniform fault displacement and fixed fault plane position.In contrast,post-e...The tunnel subjected to strike-slip fault dislocation exhibits severe and catastrophic damage.The existing analysis models frequently assume uniform fault displacement and fixed fault plane position.In contrast,post-earthquake observations indicate that the displacement near the fault zone is typically nonuniform,and the fault plane position is uncertain.In this study,we first established a series of improved governing equations to analyze the mechanical response of tunnels under strike-slip fault dislocation.The proposed methodology incorporated key factors such as nonuniform fault displacement and uncertain fault plane position into the governing equations,thereby significantly enhancing the applicability range and accuracy of the model.In contrast to previous analytical models,the maximum computational error has decreased from 57.1%to 1.1%.Subsequently,we conducted a rigorous validation of the proposed methodology by undertaking a comparative analysis with a 3D finite element numerical model,and the results from both approaches exhibited a high degree of qualitative and quantitative agreement with a maximum error of 9.9%.Finally,the proposed methodology was utilized to perform a parametric analysis to explore the effects of various parameters,such as fault displacement,fault zone width,fault zone strength,the ratio of maximum fault displacement of the hanging wall to the footwall,and fault plane position,on the response of tunnels subjected to strike-slip fault dislocation.The findings indicate a progressive increase in the peak internal forces of the tunnel with the rise in fault displacement and fault zone strength.Conversely,an augmentation in fault zone width is found to contribute to a decrease in the peak internal forces.For example,for a fault zone width of 10 m,the peak values of bending moment,shear force,and axial force are approximately 46.9%,102.4%,and 28.7% higher,respectively,compared to those observed for a fault zone width of 50 m.Furthermore,the position of the peak internal forces is influenced by variations in the ratio of maximum fault displacement of the hanging wall to footwall and the fault plane location,while the peak values of shear force and axial force always align with the fault plane.The maximum peak internal forces are observed when the footwall exclusively bears the entirety of the fault displacement,corresponding to a ratio of 0:1.The peak values of bending moment,shear force,and axial force for the ratio of 0:1 amount to approximately 123.8%,148.6%,and 111.1% of those for the ratio of 0.5:0.5,respectively.展开更多
In this study, experiments were carried out to investigate aerodynamic characteristics of a high-speed train on viaducts in turbulent crosswinds using a 1:25 scaled sectional model wind-tunnel testing. Pressure measur...In this study, experiments were carried out to investigate aerodynamic characteristics of a high-speed train on viaducts in turbulent crosswinds using a 1:25 scaled sectional model wind-tunnel testing. Pressure measurements of two typical sections, one train-head section and one train-body section, at the windward and leeward tracks were conducted under the smooth and turbulence flows with wind attack angles between-6° and 6°, and the corresponding aerodynamic force coefficients were also calculated using the integral method. The experimental results indicate that the track position affects the mean aerodynamic characteristics of the vehicle, especially for the train-body section. The fluctuating pressure coefficients at the leeward track are more significantly affected by the bridge interference compared to those at the windward track. The effect of turbulence on the train-head section is less than that on the train-body section. Additionally, the mean aerodynamic force coefficients are almost negatively correlated to wind attack angles, which is more prominent for vehicles at the leeward track. Moreover, the lateral force plays a critical role in determining the corresponding overturning moment, especially on the train-body section.展开更多
目的探讨胰肠吻合术中胰腺断面上胰管所处位置对术后胰瘘发生的影响。方法回顾性收集2018年9月至2020年8月期间笔者所在医院胰腺外科收治的行胰十二指肠切除术患者的资料,比较术中胰腺断面与术前CT横断面图像中胰管中心到胰腺边缘距离...目的探讨胰肠吻合术中胰腺断面上胰管所处位置对术后胰瘘发生的影响。方法回顾性收集2018年9月至2020年8月期间笔者所在医院胰腺外科收治的行胰十二指肠切除术患者的资料,比较术中胰腺断面与术前CT横断面图像中胰管中心到胰腺边缘距离测定值的一致性,对术后胰瘘的发生行单因素分析和多因素logistic回归模型分析,判断胰肠吻合术中胰腺断面上胰管所处位置是否对术后胰瘘的发生造成影响。结果本研究总计纳入患者373例,选取其中44例患者于术中测量胰管中心到胰腺边缘的短距与胰腺断面处总厚度的比值为0.41±0.09,其术前影像学测量值为0.40±0.10,两种测量方法的组内相关系数(interclass correlation coefficient,ICC)检测值=0.916(>0.75),P<0.001,具有较高的一致性。患者身体质量指数(body mass index,BMI)较高[OR=1.276,95%CI为(1.154,1.411),P<0.0001]和胰腺质地软[OR=2.771,95%CI为(1.558,4.927),P=0.001]是术后胰瘘发生的独立危险因素,而随着患者胰管中心到胰腺边缘的短距与胰腺总厚度的比值增大,术后胰瘘发生的风险降低[OR=0.875,95%CI为(0.840,0.911),P<0.0001]。结论患者BMI较高和胰腺质地软是术后胰瘘发生的独立危险因素,胰管中心远离胰腺边缘时术后胰瘘发生风险降低;根据术前影像学测量的胰管中心到胰腺边缘的短距与胰腺总厚度的比值可用于评估术后胰瘘发生风险。展开更多
基金Projects(52378411,52208404)supported by the National Natural Science Foundation of China。
文摘The tunnel subjected to strike-slip fault dislocation exhibits severe and catastrophic damage.The existing analysis models frequently assume uniform fault displacement and fixed fault plane position.In contrast,post-earthquake observations indicate that the displacement near the fault zone is typically nonuniform,and the fault plane position is uncertain.In this study,we first established a series of improved governing equations to analyze the mechanical response of tunnels under strike-slip fault dislocation.The proposed methodology incorporated key factors such as nonuniform fault displacement and uncertain fault plane position into the governing equations,thereby significantly enhancing the applicability range and accuracy of the model.In contrast to previous analytical models,the maximum computational error has decreased from 57.1%to 1.1%.Subsequently,we conducted a rigorous validation of the proposed methodology by undertaking a comparative analysis with a 3D finite element numerical model,and the results from both approaches exhibited a high degree of qualitative and quantitative agreement with a maximum error of 9.9%.Finally,the proposed methodology was utilized to perform a parametric analysis to explore the effects of various parameters,such as fault displacement,fault zone width,fault zone strength,the ratio of maximum fault displacement of the hanging wall to the footwall,and fault plane position,on the response of tunnels subjected to strike-slip fault dislocation.The findings indicate a progressive increase in the peak internal forces of the tunnel with the rise in fault displacement and fault zone strength.Conversely,an augmentation in fault zone width is found to contribute to a decrease in the peak internal forces.For example,for a fault zone width of 10 m,the peak values of bending moment,shear force,and axial force are approximately 46.9%,102.4%,and 28.7% higher,respectively,compared to those observed for a fault zone width of 50 m.Furthermore,the position of the peak internal forces is influenced by variations in the ratio of maximum fault displacement of the hanging wall to footwall and the fault plane location,while the peak values of shear force and axial force always align with the fault plane.The maximum peak internal forces are observed when the footwall exclusively bears the entirety of the fault displacement,corresponding to a ratio of 0:1.The peak values of bending moment,shear force,and axial force for the ratio of 0:1 amount to approximately 123.8%,148.6%,and 111.1% of those for the ratio of 0.5:0.5,respectively.
基金Projects(51808563,51925808)supported by the National Natural Science Foundation of ChinaProject(KLWRTBMC18-03)supported by the Open Research Fund of the Key Laboratory of Wind Resistance Technology of Bridges of ChinaProject(2017YFB1201204)supported by the National Key R&D Program of China。
文摘In this study, experiments were carried out to investigate aerodynamic characteristics of a high-speed train on viaducts in turbulent crosswinds using a 1:25 scaled sectional model wind-tunnel testing. Pressure measurements of two typical sections, one train-head section and one train-body section, at the windward and leeward tracks were conducted under the smooth and turbulence flows with wind attack angles between-6° and 6°, and the corresponding aerodynamic force coefficients were also calculated using the integral method. The experimental results indicate that the track position affects the mean aerodynamic characteristics of the vehicle, especially for the train-body section. The fluctuating pressure coefficients at the leeward track are more significantly affected by the bridge interference compared to those at the windward track. The effect of turbulence on the train-head section is less than that on the train-body section. Additionally, the mean aerodynamic force coefficients are almost negatively correlated to wind attack angles, which is more prominent for vehicles at the leeward track. Moreover, the lateral force plays a critical role in determining the corresponding overturning moment, especially on the train-body section.
文摘目的探讨胰肠吻合术中胰腺断面上胰管所处位置对术后胰瘘发生的影响。方法回顾性收集2018年9月至2020年8月期间笔者所在医院胰腺外科收治的行胰十二指肠切除术患者的资料,比较术中胰腺断面与术前CT横断面图像中胰管中心到胰腺边缘距离测定值的一致性,对术后胰瘘的发生行单因素分析和多因素logistic回归模型分析,判断胰肠吻合术中胰腺断面上胰管所处位置是否对术后胰瘘的发生造成影响。结果本研究总计纳入患者373例,选取其中44例患者于术中测量胰管中心到胰腺边缘的短距与胰腺断面处总厚度的比值为0.41±0.09,其术前影像学测量值为0.40±0.10,两种测量方法的组内相关系数(interclass correlation coefficient,ICC)检测值=0.916(>0.75),P<0.001,具有较高的一致性。患者身体质量指数(body mass index,BMI)较高[OR=1.276,95%CI为(1.154,1.411),P<0.0001]和胰腺质地软[OR=2.771,95%CI为(1.558,4.927),P=0.001]是术后胰瘘发生的独立危险因素,而随着患者胰管中心到胰腺边缘的短距与胰腺总厚度的比值增大,术后胰瘘发生的风险降低[OR=0.875,95%CI为(0.840,0.911),P<0.0001]。结论患者BMI较高和胰腺质地软是术后胰瘘发生的独立危险因素,胰管中心远离胰腺边缘时术后胰瘘发生风险降低;根据术前影像学测量的胰管中心到胰腺边缘的短距与胰腺总厚度的比值可用于评估术后胰瘘发生风险。
