根据B iot饱和土理论和R ay le igh-Love杆理论,计及土层及桩的径向运动影响,导出了考虑横向惯性效应的端承桩与饱和土的纵向耦合振动频域的解析解和时域半解析解,对比了考虑与不考虑横向惯性效应时,大直径嵌岩桩纵向振动引起的土层复...根据B iot饱和土理论和R ay le igh-Love杆理论,计及土层及桩的径向运动影响,导出了考虑横向惯性效应的端承桩与饱和土的纵向耦合振动频域的解析解和时域半解析解,对比了考虑与不考虑横向惯性效应时,大直径嵌岩桩纵向振动引起的土层复阻抗的异同以及桩顶导纳和时域反射的特征。研究表明:长径比越小,横向惯性效应越明显,而泊松比和激振频率对饱和土层阻抗及桩顶响应也有重要影响。通过工程实例对比表明,当桩的长径比较小时,用考虑横向惯性效应的计算方法可以得到更好的拟合效果。展开更多
研究目的:本文以某山地米轨铁路为例,研究坡度250‰以上有砟轨道结构的稳定性和极限坡度。首先进行米轨混凝土枕的道床阻力测试试验,并建立轨排结构有限元模型,分析坡度和扣件阻力对轨排结构稳定性的影响;接着建立米轨有砟轨道三维有限...研究目的:本文以某山地米轨铁路为例,研究坡度250‰以上有砟轨道结构的稳定性和极限坡度。首先进行米轨混凝土枕的道床阻力测试试验,并建立轨排结构有限元模型,分析坡度和扣件阻力对轨排结构稳定性的影响;接着建立米轨有砟轨道三维有限元模型,研究坡度与竖曲线半径对有砟道床稳定性的影响;最后,根据扣件阻力、道床阻力与大坡道有砟轨道稳定性的关系提出米轨有砟轨道极限坡度和竖曲线半径的建议值。研究结论:(1)通过试验测试,得到了道床阻力-位移关系,结果表明轨排结构的稳定性随坡度增大而减弱,在扣件阻力不大于10 k N/组时其极限坡度为500‰;(2)有砟道床的稳定性随着坡度的增大而逐渐减弱,在列车荷载作用下,有砟道床保持稳定的最大坡度为500‰;(3)变坡点凸形竖曲线附近道床稳定性弱于直坡道地段,且其稳定性随着竖曲线半径的增大而逐渐增强,在坡度为250‰的情况下,为了保持有砟道床稳定竖曲线半径不能小于400 m;(4)本文研究成果可为米轨铁路大坡道有砟轨道结构稳定性分析提供理论与试验依据。展开更多
To study the influence of rainfall on pavement skid-resistance performance and driving safety,the water film thickness(WFT)concept considering the longitudinal and transverse slopes of the pavement was utilized based ...To study the influence of rainfall on pavement skid-resistance performance and driving safety,the water film thickness(WFT)concept considering the longitudinal and transverse slopes of the pavement was utilized based on the total discharge formulation and turbulence theory of slope flow.Using experimental data measured using the British pendulum test under varying WFT levels,a model for calculating the skid resistance,namely the British pendulum number(BPN),was formulated and used to quantitatively evaluate the effects of rainfall intensity,transverse,and longitudinal slopes on the computed BPN.The study results reveal that skid resistance is linearly proportional to the pavement transverse slope and inversely proportional to the rainfall intensity and the pavement longitudinal slope.In particular,rainfall intensity,along with pavement texture depth,exhibited a significant impact on the tire-pavement friction and skid-resistance performance.The results further indicate that driving safety under wet weather is predominantly governed by skid resistance and visibility.The BPN and sideway force coefficient(SFC60)values for new asphalt pavements under different rainfall intensities are provided along with some modification to the stopping sight distance(SSD)criteria.Safe driving speed limits are also determined using a safe-driving model to develop the appropriate speed limit strategies.The overall study results provide some insights,methodology approach,and reference data for the evaluation of pavement skid-resistance performance and driving safety conditions under different pavement slopes and rainfall intensities.展开更多
This study aimed to explore groundwater potential zones in the EGMB of Alluri Seetharama Raju district, Andhra Pradesh, India, for drinking and agriculture purposes. To achieve this goal, 72 Vertical Electrical Soundi...This study aimed to explore groundwater potential zones in the EGMB of Alluri Seetharama Raju district, Andhra Pradesh, India, for drinking and agriculture purposes. To achieve this goal, 72 Vertical Electrical Soundings(VES) were conducted using the Schlumberger electrode configuration. The resistivity sounding data were analyzed to determine the aquifer thickness, basement depth, Dar-Zarrouk parameters,and aquifer transmissivity. Spatial distribution maps were generated for these parameters to understand the subsurface formation. The analysis revealed a linear groundwater potential zone(8.46 km~2) in the eastern part of the study area, extending in the NNE-SSW direction for 9.6 km. Six VES locations(P24, P27, P29,P30, P33, and P38) in this zone exhibit good potential(>30 m aquifer thickness), while the three VES locations(OP19, P5, and P46) in the central region are recommended for drilling bore wells. Additionally,moderate aquifer thickness(20–30 m) are identified in other VES locations(OP14, OP20, P4, P10, P12,P13, P15, P17, P18, P31, P46, and P50) along streams in the western and central part of the area, which can yield reasonable quantities of water. This information is useful for groundwater exploration and watershed management to meet the demands of tribal population in the study area.展开更多
文摘根据B iot饱和土理论和R ay le igh-Love杆理论,计及土层及桩的径向运动影响,导出了考虑横向惯性效应的端承桩与饱和土的纵向耦合振动频域的解析解和时域半解析解,对比了考虑与不考虑横向惯性效应时,大直径嵌岩桩纵向振动引起的土层复阻抗的异同以及桩顶导纳和时域反射的特征。研究表明:长径比越小,横向惯性效应越明显,而泊松比和激振频率对饱和土层阻抗及桩顶响应也有重要影响。通过工程实例对比表明,当桩的长径比较小时,用考虑横向惯性效应的计算方法可以得到更好的拟合效果。
文摘研究目的:本文以某山地米轨铁路为例,研究坡度250‰以上有砟轨道结构的稳定性和极限坡度。首先进行米轨混凝土枕的道床阻力测试试验,并建立轨排结构有限元模型,分析坡度和扣件阻力对轨排结构稳定性的影响;接着建立米轨有砟轨道三维有限元模型,研究坡度与竖曲线半径对有砟道床稳定性的影响;最后,根据扣件阻力、道床阻力与大坡道有砟轨道稳定性的关系提出米轨有砟轨道极限坡度和竖曲线半径的建议值。研究结论:(1)通过试验测试,得到了道床阻力-位移关系,结果表明轨排结构的稳定性随坡度增大而减弱,在扣件阻力不大于10 k N/组时其极限坡度为500‰;(2)有砟道床的稳定性随着坡度的增大而逐渐减弱,在列车荷载作用下,有砟道床保持稳定的最大坡度为500‰;(3)变坡点凸形竖曲线附近道床稳定性弱于直坡道地段,且其稳定性随着竖曲线半径的增大而逐渐增强,在坡度为250‰的情况下,为了保持有砟道床稳定竖曲线半径不能小于400 m;(4)本文研究成果可为米轨铁路大坡道有砟轨道结构稳定性分析提供理论与试验依据。
基金The National Natural Science Foundation of China(No.51478114)
文摘To study the influence of rainfall on pavement skid-resistance performance and driving safety,the water film thickness(WFT)concept considering the longitudinal and transverse slopes of the pavement was utilized based on the total discharge formulation and turbulence theory of slope flow.Using experimental data measured using the British pendulum test under varying WFT levels,a model for calculating the skid resistance,namely the British pendulum number(BPN),was formulated and used to quantitatively evaluate the effects of rainfall intensity,transverse,and longitudinal slopes on the computed BPN.The study results reveal that skid resistance is linearly proportional to the pavement transverse slope and inversely proportional to the rainfall intensity and the pavement longitudinal slope.In particular,rainfall intensity,along with pavement texture depth,exhibited a significant impact on the tire-pavement friction and skid-resistance performance.The results further indicate that driving safety under wet weather is predominantly governed by skid resistance and visibility.The BPN and sideway force coefficient(SFC60)values for new asphalt pavements under different rainfall intensities are provided along with some modification to the stopping sight distance(SSD)criteria.Safe driving speed limits are also determined using a safe-driving model to develop the appropriate speed limit strategies.The overall study results provide some insights,methodology approach,and reference data for the evaluation of pavement skid-resistance performance and driving safety conditions under different pavement slopes and rainfall intensities.
文摘This study aimed to explore groundwater potential zones in the EGMB of Alluri Seetharama Raju district, Andhra Pradesh, India, for drinking and agriculture purposes. To achieve this goal, 72 Vertical Electrical Soundings(VES) were conducted using the Schlumberger electrode configuration. The resistivity sounding data were analyzed to determine the aquifer thickness, basement depth, Dar-Zarrouk parameters,and aquifer transmissivity. Spatial distribution maps were generated for these parameters to understand the subsurface formation. The analysis revealed a linear groundwater potential zone(8.46 km~2) in the eastern part of the study area, extending in the NNE-SSW direction for 9.6 km. Six VES locations(P24, P27, P29,P30, P33, and P38) in this zone exhibit good potential(>30 m aquifer thickness), while the three VES locations(OP19, P5, and P46) in the central region are recommended for drilling bore wells. Additionally,moderate aquifer thickness(20–30 m) are identified in other VES locations(OP14, OP20, P4, P10, P12,P13, P15, P17, P18, P31, P46, and P50) along streams in the western and central part of the area, which can yield reasonable quantities of water. This information is useful for groundwater exploration and watershed management to meet the demands of tribal population in the study area.
