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Numerical simulation of flow field deposition and erosion characteristics around bridge-road transition section

Journal of Mountain Science 2024年第5期21卷 1491-1508页

作者： ZHANG Kai wang zhenghui wang Tao TIAN Jianjin ZHANG Hailong LIU Yonghe College of Civil Engineering Lanzhou Jiaotong UniversityLanzhou 730000China Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

Wind-sand flow generates erosion and deposition around obstacles such as bridges and roadbeds, resulting in sand damage and endangering railway systems in sandy regions. Previous studies have mainly focused on the flow field around roadbeds, overlooking detailed examinations of sand particle erosion and deposition patterns near bridges and roadbeds. This study employs numerical simulations to analyze the influence of varying heights and wind speeds on sand deposition and erosion characteristics at different locations: the bridge-road transition section(side piers), middle piers, and roadbeds. The results show that the side piers, experience greater accumulation than the middle piers. Similarly, the leeward side of the roadbed witnesses more deposition compared to the windward side. Another finding reveals a reduced sand deposition length as the vertical profile, in alignment with the wind direction, moves further from the bridge abutments at the same clearance height. As wind speeds rise, there’s a decline in sand deposition and a marked increase in erosion around the side piers, middle piers and roadbeds. In conclusion, a bridge clearance that’s too low can cause intense sand damage near the side piers, while an extremely high roadbed may lead to extensive surface sand deposition. Hence, railway bridges in areas prone to sandy winds should strike a balance in clearance height. This research provides valuable guidelines for determining the most suitable bridge and roadbed heights in regions affected by wind and sand.

关键词： Sandstorm Flow field Bridge-road transition section Sedimentation erosion Numerical simulation

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Numerical simulation on sand sedimentation and erosion characteristics around HDPE sheet sand barrier under different wind angles

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Journal of Mountain Science 2024年第2期21卷 538-554页

作者： ZHANG Kai ZHANG Peili ZHANG Hailong TIAN Jianjin wang zhenghui XIAO Jianhua College of Civil Engineering Lanzhou Jiaotong UniversityLanzhou 730000China Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

For the safety of railroad operations,sand barriers are utilized to mitigate wind-sand disaster *** disasters,characterized by multi-directional wind patterns,result in diverse angles among the *** this study,using numerical simulations,we examined the behavior of High Density Polyethylene(HDPE)sheet sand barriers under different wind angles,focusing on flow field distribution,windproof efficiency,and sedimentation erosion *** study discovered that at a steady wind speed,airflow velocity varies as the angle between the airflow and the HDPE barrier ***,a 90°angle results in the widest low-speed airflow area on the barrier’s downwind *** the airflow is not perpendicular to the barrier,it prompts a lateral airflow movement which decreases as the angle *** windproof efficiency correlates directly with this angle but inversely with the wind’s ***,with a wind angle of 90°,wind speed drops by 81%.The minimum wind speed is found at 5.1H(the sand barrier height)on the barrier’s downwind *** the angle grows,the barrier’s windproof efficiency improves,extending its protective *** is most prominent on the barrier’s downwind side,as the wind angle shifts from 30°to 90°,the sand sedimentation area on the barrier’s downwind side enlarges by *** the angle grows,sedimentation intensifies,eventually overtakes the forward erosion and enlarges the sedimentation area.

关键词： Multi-wind direction HDPE sheet sand barrier Numerical simulation Windproof efficiency Sedimentation erosion

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Flow field, sedimentation, and erosion characteristics around folded linear HDPE sheet sand fence: Numerical simulation study

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Journal of Mountain Science 2024年第1期21卷 113-130页

作者： ZHANG Kai ZHANG Hailong TIAN Jianjin QU Jianjun ZHANG Xingxin wang zhenghui XIAO jianhua College of Civil Engineering Lanzhou Jiaotong UniversityLanzhou 730000China Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China College of Civil Engineering Chongqing UniversityChongqing 400045China Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

Wind and sand hazards are serious in the Milan Gobi area of the Xinjiang section of the Korla Railway. In order to ensure the safe operation of railroads, there is a need for wind and sand protection in heavily sandy areas. The wind and sand flow in the region is notably bi-directional. To shield railroads from sand, a unique sand fence made of folded linear high-density polyethylene(HDPE) is used, aligning with the principle that the dominant wind direction is perpendicular to the fence. This study employed field observations and numerical simulations to investigate the effectiveness of these HDPE sand fences in altering flow field distribution and offering protection. It also explored how these fences affect the deposition and erosion of sand particles. Findings revealed a significant reduction in wind speed near the fence corner;the minimum horizontal wind speed on the leeward side of the first sand fence(LSF) decreased dramatically from 3 m/s to 0.64 m/s. The vortex area on the LSF markedly impacted horizontal wind speeds. Within the LSF, sand deposition was a primary occurrence. As wind speeds increased, the deposition zone shrank, whereas the positive erosion zone expanded. Close to the folded corners of the HDPE sand fence, there was a notable shift from the positive erosion zone to a deposition zone. Field tests and numerical simulations confirmed the high windproof efficiency(WE) and sand resistance efficiency(SE) in the HDPE sand fence. Folded linear HDPE sheet sand fence can effectively slow down the incoming flow and reduce the sand content, thus achieving good wind and sand protection. This study provides essential theoretical guidance for the design and improvement of wind and sand protection systems in railroad engineering.

关键词： Folded linear HDPE sheet sand fence Numerical simulation Flow field characteristics Protection benefits

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Protective benefit of folded linear HDPE board sand fences along the Golmud-Korla Railway,China:Field observation and wind tunnel study

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Journal of Mountain Science 2024年第7期21卷 2206-2219页

作者： ZHANG Kai TIAN Jianjin wang zhenghui ZHANG Hailong ZHANG Xingxin College of Civil Engineering Lanzhou Jiaotong UniversityLanzhou 730000China Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China College of Civil Engineering Chongqing UniversityChongqing 400045China

The Milan Gobi area of the Golmud-Korla Railway in northwest China is located in the lower dispersal area of the mountain pass and has strong winds with evident double wind direction *** study introduced a novel sand fence deployment technique,termed‘folded linear deployment',designed to position the sand fence orthogonally to the two predominant wind directions for optimal *** study used wind tunnel and field tests to evaluate the wind and sand flow characteristics,as well as the windproof and sandresistant performance of folded linear HDPE(Highdensity polyethylene)board sand *** results suggest that the airflow around the fence creates clear zoning *** deceleration area on the BSF(backwind side of the sand fence)is much larger than that on the DSF(downwind side of the sand fence).Thus,sand particles are primarily deposited on the *** different wind speeds,the airflow at 2 and 5 h on the DSF is not *** WSP(wind speed profile)presents a logarithmic *** airflow is disturbed at 1-20 h on the BSF,and the WSP gradually deviates from the logarithmic ***,as the airflow moves away from the fence,the WSP gradually approaches a logarithmic ***,the WPE(windproof efficiency)and SRE(sand-resistant efficiency)of the sand fence exceed 80%.In addition,the results of wind tunnel tests are compared with those of field *** overall dispersion is good,and the best dispersion is found at z/H=2.00,indicating good agreement between the two test *** study provides a scientific basis for the design of sand hazard control measures,similar to the railway project in the Gobi Gale area.

关键词： Folded linear HDPE board sand fence Double wind direction Gobi area Protection benefit

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大风区高速铁路路基双侧挡风墙周围沙粒沉积数值模拟研究

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铁道学报 2024年第6期46卷 148-155页

作者：张凯赵礼明王正辉邓育辉谭立海兰州交通大学土木工程学院甘肃兰州730070 中国科学院西北生态环境资源研究院沙漠与沙漠化重点实验室甘肃兰州730000

兰新高速铁路横穿多个大风区,对其安全运营造成严重影响。为降低强风对线路的危害,在大风区修筑大量防风构筑物,其中以路基挡风墙最为常见,挡风墙降低了风害的影响,但是带来严重的线路积沙问题。通过数值模拟研究不同风速下路基双侧挡... 详细信息

兰新高速铁路横穿多个大风区,对其安全运营造成严重影响。为降低强风对线路的危害,在大风区修筑大量防风构筑物,其中以路基挡风墙最为常见,挡风墙降低了风害的影响,但是带来严重的线路积沙问题。通过数值模拟研究不同风速下路基双侧挡风墙周围的流场特征,利用风产生的壁面剪切应力与沙粒剪切应力的比值确定地表沙粒沉积与侵蚀类型。研究发现,气流在两道挡风墙之间分别形成一个顺时针涡流和一个逆时针涡流,在第二道挡风墙背风侧形成一个顺时针大涡,随着来流风速增大,漩涡尺寸和涡流强度均在增大;由于涡流的存在,部分沙粒被卷走,路堤背风坡附近以及路基面上的沙粒沉积显著减少,当来流风速为24、30 m/s时,南北侧线路道床面均出现沙粒反向侵蚀;单双侧挡风墙的积沙规律对比结果表明,设置双侧挡风墙时,线路积沙显著减少。研究揭示了大风区铁路双侧挡风墙周围路基面上的沙粒沉积规律,对未来风区铁路的防护建设具有指导意义。

关键词：大风区高速铁路路基挡风墙数值模拟沙粒沉积

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复杂多变地物散射特征区域InSAR融合方法研究

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河南科技 2024年第3期51卷 52-59页

作者：夏锦王峥辉南京地铁建设有限责任公司江苏南京210017 江苏衡通勘测技术有限公司江苏南京210012

【目的】PS-InSAR和SBAS-InSAR在应对复杂多变地物散射特征沉降区域时均存在解算局限性,有必要通过对比两者技术差异和适用性,开展融合方法研究。【方法】根据不同地物散射特征区域PS点分布的相干系数统计特性,寻找与强地物散射特征区... 详细信息

【目的】PS-InSAR和SBAS-InSAR在应对复杂多变地物散射特征沉降区域时均存在解算局限性,有必要通过对比两者技术差异和适用性,开展融合方法研究。【方法】根据不同地物散射特征区域PS点分布的相干系数统计特性,寻找与强地物散射特征区域强关联的PS点数据簇,再根据不同散射特征区域PS点分布的密度差异,采用空间聚类算法识别覆盖城镇用地的数据簇,并采用三角网格法对照全国土地利用现状数据确定监测数据融合的边界,剔除边界外低密度、低质量的PS点数据簇,在边界外采用SBAS-InSAR解算出SDFP点数据,得到最终结果。【结果】数据融合后,弱地物散射区域高质量监测点数据大幅增加,强地物散射区域内高质量、高密度PS点被保留,该部分PS点解算位置精度更高,可在建成区实现小尺度精细化监测,最终实现根据区域内的可变散射特征自动选择匹配的干涉测量数据的结果。【结论】InSAR融合方法在应对复杂多变地物散射特征区域时,可兼顾监测点的数量和质量。

关键词：地面沉降 SBAS-InSAR PS-InSAR 地物散射融合方法

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水下无线光通信动态阈值判决技术研究与性能分析

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光通信技术 2024年第2期48卷 7-11页

作者：王争辉高冠军张家梁李哲北京邮电大学电子工程学院北京100876 中国电子科技集团公司第三十四研究所广西桂林541004

针对海洋湍流信道环境下固定阈值判决方案导致水下无线光通信系统性能恶化的问题,提出了一种动态阈值判决方案。该方案基于水下湍流信道慢衰落的特性,在发送端将数据以帧为单位进行发送,接收端则根据接收帧前导码的幅度每帧更新一次判... 详细信息

针对海洋湍流信道环境下固定阈值判决方案导致水下无线光通信系统性能恶化的问题,提出了一种动态阈值判决方案。该方案基于水下湍流信道慢衰落的特性,在发送端将数据以帧为单位进行发送,接收端则根据接收帧前导码的幅度每帧更新一次判决阈值。采用蒙特卡洛法和Gamma-Gamma信道模型对水下无线光通信系统进行仿真,仿真结果表明:在弱湍流信道环境下,当系统误码率为10^(-6)时,动态阈值判决方案比固定阈值判决方案的误码性能提升5.4 dB;在中、强湍流信道环境下,动态阈值判决方案能够有效抑制误码率门限现象的产生。

关键词：水下无线光通信动态阈值判决海洋湍流 Gamma-Gamma信道模型

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2016—2021年江汉平原水质时空变异分析

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广西师范大学学报（自然科学版） 2024年第4期42卷 195-202页

作者：陈鹏陈晓飞李世龙何乾坤汪政辉湖北省生态环境科学研究院(湖北省生态环境工程评估中心) 湖北武汉430061

近年来,人类活动的加剧造成江汉平原水体水环境质量下降,导致河网中下游水质序列发生复杂的演变。本文基于2016—2021年江汉平原四湖流域水环境质量监测数据,分析特征污染物的分布特征、变化规律及主要环境影响因素,诊断水质序列时空变... 详细信息

近年来,人类活动的加剧造成江汉平原水体水环境质量下降,导致河网中下游水质序列发生复杂的演变。本文基于2016—2021年江汉平原四湖流域水环境质量监测数据,分析特征污染物的分布特征、变化规律及主要环境影响因素,诊断水质序列时空变异,探讨可变要素集和影响因素集。研究表明:1)四湖流域中下游水质序列变异普遍显著,存在明显浓度梯度变化。2)过度水产养殖导致河道水质季节性超标现象凸显。3)面源污染和生态基流是影响干渠水质变化的主导因素。结果表明,本文分析方法在水质变化分析中具有一定的适用性。

关键词：变化环境水质 Hurst系数基尼系数变异分析江汉平原

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脐针疗法治疗气滞血瘀型急性腰扭伤临床研究

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新中医 2024年第3期56卷 160-164页

作者：党长林张海娜陈冲王佳瑶王正辉新乡医学院第一附属医院河南卫辉453100 新乡市康复医学重点实验室河南卫辉453100

目的:观察脐针疗法治疗气滞血瘀型急性腰扭伤的临床疗效。方法:选取60例急性腰扭伤患者,按随机数字表法分为脐针组及普针组各30例,普针组采用普通针刺疗法治疗,脐针组采用脐针疗法治疗。比较2组治疗前后视觉模拟评分法(VAS)、腰椎活动... 详细信息

目的:观察脐针疗法治疗气滞血瘀型急性腰扭伤的临床疗效。方法:选取60例急性腰扭伤患者,按随机数字表法分为脐针组及普针组各30例,普针组采用普通针刺疗法治疗,脐针组采用脐针疗法治疗。比较2组治疗前后视觉模拟评分法(VAS)、腰椎活动障碍评分的变化,比较2组及时止痛总有效率。结果:治疗后,2组VAS评分、腰椎活动障碍评分均较治疗前下降(P<0.05),脐针组上述2项评分均低于普针组(P<0.05)。脐针组即时止痛疗效总有效率为93.3%,普针组即时止痛疗效总有效率为86.7%,2组比较,差异有统计学意义(P<0.05)。结论:脐针疗法能有效改善急性腰扭伤患者的疼痛程度及腰椎活动度,即时止痛效果较好。

关键词：急性腰扭伤气滞血瘀型脐针疗法即时止痛

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Research on the generation method of seawater sound velocity model based on Perlin noise

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Acta Oceanologica Sinica 2024年第1期43卷 99-111页

作者： Zhimiao Chang Fuxing Han Zhangqing Sun zhenghui Gao Xueqiu wang College of Geoexploration Science and Technology Jilin UniversityChangchun 130026China

In the processing of conventional marine seismic data,seawater is often assumed to have a constant velocity ***,due to static pressure,temperature difference and other factors,random disturbances may often frequently in seawater *** impact of such disturbances on data processing results is a topic of theoretical *** seawater sound velocity is a difficult physical quantity to measure,there is a need for a method that can generate models conforming to seawater *** article will combine the Munk model and Perlin noise to propose a two-dimensional dynamic seawater sound velocity model generation method,a method that can generate a dynamic,continuous,random seawater sound velocity model with some regularity at large ***,the paper discusses the influence of the inhomogeneity characteristics of seawater on wave field propagation and *** results show that the seawater sound velocity model with random disturbance will have a significant influence on the wave field simulation and imaging results.

关键词： Munk model Perlin noise seawater inhomogeneity

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