Progress on research and mitigation of wind-blown sand risk in Dunhuang Singing Sand Mountain and Crescent Spring Scenic area,China

The Singing Sand Mountain and Crescent Spring Scenic Spot in Dunhuang,Northwest China is a world-renowned desert attraction that is also an integral component of the Dunhuang UNESCO Global Geopark.This scenic area underwent a 30-year transformation,i.e.,from a severe sand risk with spring water threatened by sand burial due to dune deformation,to restoration of the original sand flow field and mitigation of the sand burial problem.The current paper summarizes the research on the intensive monitoring of the dynamic change of star dunes near the spring,observation of wind and sand flow movement,and then restoring the harmonic vibration of the sand particles(singing sand)that were previously silenced.The existing and prospective impacts of anthropogenic and natural forces on the deformation of the sand dunes are investigated by integrated methods,guiding the implementation of mitigating measures with significant ameliorative effects.Contrast to common sand control practices that aim to reduce wind speed and stop blown sands,our research highlights the importance of maintaining the natural wind flow field in stabilizing surrounding dunes.These mitigation measures consist of removing excessive vegetation and newly constructed buildings to recover the original wind flow field and sand transport activity.Such research and mitigation efforts ensure the scientific protection and restoration of the special desert landform,and contribute to the mutual enhancement of the conservation and exploitation of this desert scenic spot and similar sites.

Damage by wind-blown sand and its control measures along the Taklimakan Desert Highway in China

Desertification is one of the most serious environmental problems in the world,especially in the arid desert regions.Combating desertification,therefore,is an urgent task on a regional or even global scale.The Taklimakan Desert in China is the second largest mobile desert in the world and has been called the''Dead Sea''due to few organisms can exist in such a harsh environment.The Taklimakan Desert Highway,the longest desert highway(a total length of 446 km)across the mobile desert in the world,was built in the 1990s within the Taklimakan Desert.It has an important strategic significance regarding oil and gas resources exploration and plays a vital role in the socio-economic development of southern Xinjiang,China.However,wind-blow sand seriously damages the smoothness of the desert highway and,in this case,mechanical sand control system(including sand barrier fences and straw checkerboards)was used early in the life of the desert highway to protect the road.Unfortunately,more than 70%of the sand barrier fences and straw checkerboards have lost their functions,and the desert highway has often been buried and frequently blocked since 1999.To solve this problem,a long artificial shelterbelt with the length of 437 km was built along the desert highway since 2000.However,some potential problems still exist for the sustainable development of the desert highway,such as water shortage,strong sandstorms,extreme environmental characteristics and large maintenance costs.The study aims to provide an overview of the damages caused by wind-blown sand and the effects of sand control measures along the Taklimakan Desert Highway.Ultimately,we provide some suggestions for the biological sand control system to ensure the sustainable development of the Taklimakan Desert Highway,such as screening drought-resistant species to reduce the irrigation requirement and ensure the sound development of groundwater,screening halophytes to restore vegetation in the case of soil salinization,and planting cash crops,such as Cistanche,Wolfberry,Apocynum and other cash crops to decrease the high cost of maintenance on highways and shelterbelts.

Dynamic Characteristics Analysis on Wind-Blown Sand Ground under Dynamic Compaction Vibration

In the 6000 kN·m energy level dynamic compaction on Inner Mongolia wind-blown sand foundation treatment process, the dynamic characteristics and dynamic response are measured. Vibration action time, vibration main frequency, peak acceleration and peak velocity are analyzed. The vibration acting time is very short, the vertical average vibration acting time increases obviously with distance increasing, and the horizontal average vibration time does hardly change. The main frequency of vibration is at 4.60 - 24.90 Hz, which depends on the soil properties and soil layer distribution. The peak acceleration and peak velocity space distribution are similar. The maximum of horizontal acceleration peak is close to vertical velocity peak, and is near to 51 g under rammer. The maximum of horizontal velocity peak is close to vertical velocity peak, and is near to 54 m/s under rammer. The peak acceleration and velocity are rapidly attenuated, but the vertical peak acceleration and peak velocity are slowly attenuated than horizontal direction. The effective treating depth arrives 13 m for wind-blown wind, peak acceleration is 1.8 g or so, and peak velocity is 2.1 m/s or so. Horizontal treating range is 2.6 times of rammer diameter, and vertical treating range is 5.65 times of rammer diameter.

Effect of the W-beam central guardrails on wind-blown sand deposition on desert expressways in sandy regions

Many desert expressways are affected by the deposition of the wind-blown sand,which might block the movement of vehicles or cause accidents.W-beam central guardrails,which are used to improve the safety of desert expressways,are thought to influence the deposition of the wind-blown sand,but this has yet not to be studied adequately.To address this issue,we conducted a wind tunnel test to simulate and explore how the W-beam central guardrails affect the airflow,the wind-blown sand flux and the deposition of the wind-blown sand on desert expressways in sandy regions.The subgrade model is 3.5 cm high and 80.0 cm wide,with a bank slope ratio of 1:3.The W-beam central guardrails model is 3.7 cm high,which included a 1.4-cm-high W-beam and a 2.3-cm-high stand column.The wind velocity was measured by using pitot-static tubes placed at nine different heights(1,2,3,5,7,10,15,30 and 50 cm)above the floor of the chamber.The vertical distribution of the wind-blown sand flux in the wind tunnel was measured by using the sand sampler,which was sectioned into 20 intervals.In addition,we measured the wind-blown sand flux in the field at K50 of the Bachu-Shache desert expressway in the Taklimakan Desert on 11 May 2016,by using a customized 78-cm-high gradient sand sampler for the sand flux structure test.Obstruction by the subgrade leads to the formation of two weak wind zones located at the foot of the windward slope and at the leeward slope of the subgrade,and the wind velocity on the leeward side weakens significantly.The W-beam central guardrails decrease the leeward wind velocity,whereas the velocity increases through the bottom gaps and over the top of the W-beam central guardrails.The vertical distribution of the wind-blown sand flux measured by wind tunnel follows neither a power-law nor an exponential function when affected by either the subgrade or the W-beam central guardrails.At 0.0H and 0.5H(where H=3.5 cm,which is the height of the subgrade),the sand transport is less at the 3 cm height from the subgrade surface than at the 1 and 5 cm heights as a result of obstruction by the W-beam central guardrails,and the maximum sand transportation occurs at the 5 cm height affected by the subgrade surface.The average saltation height in the presence of the W-beam central guardrails is greater than the subgrade height.The field test shows that the sand deposits on the overtaking lane leeward of the W-beam central guardrails and that the thickness of the deposited sand is determined by the difference in the sand mass transported between the inlet and outlet points,which is consistent with the position of the minimum wind velocity in the wind tunnel test.The results of this study could help us to understand the hazards of the wind-blown sand onto subgrade with the W-beam central guardrails.

Electromagnetic scattering of charged particles in a strong wind-blown sand electric field

Some field experimental results have shown that the moving sands or dust aerosols in nature are usually electrified,and those charged particles also produce a strong electric field in air, which is named as wind-blown sand electric field.Some scholars have pointed out that the net charge on the particle significantly enhances its electromagnetic(EM) extinction properties, but up to now, there is no conclusive research on the effect of the environmental electric field. Based on the extended Mie theory, the effect of the electric field in a sandstorm on the EM attenuation properties of the charged larger dust particle is studied. The numerical results indicate that the environmental electric field also has a great influence on the particle's optical properties, and the stronger the electric field, the bigger the effect. In addition, the charged angle, the charge density, and the particle radius all have a specific impact on the charged particle's optical properties.

Energy Consumption and Erosion Mechanism of Polyester Fiber Reinforced Cement Composite in Wind-blown Sand Environments

Considering the economic and environmental benefits associated with the recycling of polyester(PET)fibres,it is vital to study the application of fibre-reinforced cement composites.According to the characteristics of the wind-blown sand environment in Inner Mongolia,the erosion resistance of the polyester fibre-reinforced cement composites(PETFRCC)with different PET fibre contents to various erosion angles,velocities and sand particle flows was investigated by the gas-blast method.Based on the actual conditions of sandstorms in Inner Mongolia,the sand erosion parameters required for testing were calculated by the similarity theory.The elastic-plastic model and rigid plastic model of PETFRCC and cement mortar were established,and the energy consumption mechanism of the model under particle impact was analyzed.The experimental results indicate that the microstructure of PETFRCC rafter hydration causes a spring-like buffering effect,and the deformation of PETFRCC under the same impact load is slightly smaller than that of cement mortar,and the damage mechanism of PETFRCC is mainly characterized by fiber deformation and slight brittle spalling of matrix.And under the most unfavorable conditions of the erosion,the erosion rate of 0.5PETFRCC is about 57.69%lower than that of cement mortar,showing better erosion resistance.

Experimental analysis of sand particles' lift-off and incident velocities in wind-blown sand flux

The probability distributions of sand particles' lift-off and incident velocities in a wind-blown sand flux play very important roles in the simulation of the wind-blown sand movement. In this paper, the vertical and the horizontal speeds of sand particles located at 1.0 mm above a sand-bed in a wind-blown sand flux are observed with the aid of Phase Doppler Anemometry (PDA) in a wind tunnel. Based on the experimental data, the probability distributions of not only the vertical lift-off speed but also the lift-off velocity as well as its horizontal component and the incident velocity as well as its vertical and horizontal components can be obtained by the equal distance histogram method. It is found, according to the results of the χ2-test for these probability distributions, that the probability density functions (pdf's) of the sand particles' lift-off and incident velocities as well as their vertical components are described by the Gamma density function with different peak values and shapes and the downwind incident and lift-off horizontal speeds, respectively, can be described by the lognormal and the Gamma density functions. These pdf's depend on not only the sand particle diameter but also the wind speed.

Prevention and management of wind-blown sand damage along Qinghai-Tibet Railway in Cuonahu Lake area

This paper analyzes the characteristics of climate,geology and geomorphology,vegetation,and sand dune distribution in the Cuonahu Lake area beside the Qinghai-Tibet Railway.The types and causes of railway blown-sand hazards are discussed,and the effectiveness of various sand-controlling measures is assessed.From the perspective of integrated management,a sand-controlling system that combines several engineering measures,including nylon net sand barriers,concrete sand barriers,movable-board sand barriers,sand interception ditches,gravel/rock cover,film sandbags,and permanent vegetation is most beneficial.

Probability of rebound and eject of sand particles in wind-blown sand movement

当事件粒子在被风吹的沙运动影响进一张沙床时，事件粒子反弹并且由粒子直接影响的事件沙粒子弹射风的发展沙流动。以便获得反弹并且逐出沙粒子的起飞概率，我们使用随机的碰撞模型在我们的能接受的工作介绍了导出这个事件的速度的分析答案并且影响的粒子床在碰撞以后的床上的粒子。以便描述在真实粒子床碰撞固有的随意，我们作为随机的变量在影响的沙粒子上在沙床上拿事件角度，影响位置和沙粒子的结果的行动的方向，并且计算反弹并且逐出速度，角度和系数(反弹的比率并且逐出速度到事件速度)。数字结果根据当前的试验性的结果被发现。反弹并且逐出起飞可能性对这个事件，爬的速度被预言。

Mechanisms of the formation of wind-blown sand hazards and the sand control measures in Gobi areas under extremely strong winds along the Lanzhou-Xinjiang high-speed railway

The Lanzhou-Xinjiang high-speed railway(HSR)traverses areas of the Gobi Desert where extremely strong winds are frequent.These strong winds cause sand/gravel hazards,an unaddressed issue that often seriously compromises the safe operation of the HSR.This paper studies the mechanisms leading to wind-blown sand hazards and the outcomes of sand control projects in these areas.The main findings are as follows:(1)Cold northern airflows over the Tian Shan mountain range are accelerated by the wind tunnels and downslope effect as they pass over complex terrain comprising passes,gullies,and proluvial fans.Consequently,the wind intensity often increases two-to threefold,creating frequent high-speed winds that lead to severe sand damage along the HSR.(2)In the Gobi areas with extremely strong winds,sand grains can be lifted as high as 9 m from the ground into the air,far higher than in other areas of the desert.The sand transport rate decreases exponentially with increasing height.Both wind speed and particle size determine saltation height.Coarser particles and stronger winds provide the particles with a higher kinetic energy as they collide with the ground.In the wind zones of Baili and Yandun,the analysed study areas,the saltation layer height of wind-blown sand/gravel exceeds 3 and 2 m,respectively.(3)Based on the above findings,recently emerging sand control materials,suitable for the areas of interest,were screened and developed.Furthermore,under the proposed principle of‘supplementing blocking with trapping’,a comprehensive sand control measure was established,featuring sandblocking belts comprised of multiple rows,and high,vertical sand-trapping installations with a large grids size.The installed system showed a high efficacy,reducing sand transport rate by 87.87%and significantly decreasing the deposition of sand along a trial section of the HSR.

A laboratory test of the electrification phenomenon in wind-blown sand flux

The measured data in the wind-tunnel tests show that the wind-blown sand particles acquired a negative charge when their diameters are smaller than 250 μm and positive charge when their diameters are larger than 500 μm, which confirms Latham’s assumption that the large particles in wind-blown sand flux acquired positive charge while negative charge developed on small ones. In the meanwhile, the measured data also show that the average charge-to-mass ratio for wind-blown sand particles decreases with the increase of the particle diameter and the wind velocity, and increases with the rise of height. The electric field in wind-blown sand flux is mainly formed by the moving charged sand particles. Its direction is vertical to the Earth’s surface and upward, which is opposite to that of the fair-weather field. The electric field increases with wind velocity and height increasing. These experimental results will lay the foundation for developing the theoretical analysis of the electrification phenomenon in

含沙量对地面光伏阵列的气动载荷研究

沙粒体积分数是风沙环境中影响光伏板及其承载结构使用寿命的重要因素之一,光伏板表面压力和倾覆力矩预测对光伏阵列的安装与设计,以及挡风沙结构的设计都有十分重要的意义。以安装倾角为25°,4×4方阵形式的光伏阵列为研究对象,采用欧拉双流体模型探究不同浓度对光伏板表面及其周围流场结构和倾覆力矩的影响规律。结果表明,不同沙粒浓度下,光伏板上表面的风沙压力变化分布情况基本相同,而随着入口处沙粒体积分数的增大,光伏板上表面同一区域的风沙压力不断增大。除第二排光伏板,其余光伏板倾覆力矩随入口处沙粒体积分数增大而增大,且第一排倾覆力矩最大。研究工作可为荒漠地区光伏阵列的设计和安装提供一定的理论依据。

路堑风吹雪灾害的形成和防治研究

风吹雪灾害是一种寒冷山区交通线路比较常见的自然灾害,现场调研发现路堑是风吹雪灾害最为严重的路基形式之一。本文针对路堑风吹雪灾害的形成和防治展开研究,基于Euler-Euler方法和Mixture模型模拟风雪两相流,同时利用现场实测数据验证模拟结果。研究典型路堑风吹雪灾害中风雪分布的演化过程,并比较分析不同形式路堑的风吹雪灾害特征,结果发现两侧边坡比小于1∶2的路堑风吹雪灾害最为严重。该类路堑严重的风雪灾害的形成原因是两侧边坡积雪的增加压缩了路面旋涡尺度,进而削弱了旋涡的回流加速作用。同时发现雪檐在推进到上风侧边坡中点前为安全储备期,此时上风侧边坡积雪量即为临界储雪量。

南疆农作物风沙危害理论及防治研究进展

南疆沙漠边缘的绿洲农区是我国风沙危害最严重的地区之一,特别是棉花苗期和果树花果期,风沙造成幼苗死亡、茎倒枝折、落花落果,经济损失巨大,因此,开展南疆农作物风沙危害及防治研究具有重要的现实意义和区域经济价值。本文通过回顾农田的风沙流结构特征,梳理了风沙对农作物的2种危害形式,概述了农作物风沙防护机制及防治措施研究现状;最后,指出了农作物风沙危害研究中存在的问题,基于南疆的农作物类型及风沙环境特征,提出了未来南疆农作物风沙危害及防治研究重点并对未来研究进行了展望。

风沙流环境地表剪切力测量

地表剪切力是风沙运动的关键驱动力,在风沙运动研究中非常重要,但目前针对风沙流环境地表剪切力的实验测量却较为匮乏,已经成为风沙运动研究深入发展的瓶颈。本文介绍了一种基于热膜技术的适用于风沙流环境地表剪切力精确测量的方法,使用热膜传感器和二维热线探头对净风条件下的地表剪切力进行了测量,结果显示:热膜传感器对地表剪切力有较好的响应,其与二维热线探头对摩阻风速的测量结果相差小于6.6%。热膜传感器对方柱绕流条件下地表剪切力的测量结果与OpenFOAM数值模拟结果具有较好的一致性,进一步证明了热膜传感器测量地表剪切力的可行性。热膜传感器的沙粒撞击实验结果表明:沙粒撞击对热膜信号的影响可以忽略,在风沙流环境中可以采用热膜传感器对地表剪切力进行有效测量。基于该技术测量了风沙流环境地表剪切力沿流向的空间分布特征,采用实测方式获得了风沙流环境地表剪切力的空间分布规律。

干枯植被覆盖对公路沿线地表风沙流结构的影响

[目的]以内蒙古S105草原公路沿线地表为研究对象,探讨挟沙风作用下干枯植被覆盖度对风沙流结构的影响,旨在为防治公路两侧土壤风蚀提供理论参考依据。[方法]采用风洞模拟试验,在0%,20%,40%和50%覆盖度水平下测定输沙率。[结果]在挟沙风作用下,输沙率随干枯植被覆盖度的增大而递减,最大输沙率点的高度层不断上升。覆盖度为0%时,输沙率随高度的增加呈指数函数规律降低;覆盖度为20%,40%和50%时,输沙率随高度的增加呈递减→递增→递减→趋于平缓的变化规律;在85 mm高度以下符合多项式函数关系,85 mm高度以上符合指数函数关系。随覆盖度的增大总输沙量递减,最大抗风蚀效率达65.73%。[结论]干枯植被覆盖显著影响地表风沙流结构,可削弱挟沙风侵蚀力,是抑制公路沿线地表土壤风蚀沙化的有效措施。

无定河上游流域水体微塑料污染现状与分布特征

调查了黄河一级支流无定河上游干流和纳林河、海流兔河、榆溪河、芦河等支流水体微塑料的丰度和分布情况.结果显示:无定河上游流域水体微塑料的平均丰度为15.58n/L,范围2.5~35.63n/L.微塑料类型丰富,占比依次为PEG(62.96%)、PE(6.17%)、PPS(3.09%)、4-vinylbiphenyl(2.78%)、PCTG(2.47%)、PS(2.16%)、PTFE(2.16%)、PPSU(1.85%)、PMMA(1.54%)、其他(14.81%).超过96%的微塑料小于1mm,极易进入生物体富集.形状以片为主,其次是薄膜和颗粒状;大部分为透明或棕色,其他颜色占比约25%.基于微塑料的源特定分类体系,初步判定微塑料主要来源于农用地膜、个人洗护用品.结果表明无定河上游流域水体微塑料整体处于轻度污染水平.有毒有害塑料的滥用尤为需要引起关注.无定河上游流域位于毛乌素沙漠东南部的风沙滩地,其微塑料研究一方面揭示了风沙滩地水体微塑料的赋存现状和潜在污染风险;另一方面提供了一个典型案例,即以微塑料的视角,科学认识沙漠地区的城市发展和农业生产对水体环境的影响.

挡风墙周围风沙流运动特性SPH数值分析

光滑粒子流体动力学方法(Smoothed Particle Hydrodynamics, SPH)是一种纯拉格朗日、无网格的流体模拟方法。首先对SPH法的基本原理、核函数构造及控制方程离散方法、边界处理及邻域粒子搜索算法、时间积分等作了具体介绍。通过Linux平台编写的二维SPH程序较好地模拟了挡风墙周围风沙两相流的运动特性。仿真结果再现了沙障附近积沙的复杂物理现象:挡风墙周围积沙量以挡风墙为中心,呈“正态性”分布,中间多,两边少。且挡风墙存在时,对风速的阻挡作用随挡风墙高度增加而减小,水平风速超过其垂向高度后逐渐恢复至无挡风墙时的风场状态。表明风沙流运动过程中挡风墙对跃移沙粒和来流风具有明显的阻挡效应,与已有相关模拟结果相符,验证了SPH数值模拟方法的有效性。并为SPH方法在风沙两相流领域的进一步拓展和应用奠定了基础。

排风流与喷淋液滴的流动及传热特性研究

为研究矿井排风与喷淋液滴的对流传热过程,构建了喷淋扩散塔模型,通过CFD对喷淋液滴流动及传热过程进行仿真。首先,分析了扩散塔中连续相、离散相速度场;随后,以单液滴运移过程为基础,结合理论公式,得到了液滴所受单位质量曳力、Nu模拟值及理论值;最后,针对液滴群传热过程,分析了液滴运移轨迹、温度变化规律及传热热流量。结果表明:排风在出口内轮廓线边角处达到最大速度时,风吹损失的液滴从出口内轮廓线边角处逃逸;上喷液滴的Nu模拟值及理论值变化规律相似,两者相互验证,表现为在上升阶段随高度增加而减小,下降阶段出现振荡趋势;当液滴粒径小于0.8 mm时,传热主要受粒径影响,当液滴粒径超过0.8 mm时,传热受粒径和喷淋速度两者共同影响;考虑风吹水损率、捕集液滴温度标准偏差及传热热流量,液气速度比0.5,液滴粒径1.2 mm,热回收效果最好。

风力机叶片涂层冲蚀磨损实验装置的设计

风力发电机叶片在风沙环境中运行时会受到挟沙风的冲蚀,导致叶片表面涂层损毁并且降低叶片使用寿命,同时也增加叶片的维护成本。为了探究风力机叶片受挟沙风冲蚀磨损情况,研制一种涂层冲蚀磨损实验装置,该实验装置以压缩空气为动力,通过压缩空气气管接通气源。压缩空气在冲蚀管中建立工作压力,在冲蚀管内完成沙料和压缩空气充分混合,形成高速运动的挟沙风;再利用PLC控制步进电动机转速,通过螺旋推进器进行输沙率控制,由冲蚀管喷嘴喷出,喷射到风力机叶片模型表面对其进行冲蚀磨损实验。该冲蚀装置可实现多种冲击风速、携沙量、冲击角度的多工况磨损实验,能够提供较为精确的实验数据。