Wind tunnel experimental study on shed tunnels to prevent and control blowing snow on highways北大核心CSCD

There is a severe phenomenon of blowing snow by wind in winter in Mayitas area of Xinjiang. Road traffic interruptions and casualties caused by wind and snow disasters often occur. The existing engineering measures can alleviate the problems of low visibility and problems with accumulating snow on pavement caused by wind and snow to a certain extent, but cannot completely eliminate the impact. Aiming at the problem that the blowing snow disaster difficult to be completely cured under strong wind conditions, a shed tunnel engineering treatment scheme is proposed, and a wind tunnel simulation experiment is carried out on the shed tunnel form and snow prevention scheme at the entrance of the tunnel. The wind tunnel experimental section is 8 m long, 1. 3 m horizontally wide and 1 m high. The shed tunnel model is made by 1:60 scale 3D printing method, the snow barrier model is made of wooden strips, and the simulation medium is made of fine sand, refined salt and sawdust. Firstly, three kinds of shed structures, including fully enclosed, overhanging and ventilated, were simulated under the condition of 90° wind direction, and compared with the form of blowing snow stacking. Three parameters for similarity were used:density, particle size and stacking shape. The similarity is determined by weighted Euclidean distance between simulation medium and blowing snow, the similarity of the slump angle of the predecessors is verified, and the most suitable medium for simulating blowing snow is deduced. According to the experimental results, combined with the actual situation of wind blowing and snow disasters in Mayitas, flow field of the closed shed tunnel by a wind direction angle of 30° has been separately conducted with or without protective measures. The results show that when the wind tunnel stacking experiment is used to study the deposition state of blowing snow under non-low temperature conditions, the sawdust has good similarity with the blowing snow in the process of wind and snow movement. A large amount of medium was poured into the ventilated shed during the experiment, which proved that its anti-wind and snow performance was not ideal. By contrast, the closed shed and the overhanging shed have better wind and snow prevention effects. The snow barrier has a good blowing snow inhibition function at the entrance. From the stacking experiment, in the comparison with and without snow barrier, volume of the medium in the shed is very different, which proves that the snow barrier can effectively prevent the blowing snow from entering the shed. Among them, the difference in wind speed inside and outside the shed is obvious, which proves that snow barrier can significantly reduce the wind speed outside the shed and has the function of inhibiting the formation of weak wind areas inside the shed. The study has confirmed that the shed tunnel project with suitable snow barrier layout plan for tunnel entrance protection is an effective means to control wind and snow disasters. For highway traffic in Xinjiang, it is a feasible solution to use shed tunnel engineering to control blowing snow disasters. After dealing with the snow deposition at the entrance of shed tunnel, the shed tunnel engineering form of low-cost environment integration and the vehicle operation safety guarantee measures of long-distance shed tunnel are the problems that need to be solved in the future. © 2022 Tianjin Press of Chinese Herbal Medicines. All rights reserved.     

华北平原沧县隆起边界断裂的第四纪活动性及深部构造特征

沧东断裂是渤海湾裂谷盆地西侧规模最大的正断层,也是沧县隆起与黄骅坳陷的分界断裂,其活动和发展直接控制了沧县隆起和黄骅坳陷的发育与演化。采用近三十年来横跨沧东断裂不同段落获取的5条浅层地震勘探成果资料,并结合测线附近的钻孔资料,深入研究沧东断裂的第四纪活动性及深部构造特征。浅层地震勘探结果发现,沧东断裂上断点埋深从南至北由深变浅,但集中在埋深118～300 m范围,错断的最新地层为中更新统,推断其最新活动时代为中更新世,而且断裂的活动时代未发现具有分段性特征。进一步综合深地震反射、大地电磁测深、沧州地区小地震分布与中强地震震源机制等资料,对沧东断裂的深部构造特征分析后发现,沧东断裂具有典型的铲状正断层特点,在深度10 km左右转为了近水平延伸,沧东断裂并非区域上主要控震断裂,或者只是低风险活动断裂,未来发生中强地震的风险可能相对较低。     

鄂尔多斯盆地JX井延长组砂岩固碳潜力分析

神华集团在我国CO₂地下埋藏的潜在目标区(鄂尔多斯盆地)实施的CO₂注入工程仍存在有关其注入层之上泥岩盖层安全性方面的争议.通过对与神华集团CO₂注入井相邻且钻遇地层系统、岩石组合一致的JX井三叠系延长组(位于注入层之上)的研究预测一旦CO₂透过盖层后的再续固碳能力.研究层位岩屑样品类型主要为长石砂岩和岩屑长石砂岩,其次为岩屑砂岩和岩屑石英砂岩;其物源区岩石类型主要为长英质火山岩、其次为中性火山岩及少量富含石英的沉积岩,具中性斜长岩成分特征;其上段(466~534 m)及下段(666~958 m)砂岩母岩受到弱-中等化学蚀变,并可能经历了再旋回过程;中段(534~666 m)砂岩母岩未受化学蚀变影响,并可能为第一次旋回沉积物.作为潜在的CO₂再续固碳场所,延长组砂岩具有实现CO₂矿物圈闭的物质条件及形成片钠铝石、方解石、铁白云石和菱铁矿等固碳矿物的潜力.     

GPS-R技术辅助的土壤水含量变化监测

针对传统地表土壤含水量测量方法时空分辨率小等不足,研究一种基于GPS卫星信号的矿区地表土壤水含量反演算法。针对傅里叶变换难以处理非均匀时序数据,设计了一种Lomb Scargle算法分析GPS信噪比特性。直接分离其中的直射信号和反射信号,提取多路径反射信号并分析其时频特征。通过与实测数据对比,分析反演土壤含水率的可行性。结果表明:反射信号频谱特征与实际数据具有较强的相关性。该方法为高时空分辨率监测地表土壤含水率提供了一种新的思路。     

黄河头道拐水沙变化多元驱动因子贡献率分析

根据1950—2010年水沙实测资料,采用统计分析方法,通过构建非线性响应模型,辨识了水沙变化主导驱动因子,定量评估了多因子对黄河上游头道拐水沙变化的贡献率.结果表明:头道拐1950—2010年多年平均径流量减少速率为2.23亿m3/a,多年平均输沙量减少速率为0.027亿t/a,1987—2010年径流泥沙减少趋势更为明显,同期输沙量减幅明显大于径流量减幅;1969—2010年气候因子和下垫面因子对头道拐站年径流模数和年输沙模数变化的贡献率均约为2:8,下垫面因子明显占主导地位,其中宁蒙灌区年引水量对年径流模数变化的贡献率最大,达到42%,龙羊峡和刘家峡等水库运用对年输沙模数变化的贡献率最大,达到34%.预计今后兰州以上径流变化和兰州至头道拐区间主要支流来沙变化两大自然因素将是头道拐水沙变化的主导因子;灌区引水和支流水土保持综合治理减沙对头道拐水沙变化的贡献率将居主导地位.     

下一代重力卫星任务研究概述与未来展望

近20年来,利用重力卫星研究地球系统的质量分布得到了广泛的发展,使人类对发生在大气、水圈、海洋、极地冰盖等地球圈层的动态过程有了更为深刻的理解。现阶段重力卫星主要包括挑战性小卫星有效载荷计划、地球重力场恢复及气候探测计划（gravity recovery and climate experiment,GRACE）,地球重力场稳态海洋环流探测计划和GRACE后续任务,回顾其发展历程,简要说明其在地球重力场解算的研究进展及存在的问题。为了改善现阶段重力卫星的缺点,国际上各研究机构为下一代重力卫星任务（next generation gravity mission,NGGM）提出众多远景规划和模拟分析,梳理了国际上提出的12种下一代重力卫星任务的任务概念、预期精度及任务状态。为了更加清晰介绍NGGM和整体把握其进展,根据星座构型和卫星载荷技术将其划分为4类,即Sharifi型重力卫星星座、Bender型重力卫星星座、星链型重力卫星星座和量子型重力卫星星座,并综合分析其性能,尝试性地给出相应的参考性实施建议。     

印尼马都拉海峡盆地晚渐新世至早中新世珊瑚生物礁特征及其古地理指示

马都拉海峡盆地属特提斯构造域东段,晚渐新世至早中新世裂后稳定沉降时期沉积大面积碳酸盐岩,是区内最重要的油气储层之一.为探讨该时期盆地演化模式,依据马都拉海峡盆地钻遇库炯组的钻井数据和岩心照片以及约120 km长的二维地震数据,通过井沉积相和地震相分析,将盆地地震相划分为6种类型,识别出库炯组珊瑚生物礁以区内F₆反转断裂带为界具有明显的南北分区特征.依据珊瑚生物礁生长发育所需特殊环境,认为马都拉海峡盆地裂后沉降期被一系列EW向正断层分为中南部浅海陆架开阔台地区和北部相对深水区,呈现出"南高北低"的古地理特征.      

新西兰2016年凯库拉MW7.8地震灾害考察与启示

在2016年新西兰凯库拉M_W 7.8地震中,北东—北东东向科科仁古断裂水平右旋位移量最大,为10—12m;北北西—近南北向帕帕提断裂垂直位移量最大,达到5—6m。对直接坐落在这2条地震地表破裂带或变形带之上的建筑物的破坏现场调查表明,尽管房屋出现歪斜,但上部主体部分基本完整,没有出现倒塌或部分倒塌现象,避免了人员伤亡。在无法回避活动断裂及其大震危险性的情况下,隔震系统的广泛采用可以有效地提高建筑物抵御地震灾害的能力。此次地震触发了数万个滑坡体,最大滑坡体可达数百万立方米。对沃罗村北边2处边坡失稳地带的考察结果表明,针对该地至少从2个方面进行了考虑和处置:一是在选址上,避开了突出山嘴等高陡坡地带;二是在房屋正对的山坡地带,种植或保护了茂密的树木,这既增加了山体的稳定性,又可以在地震中有效地减缓崩塌的石块对房屋的冲击。对比中国中东部一些大震,如1976年唐山7.8级地震和2008年汶川8.0级地震中触目惊心的巨大人员伤亡和财产损失,即使在人口密度与滑坡规模上存在明显不同,对新西兰凯库拉地震灾害现场的考察结果,还是在如何有效抵御地震灾害方面给我们提供了很好的启示。     

唐山地区跨断层流动形变监测场地优选

针对隐伏断裂的特点,在前人研究成果的基础上,充分利用唐山活动断层探测成果,进行野外调查;依据相关规范,结合环境条件、自然条件,对6个场地进行了综合分析,优选出适宜于跨断层流动形变监测的场地。