高烈度地震区隧道软硬围岩交接段刚柔并济抗减震技术研究*

为提高高烈度地震区隧道抗震性能，以某铁路隧道为研究背景，分析3种抗减震措施下隧道不同监测点隧道拱顶沉降、边墙收敛、衬砌结构PGA及最小安全系数，通过对比分析得到最优抗减震措施。结果表明:相比于工况1，工况2隧道拱顶沉降减小10.54%~81.10%，边墙收敛减小13.92%~78.77%，衬砌结构PGA减小31.42%~72.02%，最小安全系数增加18.04%~66.13%；相比于工况1，工况3结构拱顶沉降减小3.04%~18.02%，边墙收敛减小4.70%~32.00%，PGA增加13.95%~27.48%，最小安全系数增加7.49%~30.99%；工况4即“减震层+SFRC衬砌”刚柔并济法，相比于工况1，隧道拱顶沉降减小18.46%~83.98%，结构边墙收敛减小17.54%~85.47%，PGA减小30.00%~69.98%，最小安全系数增加47.95%~83.56%；4种工况抗减震性能由高到低依次为:工况4＞工况2＞工况3＞工况1。研究结果可为隧道软硬围岩交接段抗震设防提供理论参考。     

基于遥感影像的2019—2020年盐城市生态保护红线区人类活动动态分析

以盐城市生态保护红线区为研究对象,选用哨兵-2号卫星遥感影像进行目视解译及变化斑块提取,分析其区域内2019—2020年人类活动的变化趋势。结果显示,动态变化情况分为正变化和逆变化,其中逆变化占变化总面积的绝大部分,主要呈现为水田的减少;正变化主要呈现为农村居民点的拆除。总体来说,人类活动变化面积非常少,无工业用地的增加。该技术获取数据速度快、效率高、成本低,可作为国家生态保护红线区等动态监管和生态评估的重要支撑手段。     

Effects of urban greenspace configuration and native vegetation on bee and wasp reproduction

Pollinator welfare is a recognized research and policy target, and urban greenspaces have been identified as important habitats. Yet, landscape-scale habitat fragmentation and greenspace management practices may limit a city's conservation potential. We examined how landscape configuration, composition, and local patch quality influenced insect nesting success across inner-city Cleveland, Ohio (U.S.A.), a postindustrial legacy city containing a high abundance of vacant land (over 1600 ha). Here, 40 vacant lots were assigned 1 of 5 habitat treatments (T1, vacant lot; T2, grass lawn; T3, flowering lawn; T4, grass prairie; and T5, flowering prairie), and we evaluated how seeded vegetation, greenspace size, and landscape connectivity influenced cavity-nesting bee and wasp reproduction. Native bee and wasp larvae were more abundant in landscapes that contained a large patch (i.e., >6 ha) of contiguous greenspace, in habitats with low plant biomass, and in vacant lots seeded with a native wildflower seed mix or with fine-fescue grass, suggesting that fitness was influenced by urban landscape features and habitat management. Our results can guide urban planning by demonstrating that actions that maintain large contiguous greenspace in the landscape and establish native plants would support the conservation of bees and wasps. Moreover, our study highlights that the world's estimated 350 legacy cities are promising urban conservation targets due to their high abundance of vacant greenspace that could accommodate taxa's habitat needs in urban areas.     

新疆阿克苏地区平原区高砷地下水分布特征及富集因素分析

地下水砷污染是全球化环境问题.本文基于阿克苏地区平原区2017年75个地下水砷实测含量进行分析.结果表明,研究区地下水砷含量变化范围为ND—98.70μg·L^-1,平均值为9.42μg·L^-1,超标率达26.7%.水平方向上,高砷地下水主要集中在研究区的中部偏南一带;垂直方向上,山麓斜坡冲洪积砾质平原潜水区地下水砷含量平均值表现为深层潜水>浅层潜水,中下游河流冲积平原区承压水区地下水砷含量平均值表现为深层承压水>浅层承压水>潜水.采用绘制Piper三线图、Gibbs图、离子比例图等方法对研究区地下水砷的富集因素进行研究.结果表明,研究区地下水砷主要为自然来源;封闭的地质构造和造山带与河流等沉积环境相结合的水文地质条件有利于研究区地下水砷的富集;研究区高砷地下水水化学类型主要为HCO3·SO4-Na,还原性-弱碱性环境利于地下水砷富集;研究区地下水砷受强烈的蒸发浓缩作用进一步浓缩,同时地下水阴离子浓度增大加剧了地下水中阴离子与砷酸根、亚砷酸根之间的竞争吸附,利于地下水砷的富集.     

Public participation in NGO-oriented communities for disaster prevention and mitigation (N-CDPM) in the Longmen Shan fault area during the Wenchuan and Lushan earthquake periods

ABSTRACT

The Longmen Shan fault area in southwest China is one of the world’s most active earthquake zones. The epicenters of the two most recent earthquakes, the 2008 Wenchuan earthquake (8.0?Ms) and the 2013 Lushan earthquake (7.0?Ms), both of which caused serious losses, were only 85?km apart. Community-based disaster risk reduction is the foundation of the disaster management system pyramid and is critical to the success of ‘sustainable hazard mitigation’. Based on multiple collaborative stakeholder perspectives, this paper examines public participation in an NGO-oriented Community for Disaster Prevention and Mitigation (N-CDPM) in the period between the two earthquakes as a multi-stage problem; N-CDPM establishment, normal operations, disaster testing, and continuous improvement. Multi-stage field research was conducted in the affected areas in the Longmen Shan fault area to examine the collaboration in each stage, after which the differences were compared across the four stages based on eight key indices; scales, core stakeholders, core network stability, mean number of lines, mean collaborative level, governments, and individual and public organization participation. The government participation, individual participation, and public organization participation are then discussed. This paper provides a novel research approach to CDPM in multiple earthquake regions and gives rich insights into the collaboration between the government and the public for N-CDPM.     

基于支持向量回归机的南黄海浒苔分布面积预测模型

绿潮作为一种新型的海洋灾害,已经引起了各个国家的重视.依据2012年南黄海海域浒苔遥感监测分布面积数据,选取了温度、天气状况、风向、风力、浪高5种影响浒苔扩散的气候因子,建立了基于SVR的浒苔分布面积预测模型,并与经典的最近邻点插值模型、线性插值模型、3次样条函数插值模型和分段3次Hermite插值模型进行了回归效果的对比.分析结果表明,基于SVR的浒苔分布面积预测模型能够为浒苔遥感数据的插补提供一种方法,且回归效果优于传统的回归方法,为浒苔的防治提供辅助决策信息.     

ASE-气相色谱法测定油田区土壤中多种石油烃

采用气相色谱法测定油田区土壤中C_(10)～C_(40)的石油烃,通过优化加速溶剂萃取的条件,使方法在62 mg/L～3 100 mg/L范围内线性良好,方法检出限为4.8 mg/kg。用该方法测定石油区短期、中期、长期油井污染土壤样品,5次测定结果的RSD为1.3%～5.2%,加标回收率为84.8%～98.5%,有证标准样品测定结果在可信区间内。     

Multi-stakeholder collaboration in community post-disaster reconstruction: case study from the Longmen Shan Fault area in China

While multi-stakeholder collaboration is critical for effective community post-disaster reconstruction (CPDR), it is often very difficult in practice. The Longmen Shan Fault active seismic zone in China has experienced several recent earthquakes with the 2008 Wenchuan earthquake and 2013 Lushan earthquake, both of which caused extensive and widespread damage to many communities, presenting unprecedented challenges for post-disaster reconstruction. This paper develops a multi-cycle field research method that involves three interconnected cycles: internet research, field visits, and extensive surveys: to examine multi-stakeholder collaboration for the CPDR following the Wenchuan earthquake. It was found that there were 12 types of active stakeholders engaged across four main areas: infrastructure rebuilding, psychological recovery, socio-economic rehabilitation, and ecological restoration. Specifically, local community participation and effective collaboration between the community and the external stakeholders were found to be the most crucial elements for successful reconstruction. Multi-stage field research after the Lushan earthquake verified that CPDR was effective and that multi-stakeholder collaboration had improved from the lessons learnt from the Wenchuan earthquake reconstruction experience. Some advantages and limitations of this research are also given.     

上海城区交通干道黑碳污染调查

采用设置在上海市中心城区交通主干道旁空气质量自动监测站2018年1—12月的观测数据,分析黑碳气溶胶(BC)污染特征及其与PM_(2.5)、SO_2、NO_x、CO、O_3、苯、甲苯、乙苯、二甲苯和气象参数的相关性。结果表明,观测期间内,BC小时均值为(3 038±22) ng/m~3,ρ(BC)在ρ(PM_(2. 5))中占比为(11. 48±0. 12)%。日内ρ(BC)变化呈双峰型,各月份之间ρ(BC)变化不大。ρ(BC)与风速呈负相关,与PM_(2. 5)、NO_x、CO、苯、甲苯、乙苯和二甲苯呈正相关。     

砒砂岩区不同留茬高度及坡向下沙棘根系分形特征

为提高内蒙古砒砂岩区沙棘(Hippophae rhamnoides)人工林根系的生长能力,对东(E)、南(S)、西(W)、北(N)不同坡向沙棘植株进行了距地表0、10、15、20 cm(即a、b、c、d)留茬高度处理,而根系分形特征是植物根系构型应对环境异质性的表型可塑性,为反映沙棘根系对不同坡向不同留茬生长环境的适应结果,基于分形理论在砒砂岩区对东、西、南、北不同坡向下留茬后的沙棘人工林的全根、主根、一级侧根及二级侧根分形特征以及根系和土壤含水率关系进行研究,以未平茬沙棘为对照(即e)。结果表明,(1)不同坡向相同留茬下沙棘根系分形维数(D)变化为E>N>W>S;土壤含水率为E>N>W>S,这与根系分形维数变化规律一致。(2)相同坡向不同留茬下沙棘根系分形维数(D)变化为c(留茬15 cm)>b(留茬10 cm)>a(留茬0 cm)>d(留茬20 cm)>e(未平茬)。(3)不同坡向不同留茬下沙棘根系各级分形维数变化为D3(二级侧根)>D2(一级侧根)>D1(主根),且D3与D呈显著正相关。(4)在相同坡向不同留茬下土壤含水率变化为:c相似文献