Impact of typical environments in China’s western mountainous areas on the durability of railway concrete:a review

Purpose–This study aims to analyze the impact mechanism of typical environments in China’s western mountainous areas on the durability of railway concrete and propose measures to improve durability.Design/methodology/approach–With the continuous promotion of infrastructure construction,the focus of China’s railway construction has gradually shifted to the western region.The four typical environments of large temperature differences,strong winds and dryness,high cold and low air pressure unique to the western mountainous areas of China have adverse effects on the durability of typical railway structure concrete(bridges,ballastless tracks and tunnels).This study identified the characteristics of four typical environments in the western mountainous areas of China through on-site research.The impact mechanism of the four typical environments on the durability of concrete in different structural parts of railways has been explored through theoretical analysis and experimental research;Finally,a strategy for improving the durability of railway concrete suitable for the western mountainous areas of China was proposed.Findings–The daily temperature difference in the western mountainous areas of China is more than twice that of the plain region,which will lead to significant temperature deformation and stress in the multi-layered structure of railway ballastless tracks.It will result in cracking.The wind speed in the western plateau region is about 2.5 to 3 times that of the plain region,and the average annual rainfall is only 1/5 of that in the plain region.The drying effect on the surface of casting concrete will significantly accelerate its cracking process,leading to serious durability problems.The environmental temperature in the western mountainous areas of China is generally low,and there are more freeze-thaw cycles,which will increase the risk of freeze-thaw damage to railway concrete.The environmental air pressure in the western plateau region is only 60%of that in the plain region.The moisture inside the concrete is more likely to diffuse into the surrounding environment under the pressure difference,resulting in greater water loss and shrinkage deformation of the concrete in the plateau region.The above four issues will collectively lead to the rapid deterioration of concrete durability in the western plateau region.The corresponding durability improvement suggestions from theoretical research,new technology development and standard system was proposed in this paper.Originality/value–The research can provide the mechanism of durability degradation of railway concrete in the western mountainous areas of China and corresponding improvement strategies.

Primary Deformation Analyses of High Pressure Metamorphic Rock in Western Dabie Mountain Area

In the western Dabie Mountain area, the eclogites have similar compositions and tectonic environment, which could be contrastively researched. Except for the reservation of the early structural deformation inside and outside of the eclogite lens, there is no obvious difference between the characteristics of the foliation and lineation in the eclogite lens from the one in surrounding region. So this paper concludes that the eclogites or blueschists (high pressure metamorphic rocks, i. e. HPM) are basically situated in the original position. The eclogites are mostly superposed by the ductile shear zone and show the feature of structural displacement, but so far we have not discovered any large scale structural zone to uplift eclogite return. Based on the analyses of finite strain measure, petrofabric analysis and TEM image for some minerals such as quartz and garnet, we could efficiently know the deforming characteristics of the eclogite in the prophase and anaphase of the main deforming epoch, and finally determine the forming condition of eclogite according to the strain and the differential stress. This paper puts forward preliminary conclusion that some HPM rocks could be formed by the deep layer embedding and local stress concentration in the process of regional metamorphism.

Study on security and protection of original ecotourism resources in the mountain areas of western Guangxi

Original ecotourism resources mainly refer to natural and human original ecotourism resources, and it＇s of fragility, rarity and irreversibility. As a valuable historic heritage and hnportant tourism resources, it plays a significant role in developing tourism and economy in such areas as the underdeveloped areas, the mountain areas and mimority areas. The tourism resources in the western mountain areas of Guangxi owe ,superiorities and characteristics ＇o their original ecology, Yet, western Guangxi is an ethnic region with fragile karst eco-environment, so it is specialto exploit the tourism resources. The paper defines original eeotourism and analyses the specialties and advantages of the original ecotourism resources as well as thefrailty of the ecotourism resources of the region. The ways of thinking are put forward for safe preservation and sustainable development of the original ecotourism resources, i.e. carrying out measures for the multi-grade protection of heritage resources, setting up a ethnic eco-museum/ ethnic culture eco-park and a gene pool of ethnic cultures, etc.

连片特困地区县域交通扶贫效率测度及影响因素——以滇西边境山区为例

交通扶贫效率测度可为乡村振兴阶段区域交通规划方案制定提供重要的理论依据。以滇西边境山区56个县域四年间交通与经济发展面板数据为样本,构建交通扶贫效率投入产出指标体系,运用DEA模型、Malmquist指数测度滇西边境山区各县交通扶贫效率,并分析其时空分布特征。同时,构建Tobit回归模型,探究县域交通扶贫效率的影响因素。研究表明:滇西边境山区县域交通扶贫效率整体呈逐步增长态势,在乡村振兴阶段仍然有较大提升空间,且交通扶贫综合效率主要受到规模效率的影响;滇西边境山区县域交通扶贫效率大幅提升;依据交通扶贫综合效率的平均值和Malmquist指数值两个维度,滇西边境山区56个县可划分为潜力型、发展型、成熟型及巩固型4种类型,而发展型和成熟型是滇西边境山区交通扶贫效率的主要形态;县域规模、产业结构对交通扶贫效率的提升具有反向抑制作用,就业支持、消费水平、区位优势、投资规模均在不同程度上对滇西边境山区交通扶贫效率产生正向促进作用;各影响因素对不同发展阶段的县域交通扶贫效率在影响强度和作用路径上存在差异。因此,应进一步优化县城交通基础设施空间布局,强化劳动力就业等因素与交通运输发展的“联动效应”,针对不同交通扶贫发展阶段及影响因素短板,采取差异化、合理化发展策略。

高地应力蚀变花岗岩隧道大变形特征及成因分析

西部山区某蚀变花岗岩隧道施工过程中,围岩大变形不同程度地造成喷射混凝土剥落、钢架扭曲变形、钢拱架断裂、初支变形侵限以及隧道内坍塌等。为揭示蚀变花岗岩隧道围岩大变形的孕育机理,通过岩石试验、监控量测、数值计算分析和地质综合分析等多种方法,对蚀变花岗岩隧道高地应力及大变形特征、影响因素进行探讨分析。蚀变花岗岩隧道工程区受构造影响强烈,蚀变特征显著,岩体结构疏松,蚀变花岗岩地层为大变形提供充足的物源条件。隧道现场监控量测显示发生大变形的蚀变花岗岩区段与地下水紧密相关,蚀变花岗岩中的伊蒙混石、绿泥石等亲水性矿物成分含量较高,遇水极易崩解,使得岩体抵抗变形的能力大幅降低。结合隧道地质条件和地应力测试,反演分析了隧道初始地应力场,发现蚀变花岗岩隧道以水平构造应力为主,隧道沿线多处于高地应力状态,为大变形的发生提供内动力地质条件。根据隧道开挖过程中发生的支护变形及监控量测分析,复杂地质条件对隧道设计的影响以及施工工艺与支护结构的质量是引起围岩大变形的重要主观因素。

基于GF-7数据的豫西山区地质灾害遥感解译

【目的】查明豫西山区部分区域内崩塌、滑坡等地质灾害的空间分布特征,为地质灾害监测与治理提供科学依据。【方法】主要利用高分七号卫星影像数据,通过构建遥感解译标志、室内初步解译、野外核查验证、内外业综合解译、编制解译成果图件等步骤开展遥感解译工作。此外,还对比分析了多类型多时相的遥感影像,并结合研究区的地形地貌等地质资料,进一步提高了地质灾害的可解译性。【结果】在此次地质灾害遥感解译中,实际正确识别了15处滑坡、6处崩塌,解译正确率达91.3%。遥感解译的精度和效率较高,取得了较好的成果。【结论】本研究提出的利用高分七号遥感卫星数据开展地质灾害遥感解译思路及方法,在该地区所进行的地质灾害遥感解译工作中表现出显著优势,具有较强的实用性和可行性,能够为其他地质灾害遥感解译工作提供有力的参考和指导。

基于联合时序InSAR技术的矿区沉降隐患区识别

针对目前单一InSAR解译技术方法在复杂地表形变解译中精度及可靠性有限的难点,提出了利用PS-InSAR(persist scatterers InSAR)、SBAS-InSAR(small base-line subsets InSAR)这2种时序InSAR技术联合进行山地矿区地面沉降隐患区圈划的方法。以湖北省宜都市松宜矿区为例,基于大样本理论,利用矿区内高精度的PS点形变结果,校正具有高空间覆盖率的SBAS-InSAR处理结果,从而进一步提高地表形变监测精度并增加形变靶区范围圈划的准确度。通过对比使用单一PS-InSAR技术和经过PS-SBAS联合方法处理后得到的典型形变点时序曲线及野外实地调查,验证了解译结果的可靠性。研究表明:联合时序InSAR技术可以提高地表沉降监测精度并增加地表变形靶区范围圈划的准确度,为类似山地矿区的地面沉降隐患监测与分析提供新的技术思路。

辽西低山丘陵区坡面暴雨产流产沙过程及水保效益

基于辽西低山丘陵区二道岭小流域坡面径流和泥沙现场观测,研究暴雨条件下(7·28暴雨)6种不同水土保持措施的坡面产流产沙过程及水土保持效益。结果表明,在暴雨过程中,与裸地相比,耕作措施中的顺垄耕作缩短了初始产流时间,工程措施和林草措施延长了初始产流时间。不同措施的产流产沙过程和雨强变化趋势相似,横垄耕作的径流和含沙量与雨强存在延后现象。在暴雨条件下,以裸地作为对照,林草措施具有良好的减流减沙效果,而农业措施的顺垄耕作则增大了产流产沙作用,加剧了水土流失。

西部山区泥石流灾害下建筑物破坏特征与破坏等级划分

近年来我国西部山区泥石流灾害频发,严重威胁当地居民的生命财产安全,其中,建筑物的破坏是造成各类损失的重要原因。正确认识泥石流的致灾机理和泥石流灾害下建筑的破坏特征不仅是正确评价泥石流灾害风险的基础,也是科学构建泥石流下房屋建筑易损性模型的依据。基于文献查阅、新闻资料和现场调研,首先对西部山区泥石流灾害主要特点进行了归纳阐述,其次梳理了近年来发生泥石流灾害中建筑物的破坏特征,最后结合泥石流的动力学特性和建筑结构情况剖析了建筑结构的受损机理。基于建筑物的空间分布与泥石流强度的时空耦合变化特征,对泥石流强度表征方式给出方向性建议;基于建筑的受损机理,参考地震作用下建筑的破坏等级划分标准,初步提出了泥石流下建筑物破坏等级划分方式,旨在为防灾减灾工作提供一定参考。

西部民族地区“两山”转化指数测度及对共同富裕影响效应研究

文章从“绿水青山”和“金山银山”两个维度测度了“两山”转化指数,从发展性、共享性和可持续性三个维度测度了共同富裕发展水平,利用2011—2020年西部民族地区省域面板数据实证考察了“两山”转化对共同富裕的影响效应和作用机制。研究发现:在我国西部民族地区,“两山”转化显著推动了共同富裕的实现,且产业结构升级是“两山”转化推动共同富裕实现的重要传导机制,“两山”转化通过促进产业结构高级化和产业整体结构优化加快共同富裕发展;“两山”转化与共同富裕发展间的正向关系存在显著的异质性,在“绿水青山”程度较高、第三产业占比较高、科技发展水平较高以及政府转移支付较高的情境下推动作用更明显。

鄂西山区日本落叶松人工林全林整体模型研究与应用

为解决林分各测树因子及其生长模型之间的相容性问题,采用非线性度量误差联立方程组法建立鄂西山区日本落叶松人工林全林整体模型。研究结果表明,非线性度量误差联立方程组方法,能保证模型的相容性与无偏性;各林分因子的平均相对误差和相对均方误差均在6.5%以下,模型参数稳定性及预测精度均较高;建立的全林整体模型可用于不同初始条件的日本落叶松人工林林分生长收获预估、定量间伐作业设计以及林分密度控制图绘制。相关研究结果可为研究区日本落叶松人工林高效可持续经营提供科学参考。

西昆仑山前柯深—柯东地区断裂传递型超压的识别与计算

西昆仑山前柯深—柯东地区断裂构造活动剧烈,在浅部地层中存在压力系数高达2.1的极高超压,对于这种超压分布特征和形成机制的研究和认识对钻井工程和油气运移研究具有十分重要的意义。综合储层实测压力、间接估算的泥岩地层压力以及超压地层岩石力学与物性的关系等资料,并结合研究区断裂发育条件和油气运移史,分析了地层压力分布特征和主控机制。结果表明,西昆仑山前柯深和柯东两地区在古近系—白垩系储层中各自形成了相对统一的异常压力系统,系统内地层压力向深部以静水压力梯度增加,储层压力大于附近泥岩压力。研究区储层压力分布特征与深部流体沿开启性断裂的向上传递密切相关。在此基础上,估算了压力传递量,并探讨了影响压力传递量的地质因素。柯深和柯东地区断裂传递增压量分别为15.0~34.0 MPa和8.1~16.5 MPa,与实测总剩余压力的比值分别为24.2%~67.2%和23.4%~53.7%。两个地区断裂传递增压量的差异主要受断裂发育及其与地层的空间配置关系的影响。

西部山区农业生态效率测度及影响因素研究——基于湖南省湘西州8县市的实证分析

文章采用非期望产出的SBM模型和随机效应面板Tobit模型,将2003—2018年湖南省湘西土家族苗族自治州县域行政单位的面板数据作为样本,对湘西8县市的农业生态效率进行测算,探讨影响湘西8县市农业生态效率的因素。结果显示:湘西8县市农业生态效率总体呈现波动上升趋势,同时存在一定的县市差异,其中,古丈县农业生态效率最高,凤凰县最低;在各影响因素中,城乡收入比、有效灌溉率、人均耕地面积呈现负向效应,种植结构影响呈现正向效应,产业结构和农业机械化水平未通过显著性检验。因此,提高西部山区的农业生态效率,需加大财政支农力度,加强农业科技创新,切实转变农业发展方式,平衡好各生产要素之间的关系,稳步实现农业高质量发展。

豫西山区特色农业产业发展的SWOT分析——以河南省卢氏县蜂产业为例

河南省西部多为山地、丘陵地貌,植被资源丰富,具有发展蜂产业这一特色产业的区域优势和潜力。以卢氏县为例,运用SWOT分析方法,对该地区发展蜂产业的优势、劣势、机遇与挑战进行分析,提出了促进豫西山区蜂产业持续健康发展的对策建议与保障措施,为进一步推动山区发展蜂产业提供模式参考与经验借鉴。

皖西大别山区传统村落空间分布特征及其影响因素研究

以皖西大别山区31个国家级传统村落和83个省级传统村落为研究对象,运用GIS空间分析方法,从空间分布的类型、均衡程度、自然地理、社会经济等方面揭示皖西大别山区传统村落空间分布的主要特征;通过地理探测器工具进一步探究影响其分布的主要因子及各因子的驱动力大小。结果表明:传统村落空间分布呈现“大分散、小聚集”的特征,潜山市、岳西县和金寨县为核心区;传统村落空间分布与地形地貌、河流水系和土地类型等自然地理条件密切相关,同时也与主要道路和城镇化水平等社会经济方面存在一定的相关性;自然环境条件对皖西大别山区传统村落分布的驱动力高于社会经济方面。

鄂西山区柳杉人工林全林整体模型研建与应用

在对鄂西山区柳杉Cryptomeria fortunei人工林60块标准地立地分级基础上,采用非线性度量误差联立方程组法建立了柳杉人工林全林整体模型,保证了模型的相容性和无偏估计;模型检验结果表明各林分因子的平均相对误差和相对均方误差均在6.5%以下,模型参数稳定性及预测精度均较高;同时,应用全林整体模型可对不同初始条件的柳杉人工林林分生长进行模拟预测、定量间伐作业设计以及绘制不同立地条件的林分密度控制图。

基于PLUS模型的鄂西山区耕地景观格局多情景模拟

以鄂西山区19个县(市、区)为研究对象,利用PLUS模型模拟耕地景观在自然条件约束情景和自然与社会经济条件双重约束情景下的时空演化规律,明确耕地景观格局的重要影响因素。结果表明,未来鄂西地区耕地数量仍表现为下降趋势。影响耕地变化的因素主要为高程、植被覆盖、水文条件。斑块形态的空间分布格局受地形影响显著,表现为北优南劣的格局;耕地斑块形态随时间变化呈明显优化发展的趋势。在斑块格局上,鄂西地区耕地斑块整体空间聚集性差、连通性低、破碎化程度高,耕地斑块格局存在持续恶化的风险。多情景模拟的差异表明,耕地斑块的规则化发展会受到社会经济活动因素的限制,而仅在自然条件驱动下,耕地景观更易向复杂化、破碎化方向发展。

塔北隆起西部地区白垩系碎屑岩油气成藏规律及成藏模式

以岩心观察、物性分析、地球化学分析和三维地震资料为基础,通过单井、连井沉积相分析、地震精细解释及优势砂体识别等方法,从油气来源、油气充注特征、输导体系及储盖组合等4个方面对塔北隆起西部地区白垩系碎屑岩油气成藏规律及模式进行了研究。研究结果表明:(1)研究区白垩系油气具有“陆源”特征,石油主要来自库车坳陷三叠系湖相烃源岩,天然气主要来自库车坳陷侏罗系煤系烃源岩,区内深部三叠系海相烃源岩贡献极小。(2)研究区白垩系油气充注持续时间长,成藏时期晚,早期生油,晚期生气,油成藏于中新世(4.0~22.0 Ma),气成藏于晚中新世—中上新世(3.5~11.0 Ma),受2.6~3.5 Ma构造隆升影响,气藏成熟度较低。(3)研究区油气输导体系较发育,天山南地区以断裂和不整合面作为主要运移通道;顺北地区以不整合面和巴西改组薄层砂体为运移通道。(4)研究区储层主要发育在舒善河组和巴西改组,含砂率一般高于60%,与其上部发育的连续泥岩构成良好的储盖组合;优质储层的分布受沉积相控制,天山南地区优质储层主要分布在扇三角洲前缘砂坝及滩坝,顺北地区优质储层主要分布在辫状河三角洲前缘朵体,目前探井未钻遇朵体最高部位,油气显示相对较差;顺北地区储层物性更佳。(5)研究区天山南与顺北地区因断裂活动强度及储盖组合特征存在差异造成了二者的油气藏类型不同,前者以低幅度构造、构造-岩性复合油气藏为主,后者以规模较小的岩性油气藏为主。

Comprehensive Evaluation of Farm Household Livelihood Assets in a Western Mountainous Area of China: A Case Study in Zunyi City

As the foundation of farm household structure,livelihood asset status is the basis for farmers to gain opportunities,adopt livelihood strategies,resist livelihood risk,and engage in positive livelihood achievements.Quantifying farm household assets identifies future development trends that are fundamentally necessary to predict farm household vulnerability and strategy,as well as understanding farmers’current living situations.Using Zunyi City in China’s western mountainous area as a case study,we conducted stratified sampling and participatory rural investigation appraisal to collect data on the attributes of farm households’livelihood assets and livelihood strategies to establish an index evaluation system and enable evaluation and analysis of farm households with different livelihood strategies.Our research indicates that due to structural differences,total livelihood assets of farm households with different livelihood strategies are similar.Rural households have an abundance of natural and material assets and deficiencies in human,financial and social assets.Non-rural households and part-time households are abundant in human,financial and social assets and deficient in natural and material assets.

Topographical relief characteristics and its impact on population and economy:A case study of the mountainous area in western Henan,China

Topographical relief is a key factor that limits population distribution and economic development in mountainous areas. The limitation is especially apparent in the mountain-plain transition zone. Taking the transition zone between the Qinling Mountains and the North China Plain(i.e. the mountainous area in western Henan Province) as an example and based on the 200-m resolution DEM data, we used the mean change-point analysis to determine the optimal statistical unit for topographical relief, and thereafter extracted the relief degree. Taking the 1:100,000 land use data, township population and county-level industrial data, population and economic spatial models were constructed, and 200-m resolution grid population and economic density maps were generated. Afterwards, statistical analysis was carried out to quantitatively reveal the impact of topographical relief on population and economy. In addition, the impacts of other topographical factors were discussed. The results showed the following.(1) The relief degree in western Henan is generally low, where 58.6% of the regional topography does not exceed half the height of a reference mountain(relative elevation ≤250 m). Spatially, the relief degree is high in the west while low in the east, and high in the middle while low in the north and south. There is a positive correlation between relief degree and elevation, and a much stronger correlation between relief degree and slope.(2) The linear fitting degree between the population and economic validation data and the corresponding simulation data are 0.943 and 0.909, respectively, indicating that the spatialized results can reflect the actual population and economic distribution.(3) The impact of topographical relief on population and economy was stronger than that of other topographical factors. The relief degree showed a good logarithmic fit relationship with population density(0.911) and economic density(0.874). Specifically, 88.65% of the population lives in areas where the topographical relief is ≤0.5 and 88.03% of the gross regional product was from areas where the relief is ≤0.3. Compared with the population distribution, the economic development showed an obvious agglomeration trend towards low relief areas.