地面激光扫描与无人机摄影测量结合的地形测量探讨

航空摄影测量和激光扫描是大比例尺地形测量的常用方法,但当测量对象存在遮挡时,不可避免会产生数据阴影。将地面激光扫描和无人机摄影测量结合,在地面激光扫描数据覆盖不足的地区,采用无人机点云进行有效补充,通过选取广东省西部某座陡峭山峰进行实验,生成地形高分辨率点云和数字高程模型,经检测,测量精度达到厘米级,该方法可应用于包含崎岖山地在内的大比例尺地形测量。

高山河谷地形下采空区顶板变形及其影响因素分析

研究高山河谷地形下采空区顶板的变形特征是采空区地压管理和安全生产的重要基础。基于薄板小挠度弯曲理论,在满足边界条件及连续条件下,采用Levy单三角级数解法推导出高山河谷地形采空区顶板变形的挠度解析解。以宜昌某磷矿为工程背景,根据求解的采空区顶板挠度方程,分析了地表谷坡倾角θ、采空区走向与倾向长度比a/b、均布荷载分量q0等因素对顶板最大挠度w及最大挠度点位置的影响规律。分析结果表明:高山河谷地形下采空区顶板最大挠度w随谷坡倾角θ先缓慢再急剧递增,随a/b值呈“S”形递增,随q0值呈线性递增;此外高山河谷地形下采空区顶板最大挠度点位置均向高山侧偏移,其偏移距离受地表谷坡倾角θ及均布荷载分量q0影响较小,受采空区尺寸a/b值影响较大;最后根据现场调研结果分析得到顶板最大挠度点位置,验证了计算的理论结果与实际基本相符。研究可为高山河谷地形下采空区支护和采场地压管理提供理论依据。

高山峡谷地形泥石流沟治理措施与效果评价

随着各流域水电开发进展,当前大型水电站主要位于山区河流深山峡谷中,坝址选择时除兼顾区域地形地质情况,还会考虑水库库容的最大化,因此,枢纽区域常常出现冲沟治理。在建设初期,由于多种因素往往仅考虑水流疏导,随着排水设施运行情况会进一步对地质条件等进行复核,会调整治理措施,以保障安全运行。两河口水电站瓦支沟在建设初期仅做了排水疏导设施,运行前两年沟内松散堆积体受降雨影响形成了一定规模的泥石流,在重新对地形地质复核后,认为瓦支沟为泥石流沟,需进行治理。结合瓦支沟泥石流物源分析、治理思路梳理、治理设施布置及设计、后期运行情况等多方面进行介绍。

川东北高含硫气田井喷失控下气体扩散浓度研究

应用高斯烟羽模型计算在井喷失控条件下天然气的扩散浓度,并通过典型高山地形烟流运行轨迹规律,对烟羽模型进行修正,得出山地井喷流扩散模型。选取合适的扩散模型各参数的求取方法,其测算的数据与现场有较好拟合,为高含硫气田井喷后的救援提供了参考数据。

宜昌晒旗河磷矿条带充填法采场结构及回采顺序研究

复杂地形条件下矿体安全高效开采研究对于释放矿山资源产能有着重要意义。为解决目前房柱法开采对地表扰动程度大且矿柱难以回收等问题,基于条带充填开采技术,从采场结构及回采顺序两个方面对宜昌晒旗河磷矿展开了适应性研究,以期在提高矿石回收率的同时减少地表扰动。首先依据晒旗河高山河谷地形下地应力特征,在盘区内划分了高低应力采区,构建了分区采场结构,并引入极限强度理论得到条带矿柱的合理宽度;然后设计了高应力采区"隔一"、低应力采区"隔一采一"的条带回采顺序,运用FLAC3D数值软件优选出高、低应力采区间的回采顺序,研究矿体在开挖过程中围岩应力变化特征及地表变形特征。结果表明:①从低应力采区向高应力采区的回采顺序优势明显,可缓解高低应力采区的应力不均匀程度;②在整个回采及充填过程中,采场围岩较稳定,矿柱所受的垂直压应力均小于抗压强度;③高山河谷地形下地表沉降曲线演化特征为"U→V→U→W",地表沉降得到了有效控制;④所设计的条带充填法与传统房柱法开采相比,矿石开采效率得到了大幅提升,可为晒旗河磷矿及类似高山河谷地形下矿床开采提供技术指导。

省道217线桥梁防护经验浅谈

结合我院承担的项目"省道217线甘孜至新龙至理塘君坝大桥段改建工程"中桥梁基础防护的实例,浅析了在川西高原上高山峡谷地形区域桥梁防护的重点,供类似地区新建桥梁项目应用参考。

Spatial and temporal variation of drought index in a typical steep alpine terrain in Hengduan Mountains

This study describes the spatial and temporal variation of a drought index and makes inferences regarding the environmental factors that influence this variability in the Hengduan Mountains. A drought index is typically used to determine the moisture conditions and the magnitude of water deficiency in a given area. Based on data from 26 meteorological stations over the period 1960-2012, the spatial and temporal variations of the drought index were analyzed using a thin plate smoothing splines method that considered elevation as a covariate. The drought index was estimated based on the potential evapotranspiration(E0) as defined by the Penman Monteith model modified by FAO(1998). The results of the reported analysis showed that the drought index in the Hengduan Mountains has been decreasing since 1960 at a rate of-0.008/a. This represented a progressive shift from the "sub-humid" class, which typified the wider area in the Hengduan Mountains, toward the "humid" class, which appeared in the Hengduan Mountains areas. The drought index was relatively high in the north and low in the south and the variation of the drought index varied with seasons. The drought index showed increasing trends in summer and autumn and it is greater in autumn than in summer, while it showed a decreasing trend in spring and winter. Drought index is inversely proportional to the soil relative humidity and Normalized Difference Vegetation Index(NDVI).

Spatial association between landslides and environmental factors over Guizhou Karst Plateau,China

Guizhou Karst Plateau is located at the center of the karst region in Asia, where landslides are a typical disaster. Affected by the local karst environment, the landslides in this region have their own characteristics. In this study, 3975 landslide records from inventories of the Guizhou karst plateau are studied. The geographical detector method is used to detect the dominant casual factor and predominant multi-factor combinations for the local landslides. The results show that landslides are prone to areas on slopes between 10° and 35°, of clay rock, in close proximity to gullies, and especially in areas of moderate vegetation, dryland, and mild rocky desertification. Continuous precipitation over 10 days has a great effect on landslide occurrence. Compared with the individual factors, the impact of two-factor interaction has greater explanatory power for landslide volume. The volume of earthquake-induced landslides is predominantly controlled by the interactions of faults and slopes, while that of humaninduced landslides is affected by the interactions of land cover and hydrological conditions. For rainfallinduced landslides, the dominant interactions vary in different regions. In the central karst basin, the interactions between faults and precipitation can explain over 90% of the variations in landslide volumes. In the southern hilly karst region, the interactions between lithology and slope can explain over 71% of the variations in landslide volume and those between fault and land-use can explain 50% of the variations of the landslide volumes in the northeastern mountainous karst region.

Fluid flow on centimeter-scale in deep paleosubduction zones in western Tianshan,China:Evidence from high-pressure veins

High-pressure(HP)veins were extensively developed in western Tianshan high-pressure(HP)metamorphic belt.The HP vein and host-rocks were analyzed by electronic microprobe to trace the origin of vein-forming fluids.Analytical data show that the immediately adjacent host-rocks of the studied HP vein are eclogites and gradually turned into blueschist as the distance from the veins increases,which indicates that the vein-forming fluid was derived from adjacent host-rocks;the boundaries between the vein and the host-rocks are sharp,which indicates that the fracture of the host-rocks is brittle during the vein-forming process.It is suggested that this type of HP veins is precipitated from the liquid formed by the dehydration of the host-rocks during the prograde metamorphism from blueschist to eclogite facies,which results in hydrofracturing of the rocks and provides the space for the vein to precipitate.The width of the eclogite-facies host-rocks is usually 1-2 cm,which provides the direct evidence that the fluid flow is on centimeter-scale.

Livelihood Diversification as an Adaptation Approach to Change in the Pastoral Hindu-Kush Himalayan Region

Migratory livestock raising has been one of the most important livelihood options for people residing in high mountain areas and has made a significant contribution to the economy of the Hindu Kush Himalayan(HKH) region, both in terms of supporting households and in export earnings. However, in recent decades, changes in the socioeconomic situation and increasing climate variability have led to a need to enhance adaptation by building the resilience of local socio-ecological systems, including economic diversification and sustainable management of natural resources. Based on semistructured interviews with pastoral communities in six countries within the pastoral HKH region, this paper discusses the situation, trends and driving forces behind the diversification of pastoral livelihood. For internal diversification the study highlights the need for enhancement of pastoral livelihoods through value-adding activities in the pastoral sectors. For external diversification changes on policy changes are needed to support free out-migration, market exploitation, and multiple resource use. Finally the paper highlights the role of education in determining household adaptation strategies in the face of various socio-ecological pressures and recommends integrating innovative and indigenous knowledge to develop appropriate methods for risk management and resource management in the pastoral HKH region.

泰安大气VOCs的垂直分布特征及影响

为了探究大气挥发性有机物(volatile organic compounds,VOCs)的垂直分布特征,利用GC-MS-FID连用仪,依托泰山进行泰安不同高度大气VOCs的研究,并分析臭氧生成的影响。研究结果显示,大津口(海拔330 m)总挥发性有机物(total VOCs,TVOCs)的体积分数最高,为72.6×10^(-9),臭氧生成潜势(ozone formation potential,OFP)也最高,源于本地机动车芳香烃的排放,与高山地形也有关;其次为农大(地面,TVOCs的体积分数为61.4×10^(-9))和玉皇顶(海拔1534 m,TVOCs的体积分数为60.5×10^(-9));扇子崖(海拔500 m)TVOCs的体积分数最低,为41.2×10^(-9)。不同站点大气中烷烃占比均最高,但VOCs的OFP优势物种不同。农大VOCs的OFP优势物种为烯烃,受交通和工业排放的影响较大;扇子崖和玉皇顶VOCs的OFP最低,其中扇子崖站点周围没有明显的排放源,且区域输送影响较低,玉皇顶主要受到高空大气输送的影响。揭示了大气VOCs的垂直分布差异,与排放源、区域输送和高山地形等都有关,也为山地城市大气VOCs和臭氧区域控制提供了数据支持和理论依据。