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251.
西部断陷盆地覆盖区覆盖层与基岩面地质结构及盆山关系是当今覆盖区区域地质调查研究需解决的重点与难点。基于新疆巴里坤山间断陷盆地覆盖区地质填图试点实践,梳理出断陷盆地区地质填图的基本内容和填图目标;强调覆盖区地质调查必须针对需解决的关键地质问题,贯彻地表地质调查-地球物理探测-钻孔验证相结合的基本工作思路;确定出普适性的填图技术路线和围绕填图目标及基本内容的针对性填图方法组合;最后以巴里坤断陷盆地填图为例,从调研目标的确定到物探工作及方法组合优选和钻探布设,系统介绍了巴里坤断陷盆地覆盖区地质填图的方法体系,并最终落实到地质填图成果的体现,成为西部断陷盆地覆盖区地质填图的示范。 相似文献
252.
Field instrumentation for high‐resolution parallel monitoring of bedrock erosion and bedload transport 下载免费PDF全文
Alexander R. Beer Jens M. Turowski Bruno Fritschi Dirk H. Rieke‐Zapp 《地球表面变化过程与地形》2015,40(4):530-541
River incision is fundamental in shaping the Earth's surface. In mountainous regions with steep river beds, fluvial bedrock erosion by bedload transport is an important mechanism forming channels. However, there are only a few complete field datasets that can be used to improve process understanding and evaluate erosion models, especially at the process scale. To provide a simultaneous dataset of hydraulics, bedload transport and bedrock erosion at high temporal and spatial resolution, a new measuring device has been installed in the Erlenbach, a gauged stream in the Swiss Pre‐Alps. In this stream, bedload transport rates can be calculated from surveying deposits and from geophone plate sensors and bedload transport samples can be taken directly by an automated moving basket system. To measure bedrock erosion rates simultaneously, two natural stone slabs were mounted flush with the channel bed in a steel frame hosting various measurement devices. Force sensors below the slabs record normal stress and shear stress. At‐a‐point erosion rates on the slab surfaces are continuously measured at sub‐millimetre precision at three locations on each slab. In addition, the slab topography is monitored following erosive flood events. In this article (i) the ‘erosion scale’ device is described, (ii) data resolution and data quality is assessed by means of tests and event data, and (iii) the first transport event is discussed. The erosion scales are confirmed to provide data at high spatio‐temporal resolution for process analysis. The preliminary data show evidence for the tools effect in bedrock erosion. The bedrock slabs can be exchanged to obtain measurements for catchments with different lithologies for comparison. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
253.
结合前人研究结果和野外考察,发现1936年甘肃康乐6(3/4)级地震的地表破裂带长14 km,走向NWW,主要由3小段(西段、中段和东段)呈右阶排列而成。地表破裂主要有地震陡坎、地裂缝等。西段长3.7 km,有新鲜的崩塌堆积;中段长4.4 km,有大规模的基岩崩塌,同震左旋位移和垂直位移分别为2.5 m和0.6 m;东段长约6 km,同震水平位移和垂直位移分别为1.5 m和0.3 m。同震变形以左旋走滑为主,兼具逆冲分量,最大地表垂直位错量(0.6 m)仅为水平位错量(2.5 m)的(1/4)。1936年康乐地震时崩落的岩块上零星生长着最大直径仅20~30 mm的丽石黄衣,部分无地衣生长,此次地震由围子山—大夏河断裂向东扩张所致。 相似文献
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We report bedload data and acoustic impulse measurements due to particle impact from the Pitzbach in Austria. Impulse counts can be viewed as a measure of the energy delivered to the bed by moving particles. Impulse counts show a large scatter even for the same discharge and bedload supply. This scatter is due to varying grain size distribution, grain shape, mode of transport of the sediment particles and spatial and temporal distribution of the sediment load. The mean impulse count at given hydraulic conditions may increase or decrease with increasing sediment supply, suggesting that both tools and cover effects are active on the channel bed. Dependent on the local balance between sediment supply and transport capacity, either effect may be dominant at different locations along the cross‐section at the same time. Furthermore, the same bed location may respond to increasing sediment supply as tools‐dominated at some discharges and cover‐dominated at other discharges. Our observations may have implications for modelling of bedrock erosion in landscape evolution models and of bedrock channel morphology. Erosion models that do not incorporate both tools and cover effects are not sufficient to describe observations. Furthermore, a local erosion law cannot in general be used to describe erosion averaged over the channel cross‐section. The changing balance between sediment supply and transport capacity with increasing discharge highlights that a single representative discharge is not sufficient to capture the full erosion dynamics. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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基岩上均匀场地中透镜体对地震动的非线性放大作用 总被引:1,自引:0,他引:1
本文采用有限元方法研究基岩上均匀场地中透镜体对地震动的非线性放大作用,分析非线性放大作用和线性放大作用的差别,以及透镜体埋深、宽度、厚度以及输入地震波幅值和频谱等因素对非线性放大作用的影响.研究表明,透镜体的存在对地震动有显著的非线性放大作用,该放大作用可达30%;非线性放大作用一般小于线性放大作用;透镜体宽度对地表加速度反应谱的影响较大,埋深和厚度对地表加速度反应谱的影响较小;输入地震波幅值和频谱也有很大的影响. 相似文献
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通过对天山乌鲁木齐河源冰川底床基岩与沉淀物显微结构构造分析,对大陆性山岳冰川冰下过程的认识更加深入.沉积物微观结构和构造特性显示冰川底部存在较大的挤压应力作用,由显微滞碛等现象来看,压应力在微观上的空间分布很不均匀.沉淀物中块体碎裂和基岩上冰成裂隙反映,冰川底部冰体对基岩面有巨大的剪切应力作用.滑塌构造说明,冰川底部在微小的区域内压力分布不均匀,局部有重力作用过程存在.沉淀物中块体断裂和同生变形构造的存在说明沉淀物的形成过程为先期沉淀、后期受压.通过对冰川底部各种动力作用特征的阐述及沉淀物结构、构造的成因及特性的总结,认为大陆性山谷冰川底部冰岩界面处存在水膜,且冰川运动亦有滑动性. 相似文献
260.