钾铵基聚合物泥浆在大同煤田复杂地层钻进中的应用

煤田地质钻探中,白垩系卵石层、多层采空区及泥岩地层是一大钻进难题。一是上部长孔段砂卵层胶结松散,易垮塌;二是下部泥岩水敏性强,膨胀性大,节理裂隙发育,极易产生缩径、造浆及不同程度的渗漏;三是多层采空区的护壁问题。针对这些问题,在大同煤田复杂地层钻进中,经反复实验选用了钾铵基聚合物低固相泥浆。实践证明,采用钾铵基聚合物低固相泥浆,可有效防止孔内坍塌、掉块、缩径,预防孔内事故,提高钻进效率,降低成本,达到了正常的钻进目的。     

Amphitheatre-headed canyons of Southern Utah: Stratigraphic control of canyon morphology

Amphitheatre-headed canyons are common on Earth and Mars and researchers have long sought to draw inferences about canyon-forming processes from the morphology of canyon heads and associated knickpoints, often suggesting that amphitheatre heads indicate erosion by groundwater seepage erosion. However, the conditions and processes that lead to amphitheatre-headed canyon formation have been debated for many years. We consider two hypotheses that attribute the amphitheatre-headed canyon formation to fluvial erosion of strong-over-weak stratigraphy or, alternatively, groundwater spring discharge and seepage erosion. A spatial analysis of canyon-form distribution with respect to local stratigraphy along the Escalante River and on Tarantula Mesa, Utah indicates that canyon form is most closely related to variations in local sedimentary rock strata, rather than inferred groundwater spring intensity. Lateral facies variations that affect the continuity of strong layers can induce or disrupt the formation of amphitheatres. Furthermore, we find that amphitheatre retreat rate is dictated by the interaction of fluvial processes downstream of the amphitheatre headwalls and stratigraphy, rather than waterfall and groundwater processes that likely importantly influence headwall form. We conclude that fluvial erosion of strong-over-weak stratigraphic layering alone is sufficient to form amphitheatres at knickpoints and canyon heads. Thus, we re-affirm that formation process should not be inferred from canyon-head morphology, particularly where a strong-over-weak layering is known or plausible. © 2020 John Wiley & Sons, Ltd.     

南极长城湾滨岸砾石堤特征及动力环境

本文着重讨论了长城湾现代滨岸砾石沉积的形态、规模、粒度和组构特征及滨岸带沉积动力环境。认为砾石堆积体系中高纬滨岸风暴沉积的产物。堆积体规模较小，形似堤坝，走向与海岸线大体平行。砾石主要由玄武质火山熔岩的岩屑组成，颗粒表面新鲜，多为扁度差的多角体，保留着冰碛砾石的粒态特征。粒度组成和粒级分配上具有冰川－海洋作用双重性质。砾石堤中砾石排列杂乱，层序不清，层理构造不发育，形态分带不显著，仅在堤的向海侧稍显粒度分带现象，由堤的顶部到上中部至基部，分别为砾石带、粗细砾带和砂砾带。滨岸带不同地貌部位，沉积动力环境存在一些差异。从风暴高潮位至大潮低潮位，水动力的簸选作用具有好→差→较好→较差的规律性变化，沉积物随之出现：较粗较匀→粗细混杂→较细较匀→粗细颗粒较混杂的韵律式波动。并指出这些特征与极区独特的自然地理条件有关。     

基于椭球模型的圆砾堆积特性分析

堆积特性是颗粒形状、大小等因素的综合体现,也在一定程度上反映了颗粒集合体的力学特性。以河流冲积型圆砾土中主要占比的10～50 mm圆砾为对象,利用数字图像技术,通过对大样本圆砾颗粒的形态特征分析,选取轴向系数作为圆砾的形状特征参数,并据此提出了圆砾颗粒的椭球模型构建方法,建立了与实际圆砾料在形状和大小上同分布的圆砾椭球模型数据库,进而通过数值堆积试验分析了单粒组圆砾料的堆积特性,并与室内圆筒堆积物理试验进行对比。有以下结论：圆砾的形态特征主要体现在宏观轮廓形状,棱角特性不明显;圆砾堆积数值模拟结果表明,不同大小粒组圆砾堆积孔隙比变化较小;颗粒间摩擦系数对于堆积孔隙比有显著影响,摩擦系数介于0～0.4时,孔隙比变化剧烈,随后逐渐趋于平缓;室内圆筒堆积试验结果验证了椭球模型模拟圆砾堆积的有效性,标定了重力堆积条件下圆砾料颗粒间摩擦系数约为0.3。     

卵砾石层的钢管桩施工工艺研究

卵砾石地层属钻探复杂地层，也是基础工程施工的主要地层。目前，国内外卵砾石地层的钻进方法存在局限性大、效率低、成本高、工艺复杂、易出现孔内事故等缺点。钢管桩的应用日趋广泛。卵砾石层中有效的施工工艺亟待解决。在理论研究与实践的基础上，提出高效的钢管静压冲击钻进工艺，并在实践中取得了良好的效果     

大陆东南沿海河流与台湾西部河流磁性矿物特征及判源指标

近年来发现台湾西部河流泥沙对东海内陆架区域, 尤其是泥质区南部的贡献不可忽视。建立有效的判源指标是识别海洋沉积物的前提。本文拟从大陆和台湾河流表层沉积物入手, 分析其磁性和磁性矿物特征, 并建立物源判别指标。通过对大陆东南沿海河流(长江、钱塘江、瓯江和闽江)和台湾西部河流(浊水溪、大安溪、大甲溪和乌溪)44个表层沉积物样品细颗粒组分( lf值异常高, 磁性矿物颗粒较粗, 磁黄铁矿为主要磁性矿物, 浊水溪最具代表性。这一磁性和磁性矿物的差异主要是由流域母岩以及流域内沉积物风化搬运过程的不同导致。本文提出基于SIRM/Xlf和HIRM磁性参数的物源判别指标, 可较好地示踪大陆东南沿海河流和台湾西部河流的沉积物。     

A New Method to Identify Quaternary Moraine：Acoustic Emission Stress Measurement

How to effectively identify glacial sediments, especially Quaternary moraine, has been in dispute for decades. The traditional methods, e.g., sedimentary and geomorphologic ones, are facing challenge in eastern China where controversial moraine deposits are dominatingly distributed. Here, for the first time, we introduce the acoustic emission （AE） stress measurement, a kind of historical stress measurement, to identify Quaternary moraine. The results demonstrate that it can be employed to reconstruct stress information of glaciation remaining in gravels, and may shed light on the identification of Quaternary moraine in eastern China. First, we measured the AE stress of gravels of glacial origin that are underlying the Xidatan Glacier, eastern Kunlun Mountains in western China. Second, we calculated the stress according to the actual thickness of the glacier. The almost identical stress values suggest that the glacial gravels can memorize and preserve the overlying glacier-derived aplomb stress. And then we introduce this new approach to the controversial moraine in Mount Lushan, eastern China. The results indicate that the stress is attributed to the Quaternary glacier, and the muddy gravels in the controversial moraine in Mount Lushan are moraine deposits but not others.     

The precision of sampling grain‐size percentiles using the Wolman method

The precision of sampling different grain‐size percentiles in comparison to each other is of signi?cance for choosing which percentile is appropriate to characterize riverbed surface sediments. The traditional view, based on normal grain‐size distributions derived by the Wolman grid‐by‐number method, has identi?ed the median percentile as having the highest sampling precision. However, grain‐size distributions are highly variable and often fail to follow a theoretical distribution. This paper presents both theoretical and empirical techniques to determine the precision of sampling different percentiles. These methods are then applied to a range of natural distributions found in UK rivers. It is found that grains between the 66th and 91st percentiles are the most precisely sampled, with maximum precision obtained with the 73rd percentile. Copyright © 2003 John Wiley & Sons, Ltd.     

Heat flux calculations for Mackenzie and Yukon Rivers

This study analyzes long-term (40–60 years) discharge and water temperature records collected near the basin outlets of the Yukon and Mackenzie Rivers. It defines seasonal cycles of discharge, water temperature (WT), and heat flux (HF) for the basins, and compares their main features to understand their similarity and difference. Both rivers have similar hydrographs, i.e. low flows in winter and high discharge in summer, with the peak flood in June due to snowmelt runoff. Mackenzie River has many large lakes and they sustain the higher base flows over the fall/winter season. Mackenzie basin is large with high precipitation, thus producing 50% more discharge than the Yukon River to the Arctic Ocean. The WT regimes are also similar between the two rivers. Yukon River WT is about 2–3 °C warmer than the Mackenzie over the open water months. Both rivers have the highest WT in the mid summer and they transport large amount of heat to the polar ocean system. Yukon River monthly HF is lower by 10–60% than the Mackenzie mainly due to smaller discharge. Mackenzie River heat transport peaks in July, while the Yukon HF reaches the maximum in June and July. These results provide critical knowledge of river thermal condition and energy transport to the northern seas. They are useful for large-scale climate and ocean model development and validation, and climate/hydrology change research in the northern regions.     

江河源区NDVI时空变化及其与气候因子的关系(英文)

The source regions of the Yangtze and Yellow rivers are important water conservation areas of China. In recent years, ecological deterioration trend of the source regions caused by global climate change and unreasonable resource development increased gradually. In this paper, the spatial distribution and dynamic change of vegetation cover in the source regions of the Yangtze and Yellow rivers are analyzed in recent 10 years based on 1-km resolution multitemporal SPOTVGT-DN data from 1998 to 2007. Meanwhile, the correlation relationships between air temperature, precipitation, shallow ground temperature and NDVI, which is 3×3 pixel at the center of Wudaoliang, Tuotuohe, Qumalai, Maduo, and Dari meteorological stations were analyzed. The results show that the NDVI values in these two source regions are increasing in recent 10 years. Spatial distribution of NDVI which was consistent with hydrothermal condition decreased from southeast to northwest of the source regions. NDVI with a value over 0.54 was mainly distributed in the southeastern source region of the Yellow River, and most NDVI values in the northwestern source region of the Yangtze River were less than 0.22. Spatial changing trend of NDVI has great difference and most parts in the source regions of the Yangtze and Yellow rivers witnessed indistinct change. The regions with marked increasing trend were mainly distributed on the south side of the Tongtian River, some part of Keqianqu, Tongtian, Chumaer, and Tuotuo rivers in the source region of the Yangtze River and Xingsuhai, and southern Dari county in the source region of the Yellow River. The regions with very marked increasing tendency were mainly distributed on the south side of Tongtian Rriver and sporadically distributed in hinterland of the source region of the Yangtze River. The north side of Tangula Range in the source region of the Yangtze River and Dari and Maduo counties in the source region of the Yellow River were areas in which NDVI changed with marked decreasing tendency. The NDVI change was980 Journal of Geographical Sciences positively correlated with average temperature, precipitation and shallow ground temperature. Shallow ground temperature had the greatest effect on NDVI change, and the second greatest factor influencing NDVI was average temperature. The correlation between NDVI and shallow ground temperature in the source regions of the Yangtze and Yellow rivers increased significantly with the depth of soil layer.