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71.
Yong-Xia Wu Hai-Min Lyu Jack Shuilong Shen Arul Arulrajah 《Environmental Earth Sciences》2018,77(10):392
This paper discusses the geological and hydrogeological features of Quaternary deposits in Tianjin as well as the geohazards related to groundwater hydrology in this region. The soft soil deposits, comprising silt, sand, silty clay and clay, are composed of four aquifer groups. In the first aquifer group, one phreatic aquifer and two confined aquifers have relationships with underground construction in the urban area. These three aquifers are separated by two aquitards and collectively form a multi-aquifer system. During geotechnical construction, potential geohazards present are related to the groundwater, which include water-in-rushing, quicksand and piping hazards. To prevent the aforementioned geohazards, dewatering is conducted; however, groundwater pumping may result in large settlements of the surrounding ground. To reduce pumping-induced settlement, the dewatering–waterproofing system has been adopted. According to the characteristics of the subsoil, excavation depth and the surrounding environment, the dewatering system can be divided into five patterns. In the first four patterns, when pumping is conducted in the excavation pit, the groundwater head in the adjacent aquifers outside the pit decreases due to the leakage effect of the aquitards located between the aquifers. In the fifth pattern, waterproof curtain has cut off the aquifers completely and dewatering in the pit cannot result in settlement around excavation pit. To avoid geohazards related to groundwater hydrology, countermeasures recommended include construction of an effective waterproof curtain, selection of a reasonable excavation dewatering pattern and withdrawal of required groundwater. 相似文献
72.
Science China Earth Sciences - The Middle Miocene Climate Transition (MMCT, ～14 Ma) is the largest cooling event in the Cenozoic “Coolhouse”, which significantly impacts the... 相似文献
73.
Amato Giorgia Andò Edward Lyu Chuangxin Viggiani Gioacchino Eiksund Gudmund Reinar 《Acta Geotechnica》2022,17(1):327-338
Acta Geotechnica - This short paper proposes time-series x-ray tomography as a valuable tool for quantifying freezing processes in a remoulded clay. As an example, three simple closed system... 相似文献
74.
以子长矿区内分布的300余组钻孔数据为基础,研究了陕北三叠纪煤田煤炭资源的物理化学性质,按照《煤中焦油含量分级》(MT/T1179—2019),划分了中油产率煤(7.0%<ω(Tard)<12.0%)和高油产率煤(12.0%<ω(Tard)<15.0%)的分布范围,预测了中—特高油产率煤的资源量。研究了矿区主采煤层3号煤层和5号煤层的煤质、沉积环境、变质程度等,认为矿区内中—特高油产率煤具一低两高的特征:镜质体反射率高(0.61%~0.83%)、变质程度低、挥发分高(35.78%~45.64%),认为成煤环境及变质程度是影响煤层富油的关键因素,研究区内5号煤层的焦油产率略高于3号煤层。 相似文献
75.
Bin Yong Weiqing Qi Dekai Lu Yi Lyu Aiming Liao Guoqing Wang Liliang Ren Jianyun Zhang 《水文研究》2024,38(1):e15066
The streamflow on the Tibetan Plateau (TP) plays an important role in the water supply of Asia's main river basins. To enhance understanding of hydrologic cycle under the pronounced warming over the TP, this study comprehensively investigates the streamflow changes at the upstream of six major rivers (Yellow River, Yalong River, Jinsha River, Lancang River, Nu River, and Yarlung Zangbo River) originating from the TP, and then diagnoses their possible causes by analysing the impacts of climate variability and human activities. Results indicate that these six major rivers studied have generally insignificant increasing trends in annual streamflow during the last half century, except for two stations. The significant increase appears at the Tuotuohe station in the headwater area of Jinsha River, while the dramatic decrease occurs at the Yunjinghong station in the downstream of Lancang River. In terms of climate factors, the six river basins show a distinct warming trend, along with a noticeable increase in precipitation over the central and northern regions. Pan evaporation, wind speed, sunshine duration, and relative humidity have been found to gradually decrease in most areas. As for the Tuotuohe station, both warming-induced meltwater and increasing precipitation might jointly contribute to the increasing streamflow. But for the Yunjinghong station, the results simulated by the Variable Infiltration Capacity (VIC) model indicate that human activities, especially for the impoundment processes of Xiaowan and Nuozhadu dams, significantly influenced the streamflow, contributing to approximately 69% of the streamflow reduction during 2009–2013. In the context of accelerated global warming, greater attention should be paid to hydrometeorological changes on the TP to offer further insights for the water resources management of the ‘Asian Water Tower’. 相似文献
76.
目的：分析中药熏蒸治疗腰椎间盘突出症（LDH）的用药规律。方法：计算机检索2017年1月1日至2022年7月31日中国知网（CNKI）、万方数据(WANFANG DATA)、维普中文科技期刊数据库（VIP）中关于中药熏蒸治疗LDH的处方,借助中医传承辅助平台（V2.5）分析药物的频次、性味、归经,基于关联规则和复杂系统熵聚类分析核心药物组合等遣方规律。结果：共纳入处方150首,涉及中药171味。使用频.次≥30次的药物有18味,排前10位的分别为红花、伸筋草、透骨草、川芎、当归、威灵仙、独活、牛膝、桂枝和川乌。药性以温、平、寒为主;药味以辛、苦、甘、咸为主;归经主要归肝、心、肾、脾和膀胱经。关联规则分析得到常用药物组合19组。复杂系统熵聚类分析得到核心药物组合12组与新处方6首。结论：中药熏蒸治疗LDH多采用祛风湿、活血化瘀之药,兼以补益肝肾药。 相似文献
77.
The peak in sediment transport in alluvial rivers generally lags behind the peak in discharge. It is thus not clear how the hysteresis in the sediment/discharge relationship may be impacted by damming, which can fundamentally alter the water and sediment regimes in the downstream reaches of the river. In this study, a total of 500 flood events in the Yichang–Chenglingji Reach (YCR) of the Middle Yangtze River immediately downstream of the Three Gorges Dam (TGD) are analysed to study the impacts of dam operations on the hysteresis of suspended sediment transport. Sediment rating curves, hysteresis patterns, as well as lag times, are investigated to determine the relationship between suspended sediment concentration (SSC) and flow discharge (Q) at different temporal scales, from inter-annual to individual flood events, for the pre- and post-TGD period from 1992 to 2002 and from 2003 to 2017, respectively. The results showed that the TGD operation decreased the frequency and magnitude of floods. The decrease in peak flow and increase in base flow weakened the flood contribution to the annual discharge by nearly 20%. However, the relative suspended sediment load contribution during flood events was much higher than the discharge contribution, and was little impacted by the dam. At seasonal and monthly scales, more than 80% of the suspended sediment was transported by ~65% of the water discharge in the summer and early autumn. The monthly SSC–Q relationship changed from a figure-eight to an anti-clockwise pattern after the construction of the TGD. For single flood events, the TGD operations significantly modified the downstream SSC–Q hysteresis patterns, increasing the frequency of anti-clockwise loops and the lag time between peak Q and peak SSC. These adjustments were mainly caused by differences in the propagation velocities of flood and sediment waves and the sediment ‘storage–mobilization–depletion’ process, whereas the influence of lateral diversions was small. © 2020 John Wiley & Sons, Ltd. 相似文献
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ABSTRACT Rural–urban migration is an adaptive response to location-specific environmental or socio-economic stressors. Jiangsu Province, China is witnessing rapid economic growth fuelled by manufacturing and services sector. Rural–urban migration in Jiangsu, which brings higher stress to resource-carrying capacity of urban areas, is driven by rural “push” factors, principally labour surplus and unemployment in agriculture. This study investigates possible policy interventions aimed at relieving the rapid rural–urban migration in Jiangsu based on a sensitivity analysis of driving factors in rural agricultural production. It shows that rural–urban migration is sensitive to input elasticities of precipitation and labour. Two groups of scenario analysis corresponding to possible policy interventions are implemented. The first policy focuses on providing government subsidies to rural non-agricultural industries then compensate for the shrinking agricultural production. Another policy supports education in rural areas to provide more skilled labour resource which can be absorbed by non-agricultural industries. Both two policies are effective in reducing rural unemployment and alleviating rural–urban migration. 相似文献
79.
中国绿色旅游基地适宜性综合评价 总被引：2，自引：1，他引：1
绿色旅游主要指以游览原生态自然山水获得身心愉悦的旅游。以多源地理信息数据为基础,基于GIS空间技术,通过综合分析绿色旅游资源、现状和潜力,对国家绿色旅游资源进行空间探索性分析,从而为国家绿色旅游基地建设、适宜性评价和基地选址提供参考。结果表明：① 中国绿色旅游发展适宜区域整体呈现出分片聚集状态,各片区中很适宜和适宜地区在空间上呈交叉分布。② 中部低纬度地区,绿色旅游资源基础、现状和潜力均较好;西部地区资源分布零散,发展现状和潜力相对薄弱,但区域特色优势显著,适宜依托区域特色进行深度开发。东北山脉地区的绿色旅游已达到一定规模,应提升旅游品质,扩大影响力;其他地区因气候、地形等因素,较难发展绿色旅游产业。 相似文献
80.
基于结构方程模型的宁波城市居民休闲满意度研究 总被引：2，自引：1，他引：1
休闲满意度研究对于提升城市居民美好生活质量具有重要意义。采用Beard等编制的休闲满意度量表,以问卷调查数据为基础,通过构建结构方程模型对浙江省宁波城市居民休闲满意度进行了研究。结果表明：①宁波城市居民对休闲带来的放松体验最满意,教育功能和审美体验次之,身体和心理满意度相对较低,而社会满意度最低。②审美满意度、身体满意度和心理满意度对宁波城市居民休闲总体满意度具有显著影响,其中,审美满意度的影响程度最大,其次为心理满意度和身体满意度,而放松、社交以及教育满意度对休闲总体满意度具有显著影响的研究假设未获支持。③构建的宁波城市居民休闲满意度结构方程模型具有跨样本稳定性特征。研究结果可为提升宁波城市居民休闲满意度提供理论依据。 相似文献