Experimental investigation of three-dimensional earth pressure according to aspect ratio of retaining wall     

Byung-Suk Park  Sang Duk Lee 《Marine Georesources & Geotechnology》2018,36(2):181-189

The purpose of this study is to investigate the scale and load distribution of three-dimensional active earth pressure and the load transferred to the adjacent soil by changing the aspect ratio of a retaining wall through a series of model tests. In this research, 42 earth pressure plates of different heights and widths were installed to evaluate the earth pressures by considering the wall aspect ratio and the change of earth pressure. The test results showed that the active earth pressures were uniformly converged when the percentage of limit displacement against wall height was 0.12%. The distribution of active earth pressure on the wall showed a parabola shape for most aspect ratios while the wedge shape identified by the model test was similar to the shell-shaped model. In this paper, two diagrams were proposed regarding the active earth pressure according to the aspect ratio of a retaining wall; (1) a diagram of earth pressure conversion against the aspect ratio based on evaluated three-dimensional active earth pressures with traditional two-dimensional earth pressures, (2) a load transfer diagram based on the horizontal distance by analyzing the horizontal and vertical load transfer ranges with the relevant increasing rates.  相似文献   

Identifying surface water evaporation loss of inland river basin based on evaporation enrichment model     

Zhigang Sun  Guofeng Zhu  Zhuanxia Zhang  Yuanxiao Xu  Leilei Yong  Qiaozhuo Wan  Huiying Ma  Liyuan Sang  Yuwei Liu 《水文研究》2021,35(3):e14093

Accurately quantifying the evaporation loss of surface water is essential for regional water resources management, especially in arid and semi-arid areas where water resources are already scarce. The long-term monitoring of stable isotopes (δ¹⁸O and δ²H) in water can provide a sensitive indicator of water loss by evaporation. In this study, we obtained surface water samples of Shiyang River Basin from April to October between 2017 and 2019. The spatial and temporal characteristics of stable isotopes in surface water show the trend of enrichment in summer, depletion in spring, enrichment in deserts and depletion in mountains. The Local Evaporation Line (LEL) obtained by the regression of δ²H and δ¹⁸O in surface water has been defined by the lines: δ²H = 7.61δ¹⁸O + 14.58 for mountainous area, δ²H = 4.19δ¹⁸O − 17.85 for oasis area, δ²H = 4.08δ¹⁸O − 18.92 for desert area. The slope of LEL shows a gradual decrease from mountain to desert, indicating that the evaporation of surface water is gradually increasing. The evaporation loss of stable isotopes in surface water is 24.82% for mountainous area, 32.19% for oasis area, and 70.98% for desert area, respectively. Temperature and air humidity are the main meteorological factors affecting the evaporation loss, and the construction of reservoirs and farmland irrigation are the main man-made factors affecting the evaporation loss.  相似文献   

Hydrochemistry of groundwaters in a spa area of Korea: an implication for water quality degradation by intensive pumping     

Kangjoo Kim  Min‐Ho Koo  Sang‐Ho Moon  Byoung‐Woo Yum  Kwang‐Sik Lee 《水文研究》2005,19(2):493-505

A geochemical study was carried out in a small spa area (Onyang Spa, Korea) where intensive pumping of deep thermal groundwater (1 300 000 m³ year⁻¹) is taking place. This has caused the deep fractures to lose their artesian pressure and the upper shallow fractures have been encroached by shallow, cold waters. To quantify the influence of long‐term heavy pumping on the quality of the geothermal water, groundwater sampling and chemical analysis, water‐level measurement, and well loggings were performed for the selected deep thermal wells and shallow cold wells. Chemical analysis results indicate a big contrast in water chemistry and origins between the two water types. Shallow groundwater shows a wider concentration ranges in solutes that are closely related to human activity, illustrating the water's vulnerability to contamination near the land surface. Plots of water chemistry as a function of fluoride reveal that the quality of the thermal water was greatly influenced by the shallow, cold groundwater and that intensive pumping of the deep thermal groundwater has caused the introduction of shallow groundwater into the deeper fractures. Although the deep and the shallow fractures were piezometrically separated to some extent, a mixing model based on fluoride and nitrate indicated that the cold‐water fractions in the thermal wells are up to 50%. This suggests that the thermal water is faced with water quality degradation by the downward flow of the shallow, cold water. Restriction on the total of all the pumpage permits per unit area is suggested to restore the artesian pressure of the deep thermal aquifer and to prevent cold‐water intrusion in the study area. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

深部煤层CO₂注入煤岩力学响应特征及机理研究进展          下载免费PDF全文

桑树勋  牛庆合  曹丽文  王伟 《地球科学》2022,47(5):1849-1864

为揭示CO₂注入煤岩力学响应特征及机理,回顾了CO₂注入煤岩力学性质影响因素、CO₂注入对煤岩大分子-孔隙-裂隙结构改造作用和煤岩力学参数的统计模型、理论模型与智能预测模型.结果表明:CO₂注入煤岩力学性质受控于煤阶、CO₂压力、水分、围压和时间等因素,CO₂注入压力的增高、水的加入及时间的延长均会进一步降低煤岩力学性质,而围压对CO₂注入力学性能弱化具有一定改善作用.CO₂水溶液通过溶胀作用、萃取作用和塑化作用促使煤岩大分子结构重组,通过微晶结构改变、化学溶蚀和非均匀变形改造煤岩孔隙结构,通过化学溶蚀、膨胀应力和化学-应力耦合作用诱发煤岩结构损伤,均不同程度引起煤岩力学性能弱化.在CO₂注入煤岩力学参数预测模型中,类Langmuir模型、广延指数模型和修正的粘聚力模型具有明确的物理意义,而智能预测模型具有更高的预测精度,预测准确度可达99%以上.本次研究为科学评价CO₂-ECBM安全性和促进深部煤层CO₂高效注入奠定了理论基础.   相似文献   

湖南汛期K指数时空变化特征     

孟蕾  桑友伟  何娜 《沙漠与绿洲气象(新疆气象)》2019,13(4):52-57

利用1979—2018年NCEP 0.5°×0.5°月平均再分析资料,采用TSA法、M—K趋势检验法、R/S分析法分析湖南汛期K指数时空变化特征及未来趋势。结果表明:(1)湖南省K指数总体呈现南高北低状态,但同纬度地区稳定度分布不一,山区较平原地区更加不稳定;(2)湘西北、湘西南和湘东南地区在6—8月间为全省大气最不稳定的区域,4—5月和9—10月这3个地区也同样是所在纬线上的不稳定区域;(3)近40 a湘西北、湘西南和湘东南3个地区的大气逐渐趋向不稳定,春季湖南湘西北地区对流活动潜势增加,夏季以及初秋湖南南部地区对流活动潜势增加;(4)未来湘西北、湘西南和湘东南地区大气将继续向不稳定方向发展,主要是在4—6月变得更加不稳定,其他地区随机性较大或缓慢向稳定方向发展。  相似文献   

宁夏热量资源气候变化的EOF特征   总被引：3，自引：0，他引：3  

桑建人  刘玉兰  韩世涛  邱旺 《气象科技》2007,35(2):187-190

对宁夏20个测站1961-2004年大于等于0℃、5℃、10℃积温的EOF分析表明,随着全球气候变暖,宁夏积温增加,生长季延长。大于等于0℃、5℃积温的时空变化基本一致,1997-2004年表现为连续偏多的趋势。20世纪80年代中期以前,大于等于0℃积温偏少,之后偏多。大于等于5℃积温转折时间推迟到90年代中期,之前积温偏少,之后相反。大于等于10℃积温分两种,60.1%的年份表现为整体偏多或偏少,31.6%的年份以中宁、盐池一线为分界线,南北表现为相反的趋势。生长季具有明显的年代际变化特征,生长季呈逐渐延长的趋势,每10年增加3.8天,尤其是进入21世纪以来,头4年的平均值比20世纪60年代增加14.9天。  相似文献   

露天煤矿边坡工程地质勘察中几个常见问题的刍议——以胜利煤田东二号露天煤矿、白音华煤田一号露天煤矿为例     

刘大野  陈立云  刘欣  桑国华  李德全 《中国煤炭地质》2010,(5):52-55

随着内蒙古自治区二连盆地群早白垩世陆相沉积煤田的大规模勘查和开发建设,一些大(特)型露天煤矿的边坡工程地质勘察及稳定性分析评价工作也已陆续展开,但由于各勘察施工单位的工作方法不尽一致,给边坡岩体的稳定性评价带来了一定的影响。以盆地群内的胜利煤田东二号露天煤矿、白音华煤田一号露天煤矿工程地质勘察实践为例,对下白垩统巴彦花群煤系软岩边坡工程地质勘察中的软岩强度的界定、岩心采样方法的选择、数字测井成果在解释软弱(夹)层中的应用、钻孔波速测试方法的应用和边坡稳定性随含水率变化的敏感度分析5个方面进行了详细论述,并提出了相应的划分标准与技术方法。此结果可使盆地群中露天煤矿边坡工程地质勘察工作更加合理。  相似文献   

华北晚古生代成煤环境与成煤模式多样性研究   总被引：23，自引：2，他引：23  

桑树勋  陈世悦  刘焕杰 《地质科学》2001,36(2):212-221

华北晚古生代聚煤盆地存在活动体系成煤环境和废弃体系成煤环境。前者的海相成煤环境主要为泻湖泥炭坪,陆相成煤环境以三角洲平原沼泽意义最大。晚石炭世至晚二叠世,海相为主的成煤环境逐渐被陆相为主的成煤环境所取代,由盆缘到盆内成煤环境总体呈环带状展布。成煤环境差异性影响了成煤特点,这些成煤特点成为识别海、陆相煤层的显著相标志。华北晚古生代聚煤盆地在时间上和空间上存在成煤模式的多样性,以陆表海滨岸成煤模式、废弃碎屑体系成煤模式和浅水三角洲成煤模式为主。  相似文献   

秦岭造山带根部地壳结构及流变学演化   总被引：9，自引：0，他引：9       下载免费PDF全文

索书田  游振东 《地球科学》1994,19(5):633-646

在地质和地球物理资料基础上，运用物理学观点，研究和分析了秦岭造山带根部－大别前寒武纪变质地体的三维结构及流变学演化历史，通过现代及中－新元古代时期地壳流变学剖面的构筑，强调地壳流变学分层性及变质变形分解作用对中下地壳结构及地球动力学演化的控制作用，线状强应变带与透镜状弱应变域的规律组合，是秦岭造山带及其根部地壳结构的基本样式，并具尺度不变性，将古老中下地壳近３Ｇａ的流变学演化历史划分为７个阶段。它  相似文献   

Model-derived effects of large-scale diurnal thermal forcing on meteorological fields     

J. -G. Sang  E. R. Reiter 《Meteorology and Atmospheric Physics》1982,31(3):185-203

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