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Numerical investigation of the effectiveness of radon control measures in cave mines

International Journal of Mining Science and Technology 2019年第3期29卷 469-475页

作者： Kayode Ajayi Khosro Shahbazi Purushotham Tukkaraja Kurt Katzenstein Department of Mechanical Engineering SDSM & TRapid City SD 57701USA Department of Mining Engineering and Management SDSM & TSD 57701USA Department of Geology and Geological Engineering SDSM & TSD 57701USA

Ventilation is one of the radon control measures in an underground working ***,the dynamics related to the cave mining methods particularly in block/panel cave mines,complicate the design of effective ventilation system,and *** such as hang ups(in the drawbells),leakage from old workings,and changes in cave porosity lead to differing response of an existing ventilation ***,it is difficult to investigate these conditions at the mine or with a laboratory scale ***,this study develops a discrete model to investigate the impact of different radon control measures in cave mines using computational fluid dynamics *** considered two ventilation conditions for a fully developed cave:with and without the undercut *** each of the two conditions,we studied four parameters:airflow distribution through the production drifts,radon distribution through the production drifts,the effect of increasing airflow on radon concentration,and the effect of a cave top negative pressure on radon *** results show that:the undercut ventilation significantly increases the radon concentration in the production drift;the growth of radon concentration through the production drift is nonlinear(oscillating pattern);maintaining a negative pressure on top of the cave is more effective at mitigating radon exposure,when the undercut ventilation is active;and increase in air volume flow rate decreases radon concentration in most regions,however,there might be regions with significant radon accumulation due to pressure variation across the *** findings provide vital information for designing an effective ventilation system and for proactive implementation of radon control measures in cave mines.

关键词： Radon gas Underground mining Panel cave mines Broken rocks Computational fluid dynamics(CFD) Porous media cave mining method

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Prediction of airway resistance in panel cave mines using a discrete and continuum model

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International Journal of Mining Science and Technology 2019年第5期29卷 781-784页

作者： Kayode M.Ajayi Khosro Shahbazi Purushotham Tukkaraja Kurt Katzenstein Department of Mechanical Engineering SDSMTRapid CitySD 57701USA Department of Mining Engineering and Management SDSMTSD 57701USA Department of Geology and Geological Engineering SDSMTSD 57701USA

The configuration of an airway(or production drift)in panel cave mines is different from the typical(straight)mine airway *** drawpoints are connected to the airway(cross-cuts),which allows airflow from the cave into the airway or air loss from the airway into the cave due to the ventilation approach and cave *** affect airflow in the production drifts,but it is difficult to investigate these conditions from field or laboratory scaled ***,this study develops discrete and continuum computational fluid dynamics(CFD)models to study the effects of the ventilation approach and cave porosity on the airway *** findings show that:with active undercut ventilation,a unique resistance model is required for the airway in panel cave mines;and an increase in cave porosity decreases the drift’s *** findings provide essential tools for a panel cave ventilation design.

关键词： Airway resistance Caving mining method Panel cave mines Broken rocks Porous media Computational fluid dynamics(CFD)

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Precise dating of abrupt shifts in the Asian Monsoon during the last deglaciation based on stalagmite data from Yamen cave, Guizhou Province, China

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Science China Earth Sciences 2010年第5期53卷 633-641页

作者： EDWARDS R. Lawrence Department of Geology and Geophysics University of Minnesota

Based on 33 U/Th dates and 1020 oxygen isotopic data from stalagmite Y1 from Yamen cave, Guizhou Province, China, a record of the Asian Summer Monsoon (ASM) was established. The record covers the last deglaciation and the early Holocene (from 16.2 to 7.3 ka BP) with an average oxygen isotope resolution of 9 years. The main millennial-scale deglacial events first identified in Greenland (Greenland Interstadial Events: GIS 1e through GIS 1a) and later in China are clearly present in the Y1 record. By analogy to earlier work, we refer to these as Chinese Interstadials (CIS): CIS A.1e to CIS A.1a. The onset of these events in Y1 δ18O records are nominally dated at: 14750±50, 14100±60, 13870±80, 13370±80, and 12990±80 a BP. The end of CIS A.1a or the beginning of the Younger Dryas (YD) event is nominally at 12850±50 a BP and the end of the YD dates to 11500±40 a BP. The δ18O values shift by close to 3‰ during the transition into the Bφlling-Allerφd (BA, the onset of CIS A.1e) and at the end of the YD. Comparisons of Y1 to previously published early Holocene records show no significant phase differences. Thus, the East Asia Monsoon and the Indian Monsoon do not appear to have been out of phase during this interval. The Y1 record confirms earlier work that suggested that solar insolation and North Atlantic climate both affect the Asian Monsoon.

关键词： stalagmite Asian Monsoon the last deglaciation Holocene U-series dating Yamen cave

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Stability analysis of subgrade cave roofs in karst region

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Journal of Central South University 2008年第S2期15卷 38-44页

作者：蒋冲赵明华曹文贵 Geotechnical Engineering Institute Hunan University School of Resources and Safety Engineering Central South University

According to the engineering features of subgrade cave roof in karst region, the clamped beam model of subgrade cave roof in karst region was set up. Based on the catastrophe theory, the cusp catastrophe model for bearing capacity of subgrade cave roof and safe thickness of subgrade cave roof in karst region was established. The necessary instability conditions of subgrade cave roof were deduced, and then the methods to determine safe thickness of cave roofs under piles and bearing capacity of subgrade cave roof were proposed. At the same time, a practical engineering project was applied to verifying this method, which has been proved successfu1ly. At last, the major factors that affect the stability on cave roof under pile in karst region were deeply discussed and some results in quality were acquired.

关键词： pile foundation karst subgrade cave roof cusp catastrophe model stability

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Unsteady slipstream of a train passing through a high-speed railway tunnel with a cave

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Transportation Safety and Environment 2022年第4期4卷 107-120页

作者： Xiaohui Xiong Rilong Cong Xiaobai Li Yutang Geng Mingzan Tang Shujun Zhou Yanling Na Chongxu Jiang Key Laboratory of Traffic Safety on Track of Ministry of Education Central South UniversityChangsha 410075HunanChina Joint International Research Laboratory of Key Technology for Rail Traffic Safety Central South UniversityChangsha 410075HunanChina National&Local Joint Engineering Research Centre of Safety Technology for Rail Vehicle Central South UniversityChangsha 410075HunanChina Northeast Normal University Dongan Experimental School Changchun 130000JilinChina Urban rail transit branch China Railway Design CorporationTianjin 300000China National Engineering Laboratory for Digital Construction and Evaluation Technology of Urban Rail Transit China Railway Design CorporationTianjin 300000China.

The cave is of great importance for the storage of equipment and to avoid having workers in the tunnel,but it changes the tunnel section,leads to a change of slipstream and affects the safety of trains and *** Re-normalization group(RNG)k-εturbulence method is used to investigate the slipstream induced by a single train passing through a double-track tunnel at 350 km/*** slipstream in a tunnel with and without a cave is *** slipstream components in three directions are reported *** results show that the existence of a cave changes the slipstream at the tail of the *** measurement points before and after the train passes the cave,the intensity of the slipstream at the tail ismitigated;as the train passes the cave,the tail slipstream is enhanced to a certain *** increasing lateral distance,the peak value of the slipstream with a cave decreases faster than that without a *** findings suggest that the presence of a cave mitigates the slipstream intensity,but special attention should be paid to the design of ancillary facilities,especially their relative location.

关键词： High-speed train railway tunnel cave slipstream

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Oxygen and carbon isotopic characteristics of rainwater,drip water and present speleothems in a cave in Guilin area,and their environmental meanings

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Science China Earth Sciences 2000年第3期43卷 277-285页

作者：李彬袁道先覃嘉铭林玉石张美良 Institute of Karst Geology Chinese Academy of Geological Sciences Guilin 541004 China

The studies of the oxgen and carbon isotopes of the rainwater in Guilin area, the drip water and the present carbonate deposit in Panlong cave of Guilin show that: (i) as to the general characteristics of the oxygen isotopes of the rainwater within a year and between years, the δ18O values decrease with an increase of air temperature and the rainfall, and the correlation between δ18O values and the mean monthly air temperature is much better than that between δ18O values and the rainfall, and the δ18O values of the rainwater during the summer monsoon are much smaller than those during winter monsoon; (ii) δ18O values of the drip water have a quite good correlation with the δ18O values of the rainwater in the same period; (iii) when the conditions are appropriate, δ13C can be used as an environmental proxy, that is, the smaller δ13C of speleothems is, the larger the proportion of C3 plants is and the more plentiful the rainfall is. On the contrary, C4plants may be prevailing or the environment may be a stony desert caused by climate changes or human activity.

关键词： rainwater cave drip water present speleothem oxygen and carbon isotopes environmental meanings.

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Climate indexes of phytoliths from Homo erectus' cave deposits in Nanjing

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Chinese Science Bulletin 2003年第18期48卷 2005-2009页

作者： Weiming Wang Jinling Liu Xiaodan Zhou Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences Nanjing 210008 China

A study on phytoliths and their climate indexes is carried out from Homo erectus?cave deposits in Hulucave, Nanjing. Evidence shows that phytolith assemblages of the cave deposits are dominated by the cold resistant types with a lower warm index, reflecting an overall cold inclined climate. This possibly connects the cave deposits with glacial climate to a great extent, which is in accordance with thenorthern fauna revealed by fossil mammals and temperateclimate indicated by pollen assemblages. According to the distributional state of the phytoliths and their climate in-dexes on 4 profiles in the cave, it is revealed that profiles Ⅰand Ⅱ display certain cold/warm, and dry/wet fluctuations; profile Ⅲ shows a humid and cold condition with the high-est humility in the cave deposits; while profile Ⅳ indicates a possible quick accumulating process because of its stableclimate indexes except for its bottom and top.

关键词： climate indexes phytoliths Nanjing Homo erectus cave deposits.

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Discovery of Middle Pleistocene Mammal Fauna From Tangshan Karst cave, Nanjing and Its Significance

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Chinese Science Bulletin 1993年第20期38卷 1742-1746页

作者：徐钦琦穆西南许汉奎钟石兰穆道成 Institute of Vertebrate Palaeontology and Palaeoanthropology Academia Sinica Beijing 100044 PRC Nanjing Institute of Geology and Palaeontology Academia Sinica Nanjing 210008 PRC

The material reported in this note was collected from Huludong (Calabash cave), a karst cave at the northeastern extremity of Tangshan Hill, Nanjing. The cave is located on the hillside to the south of the Nanjing-Hangzhou Highway near the west verge of the Tangshan Town, Jiangning County, 26km east of the centre of Nanjing (32°N and 119°E). The bottom of this cave is 85.9m above sea level, with a relative height of about 75m from the local highway. This karst cave developed in the Ordovician limestone assumes the shape of an east-westward extending calabash, about 80m long,

关键词： mammals Middle Pleistocene karst cave Nanjing palaeoclimate.

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The Sedimentary Features and Significances of Dripwater and Modern Speleothems in Xueyu cave,Chongqing,China

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地学前缘 2009年第S1期16卷 117-118页

作者： Aoyu Wang~1,Licheng Shen~1,Junbing Pu~1,Yuchuan Sun~1,Qiong Xiao~1,Yan Yang~1, Chengcheng Yi~1,Yang He~2 1.School of Geographical Sciences,Southwest University,Chongqing 400715,China. 2.Longhe Tourism Exploitation Co.Ltd,Fengdu 648200,China

Based on the continuous monthly monitoring works of the dripwater and modem speleothems in Xueyu cave,we measured a high deposit rate of the secondary ***,the mean deposit rate of calcite is 5.33 mg/day,but the variation amplitude is significant during the ***,the monthly variation does not coincide with the geochemical characteristics of the relevant dripwater, and a preliminary test of some hydrophilic and

关键词： Xueyu cave dripwater modern speleothems deposit rate geochemical characteristics carbon and oxygen stable isotopes

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cave立体显示系统的搭建及立体图像的几何校正

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计算机辅助设计与图形学学报 2008年第10期20卷 1366-1373页

作者：赵猛金一丞尹勇大连海事大学航海动态仿真及控制交通部重点实验室大连116026

为了解决由投影机的位置不准确而引起的立体图像视差畸变问题,根据立体图像产生方式以及显示方式的不同,给出了适合于工程上搭建"经济型"cave立体显示系统的几种实现方式,包括主动立体方式、主动变被动方式以及直接被动立体方式.将帧缓... 详细信息

为了解决由投影机的位置不准确而引起的立体图像视差畸变问题,根据立体图像产生方式以及显示方式的不同,给出了适合于工程上搭建"经济型"cave立体显示系统的几种实现方式,包括主动立体方式、主动变被动方式以及直接被动立体方式.将帧缓存中双眼的视景图像分别拷贝到纹理内存中,通过重投影变换计算出B样条曲面控制点坐标并绘制B样条曲面,分别映射纹理内存中双眼图像的纹理到各自的B样条曲面上.通过对左右眼立体图像分别进行几何校正,实现了cave多通道立体显示的无缝拼接;通过微调B样条曲面的控制点坐标以及确定曲面阶数,实现了左右立体图像局部位置的调整以及图像平滑度的调整.实验结果显示,该方法不影响视景实时绘制.

关键词： cave 立体显示几何校正重投影变换 B样条曲面

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