辛安煤矿1402工作面临空窄煤柱采掘响应及动态加固     

汪北方  梁冰  刘维  张晶  迟海波  刘亚辉 《煤田地质与勘探》2020,48(1):145-153

随着我国煤炭资源去产能整合煤矿的增多，复采工作面临空窄煤柱采动失稳问题日益凸显，已严重制约矿井安全高效生产。为此，针对辛安煤矿复采1402工作面辅运巷道5号钻场临空窄煤柱稳定性控制的工程难题，运用数值模拟与理论分析相结合的方法，探究5号钻场临空窄煤柱稳定性采掘扰动响应特征，提出5号钻场临空窄煤柱动态注浆加固技术方案并开展现场应用和效果检验。研究结果表明:1402工作面辅运巷道掘进对5号钻场临空窄煤柱稳定性影响较小；在1402工作面回采期间，距5号钻场18~6 m范围，临空窄煤柱集中垂直应力由非对称马鞍形分布逐渐过渡为拱形分布；距5号钻场6 m时，临空窄煤柱承载叠加垂直应力超过煤体强度，塑性区完全贯通，极易破坏失稳；现场采用MP364型注浆材料及专用注浆设备对5号钻场临空窄煤柱前后5 m区域进行加固，动态注浆始终超前工作面10 m，通过深孔窥视和气体监测手段验证临空窄煤柱良好的封堵固化效果，保障了工作面安全回采，为我国整合矿井类似条件下煤柱稳定性控制提供借鉴和参考。移动阅读   相似文献   

Conversion relationship of rainfall-soil moisture-groundwater in Quaternary thick cohesive soil in Jianghan Plain,Hubei Province,China     

《China Geology》2020,3(3):462-472

The scientific field test site of rainfall-soil moisture-groundwater conversion in Dabie Mountain Area–Jianghan Plain is located in the northern region of the Jianghan Plain, the transition zone between the Dabie Mountain Area and Jianghan Plain. It’s a great field test site to study the material and energy exchange among rainfall, soil moisture, and groundwater of the Earth ’s critical zone in subtropical monsoon climate plain areas. This paper analyzed the connection between rainfall and volume water content (VWC) of soil at different depths of several soil profiles, and the dynamic feature of groundwater was discussed, which reveals the rainfall infiltration recharge of Quaternary Upper Pleistocene strata. The results show that the Quaternary Upper Pleistocene aquifer groundwater accepts a little direct rainfall recharge, while the lateral recharge is the main supplement source. There were 75 effective rainfall events among 120 rainfall events during the monitoring period, with an accumulated amount of 672.9 mm, and the percentages of effective rainfall amount and duration time were 62.50% and 91.56%, respectively. The max evaporation depth at the upper part in Quaternary cohesive soil was no less than 1.4 m. The soil profile was divided into four zones: (1) The sensitive zone of rainfall infiltration within 1.4 m, where the material and energy exchange frequently near the interface between atmosphere and soil; (2) the buffer zone of rainfall infiltration between 1.4 m and 3.5 m; (3) the migration zone of rainfall infiltration between 3.5 m and 5.0 m; and (4) the rainfall infiltration and groundwater level co-influenced zone below 5.0 m. The results revealed the reaction of soil moisture and groundwater to rainfall in the area covered by cohesive soil under humid climate in Earth ’s critical zone, which is of great theoretical and practical significance for groundwater resources evaluation and development, groundwater environmental protection, ecological environmental improvement, drought disaster prevention, and flood disaster prevention in subtropical monsoon climate plain areas.  相似文献   

中国台商农业技术时空扩散的格局、路径与机制——以福建省漳浦县为例     

陈嘉  韦素琼  陈松林 《地理科学》2019,39(6):957-966

结合统计数据及实地调研、访谈数据,研究中国台湾青枣种植技术透过台商直接投资渠道在福建省漳浦县落地、发散与传播过程,分析其时空扩散路径、格局与机制,以期揭示中国台商农业技术在中国大陆地区独具特色的扩散规律与机制,为加速两岸农业合作交流、制定技术应用政策提供理论与实践依据。研究发现,在时间维度,中国台商农业技术扩散过程呈现典型的S型曲线,但其扩散迅速、周期较短,扩散阻力小且示范效应显著;在空间维度,形成多核心、多强度、梯度扩散体系（中国台湾扩散源与本地扩散节点）,扩散场相互叠加,以就近扩展扩散为主、等级扩散为辅的特色扩散格局。  相似文献   

Evaluation of urban underground space resources using a negative list method: Taking Xi’an City as an example in China     

《China Geology》2020,3(1):124-136

Utilization of urban underground space has become a vital approach to alleviate the strain on urban land resources, and to optimize the structure and pattem of the city. It is also very important to improve the city environment, build livable city and increase the capacity of the city. Based on the analysis of existing evaluation methods and their problems, a method for evaluating underground space resources based on a negative list of adverse factors affecting underground space development is proposed, to be primarily used in urban planning stages. A list of the adverse factors is established, including limiting factors, constraining factors and influencing factors. Taking Xi’an as an example, using a geographical information system platform, a negative list of adverse factors for the underground space resources in Xi’ an City are evaluated, and preventive measures are proposed. Natural resources, exploitable resources, and the potential growth of exploitable underground space resources are evaluated. Underground space assessment in the different development stages of the city, collaborative utilization and safety evaluation for multiple subsurface resources, environmental impact and assessment, as well as evaluation methods based on big data and intelligent optimization algorithms are all discussed with the aim of serving city planning and construction.  相似文献   

中部地区农民城镇化意愿及其影响因素研究     

张荣天  李传武 《世界地理研究》2020,29(1):112-119

城镇化本质是“人”的城镇化，“人”的城镇化关键是实现由农民向市民的转化。首先，本文从理论上构建出农民城镇化意愿的二元logistic模型；其次，选取我国中部地区安徽皖南芜湖县、皖北临泉县作为典型案例地进行实证对比研究。结果表明：①总体上，典型县域农民城镇化意愿相对较强烈（75.01%）；②个体特征因素、家庭因素及社会因素均对安徽典型县域农民城镇化具有十分显著影响，其中受教育程度、家庭年总收入、学龄儿童、政府就业政策及教育政策等对农民城镇化意愿产生显著正向效应；务工年限、城里社会关系等也对农民城镇化意愿产生正向影响，但显著性程度相对不高；而农民年龄、户籍社保制度对农民城镇化意愿产生显著负向影响。③最后，从增加城镇就业岗位、开展职业教育培训、深化改革社保制度及加强社区治理体系建设等方面提出促进农民城镇化发展的政策建议。  相似文献   

中国北极科技外交论析     

张佳佳  王晨光 《世界地理研究》2020,29(1):63-70

鉴于北极特殊的地理位置和自然环境，北极科技外交往往是各国参与北极事务的起点和实现北极利益的先导。中国也概不能外，北极科技外交对保障北极科研装备、提高北极认识水平和促进北极资源开发等都具有重要意义。回溯中国参与北极事务的历程，北极科技外交是其中的主要线索和核心内容，现已取得了一些成绩。但作为域外国家和发展中国家，中国北极科技外交还面临着缺乏顶层设计、政策和资金支持不足以及若干国际因素的掣肘。对此，中国应通过充分发挥政府的主导作用、强化和完善运行机制、扩展北极科技外交的广度和深度等加以改进。  相似文献   

农户的非农就业如何影响中国的土地流转?   总被引：1，自引：0，他引：1  

王佳月  辛良杰  王亚辉 《地理学报(英文版)》2020,30(3):378-400

To clarify the impact of non-agricultural employment on rural land circulation in China,we built logit models using the Chinese Household Income Project 2013 dataset,which includes 18,948 household samples over 15 provinces,126 cities and 234 counties of China in 2013.We use the proportion of non-agricultural income,the proportion of non-agricultural laborers and non-agricultural fixed operating assets to reflect the degree of the households’dependence on agriculture,the degree of the households’laborers committed to non-agricultural employment and the stability of non-agricultural employment,respectively.The results show that the stability of non-agricultural employment is an important reason for farmers to transfer out their land,and an increase in non-agricultural income is the fundamental reason.The proportion of non-agricultural assets has the greatest impact on the decision to transfer land,followed by the proportion of non-agricultural income.Per unit increase in the non-agricultural income ratio has a stronger effect on the transfer-out decision than it does on the transfer-in decision,which is a 0.09 increase of the probability of transfer-out the land and a 0.07 decrease of the probability of transfer-in the land.In terms of regional differences,when considering the impact of non-agricultural employment on the land transfer-out decision,the impacts of non-agricultural income and labor force are the greatest in the Central region.The impact of non-agricultural assets is the greatest in the Eastern region.For the Eastern region,the decision to transfer out land is mainly affected by non-agricultural assets and the non-agricultural labor force,and the decision to transfer in land is mainly affected by non-agricultural assets.In the Central and Western regions,the decision to transfer out land is mainly affected by non-agricultural assets,non-agricultural income and the non-agricultural labor force,in that order.The decision to transfer in land in the Central region is not significantly affected by non-agricultural employment.The decision to transfer in land in the Western region is mainly affected by non-agricultural assets,non-agricultural labor force and non-agricultural income,in that order.We note that non-agricultural assets have a prominent impact on land transfer,which shows that the stability of non-agricultural employment has an important impact on land transfer decision-making.Vocational training for rural labor forces may be an effective means to promote stable non-agricultural employment and simultaneously facilitate rural land circulation,especially in Central and Western China.  相似文献   

东北大兴安岭北段蛇绿岩的时空分布及与区域构造演化关系的研究   总被引：2，自引：0，他引：2  

冯志强  刘永江  金巍  蒋立伟  李伟民  温泉波  李小玉  张铁安  杜兵盈  马永非  张丽 《地学前缘》2019,26(2):120-136

大兴安岭北段作为中亚造山带东段重要组成单元，该区域的构造背景一直悬而未决，它涉及兴安与松辽地块基底属性、额尔古纳地块亲缘性以及三者之间的拼贴位置、时限和方式等众多科学问题。蛇绿岩作为研究造山带的重要工具之一，不仅是古板块或微地块的重要边界，而且是认识地幔组成和壳幔演化的重要窗口。然而大兴安岭北段蛇绿岩却鲜有报道。根据近年来野外工作及结合前人研究成果，文章探讨了蛇绿岩形成时代及构造环境。研究表明：(1)大兴安岭北段蛇绿岩整体呈北东向展布，但时代跨越较大，主要包括新元古代、早奥陶世-志留纪、石炭纪-二叠纪；(2)大兴安岭北段蛇绿岩均有E-MORB地球化学特征，其中新元古代的蛇绿岩明显亏损高场强元素Nb、Ta，而晚古生代的蛇绿岩则相对富集高场强元素；(3)大兴安岭北段新元古代蛇绿岩可能形成于洋内岛弧环境，记录着前寒武纪陆弧碰撞信息，而早奥陶世-志留纪蛇绿岩可能与早古生代弧盆体系演化相关。尽管上述认识为大兴安岭北段古生代的地球动力学背景研究提供了新的依据，但大兴安岭北段蛇绿岩仍存在较多问题亟须解决。  相似文献   

Plastic ingestion by fulmars and shearwaters at Sable Island,Nova Scotia,Canada     

《Marine pollution bulletin》2014,88(1-2):68-75

Plastic pollution is widespread in the marine environment, and plastic ingestion by seabirds is now widely reported for dozens of species. Beached Northern Fulmars, Great Shearwaters, Sooty Shearwaters and Cory’s Shearwaters are found on Sable Island, Nova Scotia, Canada regularly, and they can be used to assess plastic pollution. All species except Cory’s Shearwaters contained plastic debris in their gastrointestinal tracts. Northern Fulmars, Sooty Shearwaters and Great Shearwaters all showed high prevalence of plastic ingestion (>72%), with Northern Fulmars having the highest number and mass of plastics among the species examined. There was no difference in plastic ingestion between sexes or age classes. In all species user plastics made up the majority of the pieces found, with industrial pellets representing only a small proportion in the samples. Sable Island could be an important monitoring site for plastic pollution in Atlantic Canada.  相似文献   

Rb–Sr dating of sulfides and S–Pb isotopic study of the Bayanbaolege Ag polymetallic deposit,Inner Mongolia,NE China     

《Chemie der Erde / Geochemistry》2021,81(1):125724

The large-scale Bayanbaolege Ag polymetallic deposit is situated in the Tuquan–Linxi Fe-Sn-Cu-Pb-Zn-Ag metallogenic sub-belt in eastern slopes of the southern Great Xing’an Range, NE China. The sulfide-quartz vein-type orebodies in the deposit are hosted primarily in the Early Cretaceous granodiorite porphyry and Late Permian strata. Three primary paragenetic stages of veining have been identified: (I) arsenopyrite- pyrite-quartz stage, (II) pyrite-sphalerite-quartz stage, and (III) galena-silver minerals (pyrargyrite, argentite, and pearceite)-calcite stage. The Rb–Sr dating of sulfides yielded an isochron age of 129.9 ± 2.9 Ma (MSWD = 2.1) for the sphalerite, which constrains the mineralization age to the Early Cretaceous. Rb and Sr concentrations in the sulfides ranged from 0.0940 to 1.0294 ppm and 0.0950–3.3818 ppm, respectively. The initial ⁸⁷Sr/⁸⁶Sr value of the sphalerite was 0.70852 ± 0.00018, indicating that the mineralized materials were derived from the mixed crust-mantle source area. S isotope analysis showed that the δ³⁴S values of the sulfide samples varied in a narrow range, from −1.5‰ to +1.3‰ (mean −0.65‰), indicating a magmatic S source. Pb isotopic ratios of the sulfides (²⁰⁶Pb/²⁰⁴Pb = 18.306–18.416, ²⁰⁷Pb/²⁰⁴Pb = 15.524–15.605, ²⁰⁸Pb/²⁰⁴Pb = 38.095–38.479) and the granodiorite porphyry (²⁰⁶Pb/²⁰⁴Pb = 18.341–18.933, ²⁰⁷Pb/²⁰⁴Pb = 15.539–15.600, ²⁰⁸Pb/²⁰⁴Pb = 38.134–38.944) reflect that the ore-forming materials originated from contemporaneous magma with Early Cretaceous granodiorite porphyry. This study of the Bayanbaolege deposit and other hydrothermal deposits in the area provides compelling evidence that the widespread Mesozoic magmatism and mineralization in the southern Great Xing’an Range occurred in an intracontinental extensional tectonic setting, which was associated with the westward subduction of the paleo-Pacific plate.  相似文献