Characteristics of Permeability Changes in Bituminous Coal Under Conditions of Stress Variation Due to Repeated Mining Activities

The factors affecting permeability change under repeated mining of coal seams are important study aspects that need to be explored. This study combined various stress variation characteristics of protective seam mining and simplified the stress path of repeated mining in protective seam mines. Based on the results from the bespoke gas flow and displacement testing apparatus, seepage tests for simulated repetitive mining were carried out. The results simulated the actual behavior very well. With any drastic increase in the mining influence, the axial deviation stress in the stress path increased, and the greater the difference in coal permeability during the unloading and stress recovery stage, the more substantial the increase in permeability. The change in coal permeability was significantly influenced by the severity of simulated repeated mining cycles. When the mining stress exceeded a critical value, the permeability of the coal sample increased with the increase in the number of loading and unloading cycles, but the reverse was true when the mining stress was lower than the critical value. The effective sensitivity of seepage to the applied stress decreased with an increase in the number of stress cycles. With a decrease in the deviation stress, that is, with lower severity of mining influence, the effective sensitivity of coal seepage to stress gradually decreased.

     

Rock Weathering Processes in Antarctica: A Comparison of Some Recent Studies with Those from the Northern Hemisphere

A review of some recent studies on rock weathering in Antarctica has revealed that Antarctic weathering research has a significant contribution to make to the ongoing debate about rock weathering in cold climates. Largely conducted in the field rather than the laboratory as in the Northern Hemisphere, it demonstrates that whilst all weathering processes can occur in Antarctica this is highly localised and dependent on the particular micro‐environment. Freeze‐thaw, for example, is not the most dominant process in many parts of Antarctica. The right combination of rock temperature and moisture can mean that salt, insolation, hydration or even chemical weathering can predominate.     

Comparison of the Bedding Errors of Artificially and Naturally Deposited Sediments with Those Predicted from a Simple Model

Summary. Sediment of fine silt grade (10μm median diameter) has been deposited in a flume on beds of various small slopes. The deviation of the remanence due to the slope (the "bedding error"β) has been measured and its variation with the angle of slope α has been ascertained for a geomagnetic field inclination of 80°. The ratio β/α is compared with that observed by Rees (1964) in natural sediments, and with that predicted from a simple theoretical model. The observed and predicted results are in satisfactory agreement for both natural and artificial sediments.     

“4·20”芦山7.0级地震次生山地灾害活动特征与趋势

2013-04-20芦山县发生7.0级地震,震源深度13 km.截至4月29日地震共造成196人遇难,21人失踪,13484人受伤,200余万人受灾.地震发生后,我们立即开展了地震次生山地灾害的遥感解译、实地调查及危险性评估工作.作者定义了地震次生山地灾害,分析了次生山地灾害的活动特征、形成机制与模式以及发展趋势,并与汶川地震次生山地灾害进行了对比.初步查明芦山地震诱发了1460余处崩塌和滑坡,大量落石和4处堰塞湖.次生山地灾害具有规模小、群发性和高位破坏的特征.崩塌和落石成群发育于坚硬岩石形成的陡坡上,主要发育区段有:芦山县的宝盛乡金鸡峡、双石镇大岩峡以及省道S210线K317路段和灵关镇以北小关子段,对沿河公路及救援生命通道影响严重.滑坡数量较少,以中小规模为主,主要发生于砂岩、页岩和松散堆积层中,仅发现一处大型滑坡并转化为碎屑流.堰塞湖主要由崩塌、滑坡形成,均为低危险性小型堰塞湖.芦山地震次生灾害的主控因素为构造、岩性、结构面和地形,崩塌破坏主要表现为顺层滑动破坏型、切层倾倒破坏型和结构面控制破坏型3种模式.芦山地震诱发崩塌、滑坡的数量、分布范围和规模比汶川地震小得多,其数量仅为汶川地震的5.53％,造成的地表破坏面积(3.06 km2)仅为0.57％.芦山地震区两次地震扰动的叠加效应,大大降低坡体的稳定性,震后崩塌、滑坡和泥石流的活动性增加,增幅有限,活跃期也相对较短,但震区山地灾害的隐伏性和隐蔽性强,给隐患排查带来困难.     

Women, Disempowerment and Resistance: An Analysis of Logging and Mining Activities in the Pacific

There are many arguments supporting the need for a reduction of large scale logging and mining activities in Pacific Island countries. In addition to ecological and economic concerns, logging and mining have had significant social impacts, including gendered impacts. Women tend to be excluded from decision-making processes, and they have limited access to royalty payments and business and employment opportunities which emerge. Women also bear a disproportionate share of the responsibility for dealing with the social and environmental mess which accumulates. However, women are not simply passive victims of logging and mining activities, as this discussion of the Solomon Islands and Papua New Guinea will argue. They are often the first to feel dissatisfaction with logging and mining and it is such dissatisfaction which has fuelled civil unrest, from family break-ups to sabotage of machinery to civil war, in some communities. It may thus be useful for companies to more carefully monitor the effects of their activities on women and involve women more actively in decision-making bodies if they wish to avoid such unrest in the future.     

近50年人类活动引起的杭嘉湖平原区水位变化

针对杭嘉湖地区洪涝灾害日益加剧的现状,基于1960~2007年日降水和日水位资料,采用Spearman检验、有序聚类分析和线性模拟方法,研究了近50 a来降水和水位变化,在此基础上探讨了降水和人类活动对特征水位变化的贡献率。结果表明,区域近50 a降水变化未见明显趋势,水位呈增加趋势,年最高水位、年平均水位和年最低水位增率分别为0.03 m/10a、0.05 m/10a和0.09 m/10a,且平均水位和最低水位增加达到显著性水平。8个代表站点特征水位均呈增加趋势。空间上沿水流方向,线性坡度值增大。水位降水响应率和平水年水位序列分析显示人类活动是水位变化的重要原因。人类活动对最高水位、平均水位和最低水位变化的贡献值分别为39.0%、56.2%和82.9%。     

科尔沁沙地自然与人为因素对沙漠化影响的累加效应分析

采用滑动平均法分析了科尔沁沙地年平均温度、年降水量(代表自然因素)和耕地指数、草场载畜量(代表人为因素)对沙漠化影响的累加效应。结果表明,年平均温度和年降水量的累加作用持续的时间较短(在4a之内),其中年平均温度对沙漠化影响的累加效应作用在2a最大,但作用不明显;年降水量对沙漠化的影响以4a最高,累加效应最明显,关联系数为0.801,而且二者之间有较显著的回归关系。年降水量和年平均温度的波动特点是决定累加作用时间和影响强度的关键。代表人为因素的耕地指数和草场载畜量对沙漠化影响的累加效应都比较明显、作用持续的时间较长(大于8a),其中耕地指数对沙漠化的影响以7a的累加效应最明显;草场载畜量对沙漠化的影响以10a的累加效应最明显,耕地指数和草场载畜量与沙漠化之间存在着较显著的回归关系。人口持续增长导致的对资源环境压力的增大是耕地指数和草场载畜量对沙漠化影响产生累加效应的根本原因。     

天山山区近40年秋季气候变化特征与南、北疆比较

利用新疆1959~1998年的秋季温度降水资料,分析天山山区近40年来秋季气候变化的基本特征,所得结果如下: (1) 天山山区秋季温度在冷暖变化阶段上与北疆的相似性强于南疆,但其秋季降水在干湿变化阶段上与南、北疆不同。 (2) 秋季温度空间分布的同步变化性以北疆为最好,南疆最差,天山山区居中。秋季降水空间分布的同步变化性以南疆最好,天山山区最差,北疆居中。 (3) 20世纪60~90年代,天山山区表现为波动升温,而南疆和北疆表现为持续增温,均以90年代温度最高,80年代是三大区域秋季降水最多的年代。60,70及90年代,三大区域的秋季降水均低于30年均值。     

"5.12"汶川地震次生山地灾害的分布与特点

"5.12"汶川地震的重灾区,主要分布在龙门山高山峡谷区和四川盆地深丘区等地,行政区划上涉及四川省的成都市、绵阳市、德阳市、广元市、阿坝藏族羌族自治州,甘肃省的陇南市,陕西省的汉中市等的山区,面积大于10×104km2.强烈地震除直接造成众多人员伤亡和各种设施被毁外,还在山区引发了大量次生山地灾害,形成灾害叠加,导致灾情更加严重.次生山地灾害主要沿龙门山地震断裂带集中分布和沿河谷两岸山坡分布,具有下列特点:1.类型多样,包括崩塌、滑坡、滚石、堰塞湖、泥石流等;2.数量上以滚石、崩塌、滑坡为主;3.导致了大量人员伤亡;4.堰塞湖主要由地震滑坡、崩塌形成;5.泥石流活动具滞发性,地震直接激发的泥石流仅一处;6.对生态环境破坏极大;7.加剧了防洪形势的严峻性;8.主要沿龙门山断裂带活动;9.活动强弱与地震烈度大小关系密切.     

中国产业能源消费碳排放结构及其减排敏感性分析

本文在非竞争型投入产出分析框架下,建立了区域碳排放的结构分析模型及其敏感性分析方法,并利用中国2007年非竞争型投入产出表.研究了中国产业能源消费碳排放根源以及由贸易产生的碳排放转移问题,并进一步对中国经济结构调整的排放敏感性进行了研究.研究结果标明.出口是中国碳排放总量迅速增加的主要推动力之一.2007年中国对外贸易导致的净出口碳占中国碳排放总量的29.1%.而国内建筑业的投资,机械交通电子设备的出口与投资.国内对食品、电力热力以及服务业的消费,化工金属等高耗能产品的出口等经济活动是我国碳排放的主要根源.也是排放敏感性较高的经济活动.因此,在调整产业结构,促进产业升级,优化出口结构,加快产能转移,抑制基础原材料工业产品的出口规模并逐步实施进口替代,提高出口层次和出口产品附加值的同时,重视提倡全民减排.积极建立节约型社会,特别是减少建筑业的浪费和服务业能耗,将是中国节能减排工作的重点任务.     

中国城市经济网络结构空间特征及其复杂性分析

通过对当前城市体系研究进展和分析方法的阐述与总结,结合统计物理中复杂网络分析 工具,采用GIS、Matlab 和数据库等技术手段,构建城市联系网络,一定程度上突破了传统的等级 或位序城市关系研究,最后以2003 年和2007 年的Top1、Top5 和Top10 网络(城市联系强度的最大 值、前5、前10 名所连接的城市)为例证进行实证研究。研究表明：① 可将中国城市划分为北方城 市区、长江城市区、南部城市区３大城市区,形成了“三极多核”的空间格局。全国城市网络的联 系方向主要集中在环渤海地区、长三角地区和珠三角地区的主要城市(如北京、上海、广州)。但 是,从三大地区内部差异来看,环渤海地区城市等级性明显,长三角地区和珠三角地区呈现多核 化发展趋势,即城市网络化发展加强。Top10 网络反映各个城市前10 名的联系方向有所分散,即 呈现“最大联系极化、联系广度分散化”的发展趋势;② 从Top5、Top10 网络与随机网络、空间邻 近网络的对比来看,中国城市的实际网络既具有空间邻近网络这种规则网络的高聚类系数,又 具有随机网络所拥有的稀疏、长距离连接特性,表现为高聚类系数和短路径的双重特性,呈现 “小世界”网络特征;③ 从聚类系数的纵向变化看,2007 年比2003 年的城市网络连接更加分散, 区域的开放程度正在提高;④ 2007 年的平均路径长度稍有下降,说明全国城市网络中城市联系 更为紧密,连接通道增多。     

进城务工人员购物活动时空特征解析——以南京市为例

以南京市进城务工人员为研究对象,在宏观把握其社会经济及空间概况的基础上,分析其线下购物的时空特征及典型时空轨迹。结果表明:(1)时间特征上表现为以低频购物为主;购物时段集中在上下班途中及休息日下午;购买低等级商品时对出行时间较为敏感,约为10 min;购买高等级商品时对出行时间不太敏感,多集中在1 h内。(2)空间特征上表现为购买低等级商品时对出行距离较为敏感,约为0.5 km,购物活动空间较为集聚;购买高等级商品对出行距离敏感性较低,购物出行空间较为分散。(3)时空轨迹上表现为单纯购物活动的购物场所及出行空间等级均较低,购物时长较短,购物时段的连续性在工作日要高于休息日;多目的购物活动的购物场所及出行空间等级则较高,购物时长较长,购物时段集聚度较高。     

Species Diversity Characteristics of a Natural Pinus taiwanensis Community with Different Diameter Classes and Forest Densities

Pinus taiwanensis is a species endemic to China. This study selected four typical plots of Pinus taiwanensis in the natural secondary forest around Macheng City, in order to reveal the characteristics of and the relationships between different diameter classes (determined based on the diameter at breast height or DBH), forest densities and species diversity, as well as the similarities of species diversity of different plots within the community. The result showed that Pinus taiwanensis was the dominant species in the community. The ratio of Pinus taiwanensis trees of diameter class IV reached a peak of 19.46% of the total followed by diameter class VII at 18.92%. The study recorded 156 species of vascular plants from 130 genera of 71 families; Pinus taiwanensis was the dominant species in the community. When the forest density was 1200 trees ha ^-1 with the largest average diameter of DBH=36.779±4.444 cm, the diversity (Shannon index H'=1.6716) and the evenness (Pielou index E=0.6727) of the tree layer was the highest. When the forest density reached 1525 trees ha ^-1 with the lowest average diameter of DBH=18.957±5.141 cm, the richness (D_ma=5.4308), the diversity (H'=2.9612) and the evenness (E=0.8985) of all shrub layers climbed to the maximum. When the forest density was 1325 trees ha ^-1, the richness (D_ma=5.8132), the diversity (H'=3.0697) and the evenness (E=0.9025) of all herb layers peaked. In terms of vertical structure, the average diversity indexes were herb layer>shrub layer>tree layer. High canopy density weakened light intensity in the community, causing a reduction in the species diversities of herbs and shrubs. The average similarity coefficient between the sample plots was 0.3356, which was at the medium dissimilarity level. External disturbances and improper management were major contributors to the low species diversity of the community. The implementation of scientific management measures is urgently needed to optimize the forest structures of Pinus taiwanensis, create a benign community environment, and promote species diversities and establish a stable forest community structure.     

高岭土矿区生态环境特征与植被恢复技术研究

以福建省闽清县高岭土采矿废弃地研究为例,在对矿区生态环境调查的基础上,选择马尾松、胡枝子、桃金娘、茶树、绿竹、香根草、五节芒等几种植物作为植被恢复的的先锋植物,采取不同的试验处理方法.经过3 a时间,对其生长状况进行测定.结果表明:高岭土矿山分布区植被贫乏;矿区废弃地土壤养分缺乏、土壤pH值较低,它们是植物生长的重要限制因素;选择马尾松、茶树、绿竹、香根草、五节芒进行乔灌草相结合的植物群落配置,结合熟土回填的处理,有利于植物较快生长,取得较好的生态效益和明显的经济效益.鉴于这几种植物在亚热带的广布性,它们是亚热带高岭土矿区进行植被恢复的首选植物.     

高岭土矿区生态环境特征与植被恢复技术研究

以福建省闽清县高岭土采矿废弃地研究为例,在对矿区生态环境调查的基础上,选择马尾松、胡枝子、桃金娘、茶树、绿竹、香根草、五节芒等几种植物作为植被恢复的的先锋植物,采取不同的试验处理方法.经过3 a时间,对其生长状况进行测定.结果表明:高岭土矿山分布区植被贫乏;矿区废弃地土壤养分缺乏、土壤pH值较低,它们是植物生长的重要限制因素;选择马尾松、茶树、绿竹、香根草、五节芒进行乔灌草相结合的植物群落配置,结合熟土回填的处理,有利于植物较快生长,取得较好的生态效益和明显的经济效益.鉴于这几种植物在亚热带的广布性,它们是亚热带高岭土矿区进行植被恢复的首选植物.     

Failure Mechanism and Deformation Characteristics of Gob-Side Entry Retaining in Solid Backfill Mining: A Case Study

In solid backfilling mining, gangue and other solid materials are backfilled into the gob to restrain the roof subsidence. As a result, instead of being subjected to periodic collapse, the overlying strata will be able to maintain its integrity and bend or sink as a whole with partial fracture and failure, thus facilitating the gob-side entry to retain. To study the mechanical deformation characteristics and failure mechanism of such gob-side supporting wall, this research analyzes the structure features of the surrounding rock in gob-side entry and builds mechanical damage model for gob-side supporting based on the hypothesis of planar slip surface in the theory of Coulomb earth pressure. The relationship among normal force acting on the contact face N, the angle between the slip surface of gangue and vertical face η and other relevant factors are discussed. The result suggests that η is mainly affected by δ, the friction angle between the backfill body and the supporting wall interface, and φ, the internal friction angle of backfill materials; η increases as δ increases and decreases as φ increases. N, mainly affected by δ, φ and uniformly distributed load q, has positive correlation with q and negative correlation with δ and φ. The research also reveals that compressive stress exists only when the width of wall exceeds 1.741 m; such stress will decrease sharply when the width of wall is between 2 m and 3 m, and become stable when the width goes beyond 3 m. According to numerical simulation and field test, the maximum values of roof-to-floor longitudinal deformation and lateral deformation between two sidewalls are 350 mm and 210 mm, respectively. The research results proved that the model employed can accurately predict and evaluate the deformation and damage of the gob-side entry.