江西德兴铜矿集区土壤地球化学基准值方法的适用性

确定矿集区土壤地球化学基准值是矿山环境地质调查与评价的重要任务,而遴选出合适的地球化学基线值的定值方法是该问题的关键。以江西德兴铜矿集区表层土壤地球化学数据为依据,运用地球化学对比法、相对累积频率方法和标准化的方法分别计算了德兴铜矿集区表层土壤6种重金属元素的地球化学背景值,并将其与江西省土壤背景值对比。结合成土母岩重金属含量分析了各种基准值定值方法的适用性,结果证明标准化方法较适用于确定研究区表层土壤地球化学基准值。     

江西德兴铜矿大坞河土壤重金属累积特征与成因

江西德兴铜矿是中国超大型斑岩铜矿,随着矿业活动的增加,德兴铜矿区重金属污染问题日益严重。查明德兴铜矿土壤重金属累积作用及原因,可为政府机构、矿山开展环境整冶提供科学依据。在大坞河上游、中游、下游选定3个剖面,采集50件土壤样品,得出其基于地球化学基线的累积特征。整体来讲,Cu、Mo累积作用最为显著,Cr、As累积作用明显,同时发现一级、二级阶地上累积显著,并从矿石组合、地化背景、河流阶地、元素形态、矿山生产等角度开展累积作用的原因分析。     

Landsliding triggered by reservoir operation: a general conceptual model with a case study at Three Gorges Reservoir

The Three Gorge Reservoir, one of the largest civil engineering projects in human history, dams the Yangtze River to form a 660-km-long and 1.13-km-wide reservoir. Today, although the project has been completed and is in normal operation, the on-going landslide initiation and movement in response to the reservoir operating is one of the main geologic hazards. The Huangtupo (meaning “yellow soil slope” in Chinese) Slope typifies such on-going landslides along the reservoir. Observations from a multi-year monitoring program conducted on this slope indicate that there are multiple slides on the reservoir banks that move episodically into the reservoir and their movements appear to be highly correlated with the initial and seasonal changes in the reservoir pool level. A hydro-mechanical numerical model is constructed to investigate the quantitative links among the episodic movements and the variations in pore water pressure, suction stress, hydrostatic reservoir water loading, and slope self-weight induced by the fluctuating water levels. Modeling results identify regions within the variably saturated slope where significant changes in stress occur during the periods of the initial impoundment that raised water levels from 68 to 135 m and that occur in response to seasonal fluctuations of the reservoir pool level between 145 and 175 m. We find that the rise or decline of reservoir pool level can either increase or decrease the stability of landslide. In general, hydrostatic reservoir water loading has positive correlation with the stability; pore water pressure and suction stress have negative correlation with the stability; and the effects of slope self-weight depend on the dip angle and mechanical properties of sliding surface.     

The effect of desertification on carbon and nitrogen status in the northeastern margin of the Qinghai-Tibetan Plateau

Environmental degradation resulting from desertification often accelerates biodiversity loss and alters carbon (C) and nitrogen (N) stocks within grassland ecosystem. In order to evaluate the effect of desertification on plant diversity and carbon (C) and nitrogen (N) stocks, species compositions and C and N contents in plants and soil were investigated along five regions with different degrees of desertification in the northeastern margin of the Qinghai-Tibetan Plateau (control, light, moderate, severe and very severe stages). The study showed: (1) species composition and richness changed significantly with the development of grassland desertification; (2) the aboveground biomass C and N contents in the control were 101.60 and 4.03 g m^?2, respectively. Compared to the control, the aboveground tissue C and N contents significantly decreased from light, moderate, severe to very severe stages. (3) The root C and N contents in the control in 0–40 cm depth are 1,372.83 and 31.49 g m^?2, respectively, while the root C and N contents in 0–40 cm were also declining from the control, light, moderate, severe to very severe stages. (4) Compared to the plant, the soil made a greater contribution for C and N distribution, in which the soil organic C and total N contents in 0–40 cm depth in the control are 20,386.70 and 3,587.89 g m^?2, respectively. At the same time, soil organic C and N contents also decreased significantly from the control to very severe stages. These results suggest that grassland desertification not only alters species compositions and leads to the loss of plant diversity, but also results in greater loss of organic C and N in alpine meadow, in which there is a negative effect on reducing greenhouse gas emission.     

安徽金寨三仙山地区梅山群碎屑岩成分及其对物源区构造属性和地层时代的意义

安徽金寨三仙山地区位于大别山北缘,该地梅山群主要为一套轻微变质的碎屑岩系。砂岩碎屑组分统计表明,砂岩类型主要为岩屑石英砂岩、岩屑石英杂砂岩,石英、长石、岩屑的平均含量为87.21%、1.67%、9.64%,杂基含量为15%,石英几乎全为单晶石英（95.79%）,长石以斜长石为主,岩屑主要为沉积岩屑（75.49%）,其次为变质岩屑（24.51%）。碎屑岩地球化学元素平均含量为：SiO₂（75.99%）,Al₂O₃（11.96%）,MgO（0.72%）,CaO（0.10%）,Fe₂O₃（4.02%）,K₂O（1.70%）,Na₂O（0.26%）。ΣREE=170.49×10^-6（74.49×10^-6～309.42×10^-6）,LREE/HREE=11.16（7.89～14.26）,轻稀土略有富集,δEu=0.72（0.59～0.90）,La/Yb=22.08（13.01～31.18）,（La/Yb）_N=14.89（8.77～21.02）,δCe=0.84（0.42～0.97）。碎屑岩地球化学特征指示三仙山地区梅山群母岩主要为古老沉积岩、长英质火山岩和古老变质基底,具有多重物源区。梅山群构造背景较复杂,主要为被动大陆边缘和活动大陆边缘,其次为大陆岛弧。三仙山地区梅山群碎屑岩的源岩成分、构造背景与商城-固始地区石炭系有很大差别,故其地层时代有待于进一步研究。     

Comparison of Blast-Induced Damage Between Presplit and Smooth Blasting of High Rock Slope

This paper focuses on the comparison of damage induced by smooth blasting and presplit blasting based on the excavation of high rock slope. The whole damage process of the smooth blasting and presplit blasting excavation method is studied by using a cumulative blasting damage numerical simulation technology based on the secondary development of the dynamic finite element code LS-DYNA. The results demonstrate that, in the case of contour blasting with the method of smooth blasting, the total damage of rock slope is a result of cumulated damage induced by the production hole, buffering hole, and smooth hole. Among the total damage, the blasting of the production hole is the main resource, followed by the smooth and buffering holes. For the presplit blasting, the final damage of rock slope is mainly induced by presplit blasting itself. The spatial distribution characteristics of the final damage zone of two methods are compared. Two classes of damage zone could be found in smooth blasting excavation; one of them is the columnar high-degree damage zone around the slope surface and the other is the low-degree damage zone located in the middle of the slope. But in the case of presplit blasting, there is only the columnar high-degree damage zone around the slope surface. Finally, a damage control suggestion for two blasting excavation methods is proposed and verified based on the excavation of the temporary shiplock slopes of the Three Gorges Project in China.     

Application of in-seam directional drilling technology for gas drainage with benefits to gas outburst control and greenhouse gas reductions in Daning coal mine,China

Gas outburst disasters are becoming more serious as the underground coal mines become deeper in China, and a thick zone of deformed coal provides conditions favorable to coal and gas outbursts. The Daning coal mine’s main mining seam is the No. 3 coal seam with coal and gas outburst hazard, which often contains two normal coal sub-layers and one deformed sub-layer. Considering both the geological conditions of the coal seam and applications of the in-seam directional longhole drilling technology, a new schematic diagram of in-seam directional longholes for gas drainage is developed. The two borehole layout models of longwall panel and main entries for gas outburst disasters control have been successfully applied. The gas drainage rates of both models are >70 %, and the residual gas contents are both <8 m³/t, which can be considered that the gas outburst disasters were effectively controlled. To better guide gas drainage, gas drainage normal and failure modes have been obtained. Although in-seam directional longhole technology has been successfully applied for regional gas drainage with benefits to gas outburst control, there are also some problems that are detrimental to greenhouse gas reductions in gas drainage and gas utilization. The three main problems are air leakage failure in gas drainage, decreasing gas concentration and a low gas utilization ratio. To address the problems mentioned above, five improvements are suggested.     

Natural Variability of Shear Strength in a Granite Residual Soil from Porto

The renewal imposed by the Eurocodes regarding the methodologies of safety evaluation requires a statistical analysis of the variability of ground geotechnical parameters. However, the studies published in the reviewed literature do not cover the typical materials from the northeast region of Portugal—residual soils from granite—to which a strong heterogeneity is associated. Hence, a statistical characterization of the natural variability of a granite residual soil from Porto has been made through a significant amount of experimental tests, focusing on its geomechanical properties. In order to provide a database for probabilistic analysis of problems involving this type of soils, an appropriate statistical law has been used to model its variability, which has been quantified by means of coefficients of variation and scales of fluctuation.     

深孔及松软地层大口径绳索取心钻具的研究与应用

为解决深孔大口径及松软地层取心难的问题,推进取心钻探技术的发展,研发了一套大口径绳索取心钻具。着重介绍了大口径绳索取心钻具的结构特点、技术参数、技术创新及使用效果。应用结果表明,该大口径绳索取心钻具结构合理、各机构动作可靠、岩心采取率高,能够满足深孔及松软地层的取心要求。     

羌塘盆地结构构造与油气勘探方向

羌塘盆地是我国陆域大型中生代海相沉积盆地,富含烃源岩,但结构构造非常复杂。结合野外观测及相关资料对地震反射剖面进行地质构造详细解释,良好地揭示了羌塘盆地结构和深部构造。羌塘盆地逆冲推覆构造延伸存在显著差别,北羌塘凹陷多格错仁逆冲推覆构造、阿木错逆冲推覆构造与南羌塘凹陷肖茶卡—双湖逆冲推覆构造、多玛—其香错逆冲推覆构造仅发育于盆地表层0~3km深度范围,北羌塘凹陷龙尾错逆冲推覆构造、羌中隆起北缘逆冲推覆构造、南羌塘凹陷赛布错—扎加藏布逆冲推覆构造、拉萨地块北缘色林错逆冲推覆构造系统自地表向深部延伸深度超过6km,羌塘盆地深部还发育中生界底部逆冲系和基底逆冲系,伴有不同规模的褶皱构造。逆冲推覆构造形成活动时代包括晚白垩世、古近纪早期和古近纪晚期,晚白垩世与古近纪早期逆冲推覆构造运动导致构造隆升的裂变径迹年龄分别为87±5~75±4Ma、64±5~46±4Ma。经过多期逆冲推覆构造改造和褶皱变形,羌塘盆地中生界海相沉积地层与烃源岩显著增厚,为新生代晚期二次生烃及油气成藏提供了非常有利的地质构造条件;北羌塘凹陷发育万安湖向斜、半岛湖背斜、东湖向斜、阿木错向斜,南羌塘凹陷发育宁日圈闭、鲁雄错背斜、诺尔玛错圈闭、协德圈闭、崩则错圈闭,羌中隆起下伏侏罗系和三叠系烃源岩,色林错下白垩统下伏古近纪湖相沉积,这些构造部位都是油气勘探的重要靶区。