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1.
在对嘉祥县石灰岩矿进行地质灾害危险性评估、矿山环境地质问题评价的基础上,建立了一套评价体系,其中地质灾害危险性评估分为2个评价指标,矿山环境地质问题评价分为2种要素3个指标,同时将矿山恢复治理难易程度也作为一个评价因子。评价过程中对各指标危害性大、中、小程度均单独赋值,然后将各指标的分值进行叠加,确定出矿山环境地质问题的等级,将概划出的13个评价单元分为极差、差、一般3个区。提出了强化矿山管理、植树造林、科学避让、修建拦水坝等保护与治理措施及建议。 相似文献
2.
1INTRODUCTIONGrain production has always been top-priority issue con-cerned by government and people (MA etal., 2002). Af-ter China put household contract responsibility system in force, its domestic issue of grain was basically settled in the mid 1980s (MA and XU, 1999). However, in the days when idea of sustainable development is broadly accepted, efficiency and sustainability of grain produc-tion are now in question, which have prompted interest in reviewing grain production patterns… 相似文献
3.
Donald C. Gordon Peter J. Cranford Con Desplanque 《Estuarine, Coastal and Shelf Science》1985,20(2):205-227
The Cumberland Basin, a 118 km2 estuary at the head of the Bay of Fundy which has an average tidal range of about 11m, contains large tracts of salt marsh (15% of the area below highest high water). Low marsh (below about 0·9 m above mean high water) is composed almost exclusively of Spartina alterniflora while the vegetation on high marsh is more diverse but dominated by Spartina patens. Because of its higher elevation, high marsh is flooded infrequently for short periods by only extreme high tides. Low marsh is inundated much more frequently by water as much as 4m deep for periods as long as 4 h per tide. Temporal variability in the occurrence of extreme tides influences the flooding frequency of high marsh for any given month and year. Using a modification of Smalley's method, the mean annual net aerial primary production (NAPP) of low and high marsh is estimated to be 272 and 172 g C m?2, respectively. Vegetation turnover times average 1·0 and 2·0 y for low and high marsh, respectively. Because of abundant tidal energy, much of the low marsh production appears to be exported and distributed widely about the estuary. Since high levels of turbidity suppress phytoplankton production, salt marshes produce approximately half of the carbon fixed photosynthetically in the Cumberland Basin. It is concluded that salt marshes play a major ecological role in the Cumberland Basin. 相似文献
4.
Yanjun ZHANG Fenglong ZHANG Full QI Fuquan NI 《东北亚地学研究》2006,9(2):199-203
In view of the situation of excavation of open coal mine for the underground water disaster,we should carry out simulation studies for the numerical value of the water lowering project and improve the accuracy and the level of the water lowering project.On the basis of the hydrological geological conditions of certain open mine digging,a more reasonable seepage numerical model was built according to MODFLOW.It was simulated in advance that the process of the confined water level descending with the time,and combining with the actual observations to test the correctness of the model.The calculation showed that the results coincided well with the results of actual measurement.Based on this,different water lowering numerical simulations were built for the open coal mine digging.It could be simulated and forecast that the changes of the groundwater level in drainage process within and outside the mine pit,and it was quantitatively assessed that the possible water lowering result of the opencast water drainage process,which provide an important basis for the actual water lowering project and the possible project disposal. 相似文献
5.
Robert Arfi Daniel Guiral Jean-Pascal Torreton 《Aquatic Sciences - Research Across Boundaries》1991,53(1):39-54
Chlorophyll pigments (CHL), primary productivity (PP) and particulate nitrogen (Np) in relation to several environmental factors were monitored during planktonic colonization of an aquaculture pond (Layo, Côte d'Ivoire). How interactions between the organisms are established in an initially azoic environment were investigated. From March, 15 (D1) to March, 31 (D16), the system transformation went through three stages. First, a precolonization by heterotrophic microbial community from D1 to D2 (Np < 1 m maximum at D2: 243 mg m–2; CHL around 0). Then, a pioneer microalgal community developped from D3 to D7 (maximum CHL on D6: 19 mg m–2; PP: 1.0 g C m–2 d–1) with a significant contribution of picoplankton (CHL and PP < 3 m: 33 and 23% of the total, respectively). Finally, a second microalgal colonization was noticed from D9 to D12 (maximum CHL: 55 mg m–2, PP: 2.8 g C m–2 d–1), largely dominated by nanoplankton (CHL and PP > 3 m: 95 and 99% of the total, respectively). Overall, photosynthetic activity appeared to be closely linked to algal biomass. The study of autotrophic biomass and activity in different size classes in relation to the other parameters allowed us to precise the origin of the biomass fluctuations. The first bloom appeared to be controlled by selective grazing on small algae. The second algal development ended when N requirement represented at least 69% of N supply (in the N — NH4 form). This control was enhanced by the appearance of rotifers, leading to a more complex equilibrium. 相似文献
6.
7.
Controlling of landsides safely and economically is a great challenge to mine operators because landslides are major geological
problems especially in open-pit mines. In this paper, a case history at Panluo open-pit mine is presented in detail to share
the experiences and lessons with mine operators. Panluo open-pit mine is located in the southwestern Fujian province of China.
It is the largest open-pit iron mine in the Fujian province and was planned in 1965 and is in full operation from 1978. In
July 1990, an earthquake of magnitude 5.3 in Taiwan Strait and big rainstorms impacted the mine slope, causing tension cracks
and rather large-scale failures, and forming a U-shaped landslide. Total potential volume was estimated to be up to 1.0 × 106 m3. This directly threatened the mine production. In order to protect the mine production and the dwellers’ safety around, a
dynamic comprehensive method was implemented including geotechnical investigations, in-situ testing and monitoring, stability
analysis, and many mitigation and preventive measures. These measures slowed down the development and further occurrence of
the landslide. The results showed that the landslides were still active, it was slowed with the control measures and moved
rapidly with rainfall and mining down. However, no catastrophic accidents occurred and the pit mining was continued till it
was closed at the elevation of 887 m in 2000. As a successful case of landslide control at an open-pit mine for 10 years,
this paper reports the controlling measures in details. These experiences of landslide control may be beneficial to other
similar mines for landslide control. 相似文献
8.
Investigations were carried out at three underground coal mines in India to study the response of surface structures to underground
blasting and the likelihood of damage to the structures. The structures in the vicinity of the underground blasting area were
single and multistoried residential houses. The amplitudes of vibration due to underground blasting were monitored simultaneously
on the ground surface near the foundation of the structures and on various floors of the structures. The vibrations were also
monitored near the important surface installations. It was observed that the magnitude of vibration in structures decreased
with the increase in the height of the structures. The frequency of blast vibration from underground blasting was higher than
the natural frequency of the structures. Little energy was transmitted into the structures, which caused reduction in the
vibration level in the structures. The reduction in the vibration levels was up to 45% in the houses. It indicates that the
dominant frequency of blast vibration plays an important role in persistence of vibration and its amplification or reduction
characteristics in the structures. This paper deals with the effect of the vibrations on structures/houses standing above
the blasting faces in underground workings and their potential to likely damage to the structures at different Indian geo-mining
conditions. 相似文献
9.
Summary Left in place pillars of abandoned mines are subject to weathering (e.g action of water, bacteria) that degrades their mechanical
strength and eventually leads to collapse. A simple weathering model is proposed, that is governed by two parameters: the
rate of progression of weathered front and the rate of degradation of the compressive strength with time. Both plane strain
and axisymmetric analyses are performed and closed form solutions of the variation with time of the bearing capacity of the
pillar are given. Experimental data of the tests conducted on gypsum and anhydrite specimens attacked by water are presented.
It is shown that in order to fit the experimental data a third parameter must be introduced. New closed form solutions are
given and the data are used for estimating the time to failure of abandoned gypsum mines in Northern Italy.
Authors’ address: Dr. Riccardo Castellanza, Research Assistant, Department of Structural Engineering, Milan University of
Technology (Politecnico), Piazza Leonardo da Vinci 32, 20133 Milan, Italy 相似文献
10.
利用高精度多梯度热培养系统,对英国威尔士地区两类典型的北方泥炭沼泽中酚类物质和溶解有机碳释放的热敏感性进行了为期1年的调查研究.研究结果表明,雨养泥炭沼泽(Bog)酚类物质释放的热敏感性Q10(总酚)月变化为0.92~1.57,而矿养泥炭沼泽(Fen)的月变化范围为0.93~1.30.酚类释放的热敏感性与土壤温度大致呈正相关关系.此外,土壤温度与溶解有机碳释放的热敏感性Q10(DOC)也呈正相关关系.总体上,雨养泥炭沼泽的热敏感性比矿养泥炭沼泽略高.除温度外,水文条件和植被等多种环境因子对酚类物质和溶解有机碳释放的热敏感性也有较大影响.研究结果还表明酚碳热敏感性比值Q10o(总酚)/Q10(DOC)相对稳定,土壤温度的变化对其影响有限. 相似文献