改革采煤方法防治底板突水

通过现场实测和室内研究表明,采煤技术因素对底板突水的影响很大。如何防治底板突水,这里指出了一条改革采煤方法的途径。     

井田地温场的数值模拟

针对我国华北煤田构造地质、水文地质、地温地质特征及地温资料来源、地温研究现状,提出了先建立煤井田地温场的数学物理模型并求出其数值解,再用其结果预测井田未知区地温分布的新方案。使地温预测工作程序得以简化、预测结果更为可靠。文中详细叙述了模型建立和边界条件选定方案,并以导水断层上盘为例,展示了数值模拟的效果。     

古汉山井田地下水同位素组成特征研究

根据古汉山井田地下水中~3H、D、~(18)O和~(13)C等资料,建立了该井田鉴别主要含水层地下水的同位素标志,并对冲积层水、奥陶纪石灰岩水和煤系薄层石灰岩水之间的关系,以及矿井充水条件,做出了判断,为今后矿井基建、采矿中判别突水来源,提供了依据。     

Ultimate bearing capacity and settlement of coal pillar sub-strata

Summary This paper develops a rational approach for design of coal pillars under weak floor strata conditions considering ultimate bearing capacity (UBC) as well as pillar settlement. An approximate solution is presented for estimation of UBC for a shallow foundation on a two-layered rock system with consideration of both cohesion (c) and (ø) for both layers. Similarly, deformability underneath a full-size pillar is estimated from deformability calculated from plate loading tests. The effect of adjacent pillars on UBC and deformability of coal pillars in a panel is considered using foundation engineering analysis techniques. The design of pillars based on limiting settlements considers both differential settlements as well as mean settlement of pillar in a panel. An attempt is made to validate the proposed design approach based on field data and observations at an Illinois mine.     

Arsenic contamination in surface drainage and groundwater in part of the southeast Asian tin belt,Nakhon Si Thammarat Province,southern Thailand

The occurrence of human health problems resulting from arsenic contamination of domestic water supplies in Ron Phibun District, Nakhon Si Thammarat Province, southern Thailand was first recognized in 1987. The area has an extensive history of bedrock and alluvial mining, the waste from which is typically rich in arsenopyrite and related alteration products. In 1994 a collaborative study was instigated involving Thai and British government authorities to establish the distribution and geochemical form of As in surface drainage and aquifer systems in the affected area, the probable sources of As contamination, and the potential for problem alleviation. Hydrochemical analyses of surface- and groundwaters have confirmed the presence of dissolved As at concentrations exceeding WHO potable water guidelines by up to a factor of 500. Contamination of the shallow alluvial aquifer system is systematically more severe than the underlying carbonate-hosted aquifer. Deep boreholes may therefore provide the best available potable water source for the local population. The presence of up to 39% of total As as arsenite (H₃AsO₃) within the carbonate aquifer may, however, constitute a hidden toxicological risk, not evident in the shallow groundwater (in which arsenate species account for > 95% of total As). Mineralogical investigations of As-rich tailings and flotation wastes were undertaken to evaluate their likely impact on water quality. The results indicate that although some flotation wastes contain up to 30% As, the rate of leaching is extremely low. Consequently the As loading of drainage emanating from such waste is below the subregional average. Analyses of the silty alluvium that covers much of the central sector of the study area have highlighted As concentrations of up to 5000 mg kg^–1, probably carried by disseminated arsenopyrite. Following sulfide dissolution, the mobility of As in this material may be high (with resultant contamination of shallow groundwater) due to the low Fe content of the soil. On the basis of the data acquired, a range of pollution mitigation schemes are currently under investigation including Fe supplementation of alluvium and microbial degradation of disseminated arsenopyrite.     

FACILITATING REGIONAL SUSTAINABLE DEVELOPMENT THROUGH INTEGRATED MULTI-OBJECTIVE UTILIZATION, MANAGEMENT OF WATER RESOURCES IN THE LANCANG-MEKONG RIVER BASIN

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基于均值变点分析法的资源三号测绘卫星DSM水系自动提取研究——以云南省高海拔山区为例

水系自动提取是保证基础地理数据现势性的关键,而获得最佳集水面积阈值是提高水系提取精度的前提条件。集水面积阈值一般依靠定性分析的方法获取,采用均值变点分析法定量确定水系的集水面积阈值,可以满足基础地理数据精确性的要求。以云南省龙川江流域为研究区域,基于资源三号测绘卫星ZY-3 DSM和SRTM DEM两种数据,利用GIS工具分别提取该流域水系,再由均值变点分析法确定最佳集水面积阈值,并比较分析这两种水系的提取精度。研究结果表明:1随着集水面积阈值的增加,提取的水系密度减小且趋缓。ZY-3 DSM和SRTM DEM的最佳集水面积阈值分别是6.0 km~2和2.75 km~2;2在最佳集水面积阈值下,ZY-3 DSM提取的河流数比SRTM DEM多20.6倍,河流等级多2级,各级支流数为SRTM DEM的4.7~9.5倍不等,水系密度达到SRTM DEM的4.5倍;3与1:250 000水系数据相比,ZY-3 DSM和SRTM提取的河流点位平均相差395.23 m,RMSE为391.83 m。由此可见,利用均值变点分析法基于ZY-3 DSM提取的水系精度更高,完全满足测绘地理数据更新的现势性、准确性要求。     

Two-phase Material Point Method applied to the study of cone penetration

This paper presents numerical simulations of Cone Penetration Test (CPT) in water-saturated soft soils taking into account pore pressure dissipation during installation. Besides modelling interaction between soil skeleton and pore fluid, the problem involves large soil deformations in the vicinity of the penetrometer, soil–structure interaction, and complex non-linear response of soil. This makes such simulations challenging. Depending on the soil’s permeability and compressibility, undrained, partially drained or drained conditions might occur. Partially drained conditions are commonly encountered in soils such as silts and sand–clay mixtures. However, this is often neglected in CPT interpretation, which may lead to inaccurate estimates of soil properties. This paper aims at improving the understanding of the penetration process in different drainage conditions through advanced numerical analyses. A two-phase Material Point Method is applied to simulate large soil deformations and generation and dissipation of excess pore pressures during penetration. The constitutive behaviour of soil is modelled with the Modified Cam Clay model. Numerical results are compared with experimental data showing good agreement.     

The dissolution kinetics of atacamite in the acid range and the stability of atacamite containing soils from Namaqualand,South Africa

The Cu hydroxy mineral, atacamite, is commonly associated with saline environments and is generally thought to dissolve rapidly in the presence of fresh water. A Cu contaminated soil from the arid Namaqualand region, South Africa, shows atacamite as the dominant Cu containing mineral. The stability of the Cu phase in this soil was determined through equilibrium and leaching studies using both deionised water (DI) and a concentrated (0.5 M) NaCl solution. Initially a high concentration of exchangeable Cu was released from the soils leached with NaCl. Continued leaching with NaCl resulted in a substantial decrease in Cu release as atacamite equilibria started to control dissolved Cu. This suggests that an initial spike of Cu laden water will leach from the soils at the onset of a large rainfall event. Further additions of water will result in a lower but sustained release of Cu from the soil. The Cu contaminated soils are exposed to acidic sulphate leachate thus the dissolution kinetics of synthetic atacamite in the acidic range (pH 5.5–4.0) was determined in both NaCl and DI solutions. The kinetic data showed that atacamite dissolution rates are significantly higher in DI than in NaCl but the rates converge at pH 4. In comparison to common acid soluble minerals, atacamite displays a moderate dissolution rate (10^−9.55–10^−7.14 mol m⁻² s⁻¹) within the acid range (pH 5.5–4.0). The atacamite dissolution reaction order with respect to pH is 1.3 and 1.6 in DI and NaCl solutions, respectively, suggesting that dissolution rates of atacamite are highly pH dependent in the acid range. The type of acid used to lower the pH had no effect on the reaction kinetics, with HNO₃ and H₂SO₄ resulting in comparable dissolution rates of atacamite at pH 4.5.     

Spatial variability of soils and stream sediments and the remediation effects in a Portuguese uranium mine area

The old Senhora das Fontes uranium mine, located in central Portugal, was closed down in 1971. The treatment of ores from this mine and other mines by heap-leach ended in 1982. Seven dumps partially covered by vegetation were left in the area. Soil and stream sediment samples were collected in December 2009. The remediation was carried out from May 2010 to January 2011. Stream sediment samples were collected again in October 2013. Before the remediation, soils from inside the mine influence area have higher Al, As, Co, Cr, Cu, Fe, Ni, Sr, Th, U and Zn concentrations than soils from outside this area, due to radionuclides, metals and metalloid released from the mine dumps. The principal component analysis (PCA) shows a distinction between soils from inside and outside the mine influence area. The U(VI), As(V) and metals from soils can be adsorbed to Fe-oxyhydroxides and the humic acid can increase the U uptake. Soils must not be used for public or private green and residential areas, because they are contaminated in U, As, Co, Cd and Ni. Before the remediation, downstream sediments have higher Al, As, Cu, Mn, Ni, Pb, U and Zn than upstream sediments, due to erosion and percolation of water through the mine dumps. The PCA shows a distinction between downstream and upstream sediments. The U(VI), Th and As(V) can be adsorbed to Fe-oxyhydroxides. The stream sediments are contaminated in As, Mn, Th and U. Downstream sediments are the most contaminated in U and As. After the remediation, upstream and downstream sediments have generally higher Al, Fe, As, Cr, Ni, Th, U and Zn concentrations than before the remediation, attributed to the relocation of dumps. Radionuclides, metals and metalloids were transported by surface water. Consequently downstream sediments have higher Al, As, Cu, Mn, Ni, Th, U and Zn concentrations than upstream sediments. The U(VI), Th and As(V) can be adsorbed to Fe-oxyhydroxides. Stream sediments became more contaminated in U, Th and As than before the remediation, but more intensively downstream.