遥感技术在大同矿区地质灾害调查中的应用

煤矿是我国国民经济的支柱产业之一。而采矿引起的一系列地质灾害不仅威胁矿区安全,而且影响和制约着经济的发展,从而引发一系列社会问题和矛盾。大同地区最主要的矿山地质灾害是以煤矿开采引发的地面塌陷。而遥感作为信息获取的快速、有效的工具,具有宏观性好、更新周期快、人为因素干扰小等优点,可以直接为地质灾害监测的决策者提供丰富的客观数据,还可以通过推理、演绎和归纳等科学方法,提炼出需要的科学数据,这样不仅丰富了地质灾害监测决策的技术手段,还大大提高了决策的效率。     

Study of Thermal Degradation Kinetics of Elastomeric Powder (Ground Tire Rubber)

This paper investigates the use of thermogravimetric analysis to study the kinetics of thermal degradation of ground tire rubber (GTR) obtained from reclaimed tires. We analyzed the composition of GTR and determined the content percentage of its components (volatile compounds, rubber, and ash) using thermogravimetric analysis (TGA). T ₁ and T ₂ temperature peaks corresponding to the maximum normalized weight loss rate (NWLR) of the two main rubber components of tires NR (natural rubber) and a BR/SBR (butadiene/styrene-butadiene rubber blend) using the Gaussian deconvolution method has been determined. The influence of GTR particle size and heating rate on reaction rates (dx/dt) and on degradation time during the degradation process has been analyzed.     

Pillar design and coal burst experience in Utah Book Cliffs longwall operations

Longwall mining has existed in Utah for more than half a century. Much of this mining occurred at depths of cover that significantly exceed those encountered by most other US longwall operations. Deep cover causes high ground stress, which can combine with geology to create a coal burst hazard. Nearly every longwall mine operating within the Utah's Book Cliffs coalfield has been affected by coal bursts. Pillar design has been a key component in the burst control strategies employed by mines in the Book Cliffs.Historically, most longwall mines employed double-use two-entry yield pillar gates. Double-use signifies that the gate system serves first as the headgate, and then later serves as the tailgate for the adjacent panel. After the 1996 burst fatality at the Aberdeen Mine, the inter-panel barrier design was introduced.In this layout, a wide barrier pillar protects each longwall panel from the previously mined panel, and each gate system is used just once. This paper documents the deep cover longwall mining conducted with each type of pillar design, together with the associated coal burst experience. Each of the six longwall mining complexes in the Book Cliffs having a coal burst history is described on a panel-by-panel basis.The analysis shows that where the mining depth exceeded 450 m, each design has been employed for about 38000 total m of longwall panel extraction. The double-use yield pillar design has been used primarily at depths less than 600 m, however, while the inter-panel barrier design has been used mainly at depths exceeding 600 m. Despite its greater depth of use, the inter-panel barrier gate design has been associated with about one-third as much face region burst activity as the double-use yield pillar design.     

舟山渔场海域环境质量评价

利用2006～2007年对舟山渔场海域的海洋环境监测结果,统计分析了舟山渔场海域环境质量状况,对舟山渔场的海域环境质量进行评价.评价结果表明:舟山渔场海域环境状况总体除了油类超标营养盐类超标,无机氮部分超标,其余COD、重金属状况尚可.     

Impedance study on calcium nitrite as a penetrating corrosion inhibitor for steel in concrete

Penetrating corrosion inhibitors are thought to be able to penetrate through the capillary structure of concrete to reinforcing steel and to reduce the already initiated corrosion of steel. In this work the ability of calcium nitrite to inhibit the chloride induced corrosion of steel was studied. The test protocol was adjusted to simulate the performance of penetrating corrosion inhibitors in concrete structures. Steel samples were first prepassivated in saturated solution of Ca(OH)₂ and then exposed to the same solution with 1% NaCl addition, simulating pore liquid in chloride contaminated concrete. After the initiation of steel corrosion, the first dose of calcium nitrite was added, and then its concentration was gradually increased and the inhibition effect was related to the molar ratio of chloride to nitrite ions [Cl⁻]/[NO₂⁻]. Different rates of the increase in the inhibitor concentration were applied.Electrochemical impedance spectroscopy was used to follow the behaviour of steel at different stages of the corrosion process. The evolution of acquired spectra reflected the initiation of localized corrosion of steel and then the gradual inhibition with increasing concentration of the inhibitor. It was found, that calcium nitrite is able to inhibit the initiated corrosion (pitting) of steel and the optimum inhibitor efficiency was observed for the [Cl⁻]/[NO₂⁻] ratio below 1. The inhibition efficiency was larger, when this value of the [Cl⁻]/[NO₂⁻] ratio was reached in early stages of the corrosion development. Calcium nitrite can be effective as a penetrating corrosion inhibitor for steel in concrete, if it will be present in the sufficient concentration at the steel surface in early stages of the corrosion development.     

Evolution of strength, microstructure and mineralogical composition of a CKD–GGBFS binder

Characterization of a nontraditional binding material containing cement kiln dust (CKD) and ground granulated blast furnace slag (GGBFS) is discussed in this paper. Significant compressive strength was obtained for a CKD–GGBFS blend with 70% CKD and 30% GGBFS at a water-to-binder ratio of 0.40 after 2 days of curing at elevated temperature. Similar strength was also obtained for the samples subjected to normal moisture curing over a period of 28 days. The compressive strength increased with additional moist curing in both the cases. The microstructural and the mineralogical examinations show that the strength development was mainly due to the formation of calcium silicate hydrate (C-S-H). In addition to normal C-S-H, aluminum and magnesium incorporated C-S-H phases were also present in the CKD–GGBFS blends. The formation of ettringite appears to be a contributing factor in early age strength development of CKD–GGBFS binder.     

Sulfate attack on alkali-activated slag concrete

This paper presents an investigation into durability of alkali-activated slag (AAS) concrete in sulfate environment. Two tests were used to determine resistance of AAS concrete to sulfate attack. These tests involved immersion in 5% magnesium sulfate and 5% sodium sulfate solutions. The main parameters studied were evolution of compressive strength, products of degradation, and microstructural changes. After 12 months of exposure to the sodium sulfate solution, the strength decrease was up to 17% for AAS concrete and up to 25% for ordinary Portland cement (OPC) concrete. After the same period of exposure to the magnesium sulfate solution, the compressive strength decrease was more substantial, up to 37% for OPC and 23% for AAS. The main products of degradation were ettringite and gypsum in the case of Portland cement and gypsum in AAS. OPC samples had significant expansion, cracking, and loss of concrete, while AAS samples were not expanded but cracked in the test. During experiments with the sodium sulfate solution, some increase in strength of AAS concrete was recorded, likely due to continuing hydration.     

矿渣微粉对混凝土抗冻融耐久性的影响

试验研究了矿渣微粉对混凝土强度和抗冻性能的影响.结果表明,同基准混凝土相比,掺入20%～50%比表面积为475m2/kg的矿渣微粉,可以明显提高混凝土的后期强度,并降低冻融循环后重量和动弹性模量的损失率.这说明矿渣微粉对混凝土具有显著的增强作用,并对混凝土的抗冻性能具有很好的改善作用.     

油田地面注水系统规划技术研究

油田地面注水系统是油田注水系统的重要组成部分，其规划关系到整个系统的投资和运行成本，对于油田地面注水系统的规划技术进行了研究，采用分级优化的策略，将整个系统的规划问题分解为注水支线管网的规划和注水干线管网的规划两部分，在注水支线管网的规划中，提出了以系统投资和系统可靠性为目标的数学模型，并对模型进行了求解，针对注水干线管网的特点，通过对注水站站址的优选，主干线的走向及干线与支线交点的确定，在满足工艺要求的条件下，实现对注水干线管网的优化，使管线费用达到最少。     

疏干补偿法与渗渠（一）：开采储量释疑

井流和沟流的水,实际上是从水面以上,在其降落并扩大过程中排除的储存水,并沿垂直方向供应着,重力水从土壤颗粒间排除后减为薄膜水每需1—2天,垂直供水可以维持很久,潜流也决不会绝对稳定。除此,潜水降落漏斗的范围以及潜水储存量的类型也在此加以介绍。