三维激光扫描技术在矿山开采边坡形变监测中的应用

针对某铁多金属矿山开采边坡存在部分区域滑塌的基本现状,为及时分析边坡是否存在大规模形变灾害,使用三维激光扫描技术对该边坡进行形变监测研究。结果表明,三维激光扫描技术较好地弥补了传统单点监测模式的弊端,能够从不同时段DEM叠合图中判断形变的运动方向以及形变量大小,更好地预判形变运移方向以及演化规律;通过边坡形变监测对比,不同的DEM模型存在较明显的变化,共识别出5处微小形变区域,经过实地勘察后,与实地形变特征是吻合的,说明选择并使用该方法是合理的,能够识别出微小形变,可以在矿区其他边坡监测中推广使用。     

北冶镇裴岭村陈庄铝土矿矿山地质环境修复与综合治理

针对矿山地质环境破坏、地质灾害、水土流失及土地功能退化、生物多样性受损等生态环境问题,以北冶镇裴岭村陈庄铝土矿为例,分析了矿山主要地质环境问题,主要是高陡边坡和采坑,提出了2套具有针对性的防治工程比选方案,并根据施工难度、工程量方面、对周边原生环境的保护和对附近居民影响等方面,选择方案1。依据研究区的地形地貌条件,此次治理研究区分项工程主要有挖填方工程、覆土及平整工程、田埂工程、土壤改良工程、绿化工程、养护工程和监测工程。研究最大程度改善矿山生态环境质量,降低地质灾害的发生,保障项目区及周边生态安全。     

Electrokinetic geosynthetics in hydraulic applications

In use most geosynthetics play a passive role. New applications for geosynthetics have been identified if they can provide an active role, initiating biological, chemical or physical change to the matrix in which it is installed as well as providing the established functions. This can be achieved by combining the electrokinetic phenomena of electro-osmosis, electrophoresis and associated electrokinetic functions such as electrolysis with the traditional functions of geosynthetics of drainage, filtration, containment and reinforcement to form electokinetic geosynthetics (EKG). Electrokinetic geosynthetics can be made singly or from combinations of woven, non-woven, needle punched knitted, extruded or laminated materials and can be formed in any 2D or 3D shape.The majority of the uses of EKG are in hydraulic applications or applications with a significant hydraulic component. These can be grouped in separate engineering categories such as civil, mining, and water engineering. The concept of electrokinetic geosynthetics is described and details of applications and case studies are provided in the paper.     

Sorption Behavior of Carrier-Free Technetium-95m on Minerals,Rocks and Backfill Materials under both Oxidizing and Reducing Conditions

The sorption behavior of ^95mTc on various sorbents, including minerals, rocks and backfill materials was studied in both oxidizing (0.16 M-mol·dm^?3-NO^? ₃), reducing (0.1 M and NaBH₄) solutions. Under oxidizing condition, distribution coefficient K _d ranged from 0 to 4.5cm³·g^?1 for minerals and rocks. Under reducing condition, the values exceeded 140 cm³·g^?1 for active carbon, and ranged from 13 to 70 cm³·g^?1 for minerals and rocks, and in both cases showing a tendency to decrease with increase of coexisting salt concentration and of sorbent particle size. Similarly under reducing condition, the Freundlich sorption isotherms of Tc on active carbon and on bentonite presented a break in slope when the concentration of unsorbed Tc remaining in solution lowered to a certain level. The slopes before and after the break were more moderate on active carbon and on bentonite than on other minerals and rocks, in which case no break in slope took place on the isotherms within the range covered in the present experiment.     

Carbon monoxide electrooxidation on porous Pt–Ru electrodes in sulphuric acid

CO electrooxidation on a Pt–Ru/C catalyst was investigated in sulphuric acid electrolyte. The physico-chemical properties of the Pt–Ru/C catalyst were studied by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The influence of temperature, CO partial pressure and proton concentration on the electrochemical oxidation rate was investigated by steady-state galvanostatic polarization measurements. The apparent activation energy decreased from 70 to 30kJmol–1 as the overpotential increased from 0.5 to 0.9V vs NHE. The reaction order with respect to carbon monoxide increased, passing from 0.4 to 1, with the increase of the overpotential from 0.5 to 0.7V vs NHE; a reaction order close to –1 with respect to the protonic concentration was observed, irrespective of the potential. Tafel slopes of about 136mVdec–1 were determined for oxidation of CO and CO/N2 mixtures.     

Evaluation of corrosion resistance of two engineering alloys in molten salts by electrochemical techniques

The electrochemical behaviour of two steels typically used in power boilers has been studied in the temperature range from 540°C to 680°C. Two environments were used: a) a synthetic salt mixture of 80% V₂O₅ ? 20% Na₂SO₄ and b) oil ash collected from a high temperature reheater. Corrosion rates obtained from electrochemical potentiodynamic polarisation curves (Tafel extrapolation) were compared for both steels exposed in each environment. The results showed that increases in temperature resulted in higher corrosion rates, being this effect most notorious above about 620°C. In the synthetic salt, and at temperatures up to about 580°C, both steels showed similar behaviour. With further increases in temperature, the T22 steel was less resistant and, at the highest temperature used here, its corrosion rate was almost seven times higher than that measured for the 347H steel. The results obtained with the natural oil ash for the T22 steel showed a dramatic increase in corrosion rate as temperature goes up over the range used. For the 347H steel, and up to about 580°C, the corrosion rates were similar to those obtained with the synthetic salt. Above 580°C, the corrosion rate measured increased slightly with temperature, being at 680°C about 2.5 times higher than that found by using the synthetic salt. Therefore, an important difference in corrosion rates has been found depending upon the corrosive salt used. This is an important result because imply that, at least for materials used in fossil power plants, more realistic data can be obtained by using natural ashes in the experimental work.     

多雾条件下边坡雷达在露天矿山边坡监测中的应用研究

针对南方多雾等恶劣条件下露天矿山边坡监测困难等问题,本文以边坡雷达为监测手段,选取遂川县坚基矿业车元坳矿区为研究对象,对该矿露天采场边坡进行非接触式不间断监测,结合车元坳矿区边坡雷达2023年11月9日—2023年12月8日的监测数据,通过对数据异常区域与矿山实际现场勘查进行对比分析。研究结果表明：根据11月09日—11月14日变形数据,局部区域变形量剧增,经现场人工巡检并采取治理措施,表明边坡雷达在露天矿山边坡监测作用有效,监测数据是可靠的;边坡雷达在多雾条件下仍能维持其监测性能。研究结果可为南方其他露天矿山边坡选取监测手段提供一定的参考。     

基于粗糙集理论的岩体边坡稳定性模糊综合评判

将粗糙集理论与模糊集理论相结合,应用于边坡稳定性问题中,利用粗糙集理论中的知识约简方法挖掘评价指标。把权重问题转成粗糙集理论中的属性重要性问题,建立了关于边坡稳定性分级评价的关系数据模型。评价结果表明:预测等级比较客观地反映了边坡稳定性的复杂状况,且该方法操作简单,结果可信。     

Quantification of Tafel coefficients according to passive/active state of steel carbonation‐induced corrosion in concrete

Statistical quantification of Tafel coefficients is investigated in this study for isolated steel rebar embedded in concrete. The survey is supported by a wide experimental campaign carried out earlier to characterize the passive and active states of carbonation‐induced corrosion of steel. Electrochemical measurements (polarization resistance, corrosion potential, Tafel coefficients) and gravimetric estimations of iron loss were regularly conducted over 417 days on 108 concrete specimens. The statistical analysis reveals that the mean value of Tafel coefficients, both cathodic and anodic, is higher under active corrosion, which seems to contradict the general tendency found for chloride‐induced corrosion, while their coefficient of variation is smaller. The statistical inference was based on the first step of distributions fitting the experimental data and then on the second step of goodness‐of‐fit tests. The most suitable of the distributions proposed were the Burr, Rayleigh, and Gamma distributions. A similar analysis was made for the corrosion potential and polarization resistance. The findings of the study will be valuable for probabilistic approaches to corrosion where probabilistic distributions are required.     

Effect of steel microfibers on corrosion of steel reinforcing bars

Steel microfiber reinforcement was previously found to be successful in mitigating alkali silica reaction in concrete, an expansive phenomenon. The use of steel microfibers to mitigate rebar corrosion, another expansive reaction, was investigated. Mortar specimens with and without steel microfiber reinforcement were exposed to a corrosive environment. All specimens were prepared with water/cement ratios of both 0.40 and 0.55, cured for 28 days, and then submerged in aerated 3.5% NaCl solution. The corrosion behavior of the specimens was monitored via electrochemical measurements. Three types of electrochemical tests were performed: corrosion potential measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy. Chloride concentration measurements and microscopic analysis were performed as well. The polarization curves, Tafel, and polarization resistance measurements indicate that the steel rebar in the microfiber-reinforced mortars are more resistant to corrosion than the rebar in the control mortars, despite higher chloride concentrations. Furthermore, the steel microfiber-reinforced cement based materials have a lower electrolytic resistance. This is not indicative of a higher corrosion rate, which would be the case if it had been observed in standard mortar specimens.