Trees and wood: working with natural river processes

A history of land clearance and riparian tree and wood management has resulted in limited riparian woodland and wood along British rivers. However, river management approaches are now being promoted that ‘work with natural processes’ to reduce flood risk through measures intended to restore, protect and emulate the natural function of catchments, rivers, estuaries and coasts. Wood has started to be reintroduced into river channels during river restoration and natural flood management activities, but this needs to be undertaken using appropriate quantities, locations and designs that mimic natural tree‐wood features. This paper reviews the knowledge that is needed to support wood reintroduction activities including (i) the characteristics of the riparian tree species and wood that are present; (ii) the importance of river size relative to that of trees and wood pieces; and (iii) the way trees, wood and geomorphic processes interact across rivers and floodplains of different energy and style.     

用搅拌磨机对滑石超细粉碎的实验研究

随着现代工业的发展,对超细滑石粉的需求量日益增加,在国内外市场上供不应求。但目前用传统的粉碎设备粉碎滑石,不可能得到-1μm的超细粉。因此,笔者用搅拌磨机对滑石的超细粉碎进行了实验研究。结果表明;用搅拌磨机粉碎滑石可获得平均粒度-1μm的超细粉;结合实验结果应用输入功率计算公式和Charles公式,根据耗电量,可随意预测出粉碎产品的平均粒度。这对生产实践具有重要的实用价值。     

Electrical blasting disintegration of copper-nickel ores conjointly with separation of particles by size

Absract The effect of electrical blast parameters is studied for grinding mineral materials by example of copper-nickel ore. It is shown that the average energy consumed by the electrical blasting is within 5–50 J/g. The particle disintegration mechanism has been considered at high and low electric conductivity of ore. It is established that grinding and separation of particles by size are possible to be performed conjointly in the same apparatus. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 1, pp. 100–107, January–February, 2007.     

气缸套等离子加工机床的研制

高能等离子束适用于切割、焊接、冶炼、喷涂、表面淬火等。在对等离子束加工特性深入研究的基础上 ,研制成功气缸套等离子加工专用机床 ,可对内燃机气缸套内壁进行自动扫描淬火 ,以达到硬化和减磨效果 ,其中等离子炬的设计采用专利技术 ,而控制器以单片机 89C5 2为核心 ,并解决了强烈的电磁干扰问题     

监控量测在浅埋地下大断面平顶框架结构施工中的应用分析

城市浅埋大断面地下结构因其结构和建设的复杂性往往成为工程建设的重点和难点。施工中如何利用监控量测技术实时监控围岩、支护结构、中间构造结构等之间的受力转换往往成为施工关键。结合北京城市快速轨道交通东直门车站地下方厅工程实例,探讨和分析了应用浅埋平顶群洞暗挖法施工过程中监控量测技术和方法,并对监测结果进行了比较分析,验证了施工方法的合理有效性。     

合理设计岩屑规程保证正常钻进条件——金刚石钻进技术专题之一

论述了正常钻进的条件，提出了合理岩屑规程是保证正常钻进的关键和设计钻头的主要依据之一，讨论了岩屑规程与金刚石钻头唇面工作状态、孔底表面粗糙度和岩屑粒度的关系，提出了相应的建议。     

膨胀石墨的尺寸效应及其对油吸附的影响

用不同粒度的石墨在相同条件下酸化、高温膨胀，可获得膨胀倍数不同的膨胀石墨。通过扫描电镜及X射线衍射等观察膨胀石墨结构，证实在生产条件如酸氧化工艺、膨胀温度等相同时，鳞片石墨的粒度越大则膨胀倍数越高，对油的吸附性能越好。     

基坑开挖过程中的土体体积变化试验

为了深入研究基坑开挖过程中周围土体的体积变化情况，采用英国GDS公司生产的STDTTS＋UNSAT（7 kN/1700 kPa）型号三轴测试系统针对基坑开挖过程中土体卸荷的应力路径进行试验研究，分析了不同初始有效应力、不同应力路径条件下土体卸荷体积变化规律，得出主动区、被动区土体随轴向应变增加经历相同的过程，但体积变化量存在显著差别;并进一步从土体内部结构的角度探讨了产生这一现象的原因，得出重塑土在制样过程中也产生结构性，在垂直向上呈现的似“环形”结构以及水平向表现为均匀分布，且随各向同性固结压力增加或单向卸荷而逐渐丧失.     

新疆某铀矿石浸出试验

为了给新疆某铀矿采用地面堆浸和井下原地爆破堆浸的采矿新方法恢复生产提供依据，对该矿矿石进行了试验室搅拌浸出和柱浸试验。试验结果表明，该矿矿石氧化剂耗量少、浸出时间短、酸耗较低，属易浸矿石。矿石粒度对浸出率影响较大，当粒度从-5mm增加到-20mm时，矿石的柱浸渣计浸出率从88.7％下降到75．2％。氧化剂可提高浸出液铀浓度，但提高幅度不大。     

REINORCING THEORY AND TECHNIQUE OF SLOPE EXCAVATION

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