Mine ventilation planning in the 1980s

Conclusions In this paper, the author has attempted to trace the development of mine ventilation planning from the traditional, manual and largely empirical methods of the past to the numerate computer-based techniques of the 1980s.The computer revolution has changed the face of many engineering disciplines, not least mine environmental engineering. Nevertheless, the mining industries of the world have not all been equally progressive in adapting to the flexibility, power and practical utilization of the new methodologies. It is, for example, incongruous that current textbooks on mine ventilation separate completely the topics of network analysis and ventilation planning with very little cross-referencing. Many of the current generation of mine ventilation engineers recognize the need to know about computers but find difficulty in translating this into their daily work. The growing availability of self-teaching, friendly software for personal microcomputers, coupled with interactive graphics, will assist greatly in promoting uncomplicated but powerful usage of computers.Young engineers now graduating from universities and colleges have been brought up in a computer-oriented environment and are competent in interacting with these machines. Indeed, they wonder how the job was ever done without magnetic data bases and high-speed computation aid.     

Hydraulics of runoff and loess loam deposition

On many more or less loamy soils, rill erosion is reported to start on slopes that are equal to or steeper than 2–3°; critical Froude numbers for the start of rill wash on these slopes vary between 2·0 and 3·0. This explains why colluvial deposition often occurs on slopes below 2–3°, when water spreads out at the downslope extremities of the rills. The critical hydraulic conditions for loess loam deposition were tested in the laboratory for slopes of 0·5° and 2°, applying unit-discharges (q) up to 10 cm²/s. It appeared from these experiments that for afterflow, without raindrop impact, deposition starts for critical load concentrations (c_cr) varying between several g/1 and about 60 g/l. Under rain c_cr amounts to a minimum value of 100–125 g/l and it increases when the runoff film becomes thinner. Nevertheless, deposition in pluvial runoff is also possible, as was the case during the Weichselian, according to data from quarries in Belgium and in The Netherlands. A modified Kalinske equation is proposed for c_cr prediction, with the introduction of a typical empirical coefficient C_r and considering such factors as shear stress and mean particle size. Massive sedimentation may occur when it stops raining and afterflow starts, since c_cr values are then much lower. It is shown from the Shields' diagram that loamy suspensions are more sensitive to sedimentation than sands in clear water.     

单桩竖向抗压极限荷载的极限状态与确定

本文通过对桩的荷载传递和沉降分析，研判了桩的极限载荷的极限状态，并结合工程实例予以说明。根据文献提供的资料，建议桩的极限荷载宜采用Ｓ－ｌｏｇＰ法确定。     

Buckling of Piles under Liquefied Soil Conditions

The paper pertains to the analysis of piles embedded in liquefiable soils to predict its’ critical buckling load under partial to full loss of lateral support over a portion of the pile length. The analysis is based on extension of Mindlin solution for a point load acting inside a semi infinite elastic half space. Degenerated solutions obtained by using the developed method compares very well with reported results. Parametric studies showed that the depth of liquefiable soil, degradation of soil strength on liquefaction, slenderness ratio, pile stiffness factor and end conditions have significant influence on the buckling behavior of the piles.     

REGULATION OF FLOW AND SEDIMENT LOAD IN THE YELLOW RIVER

Small runoff, large sediment load, and incompatible relationship of flow and sediment load are very important characteristics of the Yellow River. They are also the crux of the most prominent problems of the Yellow River. To solve these problems, the regimes of flow and sediment load have to be improved by increasing water, reducing sediment load, and by using reservoirs to regulate flow and sediment load. The results of experiments for regulating the flow and sediment load in the last three years by the Xiaolangdi Reservoir have indicated that this measure is a realistic and effective way to mitigate the prominent problems in flood control of the Lower Yellow River at present and in the near future. However, the regulation system is still imperfect. It is advisable to speed up the pace of research and construction of the system for regulating flow and sediment load.     

Suspended sediment load transport in the Mississippi River basin at St. Louis: temporal scaling and nonlinear determinism

This study investigates the dynamic behavior of suspended sediment load transport at different temporal scales in the Mississippi River basin. Data corresponding to five successively doubled temporal scales (i.e. daily, two‐day, four‐day, eight‐day and 16‐day) from the St. Louis gaging station in Missouri are analyzed. The investigation is focused on identifying possible low‐dimensional deterministic behavior in the suspended sediment load transport dynamics, with an aim towards reduction in model complexity. The correlation dimension method is used to identify low‐dimensional determinism. The suspended sediment load dynamics are represented through phase‐space reconstruction, and the variability is estimated using the (proximity of) reconstructed vectors in the phase space. The results indicate the presence of low‐dimensional determinism in the suspended sediment load series at each of the five temporal scales, with the variables dominantly governing the dynamics in the order of three or four. These results not only suggest the appropriateness of relatively simpler models but also hint at possible scale invariance in the suspended sediment load transport dynamics. Copyright © 2006 John Wiley & Sons, Ltd.     

雅安市魏家岗加油站工程滑坡形成条件及治理措施

魏家岗滑坡因保坎条石砌筑的施工质量差，保坎上又堆放弃土增加荷载，加之雨水渗透而形成工程滑坡，本文对滑坡形成的条件进行了论述，并提出了治理滑坡的措施。     

水平荷载作用下单桩非线性m法试验研究

通过对大量模型试验结果的分析，提出了简便合理的水平荷载作用下单桩的计算方法。该方法将常用m法中单一m值与位移建立指数关系，并由bm有k两参数来描述。将这一关系引和常用单桩m法计算中，则计算结果可考虑单桩非线性响应影响。     

气象条件对小麦中量元素和微量元素含量的可能影响

该文通过试验研究了气象条件 (CO₂浓度、温度、土壤湿度) 变化对小麦叶片、茎、籽粒中量元素 (Mg、Ca、S) 和微量元素 (Zn、Fe) 含量及产量的影响。结果表明:高CO₂浓度、土壤干旱胁迫对这5种元素含量积累有利; 高CO₂浓度伴随高温缩短了小麦生育期, 使籽粒产量明显下降, 综合中量元素和微量元素含量的有利影响和产量的不利影响, 要想获得正常气象条件下等量的5种元素, 小麦的供给量将会是短缺的。     

LONG TERM EFFECTS OF REHABILITATION MEASURES ON BED LOAD TRANSPORT AT THE SALZACH RIVER

1 BASIC PROBLEMFlood protecton, sPreaing of settlements and occuPatin Of river valleys were maor reasons to damand lindt rivers throughout Europe in the ndd 19th century. Engineers of those days often knew very wellabout the effects of their plannings: shortening the river length would accelerat the now and thusencourage the erosion into the river's sedAnents. Two vital advanages could be obtalned from that kindof constrUction, landuse of the fOrmer flood plains on the one and increasin…