参考作物腾发量预测的径向基函数法

探讨了采用径向基函数网络模型进行参考作物腾发量预测方法的可行性,设计多组数字实验处理研究了输入因子间相关性对网络模型预测准确性的影响,预测结果与Penman-Montieth方法计算结果比较表明,所确定的模型与改进的Penman公式计算值有很高的一致性,具有一定精度。     

钻孔灌注桩与喷射注浆组合支护结构

提出采用钻孔灌注桩与喷射注浆的组合形式作为深基坑的支护结构,该种组合支护结构具有防渗效果好,施工速度快,造价低等优点,是一种很有发展前任的新型支持结构。     

Tsilmanite as a new type of jet

A new type of jet from continental Devonian deposits of the Middle Timan is described. Fragments of Archaeopteris were the substrate for jet formation. Fossils in sandstone layers are characterized by a peculiar spheroidal jointing of organic matter; the material is fusainized completely. The jet is characterized by integration of the properties of classic jet and inertinite. The proper name tsilmanite is suggested for the new type of jet after the place of its discovery.     

Ground-water investigation following a jet fuel release

A tanker truck overturned releasing about 11,350 l of aviation fuel. As two municipal supply wells were within about 396 m of the release, contaminated soil was excavated and an assessment of hydrologic conditions was completed. A recovery well (RW) and five monitoring wells were installed. Ground-water samples were collected periodically from these wells and the municipal supply wells for analysis for volatile organic compounds. Pumping tests were completed on the RW and one municipal supply well. The results of the pumping test on the RWs were used to design a remediation system to remove jet fuel components from the ground water. The pumping tests also demonstrated that there was a ground-water divide separating the spill site from the municipal supply wells. After about 7 months of remediation, samples from the RW and municipal supply wells were clean and the state issued a clean closure.     

The Eotvos force revisited

The Eotvos acceleration, too low to be the principal driving force in Wegener's theory of continental drift, where the decoupling surface was placed between crust and mantle, must be re-evaluated in the context of Plate Tectonics, where the same surface is localized at the lithosphere-asthenosphere boundary. In this note, taking into account the departure from spherical symmetry of the Earths internal gravitational potential, a value for the Eotvos acceleration is obtained that is one order of magnitude larger than pre-Plate Tectonics estimates and almost two times greater than more recent results. This force was higher in the geological past because the Earths angular velocity and flattening were greater than today, and thus may be considered in the large-scale reconstruction of continental displacements.     

简述辐射井施工工艺

为有效利用地下水,目前多采用大口径辐射集中取水。集水井主要采取沉井法和现浇逆作法进行施工;辐射管井主要采用锚孔施工机械或液压机械岩心钻机水平钻进成孔工艺施工。     

驱动板块动力源之一—地磁斥、引力初探

板块运动驱动力是当代全球动力学研究的核心问题这一。通过地磁斥，引力生产与板块运动密切关系的总结，地磁斥力与地磁引力驱使板块运动的同时效应，古－今和深－浅地磁斥，引务相对大小的计算，板块俯冲深处与地幔前缘间冷接触关系的确定，板块体磁针式转动，全球构造运动与磁暴和地磁斥，引力联合效应的讨论，初步提出地磁斥，引力可作为驱动板块动力源之一，驱动板块运动是地球自转力，重力，地幔对流和地磁力综合作用的结果。     

地球电、磁力对成矿作用控制的可能联系

基于地球内核旋转产生地球电场和磁场的同时可使深部物质上涌，地球环境电磁场应与成矿作用间存在某种联系，故笔者设想地球电、磁力可能对成矿作用有一定的控制性，地球深部电场力和浅部磁场力能使导电矿物和磁性矿物发生分离或聚集，是地壳深部巨量太质预富集的重要形成过程，该过程与地壳大型超大型矿床的形成必有一定的内在关系。根据金和黄铁矿等本身所通过的电流来描述它们周围的磁场，相互作用力的大小和含金流体的性质，铁矿性矿物巨量富集与磁引力的关系。抗磁性有色多金属矿物巨量富集与磁斥力关系的讨论等，都表明地球电、磁力对成矿作用控制的可能联系，这种可能联系对中国东部中生代成矿的解释上充分显示出地球磁力，板块构造和环太平洋成矿带三者间的内在耦合关系。     

An empirical strength criterion for jet grouted soilcrete

Based on experimental data, this paper presents an empirical strength criterion for jet grouted soilcrete. Cylindrical specimens drilled from construction sites were tested to investigate the strength characteristics of soilcrete. Experiments conducted include the uniaxial compression test, Brazilian test and the triaxial compression test. It was found that soilcrete density increases with increasing depth. The uniaxial compressive strengths obtained were significantly greater than the design values suggested by the JSG Association of Japan. Experimental Poisson's ratios varied from 0.12 to 0.22, which are closer to that for concrete than that for native soil. Based on test results, a parabolic-type empirical criterionτ_ff = N·σ_ff + T_o)^M is proposed to describe the strength behaviour of soilcrete under low and tensile stress regions.     

排海污水挟沙射流研究进展

排海污水中往往含有一定数量的悬浮物,这些悬浮物在排放口附近中呈现出复杂的扩散与沉降特性,具有挟沙射流的典型运动特征。本文系统回顾了静水、恒定流、潮流和波浪等环境下排海污水挟沙射流的研究进展,发现在不同动力环境下挟沙射流泥沙沉积形态存在显著差异性。如何精细刻画波浪-水流-射流多动力耦合过程及其对泥沙输运和沉降过程的影响是排海污水挟沙射流研究的难点所在,对此提出了基于PIV/PLIF固相分离物理试验、粒子追踪两相流数值模型和拉格朗日积分模型,系统开展波流共同作用下挟沙射流运动规律研究的设想,以期为排海污水工程的优化设计提供重要参考。     

射流泵流场的PIV测量

利用粒子图像速度场仪(PIV)对射流泵渐缩锥形入口、等径直管内有限空间水射流进行测量。该射流泵喉管面积与喷嘴面积之比为4.75,基于射流泵喷嘴直径D和喷嘴出口流速计算的雷诺数为3.68×105。通过流量比在0.20～0.80之间的变化来研究流量比对流场的影响。获得了射流泵对称面流场的速度矢量、轴心速度分布和轴向速度等值线图。结果表明:当射流泵的面积比确定后,射流泵内有限空间射流结构只与射流泵的流量比有关,流量比愈小,其轴心速度衰减得愈快,高速射流区愈短。测量结果为射流泵理论研究和优化设计提供可靠依据。     

A review of jet grouting practice and development

The jet grouting technique was originally initiated in the UK and progressively developed following the needs for larger geometries, ease of implementation, economic rationality, and better mechanical properties. This paper presents a comprehensive review of the development and practice of jet grouting through some fundamental concepts and relevant case studies. Subsequently, a laboratory testing program is performed to investigate the factors affecting the efficacy of the twin grouting system. The principal objective of this study is to define the suitable conditions for the jet grouting efficacy regarding economic rationality as well as quality control. For the first phase, a particular emphasis is placed on the properties of jet columns, site geological conditions, implementation methods, and the justification of each selected treatment option, while the second phase mainly focuses on the unconfined compressive strength (UCS) tests. It follows that the mono-fluid jet grouting system presents a valuable flexibility in dealing with complex configurations; yet, the double- and triple-fluid systems are more indicated for cases of mass treatments for which large portions of space must be treated and overlapping is fundamentally important for the reliability of the treatment. Furthermore, it was established that the efficacy of the twin-jet method primarily relies on the proper adequacy of some critical parameters, namely, the cement content, the water-cement ratio, and cement slurry-water glass ratio. In spite of some uncertainties inherently related to the technique, the UCS test represents the quintessential laboratory index for evaluating the mechanical properties of grouted elements, deriving jet grouting efficacy and the economics of jet grouts.     

长效振弦式锚索测力计应用研究

介绍了长效振弦式锚索测力计传感器的工作原理、结构特点、技术性能和配套仪器,并对主要相关技术的应用研究成果作了论述:(1)弱激发电路解决频率不一致问题;(2)微小变形原则解决长期稳定性问题;(3)新数学模型提高了传感器准确度,二次仪表提高了传感器准确度。     

Non-lethal force and peace operations

The changed national security policy of the United States government implies a new national security strategy subsuming a new military strategy. The strategic emphasis is upon a fundamentally different approach to the use of force. Within this context, the focus of the paper is upon a detailed consideration of the role of non-lethal force in peace operations.     

The interplanetary magnetic field: Radial and latitudinal dependences

Results of the analysis of spacecraft measurements at 1–5.4 AU are presented within the scope of the large-scale interplanetary magnetic field (IMF) structure investigation. The work is focused on revealing of the radial IMF component (B _r ) variations with heliocentric distance and latitude as seen by Ulysses. It was found out that |B _r | decreases as ～r ^?5/3 in the ecliptic plane vicinity (±10° of latitude), which is consistent with the previous results obtained on the basis of the analysis of in-ecliptic measurements from five spacecraft. The difference between the experimentally found (r ^?5/3) and commonly used (r ^?2) radial dependence of B _r may lead to mistakes in the IMF recalculations from point to point in the heliosphere. This can be one of the main sources of the “magnetic flux excess” effect, which is exceeding of the distantly measured magnetic flux over the values obtained through the measurements at the Earth orbit. It is shown that the radial IMF component can be considered as independent of heliolatitude in a rough approximation only. More detailed analysis demonstrates an expressed |B _r | (as well as the IMF strength) increase in the latitudinal vicinity of ±30° relative to the ecliptic plane. Also, a slight increase of the both parameters is observed in the polar solar wind. The comparison of the B _r distributions confirms that, at the same radial distance, B _r values are higher at low than at high latitudes. The analysis of the latitudinal and radial dependences of the B _r distribution’s bimodality is performed. The B _r bimodality is more expressed at high than in the low-latitude solar wind, and it is observed at greater radial distances at high latitudes. The investigation has not revealed any dependence between B _r and the solar wind speed V. The two-peak distribution of the solar wind speed as measured by Ulysses is a consequence of a strong latitudinal and solar cycle dependence of V. It is shown that the solar wind speed in high latitudes (above ±40°) anti-correlates with a solar activity: V is maximum during solar-cycle minima and minimum at the maximum of solar activity.     

Radial Permeability Measurements for Shale Using Variable Pressure Gradients

Shale gas is becoming an important component of the global energy supply, with permeability a critical controlling factor for long-term gas production. Obvious deviation may exist between helium permeability determined using small pressure gradient(SPG) methods and methane permeability obtained under actual field production with variable pressure gradients(VPG). In order to more accurately evaluate the matrix permeability of shale, a VPG method using real gas(rather than He) is established to render permeability measurements that are more representative of reservoir conditions and hence response. Dynamic methane production experiments were performed to measure permeability using the annular space in the shale cores. For each production stage, boundary pressure is maintained at a constant and the gas production with time is measured on the basis of volume change history in the measuring pump. A mathematical model explicitly accommodating gas desorption uses pseudo-pressure and pseudo-time to accommodate the effects of variations in pressuredependent PVT parameters. Analytical and semi-analytical solutions to the model are obtained and discussed. These provide a convenient approach to estimate radial permeability in the core by nonlinear fitting to match the semi-analytical solution with the recorded gas production data. Results indicate that the radial permeability of the shale determined using methane is in the range of 1×10-6– 1×10-5 mD and decreases with a decrease in average pore pressure. This is contrary to the observed change in permeability estimated using helium. Bedding geometry has a significant influence on shale permeability with permeability in parallel bedding orientation larger than that in perpendicular bedding orientation. The superiority of the VPG method is confirmed by comparing permeability test results obtained from both VPG and SPG methods. Although several assumptions are used, the results obtained from the VPG method with reservoir gas are much closer to reality and may be directly used for actual gas production evaluation and prediction, through accommodating realistic pressure dependent impacts.     

基于力链的岩石单齿截割特性研究及截割力预测

截齿是煤矿采掘机械上截割工作的主要承载对象,其与工作面的截割力预测对减小截齿磨损十分重要。利用颗粒流仿真软件PFC2D将被截割岩石作为颗粒物质进行单齿截割模拟仿真,通过研究截割时颗粒间力链的特性探讨了单齿截割岩石时接触状态对截割力的影响。利用单齿截割岩石试验台进行了截割力试验,获得了截割法向力和切向力随截割参数的变化规律及掉落碎片的特征。研究结果表明,单齿截割岩石颗粒物质的力链数目与力链长度的关系符合单轴压缩试验结果,能够采用离散元的方法对截齿截割状态进行模拟。力链网络沿着点接触方向扩散并延长,力链方向与截割角度有关,平均法向力方向呈“花生”状,切向力方向呈“花瓣”状。力链数目随截割角度的减小和截割深度的增加而减少,力链长度随截割距离的增加而增加,最大平均长度为8个颗粒尺寸。当截割角度较大时,较为容易形成力链。单齿截割天然砂岩法向力和切向力随截割角度的增加和截割深度的减小而减小。截割碎片尺寸与截割切向力线性拟合度为0.87。基于力链长度的截割力预测模型相比Evans预测模型法向力精度提高了17.6%,切向力精度提高了16.9%。研究结果能够为截齿和采掘机械截割系统的设计以及截割工艺的优化奠定一定的研究基础。     

脉冲磨料射流破碎岩石的实验研究

在淹没和非淹没状态下研究了脉冲射流的动态特性、振荡腔腔长、靶距、磨料浓度等参数与脉冲磨料射流的切割和冲蚀性能的关系,对比分析了脉冲磨料射流与前混合磨料射流在相同实验条件下对花岗岩及石灰岩等的冲蚀性能。实验结果表明,自激振荡射流频率随腔长增大而减小,随压力及流量的增大而增大;脉冲磨料射流的体积冲蚀速度在淹没状态下是前混合磨料射流的1.7倍,而在非淹没状态下为前混合磨料射流的1.4倍。     

置换式旋喷原理及工艺技术

传统的旋喷成桩工艺,在施工过程中,桩孔口有冒浆溢出,并含有一定量的水泥,为解决此问题,作者提出了液态式置换和固态式置换旋喷原理及工艺技术,可使桩孔口无溢浆或溢浆中仅含微量水泥,并通过实例介绍了该技术的应用。