NUMERICAL SIMULATION OF ROLL FORMING FORCHANNEL SECTION WITH OUTER EDGE

The finite strip method in structural analysis has been extended, and elastic-plastic large deformation spline finite strip method based on the Updated-Lagrange method (U. L. method) was established to simulate roll forming process of channel section with outer edge. The deformation characteristics of strip was analyzed, and the three-dimensional displacement field, strain field and stress field of deformed strip were got. The calculation example proves that the peak transverse pressing membrane strain is on the corner part of the deformed strip, and the peak longitudinal stretching strain is on the outer edge part of the deformed strip in front of rolls. In addition, the transverse deformation of the deformed strip is principal, and the longitudinal deformation is small.

Theory of Flexural Shear, Bending and Torsion for a Thin-Walled Beam of Open Section

Aspects of the general Vlasov theory are examined separately as applied to a thin-walled channel section cantilever beam under free-end end loading. In particular, the flexural bending and shear that arise under transverse shear and axial torsional loading are each considered theoretically. These analyses involve the location of the shear centre at which transverse shear forces when applied do not produce torsion. This centre, when taken to be coincident with the centre of twist implies an equivalent reciprocal behaviour. That is, an axial torsion applied concentric with the shear centre will twist but not bend the beam. The respective bending and shear stress conversions are derived for each action applied to three aluminium alloy extruded channel sections mounted as cantilevers with a horizontal principal axis of symmetry. Bending and shear are considered more generally for other thin-walled sections when the transverse loading axes at the shear centre are not parallel to the section = s centroidal axes of principal second moments of area. The fixing at one end of the cantilever modifies the St Venant free angular twist and the free warping displacement. It is shown from the Wagner-Kappus torsion theory how the end constrained warping generates an axial stress distribution that varies with the length and across the cross-section for an axial torsion applied to the shear centre. It should be mentioned here for wider applications and validation of the Vlasov theory that attendant papers are to consider in detail bending and torsional loadings applied to other axes through each of the centroid and the web centre. Therein, both bending and twisting arise from transverse shear and axial torsion applied to each position being displaced from the shear centre. Here, the influence of the axis position upon the net axial and shear stress distributions is to be established. That is, the net axial stress from axial torsional loading is identified with the sum of axial stress due to bending and axial stress arising from constrained warping displacements at the fixing. The net shear stress distribution overlays the distributions from axial torsion and that from flexural shear under transverse loading. Both arise when transverse forces are displaced from the shear centre.

The best hydraulic section of horizontal-bottomed parabolic channel section

The best hydraulic channel section makes the maximum flow capacity for the same flow cross-area, and the minimum cross-area and wetted perimeter for the same discharge. The construction cost can be reduced nearly to the minimum at the same time The horizontal bottom parabolic section （HBP section） is a composite section. It is important for design to find the best combination form of the horizontal bottom and the parabolic sides. This paper studies the best hydraulic section and its hydraulic characteristics. The explicit formulae are proposed to determine the dimensions and the best combination form of the horizontal bottom and the parabolic sides. These explicit formulae and the parameters make it easy to design the channel. It is shown that the ratios of the surface width to the depth and the bottom width to the depth are constant for the best hydraulic section. The comparisons with the classic parabolic, rectangular, trapezoid, triangular, semi-cubic and horizontal-bottomed semi-cubic sections show that the HBP section has the largest flow capacity and the shortest wetted perimeter for the same flow area, and has the smallest flow area for the same discharge. It is indicated that the parabolic side parts of the best hydraulic HBP section are different from those of the classic section. The results of the best hydraulic section of the classic parabolic channel cannot be applied directly to the HBC section.

Monitoring of Real-Time Complex Deformed Shapes of Thin-Walled Channel Beam Structures Subject to the Coupling Between Bi-Axial Bending and Warping Torsion

Structural health monitoring(SHM)is a research focus involving a large category of techniques performing in-situ identification of structural damage,stress,external loads,vibration signatures,etc.Among various SHM techniques,those able to monitoring structural deformed shapes are considered as an important category.A novel method of deformed shape reconstruction for thinwalled beam structures was recently proposed by Xu et al.[1],which is capable of decoupling complex beam deformations subject to the combination of different loading cases,including tension/compression,bending and warping torsion,and also able to reconstruct the full-field displacement distributions.However,this method was demonstrated only under a relatively simple loading coupling cases,involving uni-axial bending and warping torsion.The effectiveness of the method under more complex loading cases needs to be thoroughly investigated.In this study,more complex deformations under the coupling between bi-axial bending and warping torsion was decoupled using the method.The set of equations for deformation decoupling was established,and the reconstruction algorithm for bending and torsion deformation were utilized.The effectiveness and accuracy of the method was examined using a thin-walled channel beam,relying on analysis results of finite element analysis(FEA).In the analysis,the influence of the positions of the measurement of surface strain distributions on the reconstruction accuracy was discussed.Moreover,different levels of measurement noise were added to the axial strain values based on numerical method,and the noise resistance ability of the deformation reconstruction method was investigated systematically.According to the FEA results,the effectiveness and precision of the method in complex deformation decoupling and reconstruction were demonstrated.Moreover,the immunity of the method to measurement noise was proven to be considerably strong.

River Cutoff Practices on Lower Jingjiang Section of Changjiang River in the Last 30 Years

River cutoff works have been implemented on Lower Jingjiang section for 30 years. Engineering practices have shown that channel straightening has been the river regulation measure for the permanent control of the meandering Lower Jingjiang section. River cutoff have been carried out in accordance with the evolution property of meandering rivers and these works have brought about expected benefits. It has also been noted that certain aspects in river cutoff had not been fully understood. River cutoff is a dynamic engineering. River channel evolution properties shall be fully understood so as to adroitly guide actions according to circumstances in cutoff works. In addition, river channel evolution observation and engineering effectiveness monitoring should be strengthened with a view to update the designs. The diversion canals for channel shortening are of great importance that will account for the success or failure of river cutoff works. The newly formed river channels and the river regime control works on the adjacent upper and lower reaches are guarantees for river cutoff works to be brought into play in the long run.

Geologic-Geophysical Indicators of the Deep Structure of Zones of Geothermal Anomalies for Allocation of Channels of the Deep Heat and Mass Transfer

On the basis of the analysis of field thermogeochemical data along abnormal zones of a thermal stream in the Bukhara-Khiva, oil-and-gas region of the Turan (Tegermen, Chagakul, Shimoly Alat, Beshtepa) was succeeded to obtain important data on a deep structure of sites. Data of gas-chemical and geothermal observations show about confinedness of abnormal concentration of methane to zones of the increased values of the temperature field the measured values of temperatures (Tegermen Square and others). On geoelectric section mines 2-D of inversion of the MT-field depth of 4000 m are lower, among very high-resistance the chemogenic and carbonate deposits of the Paleozoic is traced the subvertical carrying-out abnormal zone. This zone is identified as the channel of a deep heat and mass transfer with which hydrocarbon (HC) deposits are connected. It is shown that electro-investigation when using a geophysical complex can and has to become “advancing” at exploration by oil and gas.

U型渠道移动式流线型量水槽扩散段水力特性及结构优化方法

移动式量水槽较固定式具有不易淤积、可移动多处重复使用等优点,流线型外形的量水槽水力性能好,量水槽的扩散段对水力性能影响大,然而当前还缺乏扩散段的设计原理与方法方面的研究。为了研究量水槽结构型式对水力特性的影响,为流线型量水槽结构设计提供理论指导,该研究建立D40U型渠道模拟模型,其后用FLOW-3D对35、45和55 L/s流量下的半椭圆+半椭圆、半椭圆+抛物线、半椭圆+圆弧、半椭圆+Myring曲线和鱼形量水槽进行模拟,结合原型试验验证数值模拟效果,探讨扩散段设计原则与方法。最后基于isight平台对水力性能较好的半椭圆+Myring曲线和鱼形量水槽进行结构优化。结果表明,45 L/s流量下不同进水口距离下水深数值模拟与试验值相对误差为0.1%~1.3%,上游、喉口和下游断面流速相对误差分别为0.19%~6.63%、0.06%~6.15%和0.02%~6.22%,模拟结果精度高。5种量水槽上游佛汝德数均小于0.5,最大壅水高度为5.71 cm,均满足测流精度和渠道安全要求。其中,半椭圆+Myring曲线量水槽水头损失和壅水高度最低,半椭圆+半椭圆量水槽临界淹没度最高,佛汝德数最小。量水槽扩散段设计原则为:在略微减少临界淹没度的条件下,扩散段前半段设计为曲率较大的曲线,以降低上游壅水高度;后半段设计为曲率相反且曲率较小的曲线,以改善过流流态,平顺水流,降低水头损失。优化后的半椭圆+Myring曲线和鱼形前半段曲率增大,后半段曲率减小,壅水高度和佛汝德数均有所降低,水头损失分别降低5.5%和6.3%,优化后曲线线型满足扩散段设计原则。研究可为流线型量水槽结构设计与优化提供理论指导。

持续冲刷期内黄河下游河床演变特点分析

基于2006年10月至2018年11月黄河下游12个典型断面观测数据,通过分析断面主槽平滩形态特征参数变化率及深泓线和主槽中心线的摆动强度,探讨了持续冲刷期内下游河床的调整变化过程及特点。结果表明:黄河下游断面形态调整表现出既有横向展宽又有冲深下切或淤高态势;河床平面摆动促进了断面主槽形态调整,河相系数变化率与深泓线和主槽中心线摆动强度均成正相关关系;来水来沙条件是主槽形态改变的主要驱动力,且可引起局部河段深泓线摆动强度增大。通过调整小浪底水库的运行模式及布设控导工程可进一步塑造并维持稳定的黄河下游中水河槽。

长江安徽段河道冲刷特征及江砂资源变化趋势

为了解新水沙形势下长江安徽段河道冲刷特征及江砂资源变化趋势,通过对长江安徽段水文泥沙测验资料、长程水道地形测量资料、护岸工程观测资料、崩岸险段监测资料的研究,分析长江水流输沙、河道冲淤、江岸崩岸等方面的变化。结果显示:长江安徽段河道来沙量大幅减少,2021年安徽长江大通水文站实测年输沙量比多年平均减少71%;长江安徽段河床持续净冲刷,2016—2021年长江安徽段冲刷量达3.375亿m^(3),年均冲刷量达6750万m^(3);安徽长江段崩岸加速发展,崩岸区总长418km,占安徽长江岸线的37.6%;原规划的可采砂区域已发生严重冲刷,冲刷总量达1297.1万t,大于年度控制开采总量的640万t。针对研究结果,提出了长江安徽段应当遵循“江砂不上岸”的原则,限制开采江砂资源直至全面禁止开采江砂的建议。

Calculations of state-selective differential cross sections for charge transfer in collisions between O^(3+) and H_2

The non-dissociative charge-transfer processes in collisions between O^3＋ and H2 are investigated by using the quantum-mechanical molecular-orbital coupled-channel （QMOCC） method. The adiabatic potentials and radial coupling matrix elements utilized in the QMOCC calculations are obtained with the spin-coupled valence-bond approach. Electronic and vibrational state-selective differential cross sections are presented for projectile energies of 0.1, 1.0 and 10.0eV/u in the H2 orientation angles of 45° and 89°. The electronic and the vibrational state-selective differential cross sections show similar behaviours： they decrease as the scattering angle increases, and beyond a specific angle the oscillating structures appear. Moreover, it is also found that the vibrational state-selective differential cross sections are strongly orientation-dependent, which provides a possibility to determine the orientations of molecule H2 by identifying the vibrational state-selective differential scattering processes.

爆炸冲击波在变截面通道中传播规律数值研究

为研究在变截面通道内爆炸冲击波的传播规律,利用LS-DYNA软件对变截面通道内部TNT爆炸进行数值模拟,在LS-DYNA中分析了不同截面变化中冲击波传播云图以及不同测点处超压时程曲线,研究了截面大小变化率和截面长度变化率对爆炸冲击波在变截面通道内传播的影响。结果表明:截面由小变大时,随着截面面积增大,消波率先迅速减小后略微增大再减小,整体上截面面积越大,消波效果越好;截面由大变小时,爆炸冲击波在刚进入截面缩小段,一部分直接以平面波的形式进入缩小段,一部分与截面变化处壁面发生碰撞反射,反射使得该部分爆炸冲击波超压变大并向反方向传播,当小截面缩小至原来一半时,出口处测得爆炸冲击波相当于原来2倍药量在直通道中爆炸的冲击波;同时得到了冲击波超压峰值在不同工况下沿变截面直通道内传播的拟合方程,可为研究新型消波系统提供理论依据。

分散梯级船闸输水时的作用水头和中间渠道断面形式对通航水流条件的影响

针对分散梯级船闸中间渠道的通航水流条件问题,研究了中间渠道断面形式对其影响。提出了矩形断面与梯形断面中间渠道的作用水头计算公式。采用数学数值模拟的方法研究两种断面形状对船闸通航水流条件的影响。结果表明:1)中间渠道充泄水的船闸作用水头一致,其水位呈现周期性的变化。2)改变中间渠道的断面形式对船闸输水时的流量变化趋势与输水时间影响较小。3)相较于矩形断面,梯形断面的中间渠道可以有效地减小上游船闸泄水过程中的水位变幅、振荡波波高、最大水面坡降和最大纵向流速。研究为分散梯级船闸中间渠道的设计提供了理论支持。

多断面多通道互联电网广域失步解列控制系统设计及实施

总结分析了多断面多通道区域互联电网失步振荡时可能存在的多断面失步存在选择性、同一断面不同通道失步不同时以及同一断面上部分通道失步特性不明显等特性,针对现有就地失步解列方案不适应上述特性的问题,采用基于就地装置动作允许命令,利用远方通信构建的广域失步解列系统方法,根据考虑解决现有就地失步解列方案问题、与现有就地失步解列功能的配合、系统防误设计以及异常情况下控制策略处理逻辑等主要设计原则,设计并实施了南方电网广域失步解列控制系统。RTDS仿真试验结果表明,该系统能够正确响应,有选择、快速、可靠地采取既定措施同时解列相关断面,有效解决现有就地失步解列方案的局限性,满足实际系统运行需要。

冷弯薄壁型钢纯弯构件截面分类

为研究冷弯薄壁卷边槽钢纯弯构件截面分类,基于试验数据验证后的有限元模型,对不同板件宽厚比下冷弯薄壁卷边槽钢纯弯构件进行了大量的参数分析。结果表明:抗弯承载力随翼缘与腹板宽厚比的减小而增大。在考虑翼缘与腹板相关作用的前提下,基于截面承载力得出板件截面宽厚比限值,提出了冷弯薄壁卷边槽钢纯弯构件截面分类方法。

急弯河段新建船闸上游引航道通航条件研究

在急弯河段已建枢纽上新建船闸工程,船闸布置受限因素众多,通航条件复杂。为分析船闸引航道通航水流条件,建立袁河石洲枢纽1:80正态物理模型,开展急弯河段船闸上游引航道通航水流条件试验,对比隔流堤不同长度口门区的流速分布,同时结合自航船模试验分析船闸口门区通航条件。结果表明,延长隔流堤对减小口门区横向流速峰值、改善流态作用明显;隔流堤延长250 m时,石洲船闸上游引航道最高通航流量可达到规范要求的20 a一遇洪水。

溃坝洪水演进一维水动力模型

中国是受洪水灾害影响最严重的国家之一。洪水数值模型可准确地反映洪水的演进与致灾过程。本研究针对天然河道洪水过程存在的尺度大、水流流态复杂、河道断面形式多变以及计算建模困难等问题,提出一套基于Godunov格式的有限体积法离散圣维南方程组的一维水动力模型,并采用求解复杂断面水力要素之间关系的方法,提高了一维水动力模型求解的精度与效率,精确地反映了复杂断面河道的水流运动特性。将模型模拟得到的数值解与算例中的解析解或实测数据进行对比,结果表明:(1)构建的一维水动力模型模拟结果与理想算例解析解及实验实测数据吻合程度均较高,所有算例的E NS均大于0.5,说明模型具有良好的稳定性和适应性;(2)将模型应用至金沙江白格堰塞湖溃坝洪水算例中,模拟得到的流量峰值及整体洪水过程均与实测过程吻合较好,在叶巴滩和苏洼龙两个测点处E NS分别为0.633和0.812,证明了模型在实际应用中的适用性与可靠性。结果表明,开发的一维水动力模型对溃坝洪水等水流流态复杂、突发性强的洪水过程具有良好的模拟效果。本研究可为河道及溃坝洪水风险的初步、快速评估等工作提供有效的模拟支撑。

钦州港东航道扩建工程复式航道设计

针对钦州港东航道不满足10万吨级及以上集装箱船不乘潮通航、制约钦州港发展远洋集装箱运输问题,经多方案对比分析论证,提出在原批复的10万吨级集装箱船双向乘潮通航的基础上,对其东半部按照10万吨级集装箱船不乘潮通航、兼顾15万~20万吨级集装箱船乘潮通航的标准进行局部浚深,形成一种特殊的新型复式航道,结合虚拟航标的应用和港口调度,可用较经济的方式同时兼顾超大型集装箱船对航道通航水深的需求和主力船型双向通航对航道宽度的需求。介绍了钦州港东航道扩建工程复式航道及其配套航标布置的设计要点,对航道建成后的航行规则和管理措施提出建议,并总结各类复式航道断面形式的特点和适用情形,可供类似项目参考借鉴。

柯街河道断面水位流量关系单值化工程措施研究

为掌握柯街河道断面工程措施后断面冲淤变化、水文要素测验条件和水位流量关系变化等水文特征规律,推进水文数据采集自动化,数据管理信息化、数字化、智慧化建设,开展柯街河道断面水位流量关系单值化工程措施研究。依据工程措施前后实测水文资料,采用对比分析法和误差分析法,对工程措施实施效果进行统计分析。结果表明:工程措施实施后河道断面冲淤变化明显减小,水位及流量监测条件得到改善,水位流量关系变化趋于稳定,河道断面河段高洪水位至保证水位行洪能力降低6.4%~14.9%。柯街河道断面单值化工程措施效果明显,可为下一步工作的推进及河道断面单值化工程措施的应用推广和研究提供参考借鉴。

遥感测绘技术下平原河道淤积断面智能监测

在平原河道淤积断面智能监测过程中,一般采用测绘数据构建河道水体模型,从而分析得出监测结果,但该过程忽略了测绘数据噪声对监测结果的影响,导致监测结果准确度不高。因此,本文提出基于遥感测绘技术的平原河道淤积断面智能监测方法。首先根据平原河道的走向布设遥感测绘的监测点位,并通过判决合并同一测点内的一致光谱波段区域。然后采用两次一维傅里叶变换去除测绘数据噪声。最后结合去噪后的测绘数据,计算平原河道水流挟沙力系数,并利用相关的平衡方程得出河道淤积断面高程的监测结果。实验结果表明,使用本文方法得到的平原河道淤积断面高程监测结果与真实结果高度一致,监测到的淤积量与实际淤积量高度一致,监测结果准确度较高,能够充分满足平原河道淤积状况管理工作的实际需求。

船闸口门区布置及其通航安全判别标准

针对应用《船闸总体设计规范》进行船闸引航道口门区及制动段布置时遇到的问题,从船舶通航安全角度阐述了船闸引航道制动段、口门、口门区和连接段的内涵。介绍了国内外现有船闸口门区通航安全判别标准并指出其存在的问题,分析引航道口门区的水流特性及船舶舵效原理,提出一种切实可行的船闸通航安全制动段水流条件判别方法,对船闸整体模型试验及船闸总体布置具有一定借鉴意义。