基于有限元剩余推力法的岩质边坡抗滑稳定性分析

针对传统有限元应力代数和法忽略了滑裂面方向对安全系数的影响,导致计算结果出现较大偏差的问题,提出了加入滑裂面方向因素的有限元剩余推力法,即将计算得到的各滑裂面上的剩余力转换到第三滑裂面上,对第三滑裂面使用等安全系数法进行迭代计算,求得总滑面的安全系数,并通过改变第三滑裂面与水平方向的夹角搜寻最危险滑裂面。运用算例对有限元剩余推力法与传统有限元应力代数和法所得安全系数进行对比分析表明,剩余推力分析法所求得的安全系数比传统的应力代数和法更接近工程实际,且可以搜索到安全系数最小的滑裂面。     

边坡稳定分析的差分进化全局求解

将一种新兴的数值优化差分进化算法引入边坡临界滑动面搜索领域,并结合瑞典条分法和简化Bishop法构建了边坡稳定分析的差分进化全局求解策略.实例分析结果表明,差分进化用于边坡稳定分析易于实现、求解精度高、稳定性好.克服了传统方法的局限性,具有一定的工程应用价值,可供借鉴.     

基于改进粒子群优化算法的边坡稳定性分析

针对标准粒子群算法存在收敛精度低、易陷入局部最优的缺点,提出了基于混沌与变异的改进粒子群优化算法(CVPSO),将其应用于边坡滑裂面搜索,研制了边坡稳定分析程序CVPSO-LEM2D。采用改进粒子群算法对澳大利亚计算机应用协会(ACADS)边坡算例进行计算分析,结果表明改进粒子群算法的全局最优搜索能力与收敛精度得到了较大提高,计算结果与ACADS推荐的裁判答案基本一致,验证了算法的有效性。最后,将CVPSO-LEM2D应用于两河口泄水建筑物进口边坡稳定性分析,验证了方法的可行性,为类似工程提供了参考和借鉴。     

基于改进粒子群优化算法的边坡稳定性分析

针对标准粒子群算法存在收敛精度低、易陷入局部最优的缺点,提出了基于混沌与变异的改进粒子群优化算法（CVPSO）,将其应用于边坡滑裂面搜索,研制了边坡稳定分析程序CVPSO LEM2D。采用改进粒子群算法对澳大利亚计算机应用协会（ACADS）边坡算例进行计算分析,结果表明改进粒子群算法的全局最优搜索能力与收敛精度得到了较大提高,计算结果与ACADS推荐的裁判答案基本一致,验证了算法的有效性。最后,将CVPSO LEM2D应用于两河口泄水建筑物进口边坡稳定性分析,验证了方法的可行性,为类似工程提供了参考和借鉴。     

三斜面法在重力坝深层抗滑稳定性分析中的应用

针对重力坝深层抗滑稳定双斜面法存在的不足,探讨了重力坝深层抗滑稳定的三斜面法,将坝趾处分界面的倾角及其上抗力方向角作为未知量,在三个倾斜滑裂面上建立等安全系数法极限平衡方程,根据抗滑稳定安全系数极值条件,通过迭代和双重搜索试算求解最小的安全系数和最危险的滑裂面形态。计算结果表明,三斜面法更贴近实际工程的客观条件,比双斜面法更合理可靠、更具有普遍适用性。     

强度折减法在三维有限元边坡稳定分析中的应用

为研究强度折减法在边坡三维稳定分析中的适用性,选择已知滑裂面和未知滑裂面共4个经典算例,运用强度折减法求解其安全系数,并与既有的极限平衡法结果进行对比。计算结果表明,数值解与既有的极限平衡法解析解非常接近,模拟的滑动方向与理论假定亦基本一致。由此证明了强度折减法在三维有限元边坡稳定性分析中的适用价值,为解决工程计算问题提供了参考。     

某料场逆层岩质边坡开挖过程数值分析

为研究逆层岩质边坡在开挖过程中的各种响应与稳定性,建立某料场逆层边坡开挖有限元模型,分析该料场边坡在开挖施工过程中的位移、稳定安全系数和滑裂面变化趋势。计算结果表明,开挖对边坡上部岩体变形影响很小,对中部和下部岩体变形影响大;开挖过程中边坡稳定安全系数逐渐减小,开挖后边坡稳定性较好;随着开挖深度的增加,滑裂面上缘起点逐渐远离开挖面,而剪出口始终位于坡脚,以此确定了不同开挖深度的重点监测区域;可采用剪应变来描述料场开挖造成的岩体损伤,并将边坡损伤等级划分为3级。研究成果可为该料场后期施工过程中的稳定性监测和加固措施采用提供参考,也可为类似工程提供借鉴。     

基于临界位移等值线的多阶边坡多级滑动面搜索方法

搜索临界滑面是边坡稳定性分析及滑坡防治的关键,但坡体内次级滑动面隐患亦不容忽视。根据位移变形的分析方法认为边坡临界滑面位于位移等值线最密集处,但需深入探讨定量化评判临界滑面与位移等值线的重合度及定位次级滑面。以典型多台阶边坡为例,借助FLAC3D平台,提出了边坡临界位移等值线的概念,通过逐步增加最大不平衡力比作为收敛条件获取坡体内剪应变增量极大值点,采用最小二乘法进行拟合,并计算剪应变增量极值点拟合曲线与位移等值线的最小相关面积,最终筛选确定边坡临界位移等值线,以表征多级临界滑动面的分布规律。通过多台阶边坡安全系数云图与工程实例验证了方法的合理性和可行性,计算结果表明该方法不仅可以得到最危险临界滑动面,还能获取次级滑动面的形态特征及安全系数,搜索结果更加直观可靠。     

边坡变形影响下锦屏一级拱坝安全性分析

锦屏一级高拱坝左岸边坡断层较多且持续变形不收敛,从而对坝体安全稳定运行造成不利影响,为合理分析左岸边坡变形对坝体安全性的影响,建立了锦屏一级拱坝三维有限元仿真模型,运用小生境与遗传模拟退火耦合算法搜索左岸边坡最危险潜在滑动面,在搜索到的潜在滑动面施加三角形位移荷载模拟左岸边坡的变形并进行持续超载,同时考虑坝体自重、水压力等荷载作用下坝体的应变情况。结果表明,边坡变形的极限超载系数在9~10之间,靠近坝体左岸岸肩1 769m高程以上的部位在边坡持续变形中会较早进入塑性屈服阶段,在不出现塑性屈服区贯通情况下,坝体弦长最大压缩变形可达到205.32mm,从而可为坝体安全运行提供参考。     

侧向阻力对重力坝深层抗滑稳定的影响分析

本文针对软弱结构面走向与坝轴线相交这一重力坝深层抗滑稳定分析中比较普遍的情况，在对滑动体所受到的侧向阻力作用机理进行分析的基础上，对单滑裂面和复合滑裂面两种基本滑动模式，计入侧向阻力，进行了深层抗滑稳定的空间刚体极限平衡分析。最后给出了一个分析侧向阻力影响的计算实例。     

基于可变权重理想点法的边坡稳定性评价

针对目前常用的综合评价模型只能确定边坡稳定性所在等级,不能评价边坡稳定性在所属等级中的好差程度的问题,考虑指标动态权重对边坡稳定性的影响,改进了理想点法,通过引入均衡函数的变权公式,提出了可变权重理想点法,并将该方法应用于四个边坡的稳定性综合评价中。结果表明,可变权重理想点法与灰色关联分析和可拓方法的评价结果基本一致,能够比较精确地确定边坡所属稳定性等级,而且可以确定同一等级内不同边坡稳定性的差别。     

改进熵权-正态云模型在边坡稳定性评价中的应用

针对边坡稳定等级影响因素的不确定性、模糊性和时变性问题,引入云模型理论,综合考虑地形地貌、水文气象、地质环境等各方面因素,选取岩石质量指标等7个评价指标,提出了基于改进熵权-正态云模型的边坡稳定性评价方法。该方法通过云模型正向发生器计算各指标对应评价等级的确定度,基于改进熵权法确定各指标权重,以此综合评价边坡稳定性等级。以桂柳高速公路边坡为例建模计算,该方法评价结论与理想点法以及神经网络一致,证明该方法是可行的。     

A novel inference method for local wind conditions using genetic fuzzy systems

Local wind climate is usually measured and described as the result of a regional wind climate modulated by local topography effects, roughness and obstacles in the surrounding area. This paper renders a fuzzy-logic-based method designed to generate the local wind conditions originated by these geographic elements. The proposed fuzzy systems are specifically conceived to modify a regional wind frequency rose attending to the terrain slopes in all directions. In order to optimize these fuzzy systems, the genetic algorithm improves an initial population and, eventually, selects the one which produces the best approximation to the real measurements. The described process coveys a method to train fuzzy systems in wind parameters down-scaling. It is clearly visible the improvement of the obtained wind frequency distribution with regard to the regional one. This fact implies that the optimized fuzzy system contains information about how to correct the wind direction over a zone using the terrain slopes. This acquired knowledge is the best statistical solution found through Genetic Fuzzy Learning according to the variables and conditions imposed to solve this particular problem in this location.     

双安全系数动态局部强度折减法在边坡稳定分析中的应用

针对传统的强度折减法未考虑到边坡破坏过程中粘聚力和内摩擦角衰减速度的差异及边坡所有单元的强度参数均折减的问题,对边坡材料强度参数粘聚力和内摩擦角分别采用不同的折减系数,并根据屈服接近度判别标准,逐步调整折减区域,提出了边坡稳定分析的双安全系数动态局部强度折减法。实例应用结果表明,该方法能够较好地反映边坡破坏过程中粘聚力和内摩擦角衰减速度的差别,可模拟边坡失稳演变过程,得到的安全系数一般小于传统强度折减法和动态局部强度折减法。     

Optimum slope of a north-south aligned absorber plate from the north to the south poles

The analytical method developed by Nijegorodov et al. [Renewable Energy, 4, 529–543 (1994)] in order to find the optimum slope of an absorber plate, variously oriented at any latitude, is applied to study the variation of daily optimum slope with latitude from the north to the south poles. For a clear, cloudless condition the daily optimum slopes are found to have symmetry features which reflect the symmetry of the motion of the sun and the north-south symmetry about the equator. Such symmetry features of the optimum slope are discussed. However, the actual optimum slope also depends on the local meteorological and sunshine conditions, due to which the symmetry features of optimum slope are not always exploitable. The effects of meteorological parameters such as temperature, pressure, relative humidity, visibility and cloud cover on the optimum slope are assessed. The method is applied to obtain the mean monthly optimum slopes for the locations of 12 synoptic stations in Botswana from which the climatic and sunshine data are available, and preliminary maps of mean monthly optimum slopes for Botswana for the months of June and December are presented.     

Electrochemical construction of Cu@NF frameworks and synthesis of self-supported microflower Cu2S@NF as bifunctional catalysts for overall water splitting

A two-step electrochemical method is proposed for the in-situ deposition of copper and synthesis of copper(Ⅰ) sulfide (Cu₂S) with controllable morphology on nickel foam (NF), and the thus-prepared self-supported Cu₂S@NF electrodes exhibit excellent performance as bifunctional electrocatalysts. Characterizations with scanning electron microscopy show rock-shape of the deposited copper through potentiostatic method, which can be further sulfurized to microflower morphology by a unique underpotential electrochemical method. The size and amount of the deposits can be adjusted by controlling applied potentials, leading to the optimization of electrocatalytic activity. The Cu₂S@NF exhibits superior electrocatalytic performance towards HER and OER in 1 M KOH with the low overpotentials of 105 mV and 194 mV at 10 mA/cm², as well as small Tafel slopes of 92.89 mV/dec and 72.81 mV/dec, respectively. This work provides a simple method for the synthesis of efficient catalysts, which can be extended to the fabrication of other transition metal-based electrocatalysts.     

Analytical and quasi-explicit four arbitrary point method for extraction of solar cell single-diode model parameters

In this paper, the five parameters of the solar cell single-diode model are analytical and quasi-explicitly extracted for the first time, just using the coordinates of four arbitrary points of the characteristic I–V curve and the slopes of the curve in these points. The new method presented, called Analytical and Quasi-Explicit (AQE) method, is exact because no simplifications of the model nor a priori approximations of the parameters are used and, it is quasi-explicit in the sense that all the parameters except one are explicitly given. The unique parameter not explicitly computed is easily obtained by solving a five-degree polynomial equation. Accurate and practical conditions are provided to select which solution of the previous equation is the desired parameter.It is also introduced a very easy method to obtain, directly from real data measurements, the needed four points of the I–V curve as well as the slopes in these points, without using any kind of sophisticated techniques.Finally, some experimental results are presented to demonstrate the high accuracy and simplicity of the new method. The results are compared with the well-known analytical five-point method and the recent oblique asymptote method.     

Ethanol electro-oxidation on Pt/C and PtSn/C catalysts in alkaline and acid solutions

Carbon supported Pt and PtSn were prepared by a modified polyol method. The electrocatalytic activities and stabilities of the Pt/C and PtSn/C catalysts towards ethanol electro-oxidation reactions (EORs) were investigated by potentiodynamic and potentiostatic methods in a 0.1 M NaOH solution (or 0.5 M H₂SO₄) containing 0.01 M ethanol. On both catalysts, the EOR currents in the alkaline solutions were much higher than those in the acid solutions, and the onset potentials of the EOR in alkaline solutions were less positive than those in acid solutions, indicating that the kinetics of the EOR improve in alkaline solutions. Even though a significant improvement was observed in acid media on PtSn/C, compared with Pt/C, only negligible improvement was observed in alkaline media. The apparent activation energies of the EOR on the PtSn/C catalyst varies from 21 to 33 kJ mol⁻¹, depending on the potentials, which are slightly lower than the corresponding values on the Pt/C catalyst (25∼42 kJ mol⁻¹) under the same conditions. The Tafel slopes are divided into two parts–at low overpotentials, Tafel slopes on both catalysts are close to 120 mV dec⁻¹, which is in agreement with the proposed mechanism–Temkin-type adsorption for both OH_ad and ethoxi at low overpotentials; in contrast, at high overpotentials, Tafel slopes on both catalysts are over 300 mV dec⁻¹ due to the oxide formation on the surface.     

考虑抗滑桩埋深的边坡抗滑机理研究

为探究有限埋深抗滑桩加固边坡的稳定性分布规律,基于点安全系数确定边坡的临界滑动面,分析不同屈服准则对确定滑动面位置的影响,研究了桩埋深不同时潜在滑动面的变化趋势及埋深相同时沿边坡纵向滑动面的分布规律。结果表明,考虑带抗拉强度的MohrCoulomb破坏准则的点安全系数确定的边坡滑动面最深;随着桩埋深的增加,边坡的稳定性先增加后减小;相同桩长下,沿边坡纵向边坡稳定性先减小后增加。     

龙羊峡近坝库岸滑坡成因机理研究

根据对龙羊峡近坝库岸的前期研究和蓄水后的库岸变形破坏地质调查及其转异特征研究,分析了龙羊峡近坝库岸滑坡的形成和破坏机制,同时提出了防范措施.