面板堆石坝流变特性研究

简要介绍了某水电站混凝土面板堆石坝工程概况和流变计算模型。采用三维有限单元法对该混凝土面板坝筑坝及蓄水过程进行模拟计算,对比考虑堆石料流变和不考虑流变的两种计算结果,分析说明筑坝材料的流变特性对面板坝坝体以及混凝土面板变形应力的影响。     

基于数值模拟K30筑坝质量检测技术

为了对黔中混凝土面板堆石坝筑坝材料填筑质量进行快速检测,基于邓肯E-B模型基本原理,通过K30法得到邓肯E-B模型参数,将结果用于对大坝工程施工有限元分析中。结果发现:采用K30法测试土石料性能(参数),建立邓肯E-B模型可迅速计算出各参数,检测填料是否满足要求,缩短了计算周期,为该方法在水利工程方面的应用提供理论参考。     

井地电阻率三维正演及Occam反演

井地ERT方法广泛应用于采油工程,用于解决水力压裂裂缝的几何参数、注水推进方向以及波及范围的探测。采用有限差分法将连续的定解区域用有限个离散的点构成的网格代替来进行电阻率正演三维的计算,推断出地下异常体反映到地表的电位异常,并比较异常体埋深不同时的电阻率异常。建立一维层状模型,并对一维的层状模型采用Occam反演方法进行深度电阻率的反演成像,得到电阻率和深度光滑模型。Occam反演对层状模型的反演结果吻合,可以初步地对野外探测进行数据解释。     

钢筋增强ECC双筋梁受弯性能研究(英文)

为探究ECC材料受弯性能,对受弯钢筋增强ECC双筋梁正截面进行了理论和试验研究.首先基于平截面假定和材料本构模型,得到各阶段承载力计算方法.然后,通过试验结果与理论结果对比,验证所提出的梁承载力计算方法正确性.最后,基于所提出的理论公式,对ECC材料的抗压强度和抗压应变、抗拉强度和配筋率进行分析,探究其对钢筋增强ECC双筋梁正截面受弯性能的影响.理论分析结果与试验结果吻合良好,说明理论分析模型能够用于预测钢筋增强ECC梁的弯矩-曲率关系.参数分析结果表明:提高ECC抗压强度将大幅改进梁受弯性能;提高ECC极限受压应变可大幅提高梁极限曲率和延性,但对受弯承载力影甚微;ECC抗拉强度对梁受弯性能影响微弱;配筋率的增大可大幅提高梁受弯承载力和刚度,但会降低梁的延性.所提出的理论计算模型和参数分析结果对于钢筋增强ECC梁受弯性能的设计研究具有指导意义.     

基于Matlab的概率积分法预计参数反演方法比较

预计参数反演是利用概率积分法预计煤矿开采后地表移动与变形的关键。总结分析了预计参数反演的最小二乘法、模式法和遗传算法,利用Matlab软件中的最优化算法工具箱,在缓倾斜煤层非充分开采条件下,对3种反演方法的计算结果进行比较。结果表明,最小二乘法计算结果准确性较好,但初始点选择不当会导致计算失败;模式法和遗传算法都无需计算函数的梯度信息,遗传算法的初值是种群,其计算结果比模式法更加准确;在各参数中,开采影响传播角θ的误差较大,通过采用遗传算法工具箱和fminbnd函数联合走向断面和倾向断面的数据进行反演,可以提高预计参数的准确性。     

不同埋深灰岩相似材料配比试验及特性分析

为获得不同埋深下具有岩爆倾向性的灰岩相似模型,引入岩爆能量原理建立岩爆相似准则,参考原岩相关参数结合岩爆相似准则推算相似模型对应的原岩目标相关参数。引入岩爆倾向性指数、弹性能和耗散能,以石英粉含量、重晶石粉含量、石膏水泥质量比、水含量为影响因素,采用4因素5水平的正交试验方案,进行单轴抗压试验得到各项参数。对试验结果进行敏感性分析及多元线性回归分析,将不同埋深下灰岩相似模型参数带入线性回归方程,并考虑敏感性分析结果对材料配比进行优化,得出不同埋深下灰岩相似模型优化配比及物理参数,为灰岩室内研究提供参考。     

方管截面铝合金轴心受压构件力学性能研究

通过有限元软件ANSYS构建非线性数值模型,并利用现有试验数据进行模型准确性验证。分析了板件宽厚比、截面尺寸效应以及是否约束某一主轴方向位移对构件稳定承载力的影响,发现三者影响均可不予考虑。在大规模参数分析的基础上,本文建议对于6061-T6,几何缺陷系数中的两个参数分别取和,对于6061-T4建议取和。对比中、欧规范计算结果发现,该建议与试验及参数分析结果具有更好的吻合性,满足计算精度和安全度的工程设计要求。     

基于ENVI/IDL的植被指数反演系统设计

针对ENVI软件在计算大范围区域遥感影像的植被指数时处理过程繁琐、效率低,根据植被指数反演模型的计算方法,经过分析和结构设计,在ENVI/IDL环境下开发了一个计算植被指数的反演系统。通过试验对比发现,利用该系统和ENVI 5.0软件分别计算10景Landsat 8 TM遥感影像的归一化植被指数,该系统在处理时间上比ENVI 5.0软件减少了11 min,且两者计算结果的信息量基本一致,不仅在处理速度上有明显优势,而且能够保证计算结果的质量。对大量遥感影像进行批量计算植被指数时,该系统可以减少遥感影像处理的重复工作,提升了植被指数的反演效率。     

孪生诱发塑性钢大变形试样制备试验参数设计

为了探究孪生诱发塑性(TWIP)钢在弯曲等大变形下的微观组织变化,需要制备给定大变形材料试样,然而在实际试验中很难精准确定合适的力学性能试验参数。针对四点弯作用下的TWIP钢试样制备条件,分别基于弹性模型、Ramberg模型和Chaboche模型,采用有限元仿真模拟了试样在不同位移条件下的变形过程,获得了与给定大变形相匹配的试验参数。基于得到的试验参数开展了24次试验,结果表明试件实际变形与仿真计算结果具有较好的一致性。基于Chaboche模型的有限元仿真能够有效获取材料大变形试验的力学参数,而合适的材料参数是决定仿真结果精确性的关键因素。     

一种利用等效模型与遗传算法的动态有限元模型修正方法

为了解决现有动态有限元模型修正方法计算效率不高或者可能获得局部最优解的问题,提出了一种利用等效模型和遗传算法的动态有限元模型修正新方法.首先,在设计参数的取值范围内,根据预设的多项式模型的阶次以及自变量的个数,利用试验设计方法获得拟合响应面模型所需要的最优样本点;通过有限元分析获得样本数据,并利用回归分析获得响应面模型,从而以响应面模型逼近结构特征与设计参数之间的函数关系.然后,在遗传算法的适应度评估环节,利用响应面模型替代有限元模型计算对应于一组设计参数的结构特征,并计算遗传个体的适应度,最终通过进化获得最优解,即为修正后的设计参数.以汽车车架模型为例,对其进行有限元分析与模态试验,并利用所提出的方法进行模型修正.修正后,模态频率误差的均方值小于2%.用修改后结构的动态特性的测试结果,对修正后有限元模型的预测能力进行检验,模态频率预测误差的均方值小于2%.     

葛洲坝截流后长江宜昌江段的铜鱼繁殖研究

本文阐述了葛洲坝水利枢纽工程截流后,宜昌江段铜鱼产卵场的分布和规模及其繁殖条件。研究表明:铜鱼产卵场最主要部分位于坝上三峡河谷近坝端的江段中,坝下首次发现有新的小规模的产卵场。铜鱼的繁殖受水文地理自然条件、水温及水位等主要环境因子的影响。铜鱼与四大家鱼不同,不仅能在水位上涨时产卵,也能在随后的退水过程中繁殖,而且持续时间较长、产卵规模也较大。     

Powell inversion mechanical model of foundation parameters with generalized Bayesian theory

The inversion mechanical model of foundation parameters based on Powell optimizing theory was studied with generalized Bayesian theory. First, the generalized Bayesian objective function for foundation parameters was deduced with maximum likelihood theory. Then, the expectation expression and the covariance expression of the foundation parameters were obtained. After selecting the Winkler foundation as representative, the governing differential equations of the typical foundation were derived. With the orthogonal series transform method, the Fourier closed form solution of a moderately-thick plate on the Winkler foundation was achieved. After the optimal step length was determined with the quadratic parabolic interpolation method, the Powell inversion mechanical model of foundation parameters was resolved, and the corresponding inversion procedure was completed. Through particular example analysis, the highlight is that the Powell inversion mechanical model of foundation parameters with generalized Bayesian theory is correct and the derived Powell inversion model has universal significance, which can be applied in other kinds of foundation parameters. Besides, the Powell inversion iterative processes of foundation parameters have excellent numerical stability and convergence. The Powell optimizing theory is unconcerned with the partial derivatives of systematic responses to foundation parameters, which undoubtedly has a satisfying iterative efficiency compared with the available Kalman filtering or conjugate gradient inversion of the foundation parameters. The generalized Bayesian objective function can synchronously take the stochastic property of systematic parameters and systematic responses into account.     

Coupled elasto-plasticity damage constitutive models for concrete

The paper is to design and construct a coupled elasto-plasticity damage constitutive model for concrete. Based on the energy dissipation principle, the Hsieh-Ting-Chen four-parameter yield function is used. The model can reflect different strength characteristics of concrete in tension and compression, and reduce the limitation and lacuna of the traditional damage constitutive models for concrete. Furthermore, numerical test for concrete stress-strain relation under uniaxial tension and compression is given. Moreover, the damage process of concrete gravity dam is calculated and analyzed in seismic load. Compared with other damage constitutive models, the proposed model contains only one unknown parameter and the other parameters can be found in the Hsieh-Ting-Chen four-parameter yield function. The same damage evolution law, which is used for tension and compression, is good for determining stress-strain constitutive and damage characteristics in complex stress state. This coupled damage constitutive models can be applied in analyzing damage of concrete gravity dam and arch dam.     

非溢流混凝土重力坝的体型分析

混凝土重力坝是中国坝工建设中的主要坝型,具有安全可靠、设计施工技术简单、对地形地质条件适应性好、施工导流和永久性泄洪问题容易解决等优点。重力坝的剖面设计是重力坝设计的一项主要内容,本文分析计算了非溢流混凝土重力坝剖面参数x1、x2、x3与上游水位、抗剪摩擦系数、扬压力折减系数的关系,结果表明随着摩擦系数的增加或上游水位的减小,上游折坡点位置逐渐变低,上游坝坡逐渐减小,直到上游变为直立面,下游坝坡逐渐减小,直到本文给定的最小下游坝坡0.5,且扬压力折减系数对坝体剖面的影响与抗剪摩擦系数的关系比较大,为工程设计提供了有益参考。     

Rockfill dam compaction quality evaluation based on cloud-fuzzy model

The quality of compaction is key to the safety of dam construction and operation. However, because of incomplete information about the construction process and the unknown relationship between compaction quality and the factors that influence it, traditional evaluation methods such as neural networks and multivariate linear regression models fail to take uncertainty fully into account. This paper proposes a cloud-fuzzy method for assessing compaction quality by considering randomness, fuzziness, and incomplete information. The compaction parameters and material source parameters are the key parameters in the assessment of compaction quality. A five-layer neural-network model of compaction quality assessment is established that considers compacted dry density and its classification membership and probability as the criteria, and the rolling speed, rolling passes, and compacted layer thickness as alternatives. Because of uncertainties in the criteria and alternatives, the cloud-fuzzy method, in which a fuzzy neural network is extended with a cloud model to handle uncertain and fuzzy problems more effectively, is introduced to determine the compaction quality. A case study is presented to evaluate the compaction quality of a hydropower project in China. The results indicate that the cloud-fuzzy model is feasible in relation to precision and makes up for the sole focus on precision by traditional methods. The proposed method provides a triple index for understanding compaction quality, which facilitates assessment of the compaction quality of an entire dam surface.     

重力坝结构优化的设计

混凝土重力坝的实用剖面优化设计是根据安全、经济和强度要求。通过分析计算,选择一个既使体积最小·又使施工方便的剖面形态和轮廓尺寸。本文建立了混凝土重力坝结构优化设计的数学模型和优化设计的VB软件,并应用该软件对工程实例进行了优化设计,结果证明该优化设计方法及软件具有较好的工程实用性。     

Inverse method for the determination of elastic properties of coating layers by the surface ultrasonic waves

INTRODUCTION The elastic properties of coating layers in coating materials are very important in the design and evaluation for engineering purpose. They can serve as ground knowledge in the selection of surface coatings for particular applications, and can be used to monitor the quality of physical processes (Every, 2002). Therefore, estimation of the elastic properties of coating layers is of great practical value. Much effort has been put into measuring the material properties of coatin…     

基于位错模型反演断层三维滑动速率

以位错理论模型为基础,导出了利用GPS水平位移场反演断层的走滑、倾滑和张裂三维运动速率分布的最佳估计反演计算公式,并结合位错理论模型模拟的地面位移场数据对断层的三维滑动速率进行了反演计算研究。结果表明：该反演计算公式具有很好的可靠性、唯一性,并且反演结果为最佳。     

Theory and application of system integration for real-time monitoring of core rock-fill dam filling construction quality

The theory and method of system integration for the real-time monitoring of core rock-fill dam filling con- struction quality are studied in this paper. First, the importance analysis of system integration factors is carried out with the analytic hierarchy process. Then, according to the analysis result of integration factors, the conceptual model of system integration is built based on function integration, index integration, technology integration and information integration, the index structure of core rock-fill dam filling construction quality control is constructed and the method of function integration and technology integration is studied. The mathematical model of process monitoring is built according to monitoring objective, process and indexes. Research results have been applied in Nuozhadu core rock-fill dam construction management, realizing system integration through building appropriate monitoring work flow and comprehensive information platform of digital dam.