Single‐and multi‐objective genetic algorithm optimization for identifying soil parameters     

A. Papon  Y. Riou  C. Dano  P.‐Y. Hicher 《国际地质力学数值与分析法杂志》2012,36(5):597-618

This paper discusses the quality of the procedure employed in identifying soil parameters by inverse analysis. This procedure includes a FEM‐simulation for which two constitutive models—a linear elastic perfectly plastic Mohr–Coulomb model and a strain‐hardening elasto‐plastic model—are successively considered. Two kinds of optimization algorithms have been used: a deterministic simplex method and a stochastic genetic method. The soil data come from the results of two pressuremeter tests, complemented by triaxial and resonant column testing. First, the inverse analysis has been performed separately on each pressuremeter test. The genetic method presents the advantage of providing a collection of satisfactory solutions, among which a geotechnical engineer has to choose the optimal one based on his scientific background and/or additional analyses based on further experimental test results. This advantage is enhanced when all the constitutive parameters sensitive to the considered problem have to be identified without restrictions in the search space. Second, the experimental values of the two pressuremeter tests have been processed simultaneously, so that the inverse analysis becomes a multi‐objective optimization problem. The genetic method allows the user to choose the most suitable parameter set according to the Pareto frontier and to guarantee the coherence between the tests. The sets of optimized parameters obtained from inverse analyses are then used to calculate the response of a spread footing, which is part of a predictive benchmark. The numerical results with respect to both the constitutive models and the inverse analysis procedure are discussed. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Intelligent control for modeling of real‐time reservoir operation,part II: artificial neural network with operating rule curves     

Ya‐Ting Chang  Li‐Chiu Chang  Fi‐John Chang 《水文研究》2005,19(7):1431-1444

To bridge the gap between academic research and actual operation, we propose an intelligent control system for reservoir operation. The methodology includes two major processes, the knowledge acquired and implemented, and the inference system. In this study, a genetic algorithm (GA) and a fuzzy rule base (FRB) are used to extract knowledge based on the historical inflow data with a design objective function and on the operating rule curves respectively. The adaptive network‐based fuzzy inference system (ANFIS) is then used to implement the knowledge, to create the fuzzy inference system, and then to estimate the optimal reservoir operation. To investigate its applicability and practicability, the Shihmen reservoir, Taiwan, is used as a case study. For the purpose of comparison, a simulation of the currently used M‐5 operating rule curve is also performed. The results demonstrate that (1) the GA is an efficient way to search the optimal input–output patterns, (2) the FRB can extract the knowledge from the operating rule curves, and (3) the ANFIS models built on different types of knowledge can produce much better performance than the traditional M‐5 curves in real‐time reservoir operation. Moreover, we show that the model can be more intelligent for reservoir operation if more information (or knowledge) is involved. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

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李祖宁  刘序俨  吴绍祖  陈光 《大地测量与地球动力学》2007,27(5):18-21

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Assessing radial transmissivity variation in heterogeneous aquifers using analytical techniques          下载免费PDF全文

Cem B. Avci  A. Ufuk Sahin 《水文研究》2014,28(23):5739-5754

Pumping tests are one of the most commonly used in situ testing techniques for assessing aquifer hydraulic properties. Numerous researches have been conducted to predict the effects of aquifer heterogeneity on the groundwater levels during pumping tests. The objectives of the present work were as follows: (1) to predict drawdown conditions and to estimate aquifer properties during pumping tests undertaken in radially symmetric heterogeneous aquifers, and (2) to identify a method for assessing the transmissivity field along the radial coordinate in radially symmetric and fully heterogeneous transmissivity fields. The first objective was achieved by expanding an existing analytical drawdown formulation that was valid for a radially symmetric confined aquifer with two concentric zones around the pumping well to an N concentric zone confined aquifer having a constant transmissivity value within each zone. The formulation was evaluated for aquifers with three and four concentric zones to assess the effects of the transmissivity field on the drawdown conditions. The specific conditions under which aquifer properties could be identified using traditional methods of analysis were also evaluated. The second objective was achieved by implementing the inverse solution algorithm (ISA), which was developed for petroleum reservoirs to groundwater aquifer settings. The results showed that the drawdown values are influenced by a volumetric integral of a weighting function and the transmissivity field within the cone of depression. The weighting function migrates in tandem with the expanding cone of depression. The ability of the ISA to predict radially symmetric and log‐normally distributed transmissivity fields was assessed against analytical and numerical benchmarks. The results of this investigation indicated that the ISA method is a viable technique for evaluating the radial transmissivity variations of heterogeneous aquifer settings. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

基于GA-Sarma算法的边坡最不利滑裂面搜索方法     

李生清 《地质与勘探》2022,58(4):887-894

传统方法在选取潜在滑裂面关键点时,未综合考量剪切滑裂点、受拉滑裂点对搜索过程的影响程度,导致搜索过程易陷入局部最优,从而丢失其他同等级搜索数据。针对这一问题,本研究设计了基于GA-Sarma算法的边坡最不利滑裂面搜索方法。该方法通过计算边坡稳定性系数的实际值提取边坡潜在滑裂面,然后根据剪切滑裂点、受拉滑裂点的特性,选取潜在滑裂面关键点。进而,基于GA-Sarma算法建立目标函数和适应度函数,在考虑变异的前提下搜索边坡的最不利滑裂面。实验测试区域中包含3处最不利滑裂面、5处刚刚形成且危险程度偏低的滑裂面、14处潜在滑裂面。测试结果表明：在20轮测试中,本文方法与两组传统方法搜索到的最不利滑裂面个数平均值分别为3处、1.4处以及0.8处,从而验证了GA-Sarma算法强化了边坡最不利滑裂面搜索效果。该方法可为边坡支护、加固及改造等地质工作提供更加可靠的技术支持。  相似文献   

基于相似性原理超固结土不排水扩张半解析解     

李镜培  刘耕云  周攀 《岩土力学》2022,43(3):582-590

在实际工程中,土体往往因卸载、再加载等复杂应力路径而处于超固结状态,而现有的圆孔扩张问题的计算模型往往不能反映超固结土中剪胀、软化等一些特殊性质。为了解决这一问题,基于相似性原理和统一硬化（UH）模型,结合相关联的流动法则和大变形理论,采用相似求解技术求解了超固结土不排水扩张问题的半解析解答。通过理想化算例分析了圆孔扩张挤土产生的应力和孔压响应,并通过分析不同超固结比OCR的土体应力路径的变化规律,讨论了UH模型的适用性。结果表明：对于轻超固结土,空腔周围土体孔压在塑性区沿径向单调递减,随着OCR增大,塑性区内孔压分布呈现出“S”形的趋势,孔壁附近的孔压逐渐减小,孔壁周围甚至出现负孔压。随着OCR增大,压力?扩张曲线收敛变慢。在扩孔过程中正常固结土一直处于剪缩硬化阶段。而对于超固结土,土体则经历了临界状态→剪胀硬化阶段→临界（特征）状态→剪缩硬化阶段。该研究成果不仅丰富了相似求解技术的应用,而且为超固结土中桩基承载力、隧道围岩变形预测和原位测试参数等岩土工程问题的计算提供了理论依据。  相似文献   

一种基于重叠区指数化互相关和优化Dijkstra算法的航摄影像镶嵌线选取方法#br#     

刘瀚阳  王博帅  王凤艳  牛雪峰 《吉林大学学报(地球科学版)》2022,52(2):662

航摄影像因含有丰富的地理信息而成为实用的可视化产品和决策工具。通常需要将多幅航摄影像沿镶嵌线拼接才能覆盖研究区域,因此如何选取最优航摄影像镶嵌线具有研究意义。本文提出了一种新颖的航摄影像镶嵌线选取方法。首先构造一种指数化互相关方法,高质量地表达航摄影像重叠对应区域的错位程度;其次优化Dijkstra算法,在重叠区找出错位差异最小的路径作为航摄影像镶嵌线;最后使用两组来自城市和城镇区域的航摄影像将本文方法与相关方法进行对比,结果表明使用本文方法获取的镶嵌线穿越更少的独立地物且用时更短。  相似文献   

基于控制区间牵引算法的地下施工变形预测     

马恩临  赖金星  王立新  汪珂  雷升祥  李储军  邱军领 《岩土力学》2023,(2):577-594

变形是地下结构施工安全状态的重要评价指标。针对数据驱动变形预测方法中地下施工动态影响因素难以量化这一问题,提出了基于控制区间牵引算法的地下施工变形预测模型。以双向长短时记忆网络（Bi-LSTM）对变形监测时间序列进行预测,以数值模拟在关键施工阶段处的结果为牵引点。根据实测值随阶段更新牵引点,并基于注意力机制双向长短时记忆网络（Bi-LSTM-AM）以牵引点修正数据驱动模型在控制区间的预测结果,实现更准确、更智能的地下施工变形预测。设置牵引相对权重,使模型可自适应判断当前合理牵引程度,准确融合了Bi-LSTM与数值模拟的结果。通过相关历史案例与数据,验证了牵引预测模型的有效性。依托西安市西咸新区丰镐三路地下通道上跨地铁1号线自动化监测实例,采用牵引算法预测了地下结构变形。结果表明：在关键施工阶段处,牵引作用改善了数据驱动预测方法存在的滞后问题,各阶段误差平均降低了24.34%;不断优化的牵引点逐渐趋近真值,降低了数值模拟出现偏差时造成的影响。该方法可为地下施工变形预测问题提供新途径。  相似文献   

一种用户均衡分配不确定性的计算方法     

程小洋  刘玉  郭建华 《南京气象学院学报》2019,11(4):421-427

为解决目前交通分配中存在的不确定性问题,基于Wardrop用户平衡原理,利用起讫点（OD,Origin Destination）估计方法和Beckman交通分配模型,建立了一种交通分配不确定性计算方法.该方法分别以不同置信水平下的OD估计结果的上下限为输入量,然后利用Frank-Wolf算法求解交通分配模型,得到不同置信水平下的路段流量区间,以此量化交通分配问题中的不确定性.以南京市区域路网为研究对象进行案例分析,并采用宽度流量比R和无效覆盖率（Kickoff Percentage,KP）对模型结果进行评价,结果表明该方法可以得到路段流量的置信区间,量化交通分配的不确定性.  相似文献   

A PREDICTION SCHEME FOR THE PRECIPITATION OF SPR BASED ON THE DATA MINING ALGORITHM AND CIRCULATION ANALYSIS     

李超  史达伟  陈誉天  张红华  耿焕同  王鹏 《热带气象学报(英文版)》2019,25(4):519-527

Based on the 74 circulation indexes provided by National Climate Center of China (hereinafter referred to as NCC) and the 24 indexes compiled by NOAA, the study used the C4.5 algorithm in data mining to establish a decision tree prediction model to predict whether the Spring Persistent Rains (hereinafter referred to as SPR) of 55 years (from 1961 to 2015) is more than the normal, and obtained 5 rules to determine whether the SPR is more than the normal. The accuracy rate of the test set, namely “whether the SPR is more than the normal”, is 98.18%. After evaluating the model by conducting ten 10-fold cross validations to take the average value, the test accuracy rate gained is 84%. There are differences between the three types of years with a SPR more than the normal when it comes to intensity and distribution. In spring, they have respective anomalous 850hPa monthly mean wind fields and water-vapor flux distribution, and 700hPa forms the zone where the vertical speed is anomalously negative. As indicated by the results, the SPR prediction model based on the C4.5 algorithm has a high prediction accuracy rate, the model is reasonably and effectively constructed, and the decision rules take comprehensive factors into consideration. The anomalous rainfall and circulation distribution characteristics obtained based on the decision classification results provide new ideas and methods for the climatic prediction of SPR.  相似文献