Developing constitutive models from EPR‐based self‐learning finite element analysis          下载免费PDF全文

Ali Nassr  Akbar Javadi  Asaad Faramarzi 《国际地质力学数值与分析法杂志》2018,42(3):401-417

A constitutive model that captures the material behavior under a wide range of loading conditions is essential for simulating complex boundary value problems. In recent years, some attempts have been made to develop constitutive models for finite element analysis using self‐learning simulation (SelfSim). Self‐learning simulation is an inverse analysis technique that extracts material behavior from some boundary measurements (eg, load and displacement). In the heart of the self‐learning framework is a neural network which is used to train and develop a constitutive model that represents the material behavior. It is generally known that neural networks suffer from a number of drawbacks. This paper utilizes evolutionary polynomial regression (EPR) in the framework of SelfSim within an automation process which is coded in Matlab environment. EPR is a hybrid data mining technique that uses a combination of a genetic algorithm and the least square method to search for mathematical equations to represent the behavior of a system. Two strategies of material modeling have been considered in the SelfSim‐based finite element analysis. These include a total stress‐strain strategy applied to analysis of a truss structure using synthetic measurement data and an incremental stress‐strain strategy applied to simulation of triaxial tests using experimental data. The results show that effective and accurate constitutive models can be developed from the proposed EPR‐based self‐learning finite element method. The EPR‐based self‐learning FEM can provide accurate predictions to engineering problems. The main advantages of using EPR over neural network are highlighted.  相似文献   

ANALYSIS OF DRIVING FORCES ON THE CHANGE OF HISTORICAL FARMLAND USE IN SHANDONG PROVINCE DURING THE QING DYNASTY (1644-1911)     

ZHANG Xue-in  GE Quan-heng  ZHENG Jing-un 《中国地理科学(英文版)》2003,13(3)

1INTRODUCTIONTheIGBP-IHDP(InternationalGeosphere-BiosphereProgramme,andInternationalHumanDimensionPro-gramme)jointproject—LUCC(landuse/coverchange)isaninterdisciplinaryprogramdesignedtoimprovetheunderstandingofthedynamicsofland-useandland-coverchangeasinputstoandconsequencesofglobalenvironmentalchangeandsustainabledevelopment(CHARLOTTE,2002).Inparticularthedifferentbio-geochemicalmodeling(e.g.theglobalcarboncycle)ac-tivitiesandcomparativestudies,suchasthoseconduct-edbyIGBP-G…  相似文献   

ANALYSIS OF DRIVING FORCES ON THE CHANGE OF HISTORICAL FARMLAND USE IN SHANDONG PROVINCE DURING THE QING DYNASTY （1644-1911）     

ZHANGXue-qin GEQuan-sheng ZHENGJing-yun 《中国地理科学(英文版)》2003,13(3):207-215

How land-cover has been changed by human use over the last 300 years is one of the five overarching questions guiding the Land-use/Cover Change (LUCC) Science/Research Plan. China has variety of historical docu-ments providing unique data superiority. So the characteristics of farmland area in Shandong Province during the Qing Dynasty (1644-1911) are summarized firstly: 1) the rising trend of farmland area was striking; 2) farmland area had re-markable fluctuation; 3) farmland area per capita decreased dramatically; 4) wasteland reclamation index increased rapidly. Then, the driving forces of farmland area change are analyzed. It is concluded that natural and human factors are jointly influential. Among the driving forces, human dimensions are the main factors of farmland area change,which direct the general tendency of the changes mentioned above. And the natural factors influence the stability of farmland area as well. Variation of the natural factors would act as the major contributory factor to farmland area change during years or periods of abrupt climatic changes, or during the intensive occurring periods of natural hazards.Besides, the passive aspects of human factors, such as war chaos also influenced the fluctuation of the farmland area.This research indicates that it is feasible to study the land-use/cover change by Chinese historical literatures, which has huge potential to provide a comprehensive picture of the growing dominance of human land-use and land-cover pat-terns that can be used in many global change research oroiects.  相似文献   

GYD-300型全液压动力头工程钻机的研制     

靳益民  高淑芳 《探矿工程》2008,35(12):23-25,34

GYD-300型全液压动力头工程钻机为全液压驱动,动力头反循环式机型。液压系统采用插装阀集成结构,电液复合操作。使用PC控制监测系统,适时检测孔底各相关压力,对不同地层进行范围设置,实现钻进过程中孔底的自动、手动恒压钻进。重点介绍了该钻机的结构特点、实验情况、主要技术参数等。  相似文献   

Efficiency analysis of open trench for impact pile driving through a single-variable method     

Amir Hamidi  Abtin Farshi Homayoun Rooz 《Marine Georesources & Geotechnology》2021,39(1):82-102

Abstract

The ground vibrations during pile driving operation have a drastic potential to undermine the surrounding structures both in land and reclaimed land. Particularly, reclaimed land necessitates ample application of pile driving due to the weak land condition. To prevent the structural damage, attenuation of the ground vibrations to an allowable level through active isolation of circular open trench is the scope of this study. In this research, finite element simulations of continuous impact pile driving process from the ground surface was executed with particular attention to the pile-soil interaction, and thereby, the efficiency of open trench application in attenuation of the unsafe distance of different structures was surveyed using the vibration sensitivity degree. Regarding the crucial parameters of an open trench (depth, width, and location), it was concluded that a sufficient high depth can attenuate the unsafe distance up to 68%, the trench width variations are less effective, and an average pile-trench distance is the most efficient option. The excavation volume was also concluded as another crucial parameter in open trench design which takes all three parameters into account. The trench depth equal to the pile’s maximum critical depth of vibration was inferred for an optimum design.  相似文献   

Influence of large-diameter pipe pile driving on surrounding marine soils and adjacent submarine pipelines     

Jinzhong Dou  Zhong-Jie Zhang 《Marine Georesources & Geotechnology》2021,39(1):15-33

Abstract

With the large-scale development and utilization of ocean resources and space, it is inevitable to encounter existing submarine facilities in pile driving areas, which necessitates a safety assessment. In this article, by referring to a wharf renovation project as a reference, the surrounding soil response and buried pipe deformation during pile driving in a near-shore submarine environment are investigated by three-dimensional (3D) numerical models that consider the pore water effect. Numerical studies are carried out in two different series: one is a case of a single pile focusing on the effect of the minimum plane distance of the pile–pipe, and the other is a case of double piles focusing on the effect of the pile spacing.  相似文献   

空间智能:地理信息科学的新进展   总被引：5，自引：1，他引：4  

黄波  吴波  刘彪  曹凯 《遥感学报》2008,12(5)

在总结多年来研究GIS智能计算的理论与实践基础上,提出地理信息科学发展的新方向:空间智能.空间智能强调发现与应用空间模式,以增强GIS处理复杂数据和解决复杂问题的能力.空间智能主要的技术体系由空间分析、空间优化和空间模拟三大模块构成,其技术基础包括空间统计与索引、智能代理、高级启发式,以及数学规划等系列智能技术.由于空间智能融合了机器学习、统计分析和人工智能等多个学科理论,面向解决实际工程需求中大量存在的复杂时空问题,因此理论上具有广阔的发展空间,实践上也有重大的应用需求.随着空间智能体系的完善和技术的进一步成熟,它将在实际应用中具有巨大的价值.  相似文献   

Numerical Modelling of Dissolving and Driving Exploitation of Potash Salt in the Qarhan Playa——A Coupled Model of Reactive olute Transport and Chemical Equilibrium in a Multi-component Underground Brine System     

LI Wenpeng  LIU Zhenying 《《地质学报》英文版》2008,82(5)

Firstly, the macroscopic chemical equilibrium state of a series of chemical reactions between intercrystal brine and its media salt layer (salt deposit) in Qarhan Salt Lake was studied by using the Pitzer theory. The concept of macroscopic solubility product and its relation with accumulated ore dissolving ratio were presented, which are used in the numerical model of dissolving and driving exploitation of potassium salt in Qarhan Salt Lake. And secondly, with a model forming idea oftransport model for reacting solutes in the multi-component fresh groundwater system in porous media being a reference, a two-dimensional transport model coupled with a series of chemical reactions in a multi-component brine porous system (salt deposits) was developed by using the Pitzer theory.Meanwhile, the model was applied to model potassium/magnesium transport in Qarhan Salt Lake in order to study the transfer law of solid and liquid phases in the dissolving and driving process and to design the optimal injection/abstraction strategy for dissolving and capturing maximum Potassium/Magnesium in the mining of salt deposits in Qarhan Salt Lake.  相似文献   

Numerical Modelling of Dissolving and Driving Exploitation of Potash Salt in the Qarhan Piaya——A Coupled Model of Reactive Solute Transport and Chemical Equilibrium in a Multi-component Underground Brine System     

LI Wenpeng 《《地质学报》英文版》2008,(5)

Firstly,the macroscopic chemical equilibrium state of a series of chemical reactions between intercrystal brine and its media salt layer (salt deposit) in Qarhan Salt Lake was studied by using the Pitzer theory.The concept of macroscopic solubility product and its relation with accumulated ore dissolving ratio were presented,which are used in the numerical model of dissolving and driving exploitation of potassium salt in Qarhan Salt Lake.And secondly,with a model forming idea of transport model for reacting solutes in the multi-component fresh groundwater system in porous media being a reference,a two-dimensional transport model coupled with a series of chemical reactions in a multi-component brine porous system (salt deposits) was developed by using the Pitzer theory. Meanwhile,the model was applied to model potassium/magnesium transport in Qarban Salt Lake in order to study the transfer law of solid and liquid phases in the dissolving and driving process and to design the optimal injection/abstraction strategy for dissolving and capturing maximum Potassium/ Magnesium in the mining of salt deposits in Qarban Salt Lake.  相似文献   

沿空掘巷合理煤柱宽度综合分析与确定   总被引：3，自引：0，他引：3  

奚家米  毛久海  杨更社  王进锋 《煤田地质与勘探》2008,36(4)

在总结分析经验法、理论计算法、数值模拟法、现场实测等确定煤柱宽度方法优缺点的基础上,提出了采用现场实测和数值模拟相结合的方法来确定保留煤柱宽度。根据石炭井二矿生产实际,分别对巷道开挖前后,不同煤柱宽度下围岩应力、变形进行了模拟,同时利用21053工作面异型煤柱的有利条件,对不同煤柱宽度下巷道围岩变形、支护结构受力等进行了实测。经过对监测数据的分析,得出了巷道围岩变形、支护结构受力与煤柱宽度之间的关系,结合数值模拟结果,确定了石炭井二矿煤柱宽度。  相似文献