共查询到20条相似文献，搜索用时 250 毫秒
1.
索膜结构为柔性的张拉结构体系,必须通过施加预应力和调整结构曲面曲率使之处于稳定的初始平衡状态,本文采用非线性有限元找形方法,以大型通用有限元软件Strand7为平台,用其二次开发程序Strand7API编制了相应的程序,对两个典型的索膜结构实例和一个大型索膜结构工程进行了找形验证.分析结果发现该找形方法适合各类索膜结构的找形分析,可以快速有效地得到索膜结构的初始平衡形态. 相似文献
2.
本文以Biot动态方程(u-p公式)为控制方程,采用有限元方法和Generalized Newmark-时间积分方法,在SWANDYNE的基础上发展了用于分析海床基础固结和动态响应分析的计算程序PORO-WSSI 2D。利用太沙基一维固结理论验证了POR-WSSI 2D中固结模块的有效性。利用该计算程序,深入研究了大型海床基础在大型复合式防波堤和静水压力作用下的固结过程以及最终的固结状态。计算结果表明计算程序PORO-WSSI 2D能够有效地分析评价海床基础在海洋结构物作用下的固结过程以及预测海床基础的剪切破坏行为。所确定的最终固结状态还可以为后续研究海床基础在波浪、地震等动力荷载作用下的动态液化和剪切破坏提供可靠的初始条件。 相似文献
3.
面向对象有限元程序设计及其VC++与Matlab混合编程实现 总被引：1，自引：1，他引：1
应用面向对象方法来研究有限元,是对有限元新方法的有益尝试和创新性发展。通过对比面向过程和面向对象的程序设计方法,讨论了面向对象方法与有限元程序设计相结合的优点,并简要回顾了国内外面向对象的程序设计方法的研究进展。应用面向对象的程序分析方法,建立了三维脆塑性有限元分析类库。采用VC 和Matlab混合编程的手段,设计了基于Windows98/2000/NT操作平台的面向对象的三维脆塑性有限元分析软件,成功地分析了国内某大型水电站地下硐室群围岩稳定性,验证了该面向对象有限元分析程序的有效性和实用性。 相似文献
4.
大岗山水电站地下厂房区初始地应力场Nelder-Mead优化反演研究 总被引：12，自引：1，他引：11
初始地应力是大型地下洞室群设计与施工所要考虑的重要因素之一。结合大岗山水电站工程地质条件以及实测地应力资料,分析了地下厂房区初始地应力的影响因素,建立了基于侧压力系数的三维地应力反演模型,提出Nelder-Mead法与有限元联合反演法,将有限元程序作为一个单独模块嵌入到Nelder-Mead算法程序中,对建立的地质概化模型进行计算,以实测点地应力值与计算应力值建立精确罚函数误差模型,进行优化逼近分析。通过实测点的计算应力值与现场实测值的比较,从而获得地下厂房区初始地应力场较为合理的分布规律,为水电站开挖模拟及长期稳定性分析提供了合理的初始条件。 相似文献
5.
小湾水电站坝址区三维初始地应力场反演回归分析 总被引：2，自引：1，他引：1
基于小湾水电站坝址区工程地质地形条件,研究分析了影响工程考察域初始地应力场的基本因素及其空间分布,建立了坝址区三维有限元计算模型和初始地应力场参数空间分布模型;利用大型通用有限元软件MSC.Marc和地应力实测资料,借助最小二乘法原理,以回归精度为目标函数,优化了构造挤压荷载的模拟和作用组合,实现了初始应力场空间分布模型的参数估计。计算结果表明,改进后的方法较传统方法回归精度有了较大提高,能较为合理地模拟小湾坝址区三维初始地应力场。 相似文献
6.
油藏多相渗流的面向对象有限元程序设计 总被引：3，自引：0，他引：3
近年来,面向对象的编程技术越来越受到人们的重视,并用来解决和模拟各种物理问题和工程问题,特别是在有限元方法编程和模拟中得到了广泛地应用。介绍了面向对象的程序设计方法和它与有限元程序相结合的原理和优点。在此基础上提出了面向对象有限元方法在油藏多相渗流中的应用实例,并按照面向对象的程序设计方法,基于Windows XP平台采用Visual C++.NET语言,建立了有关描述多相渗流的有限元模型的类,给出了类的描述和它的实现方法。建立的相关类及其实现方法主要包括处理矩阵计算的类、节点类、单元类、材料类、形函数类等。据此编制了油藏多相渗流的有限元分析的数值计算程序,并给出了一个数值实例。 相似文献
7.
基于Visual C#2008.NET开发环境,利用AutoCAD ActiveX技术,对AutoCAD2008进行二次开发,开发出快速建立初始地应力场反演计算三维有限元模型的面向对象程序,通过该程序可以根据需要自动读取一定范围内的网格节点地面高程,能够为有限元模型变地面线处理直接利用,避免了常规人工读取CAD地面高程的繁琐性和误差较大的问题,极大地提高了工作效率和准确性,快速便捷。可以快速自动建立用于初始地应力反演计算的有限元网格模型,该模型能够较好地反映地形貌地的起伏状况,为有限元计算提供了良好的基础条件。 相似文献
8.
岩体初始地应力场分析方法研究 总被引：3，自引：1，他引：2
初始地应力场是影响岩土工程稳定性的重要因素之一,如何合理地模拟初始地应力场一直是岩体力学中的重要研究课题。以国内某大型水利水电工程构筑区域实测空间地应力资料为基础,以边界位移为控制对象,采用有限元（无界元）方法对工程区大范围内的岩体初始地应力场进行了分析和研究。尝试在实际边界上满足无穷远处位移为0的模型边界上引入了无界单元,实测点上的应力拟合结果有较明显的改善,这表明所采用的方法是切实可行和有效的。 相似文献
9.
正在设计施工的某大型水电站地下洞室群地质条件复杂,其开挖支护方案对围岩稳定性非常重要,因此,对支护方案进行优化研究非常必要。为更真实地模拟岩体的力学特性,研究施工过程中岩体的损伤破坏,根据不可逆热力学理论建立了弹塑性损伤模型和损伤演化方程,并编制了三维弹塑性损伤有限元程序D-FEM,具有模拟开挖与支护、计算速度快、群组功能等特点。建立大型地下洞室群三维数值模型,将通过实测地应力反演的应力作为初始地应力。采用D-FEM模拟了不同支护方案洞室群的施工过程,通过分析洞室围岩的应力、位移和破损区,支护方案2的支护效果最好,建议采用此方案。考虑岩体损伤演化后与FLAC3D塑性区相比,洞室群边墙中部的破损区显著增加,因此,程序可应用于地下工程的稳定性分析 相似文献
10.
考虑洞室开挖后围岩的力学状态和岩石力学众多问题的不确定性本质,通过弹性模量折减的方法,建立了考虑松动圈的卡尔曼滤波与有限元耦合反分析法,并编写了相应算法程序。利用基于文件操作的Fortran与VC++交互通信技术,一方面,为隧道施工量测管理与围岩稳定智能分析系统增加了非确定性反分析模块;另一方面,也使反分析能够利用该系统的图形模块进行前后处理,使该方法的工程应用更加简单,为该法的应用推广创造了很好的条件。用反分析法求出围岩初始参数后,通过有限元正分析可求出全域最大剪应变,并与试验和理论推演获得的临界剪应变相比较,进而进行围岩稳定性判定。由于该围岩稳定性分析法摒弃了一般有限元正分析在围岩初始应力场上的不合理假设,因而结果更贴切实际,更具合理性。对白云隧道YK48+737断面的现场监测数据进行了跟踪反演,获得了该断面围岩塑性区历时变化图,从而及时地了解了围岩的稳定状况,指导了设计和施工。 相似文献
11.
Eurocode 7, the new European standard for geotechnical design, is based on the limit state design method, with partial factors and characteristic parameter values. An objective of the Eurocodes is that the chosen partial factors should achieve reliability levels for a structure close to a prescribed target value. The target ultimate limit state reliability index for a medium risk structure for 50 years is 3.8. This paper examines the reliability of an inclined-eccentrically and vertically loaded square foundation designed using all three Design Approaches in Eurocode 7 with the recommended partial factor values given in EN1997-1. The reliabilities obtained using the three Design Approaches are compared with the target reliability value and the reliabilities of traditional designs using overall factors of safety. The paper provides evidence that Eurocode 7 gives more consistent reliabilities for a greater range of parameter values than the traditional allowable stress method and demonstrates the importance of selecting appropriate characteristic values. 相似文献
12.
Li LiState Key Laboratory of Advanced Technology for Materials Synthesis Processing Wuhan University of Technology Wuhan 《中国地质大学学报(英文版)》2001,12(3)
ＩＮＴＲＯＤＵＣＴＩＯＮＥｖｅｒｓｉｎｃｅｔｈｅｉｎｔｒｏｄｕｃｔｉｏｎｏｆｐｈｙｓｉｃａｌｖａｐｏｒｄｅｐｏｓｉｔｉｏｎｔｏｅｐｉｔａｘｉａｌｇｒｏｗｔｈｏｆｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｓｕｐｅｒｃｏｎｄｕｃｔｉｎｇｃｕｐｒａｔｅｓ,ｑｕａｌｉｔｙｏｆｔｈｅｍａｔｅｒｉａｌｈａｓｂｅｅｎｇｒｅａｔｌｙｉｍｐｒｏｖｅｄ .Ａｔｐｒｅｓｅｎｔ,ｈｉｇｈ ｑｕａｌｉｔｙＹＢａ2 Ｃｕ3 Ｏ7-δ(ＹＢＣＯ)ｆｉｌｍｓｗｉｔｈＴＣ≥ 90Ｋ ,ＪＣ≥ 6× 10 6Ａ/ｃｍ2 ａｔ 77Ｋｃａｎｂｅｅａｓｉｌｙｐｒｅｐａｒｅｄｂ… 相似文献
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A passive sampling system for use with rhodamine WT (RWT) in groundwater tracing experiments was developed to assist in the
characterisation of groundwater flow paths. Amberlite XAD-7 resin was found to be suitable for adsorption of RWT, which can
then be extracted using an ethanol/water mix and analysed fluorometrically. Batch and column experiments showed that XAD-7
resin has a high RWT capacity. The adsorption was slightly dependent on pH, but was always above 75% under batch conditions.
The resin had a high percentage mass recovery at flow velocities around 1.5 m/day, but this decreased with increasing flow
velocities. Desorption of RWT off the resin in water is dependent on the flow velocity of water and the time after the peak
RWT has passed. The mass of RWT extracted from the resin bags correlated very well with both the RWT mass flux in the water
and the peak concentrations observed in the monitoring wells in a field experiment. The results of resin bags were reproducible
in the field with a mean coefficient of variation equal to 16%. This method has been successfully applied to two field situations
with different flow velocities to indicate groundwater flow paths.
Electronic Publication 相似文献
14.
HAN Hui LIU Pengwei DING Zhengang SHI Pitong JIA Jianchao ZHANG Wei LIU Yan CHEN Shiji LU Jungang Chen Kang PENG Xudong WANG Zhiyong XIAO Shuqi GAO Yuan 《《地质学报》英文版》2018,92(4):1508-1522
To investigate the influence of extractable organic matter (EOM) on pore evolution of lacustrine shales, Soxhlet extraction, using dichloromethane, was performed on a series of Chang 7 shale samples (Ordos Basin, China) with vitrinite reflectance of 0.64% to 1.34%. Low‐pressure gas adsorption experiments were conducted on the samples before and after extraction. The pore structure parameters were calculated from the gas adsorption data. The results show complex changes to the pore volumes and surface areas after extraction. The pore development of both the initial and extracted samples is strongly controlled by total organic carbon (TOC) content. Micropores developed mainly in organic matter (OM), while mesopores and macropores predominantly developed in fractions other than OM. The influence of EOM on micropores is stronger than on mesopores and macropores. Organic solvents with a higher boiling point should be used to explore the effect of EOM on pore structure in the future. 相似文献
15.
Trevor L.L. Orr 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2019,13(3):205-213
ABSTRACTTen years after their publication, the Eurocodes, including Eurocode 7 for Geotechnical design, are being revised taking into account experiences with their use and developments in design concepts and practices since their publication to produce a second generation of the Eurocodes. The objectives for this second generation of Eurocode 7 are to improve its ease of use, harmonise its structure with the other Eurocodes, reduce the number of nationally determined parameters, include measures for robustness and include sections on topics not covered in the current Eurocode 7, such as numerical methods, reinforced soil and ground improvement. The evolution of Eurocode 7 aims to hone its safety and risk assessment aspects by developing the concept of Geotechnical Categories, expanding the supervision, monitoring and maintenance requirements, and explicitly allowing for reliability differentiation. 相似文献
16.
在大量样品测试数据与野外地质调查综合分析的基础上, 对长7储层岩石学特征、物性、孔隙结构、成岩作用、成岩阶段和成岩相等进行了研究。结果表明: 研究区长7储层处于中成岩A~B期。压实作用及碳酸盐、粘土(高岭石、伊利石、伊蒙混层)矿物胶结和硅质胶结作用是造成储层原生孔隙丧失的主要原因; 绿泥石胶结抑制孔隙充填, 长石溶蚀作用使孔隙间的连通性得到改善, 储层物性得到提高。根据成岩作用类型、强度及其对储层物性的影响划分出6种成岩相, 其中压实相、碳酸盐胶结相、粘土矿物胶结相、石英加大相、浊沸石充填相不利于储层的发育, 而长石溶蚀相、绿泥石膜胶结相对储层物性改善起了重要作用。 相似文献
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在ERDAS软件支持下，对ETM遥感影像数据的TM1-TM5，TM7与其全色波段TM8进行融合，采用主成分、乘积法、Brovey转换三种融合方法，重采样方法分别为邻域法、立方卷积法及双线性内插法。采用相同的训练样本区及最大似然法分类方法，对融合产生的9幅影像及未融合影像进行土地覆盖分类，通过对分类影像的Producers Accuracy，Users Accuracy，Kappa三者的精度数据和地物波谱信息的对比分析，在总体上，上述的影像融合方法对提高土地覆盖分类的精度不明显，但就某些地物类型来说，还是值得采用的；三种融合方法和三种重采样方式它们之问相比较而言，乘积法融合法和立方卷积重采样法相对较为可取。 相似文献
20.
LI Peng JIA Chengzao JIN Zhijun LIU Quanyou BI He ZHENG Min WU Songtao HUANG Zhenkai 《《地质学报》英文版》2020,94(2):219-232
Pore distribution and micro pore-throat structure characteristics are significant for tight oil reservoir evaluation, but their relationship remains unclear. This paper selects the tight sandstone reservoir of the Chang 7 member of the Xin’anbian Block in the Ordos Basin as the research object and analyzes the pore size distribution and micro pore-throat structure using field emission scanning electron microscopy(FE-SEM), high-pressure mercury injection(HPMI), highpressure mercury injection, and nuclear magnetic resonance(NMR) analyses. The study finds that:(1) Based on the pore size distribution, the tight sandstone reservoir is characterized by three main patterns with different peak amplitudes. The former peak corresponds to the nanopore scale, and the latter peak corresponds to the micropore scale. Then, the tight sandstone reservoir is categorized into three types: type 1 reservoir contains more nanopores with a nanopore-to-micropore volume ratio of 82:18;type 2 reservoir has a nanopore-to-micropore volume ratio of 47:53;and type 3 reservoir contains more micropores with a nanopore-to-micropore volume ratio of 35:65.(2) Affected by the pore size distribution, the throat radius distributions of different reservoir types are notably offset. The type 1 reservoir throat radius distribution curve is weakly unimodal, with a relatively dispersed distribution and peak ranging from 0.01 μm to 0.025 μm. The type 2 reservoir’s throat radius distribution curve is single-peaked with a wide distribution range and peak from 0.1 μm to 0.25 μm. The type 3 reservoir’s throat radius distribution curve is single-peaked with a relatively narrow distribution and peak from 0.1 μm to 0.25 μm. With increasing micropore volume, pore-throat structure characteristics gradually improve.(3) The correlation between micropore permeability and porosity exceeds that of nanopores, indicating that the development of micropores notably influences the seepage capacity. In the type 1 reservoir, only the mean radius and effective porosity have suitable correlations with the nanopore and micropore porosities. The pore-throat structure parameters of the type 2 and 3 reservoirs have reasonable correlations with the nanopore and micropore porosities, indicating that the development of these types of reservoirs is affected by the pore size distribution. This study is of great significance for evaluating lacustrine tight sandstone reservoirs in China. The research results can provide guidance for evaluating tight sandstone reservoirs in other regions based on pore size distribution. 相似文献