拖曳锚安装缆绳在海床土中的反悬链形态研究     

柳成林  刘海笑  赵燕兵  王宸 《岩土力学》2013,34(11):3221-3228

由于在抗拔承载力和深水安装中的优势,拖曳锚在深水系泊系统中具有良好的发展前景。在拖曳锚安装过程中,安装缆绳和锚之间存在复杂的相互作用,安装缆绳在海床土中的反悬链形态将直接影响锚的嵌入和运动,对反悬链形态的研究有助于提高锚的嵌入性能、准确预测锚的运动轨迹以及解决锚在安装中的精确定位问题。基于嵌入缆单元在海床土中的力学模型,推导出适用于黏性土和无黏性土的反悬链方程,利用该方程可求出安装缆绳在海床土中的反悬链形态;通过在缆绳上布置倾角传感器并运用圆弧递推方法,设计出可实时测量嵌入缆形态的试验技术,为验证试验技术的合理性,在空气中分别选取3种典型缆绳形态进行模拟,结果表明：模拟形态与真实形态吻合良好,并具有较高精度;利用实时测量技术开展模型试验,对反悬链方程进行了考察,验证了其模拟嵌入缆反悬链形态的精度,并获取了对拖曳锚安装过程中反悬链形态变化规律的直观认识。  相似文献   

乌东德高拱坝极限抗震能力研究     

熊堃  翁永红  胡中平  曹去修 《岩土力学》2013,34(Z2):325-331

乌东德水电站是金沙江下游河段上4个水电梯级的最上游梯级,大坝为265 m高的双曲拱坝。采用非线性有限元法,将拱坝坝体-坝基作为一个整体系统,在考虑坝体横缝影响及无限地基辐射阻尼影响基础上,模拟坝肩控制性滑块各滑裂面在地震作用下张开、滑移的非线性力学行为,研究设计与校核地震作用下大坝的抗震性能,探讨大坝-坝基整体系统在强震作用下的抗震潜力。研究结果表明：设计地震条件下,坝体仅在拱端应力集中区域拉应力超过抗拉强度,压应力则均满足强度要求,坝肩块体稳定,大坝-坝基体系的整体安全性可以保证;校核地震条件下,坝体应力值略有增加,能够满足不溃坝的设防要求;以大坝-坝基代表性的位移、变形量变化曲线的拐点作为评价极限抗震能力的标准,可知拱坝-坝基体系的抗震超载安全系数为2.7,相应的基岩水平向峰值加速度0.729g,拱坝-坝基体系抗剪参数强度储备安全系数为2.0,乌东德高拱坝具备较强的极限抗震能力。  相似文献   

Nonlinear earthquake analysis of high arch dam–water–foundation rock systems     

Jin‐Ting Wang  Chu‐Han Zhang  Feng Jin 《地震工程与结构动力学》2012,41(7):1157-1176

A nonlinear finite element model for earthquake response analysis of arch dam–water–foundation rock systems is proposed in this paper. The model includes dynamic dam–water and dam–foundation rock interactions, the opening of contraction joints, the radiation damping of semi‐unbounded foundation rock, the compressibility of impounded water, and the upstream energy propagating along the semi‐unbounded reservoir. Meanwhile, a new equivalent force scheme is suggested to achieve free‐field input in the model. The effects of the earthquake input mechanism, joint opening, water compressibility, and radiation damping on the earthquake response of the Ertan arch dam (240 m high) in China are investigated using the proposed model. The results show that these factors significantly affect the earthquake response of the Ertan arch dam. Such factors should therefore be considered in the earthquake response analysis and earthquake safety evaluation of high arch dams. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Earthquake response of arch dams to spatially varying ground motion     

Anil K. Chopra  Jin‐Ting Wang 《地震工程与结构动力学》2010,39(8):887-906

The response of two arch dams to spatially varying ground motions recorded during earthquakes is computed by a recently developed linear analysis procedure, which includes dam–water–foundation rock interaction effects and recognizes the semi‐unbounded extent of the rock and impounded water domains. By comparing the computed and recorded responses, several issues that arise in analysis of arch dams are investigated. It is also demonstrated that spatial variations in ground motion, typically ignored in engineering practice, can have profound influence on the earthquake‐induced stresses in the dam. This influence obviously depends on the degree to which ground motion varies spatially along the dam–rock interface. Thus, for the same dam, this influence could differ from one earthquake to the next, depending on the epicenter location and the focal depth of the earthquake relative to the dam site. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

柱状节理坝基岩体三维各向异性数值分析   总被引：4，自引：1，他引：3  

徐卫亚  郑文棠  宁宇  孟国涛  吴关叶  石安池 《岩土力学》2010,31(3):949-955

在分析柱状节理不连续性和各向异性的工程特性基础上,对某拱坝及坝基的柱状节理岩体进行三维数值模拟分析。考虑河谷初始地应力场和岩体各向异性力学性质,采用各向同性本构和各向异性弹塑性本构进行对比分析。计算表明,坝基柱状节理岩体各向异性特性对工程整体应力、变形的影响比较明显,采用各向异性弹塑性模型计算更能反映柱状节理的特殊性。其结果为该坝区岩体工程各向异性力学分析提供了示例。  相似文献   

某异型钢管混凝土拱桥地震反应分析     

李勇  闫维明  陈彦江 《震灾防御技术》2010,5(3):346-351

本文以某异型钢管混凝土拱桥为研究对象,通过ANSYS建立了结构的空间有限元模型,计算和分析了该桥的动力特性。同时,通过MATLAB程序生成拟合规范反应谱的人工地震波,并运用时程分析法计算了该桥在一维和多维输入下的地震反应,分析了该桥的地震反应规律,为钢管混凝土拱桥的抗震性能分析提供了一定的依据。  相似文献   

钢管混凝土拱桥海上应用实例     

石彩亭 《中国勘察设计》2009,(9):38-40

近年来钢管混凝土拱桥建设在全国迅速发展,型式多样、各有千秋。本文就大跨度全钢系杆拱在大连新港50万吨级进口原油码头引桥上的成功应用做以下介绍。  相似文献   

桩承式加筋路堤作用机理理论分析与数值模拟     

骆瑞萍  陈保国 《岩土工程技术》2009,23(3):150-154

软土地基上填筑高路堤常常面临地基承载力不足、沉降和不均匀沉降过大等问题。桩承式加筋路堤能够有效地解决这些难题。通过理论分析和有限元数值模拟,研究了路堤填土-加筋材料-桩体-桩间土之间的相互作用机理,讨论了路堤填土中的土拱效率、桩体效率、路堤底面差异沉降和筋材拉力的变化规律。研究结果表明,填土中的土拱效应和筋材张力膜效应能够有效地提高桩体效率,防止软土屈服;筋材内部拉力呈非线性分布,桩顶边缘处筋材拉力最大。  相似文献   

Earthquake response of concrete arch dams: a plastic–damage approach     

Omid Omidi  Vahid Lotfi 《地震工程与结构动力学》2013,42(14):2129-2149

There are several alternatives to evaluate seismic damage‐cracking behavior of concrete arch dams, among which damage theory is the most popular. A more recent option introduced for this purpose is plastic–damage (PD) approach. In this study, a special finite element program coded in 3‐D space is developed on the basis of a well‐established PD model successfully applied to gravity dams in 2‐D plane stress state. The model originally proposed by Lee and Fenves in 1998 relies on isotropic damaged elasticity in combination with isotropic tensile and compressive plasticity to capture inelastic behaviors of concrete in cyclic or dynamic loadings. The present implementation is based on the rate‐dependent version of the model, including large crack opening/closing possibilities. Moreover, with utilizing the Hilber–Hughes–Taylor time integration scheme, an incremental–iterative solution strategy is detailed for the coupled dam–reservoir equations while the damage–dependent damping stress is included. The program is initially validated, and then, it is employed for the main analyses of the Koyna gravity dam in a 3‐D modeling as well as a typical concrete arch dam. The former is a major verification for the further examination on the arch dam. The application of the PD model to an arch dam is more challenging because the governing stress condition is multiaxial, causing shear damage to become more important than uniaxial states dominated in gravity dams. In fact, the softening and strength loss in compression for the damaged regions under multiaxial cyclic loadings affect its seismic safety. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

老挝Nam Ngum 5水电站重力拱坝裂缝处理实践          下载免费PDF全文

王玉溪  宋平  张连顺  韩小霞 《探矿工程》2012,39(6):68-71

针对老挝Nam Ngum 5水电站重力拱坝裂缝进行的灌浆处理,采用化学灌浆和水泥灌浆相结合,取得了良好的治理效果。详细介绍了裂缝深度的检测方法和裂缝止裂措施,以及灌浆施工工艺。  相似文献