共查询到19条相似文献，搜索用时 156 毫秒
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对土石坝振动台模型试验理论和技术进行系统阐述,提出基于原型和模型坝料静、动力特性试验的模型相似设计方法和不同强度地震动递进输入(白噪声微振-设计地震-校核地震-破坏试验)的振动试验方法。基于1g大型振动台和ng超重力离心机振动台设备性能现状,结合高土石坝的结构特点和动力试验相似模拟要求,对土石坝振动台模型试验的优势及局限进行深入讨论。结合已有的工程实践,对土石坝振动台模型试验在工程中的应用进行总结,并以某实际高面板堆石坝为例研究面板坝生命周期内经历多次地震情况下结构动力特性的演化规律。 相似文献
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《地震工程与工程振动》2021,41(2)
传统随机有限断层方法只能模拟水平单向地震动,不能完全满足工程抗震设计对三维(两个水平向及竖向)地震动需求。文中在传统方法的基础上发展了一种可模拟三维地震动的随机有限断层方法,利用水平向和/或垂直向P、SV、SH波在频域上的经验表达并结合随机相位合成三维地震动加速度时程。为验证方法的可靠性,模拟了2014年云南鲁甸地震的三维地震动。结果表明,改进方法合成的加速度时程波形与观测记录较相似,且模拟记录PGA、0.05～10 s周期段PSA幅值和谱形与观测记录也具有良好一致性,能合理反映地震动随距离的衰减规律;鲁甸地震三维地震动的可靠模拟也验证了路径衰减、路径持时经验模型、高频衰减参数、震源谱衰减率等模拟输入参数的可靠性,可进一步应用于该区域设定地震地震动预测。 相似文献
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工程地震动模拟研究综述 总被引：4，自引：2，他引：2
地震动时程输入是结构抗震设计发展的必然要求,工程地震动模拟则是确定输入时程的主要方法.以研究满足工程需要的地震动模拟技术为宗旨,阐述了工程界合成地震动的历史与现状,以及地震学方法的工程应用,并总结出相关方法的特点和适用性.最后结合工程应用的特点,对工程地震动合成的发展方向进行了展望. 相似文献
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面板堆石坝的动力离心模型试验研究 总被引：1，自引：0，他引：1
为研究面板堆石坝的地震响应规律,采用Parkfield波作为地震动输入,在清华大学50g-t土工离心机上进行了动力离心模型试验.试验在50倍重力加速度条件下采用电液伺服离心机振动台系统完成,采用加速度传感器测量了模型不同位置动力响应的加速度时程并且测量了面板的变形.结果表明,地震最大响应发生于坝顶,该处地震动放大系数接... 相似文献
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合理的地震动输入是定量解释震害和烈度异常的基础.以汉源老县城震害为评价基准,确定了汉源老县城高烈度异常区的汶川地震基岩地震动输入.基于汉源老县城周边的九襄、清溪、宜东和乌斯河4个强震台站记录,采用LSSRLI-1程序反演给出了各自台站的水平向基岩地震动;选取汉源县城典型场地,利用LSSRLI-1程序计算给出了不同强震台站基岩地震动作用下的场地地表加速度时程和反应谱,以最可能引起汉源老县城震害的强震台站基岩地震动作为汉源县城的基岩地震动输入.研究结果表明:九襄台站反演的基岩地震动最可能反映汶川地震时汉源老县城的基岩地震动特性,因而用九襄台站的基岩地震动作为汉源老县城的地震动输入解释汉源县城高烈度异常现象是合理的.本文的研究思路为定量解释震害的地震动输入确定提供了重要参考. 相似文献
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在高应力状态下坝料的流变较为明显。为研究坝料流变对混凝土面板坝应力变形的影响,采用长科院九参数幂级数流变模型及其试验参数,对某高混凝土面板堆石坝进行应力、变形分析。结果表明,坝料流变使坝体变形明显增加,坝体应力有所减小。考虑坝料的流变特性后的面板法向位移(挠度)明显增加,面板坝轴向和顺坡向应力极值增加。对于分期浇筑面板和分期蓄水的高混凝土面板堆石坝,选用合适的流变本构模型正确地模拟堆石体的流变特性,可以为大坝填筑进度及面板分期浇筑时间的确定提供参考,并有助于正确地预测大坝的应力变形。 相似文献
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The spatial variability of seismic ground motion is an important aspect for the earthquake resistant design of extended facilities. A modified response spectrum model, which addresses the problem of multiply supported structures subjected to imperfectly correlated seismic excitations, has already been developed (see References 1 and 2). The present paper proposes a modal combination rule for the case of non-uniform seismic input, which would be used together with the modified response spectrum model in order to compute physical responses. This rule, which accounts for modal cross-correlations, is an extension to an existing rule for the case of uniform seismic motions. It modifies the existing modal cross-correlation coefficients through a correction factor which depends on structural properties and on the characteristics of the wave propagation phenomenon. Finally, some practical considerations on the theoretical development are addressed. They aim at suggesting reasonable simplifications which render the modal combination rule more appealing for engineering purposes. The proposed practical combination rule is validated through a numerical experiment which also characterizes the effect of non-uniform seismic input on modal cross-correlation. 相似文献
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三维地震断层动力破裂的显式并行有限元解法 总被引：4，自引：1，他引：3
本文在近场波动有限元的基础上,根据断层动力破裂的摩擦模型,详细地推导出了断层面节点在破裂的不同时刻的计算公式,提出了一种模拟断层动力破裂的显式并行有限元方法,利用此方法,可以模拟断层的破裂过程、地表破裂及由此产生的地面运动。 相似文献
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基于粤港澳大湾区地震灾害风险评估的初步成果,分析了湾区城市群地震环境、承灾体分布和场地特点,提出了两种确定地震输入的设定地震原则,即潜在震源区设定地震原则和最大风险设定地震原则,按照这两种原则可以更加准确地进行城市群地震灾害风险评估。在前人工作的基础上,提出了考虑场地条件影响的地震灾害风险表达式,探索了适合三维模拟非一致激励地震动输入的建筑物和生命线工程灾害风险评估方法,提出了建筑物和生命线工程灾害风险评估中考虑场地影响的思路,为客观地评估城市群地震灾害和损失风险提出了可参考的建议。 相似文献
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Non-uniform ground motions are generated based on a single record available at a site and seismic wave scattering analysis. The Chino Hills 2008 earthquake records at the Pacoima Dam site are used to indicate the accuracy of the method. Dynamic analysis of the Pacoima dam-reservoir-foundation under uniform and non-uniform ground motions is carried out using the EACD-3D2008 software, and the results are compared to recorded responses at different locations on the dam. There is good agreement between computed and recorded displacements of the dam for non-uniform excitation. For uniform excitation, the displacements are underestimated in comparison with those obtained from recorded excitation. Significant intensification of stresses, especially near the foundation, and different patterns of stress distribution are observed for non-uniform excitation in comparison with uniform excitation. For uniform excitation maximum stresses occur in the crown cantilever near the crest, but for non-uniform excitation the maximum stresses occur along the sides and near the foundation. 相似文献
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A series of shaking table tests were conducted on scaled utility tunnel models with and without construction joints under non-uniform input earthquake wave excitation. Details of experimental setup are first presented with particular focuses on: design and fabrication of double-axis laminar shear box with a rectangular hole opened on its side walls; design of two devices for measuring the slippage between the interface of test soil and the structure, and the relative deformation and rotation between joints of the structure model; and procedure for construction of input earthquake wave. The experiments were conducted in three phases. Phase 1 is free-field test. A 2-norm index is suggested to quantify the boundary effect and it is found that the designed laminar box does not impose significant boundary effect. Phases 2 and 3 are model tests in longitudinal and transversal directions, respectively. Test results are discussed in items of shear force–slip relationship at the soil–model structure interaction surface, movement and rotation of the construction joint, and effect of non-uniform earthquake input. The comparison shows that structural response under non-uniform earthquake excitation is larger than that under uniform excitation. The effect of spatial distribution of earthquake excitation should be considered in the seismic design of utility tunnel. 相似文献
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Gaussian beam is an important complex geometrical optical technology for modeling seismic wave propagation and diffraction in the subsurface with complex geological structure. Current methods for Gaussian beam modeling rely on the dynamic ray tracing and the evanescent wave tracking. However, the dynamic ray tracing method is based on the paraxial ray approximation and the evanescent wave tracking method cannot describe strongly evanescent fields. This leads to inaccuracy of the computed wave fields in the region with a strong inhomogeneous medium. To address this problem, we compute Gaussian beam wave fields using the complex phase by directly solving the complex eikonal equation. In this method, the fast marching method, which is widely used for phase calculation, is combined with Gauss–Newton optimization algorithm to obtain the complex phase at the regular grid points. The main theoretical challenge in combination of this method with Gaussian beam modeling is to address the irregular boundary near the curved central ray. To cope with this challenge, we present the non-uniform finite difference operator and a modified fast marching method. The numerical results confirm the proposed approach. 相似文献
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D.J. BUCHANAN 《Geophysical Prospecting》1986,34(3):343-365
The imaging of faults in coal seams by the in-seam seismic method has now become standard practice. In the UK over 300 surveys have been undertaken and the technique is now part of the exploration arsenal of colliery planners. From these users comes the pressure for two major improvements, namely an increase in range and target identification. This paper is directed towards the latter problem. It has long been recognized that the reflected channel waves must contain information on the fault structure that caused the reflection, and model experiments have been undertaken to investigate the reflection process. Only recently, however, have attempts been made to quantify the reflection process. Calculations using both the finite-difference and finite-element techniques have been carried out, and estimates of the reflection coefficient as a function of frequency have been obtained. The object of this paper is to extend these considerations by calculating analytically the scattering matrix of an SH-channel wave after interaction at a fault plane. The scattering matrix is calculated as a function of frequency, hade angle, and fault throw. The method employed is based on the decomposition of the incident SH-channel wave into Fourier components, the calculation of plane wave reflection and transmission coefficients within the constraints of geometrical acoustics, and finally the synthesis of the scattering matrix by application of the Helmholtz-Kirchhoff integral. The calculation throughout is restricted to normal modes. 相似文献
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为实现地震作用下土-结构动力相互作用问题的有限元模拟,需要在人工边界上完成地震动的有效输入,目前工程和科研中常用的地震动输入方法有两种:波动输入方法和振动输入方法。波动输入方法的模拟精度高,但实施上相对复杂且耗时,而振动输入方法处理简单,但模拟精度较低。针对应力型人工边界提出一种在人工边界上实现地震动输入的新方法,该方法通过对土-结构有限元模型中由人工边界节点及相邻节点组成的局部子结构施加自由波场位移时程并进行动力分析,从而直接获得可实现地震波动有效输入的等效地震荷载,然后在土-结构有限元模型的人工边界节点上施加等效输入地震荷载并完成动力计算,由此完成土-结构动力相互作用问题的地震动输入和地震反应计算。与原有波动输入方法相比,新方法避免了原方法需分别计算人工边界上自由场应力和由引入人工边界条件引起的附加力,以及需要根据不同人工边界面的外法线方向确定荷载作用方向等较为复杂的处理过程,具有等效地震荷载计算简便、地震动输入过程更易于实施的特点。采用均匀弹性半空间和成层弹性半空间一维地震反应算例初步验证新方法的正确性和可靠性。 相似文献