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1.
有缝拱坝-地基系统非线性地震波动反应分析方法 总被引：12，自引：3，他引：9
拱坝坝体中缝界面在地震作用下的开、合模拟对拱坝地震反应有重要影响。目前在拱坝地震反应分析中应用的一些模型,如Ｆｅｎｖｅｓ模型、Ｄｏｗｌｉｎｇ的三参数模型,存在对缝界面的接触状态模拟精度不高的问题,这对于准确评价工程上关心的缝界面最大张开率是不足的。此外,坝基中存在的断层、节理、裂隙待软弱夹层的非线性力学特性和无限地基能量辐射作用对拱坝地震反应也有重要影响。在拱坝地震反应分析中同时考虑这三种影响因素 相似文献
2.
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
3.
Nonlinear seismic response analysis of arch dam-foundation systems- part I dam-foundation rock interaction 总被引：1，自引：0，他引：1
The arch dam–foundation rock dynamic interaction and the nonlinear opening and closing effects of contact joints on arch dam
are important to the seismic response analysis of arch dams. Up to date, there is not yet a reasonable and rigorous procedure
including the two factors in seismic response analysis. The methods for the analysis of arch dam–foundation rock dynamic interaction
in frequency domain are not suitable to the problem with nonlinear behaviors, in this paper, so an analysis method in time
domain is proposed by combining the explicit finite element method and the transmitting boundary, and the dynamic relaxation
technique is adopted to obtain the initial static response for dynamic analysis. Moreover, the influence of arch dam–foundation
dynamic interaction with energy dispersion on seismic response of designed Xiaowan arch dam in China is studied by comparing
the results of the proposed method and the conventional method with the massless foundation, and the local material nonlinear
and nonhomogeneous behaviors of foundation rock are also considered. The reservoir water effect is assumed as Westergaard
added mass model in calculation. The influence of the closing–opening effects of contact joints of arch dam on the seismic
response will be studied in another paper. 相似文献
4.
Based on a Chinese national high arch dam located in a meizoseismal region, a nonlinear numerical analysis model of the damage and failure process of a dam-foundation system is established by employing a 3-D deformable distinct element code(3DEC) and its re-development functions. The proposed analysis model considers the dam-foundation-reservoir coupling effect, infl uence of nonlinear contact in the opening and closing of the dam seam surface and abutment rock joints during strong earthquakes, and radiation damping of far fi eld energy dissipation according to the actual workability state of an arch dam. A safety assessment method and safety evaluation criteria is developed to better understand the arch dam system disaster process from local damage to ultimate failure. The dynamic characteristics, disaster mechanism, limit bearing capacity and the entire failure process of a high arch dam under a strong earthquake are then analyzed. Further, the seismic safety of the arch dam is evaluated according to the proposed evaluation criteria and safety assessment method. As a result, some useful conclusions are obtained for some aspects of the disaster mechanism and failure process of an arch dam. The analysis method and conclusions may be useful in engineering practice. 相似文献
5.
拱坝横缝影响及有效抗震措施的研究 总被引：6，自引：0，他引：6
大量研究结果和某些拱坝的地震震害表明，横缝对拱坝的地震响应有很大的影响。通过采用非光滑方程组方法以及考虑碰撞时刻动量、动能守恒来模拟横缝所引起的动接触问题，同时为了提高计算效率，采用隐-显式积分方法对坝-基系统的动力平衡方程进行求解。针对在拱坝中上部配筋这一抗震措施，也作了探讨。通过对小湾拱坝的分析，为高拱坝工程抗震措施的选择提供技术依据。 相似文献
6.
有横缝拱坝的非线性动力模型试验和计算分析研究 总被引：12，自引：0，他引：12
本文通过在大型三向地震模拟振动台上进行的设置伸缩横缝的某拱坝非线性动力模型试验，应用非线性有限元动力分析程序同时进行计算分析，全面系统地研究了拱坝横缝对坝体动力特性和地震反应的影响，并对计算程序进行了改进。试验与计算结果相互印证，验证了试验成果的可靠性和计算分析模型、计算程序与计算结果的合理性。 相似文献
7.
A dynamic overloading model test has been carried out on a shaking table for an arch dam of 278 m in height to investigate its behaviours under strong earthquake. The model system included the arch dam with contraction joints, part of reservoir, partial foundation rock with topographic feature near the dam. A damping boundary consisting of viscous liquid has been used to simulate the effect of dynamic energy emission to far field, which made the dynamic interaction between dam and foundation in model arch dam system be represented properly. Three sets of different seismic waves of design level have been used as the input to investigate the difference in the responses of arch dam. Artificial waves of different levels have been used to verify the behaviours of arch dam under seismic overloading. Since the opening of joints during strong earthquake reduced the response acceleration and tensile arch stress, cantilever stress on downstream face exceeded the tensile strength first for the model dam. And the arch dam responded in a non‐linear way when input seismic load increased. Some cracks appeared near abutments, and the damage made the natural frequency of arch dam to drop obviously, but the static function did not seem to change for the model tested. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
8.
《地震工程与工程振动(英文版)》2015,(3)
A seismic stability assessment of arch dam-foundation systems is presented using a comprehensive approach,in which the main factors that significantly influence the seismic response of an arch dam-foundation system are considered.A large scale finite element model with over 1 million degrees of freedom is constructed for the Baihetan arch dam(289 m high),which is under construction in the Southwest of China.In particular,the complicated geological conditions with faults intersecting interlayer shear weakness zones at the dam base and the dam abutment resisting force body is modeled in the analysis.Three performance indices are adopted to assess the seismic stability of the arch dam.The results demonstrate that the opening of the joints of the Baihetan arch dam is small and the water stop installed between the joints would not be torn during a design earthquake.The yielding formed in the interface between the dam and foundation does not reach the grouting curtain that would remain in an elastic state after an earthquake.The yielding zones occurring on the upper portion of the dam faces extend 1/8 thickness of block section into the dam body and thus cantilever blocks need not be concerned with sliding stability.The faults and interlayer shear weakness zones in the near field foundation exhibit severe yielding,and a potential sliding surface is penetrated.Although the factor of safety against sliding of the surface fluctuates with a decreased trend during an earthquake,the minimum instantaneous value reaches 1.02 and is still larger than 1.0.Therefore,a conclusion is drawn that the Baihetan arch dam-foundation system will remain stable under the design earthquake. 相似文献
9.
An integrative seismic safety evaluation of an arch dam should include all sources of nonlinearities, dynamic interactions between different components and the external loads. The present paper investigates the calibration procedure and nonlinear seismic response of an existing high arch dam. The first part explains the conducted analyses for the static and thermal calibrations of the dam based on site measurements. The second part investigates the nonlinear seismic analysis of the calibrated model considering the effect of joints, cracking of mass concrete, reservoir–dam–rock interaction, hydrodynamic pressure inside the opened joints and the geometric nonlinearity. Penetration of the water inside the opened joints accelerates the damage process. The integrative seismic assessment of a case study shows that the dam will fail under the maximum credible earthquake scenario. The dam is judged to be severely damaged with extensive cracking and the joints undergo opening/sliding. A systematic procedure is proposed for seismic and post-seismic safety of dams. 相似文献
10.
11.
An efficient method for accurately modelling the gradual opening and closing of joints in two-dimensional slabs and arches has been devised. The method is used in computing the earthquake response of an arch which is a representative horizontal cross-section of a concrete arch dam. Responses of the arch with and without joints are compared to assess the effect of joint opening. An extension to three-dimensional arch dams is proposed. 相似文献
12.
考虑横缝影响的拱坝动力分析 总被引：6，自引：0，他引：6
本文在求解三维弹性静力摩擦接触问题的有效方法-非光滑方程组方法的基础上,通过能够近似满足动量、动能守恒条件的速度、加速度的修正方法,将该方法推广到动力接触问题的求解中,以考虑地震时拱坝中横缝的开合、错动对坝体动力响应的影响。同时文中采用由多次透射公式表示的人工边界条件来考虑坝-基动力相互作用的影响。数值算例中分析了横缝的数目和布置位置对拱坝动力响应的影响。 相似文献
13.
Different procedures are compared for the three-dimensional seismic cracking analysis of gravity and arch dams during strong earthquakes. The fracture procedures include the extended finite element method with cohesive constitutive relations, crack band finite element method with plastic-damage relations, and the finite element Drucker−Prager elasto-plastic model. These procedures are used to analyze the nonlinear dynamic response of Koyna dam to the 1967 Koyna earthquake and the seismic cracking of the Dagangshan arch dam subjected to design earthquake. The cracking process and profiles of the two dams using the three different procedures are compared. The applicability and the suitability of the three procedures for seismic cracking analysis of gravity and arch dams are discussed. 相似文献
14.
15.
基于非线性指数型动接触本构模型,对实际键槽模型进行简化处理。采用的本构模型可以考虑缝面的开合非线性以及横缝键槽的咬合作用。采用点-面接触模型模拟横缝的非线性动接触行为,精细研究了缝面开度、径向位移的变化及其对坝体应力状态的影响,并与平缝结果进行了比较。以一座拟建的混凝土重力拱坝,探讨了横缝及其诱导缝对大坝工作性态的影响,并对横缝键槽的影响进行了综合分析。研究表明,横缝的径向滑移量要远大于开度,当考虑诱导缝时,由于大坝整体性受到削弱,横缝开度变大;考虑键槽效应后,径向滑移效应大幅减小,而法向开度增大,坝踵处的主拉应力以及拱冠梁顶处的拱向拉应力的最大值均变大。 相似文献
16.
Earthquake safety assessment of concrete arch and gravity dams 总被引：9，自引：1，他引：8
Based on research studies currently being carried out at Dalian University of Technology, some important aspects for the earthquake safety assessment of concrete dams are reviewed and discussed. First, the rate-dependent behavior of concrete subjected to earthquake loading is examined, emphasizing the properties of concrete under cyclic and biaxial loading conditions. Second, a modified four-parameter Hsieh-Ting-Chen viscoplastic consistency model is developed to simulate the rate-dependent behavior of concrete. The earthquake response of a 278m high arch dam is analyzed, and the results show that the strain-rate effects become noticeable in the inelastic range. Third, a more accurate non-smooth Newton algorithm for the solution of three-dimensional frictional contact problems is developed to study the joint opening effects of arch dams during strong earthquakes. Such effects on two nearly 300m high arch dams have been studied. It was found that the canyon shape has great influence on the magnitude and distribution of the joint opening along the dam axis. Fourth, the scaled boundary finite element method presented by Song and Wolf is employed to study the dam-reservoir-foundation interaction effects of concrete dams. Particular emphases were placed on the variation of foundation stiffness and the anisotropic behavior of the foundation material on the dynamic response of concrete dams. Finally, nonlinear modeling of concrete to study the damage evolution of concrete dams during strong earthquakes is discussed. An elastic-damage mechanics approach for damage prediction of concrete gravity dams is described as an example. These findings are helpful in understanding the dynamic behavior of concrete dams and promoting the improvement of seismic safety assessment methods. 相似文献
17.
Seismic responses of a 292‐m high arch dam were studied by experiment on a shaking table. The model system included the arch dam with contraction joints, a part of a reservoir, and a partial foundation with a topographic feature near the dam. Potential rock wedges on the abutments and the mechanical properties including uplift on the kinematic planes were carefully simulated. A damping boundary consisting of a viscous liquid was introduced to simulate the effect of dynamic energy emission to far field, which made the dynamic interaction between the dam and the foundation be adequately represented in the model test of an arch dam system. Dynamic responses of the arch dam system under a sequence of seismic loadings in increasing strength were examined. Eleven cracks or overstresses on the model dam due to the earthquake excitations were observed, and consequently, its natural frequency dropped by about 14%, but the model dam was stable under the hydrostatic load of the impounded water after the test. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
18.
R. J. Cmara 《地震工程与结构动力学》2000,29(4):441-460
This paper presents a method for coupled arch dam–foundation–reservoir seismic behaviour analysis. The dam is discretized by finite elements (FE) and the foundation and reservoir are discretized by boundary elements (BE). The opening of contraction joints and the spatial variability of the seismic action is taken into account. The study of Pacoima dam by this method is also presented. The computed results show that no cracks were to be expected due to the vibrations induced during the Feb. 9, 1971 San Fernando earthquake. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
19.
《国际泥沙研究》2020,35(6):621-635
The objective of the proposed method is to utilize a site investigation of a debris flow disaster and verify a real scale analysis to evaluate the impulsive load on an open sabo dam. The Nagiso debris flow disaster which occurred in Nagano in 2014, where damage caused by Typhoon Neogri was studied. The verification result of the site investigation demonstrated the weak components of the open Sabo dam experienced damage owing to the debris flow. A discrete element method is normally applied to a solid body to calculate an interaction function force with respect to the contact point between boulders and the dam. The numerical method initially concatenates elements that model the open Sabo dam. Moreover, the stiffness coefficient of flanges and coupling joints between pipes was expressed to utilize the sectional partition method to determine the structural characteristics. The method was improved to separate from the connecting elements beyond the boundary conditions. The debris flow model uses a water flow distribution model, and the debris flow flowed from 200 m upstream of the open sabo dam. Accordingly, the proposed method was examined to verify the primary cause of damage to the open sabo dam and used to reproduce the circumstances that evaluated the impulsive load occurrence mechanism in the case of a real disaster. In addition, the coupling joints between the hollow steel pipes utilized a ‘reproduction analysis’ for a real sabo dam and a ‘reinforced analysis’ for a reinforced sabo dam were applied to assess the weak point of the dam. 相似文献
20.
An experimental study of non-linear mechanisms that may occur during intense seismic response of arch dams is described in this paper. The presentation deals with three types of non-linearity that were observed during shaking table model studies: monolith joint opening, cantilever cracking, and reservoir cavitation at the dam face. The monolith joint opening phenomenon was represented by a segmental arch ring model that simulated a horizontal slice of a prototype dam. The cantilever cracking and reservoir cavitation mechanisms were studied using a model gravity dam section. The principal conclusion of the investigation was that shaking table experiments provide a practical means of studying the non-linear earthquake response of concrete arch dams, including their actual failure mechanisms. 相似文献