Papers by Keyword: High Arch Dam

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Authors: Dan Ni Luo, Yu Hu, Qin Bing Li
Abstract: The calculation method of the minimum aperture of transverse joints with spherical surface key groove was introduced in this study. Based on the computation theory of allowable height difference between adjacent monoliths proposed by Bofang Zhu, the analytical model of allowable height difference of Xiluodu arch dam was established with consideration of the effect of main factors on the transverse joints deformation, including the temperature, autogenous volume deformation, self-weight and foundation. After the horizontal and vertical deformations of transverse joints was required, according to the form of spherical surface key groove, the aperture of each part of key groove and the minimum aperture were obtained at several height difference between adjacent monoliths. The allowable height difference was determined on the condition of meeting the grouting requirements of transverse joints. The result shows that the allowable height difference for Xiluodu arch dam should not be more than 30m.
Authors: Ke Hong Zheng, Bing Yin Zheng
Abstract: The calculation of thermal stress is important to high concrete arch dam. In the progress of construction simulation analysis, the distribution of thermal stresses should be paid attention for it has great influence to arch design and rapid construction. The impacts on thermal stress are water temperature and air temperature and so on. In this paper, the author also thought about of the influence of creep, and applied the formulations of predecessors to finite element program. A engineering example about some high arch dam proves correctness and feasibility of considering thermal-creep –stress.
Authors: Zhi Qiang Wang, Xiao Bin Wu
Abstract: According to the existing arch dam design specification, the temperature load is obtained based on analytic solution of infinite long free plate, it only considers the average temperature and the equivalent linear temperature difference of dam section in operation period, the influence of non-linear temperature difference has not been considered. This kind of simplification has some approximation; especially it can not reflect spatial effect of larger temperature gradient changes in the upstream and downstream water level change area. This paper first takes the free plate as an example, has calculated the temperature field corresponding to analytical method, finite element method, standard method, explains the rationality of using written program to carry on finite element analysis. On this basis, take Xiluodu arch dam as an example, the dam temperature load and temperature stress has been analyzed by using finite element method and standard method, the difference between both has been discussed
Authors: Peng Fei Gao, Xin Feng, Jing Zhou
Abstract: This paper presents the experimental investigations into the seismic failure for high arch dam with shaking table test. The similitude scale of high arch dam was studied firstly. Then we developed a like concrete material to simulate the mechanical behavior of the structural concrete in high arch dam. The shaking table tests have been performed on the scale model. The experimental results reveal the failure process of high arch dam with respect to the different earthquake intensities.
Authors: Huan Feng Qiu, Shao Jun Fu
Abstract: The factors resulted in the cracking of Xiao-wan arch dam are extremely complicated. A numerical analysis based on elastic-viscoplastic mechanics theory has been developed to study the cracks in the middle diversion pier of Xiaowan Arch Dam. This analysis aims to investigate the cause of cracks and the reliability and accuracy of the analysis model have been examined. By using this analysis and the obtained results, the following conclusions are drawn: 1) cracks were not induced by a single cause, but a multitude of various effect such as stresses induced by thermal movements, the bond between the anchor cables and the surrounding concrete and the pressure due to the impounded water, amongst which the thermal stress is the most significant reason; and 2) with the presence of water in cracks, if the drainage hole continues to run overflowing water, the stress intensity factor of a crack tip will exceed the fracture toughness of the concrete. With the hydraulic fracture effect, the crack will grow continuously. The findings derived from this study will provide useful information for future projects of the similar nature.
Authors: Chun Tao Wang, You Ping Wu
Abstract: The dynamic analysis of arch dam need to take complex coupling action of dam-foundation-water into account, so the dam is always simplified in former research. The disadvantage of simplification is that it cannot be determined how much influence on natural frequency and dynamic response can be caused. In view of this, Xiaowan high arch dam finite element model is set up, the result shows : whether the reservior is empty or full, the natural vibration frequency of the actual body form has little change compare with the simplified body form. Therefore, it is feasible to apply the simplified body form to substitute the actual body form for the rough calculation of the frequency of dam body. However, the simplified body form is impossible to present the dynamic response and stress concentration of accessory structures. For this reason, it should apply the actual body form for calculation.
Authors: Hong Wang, Chong Jin, Xiao Zhou Xia, Hong Yuan
Abstract: A fitting curve of stress-strain relation given is applied in numerical analyzing based on Legendre orthogonal polynomial and least square method. The nonlinear constitutive model is employed to examine the shape of an arch dam. For the asymmetries and high water pressure, the safety of High Arch Dam is one of key issues in the design and construction of High Arch Dam. The simulation results show that the basic mechanical performance index is symmetrical distribution. The dam mainly bears pressure and no obvious tensile stress exists in the dam when water level is normal. Material yields in dam heel when 1.4 times overloading is considered. It can be concluded that the dam is reliable and the safety margin is satisfactory.
Authors: Qiu Jing Zhou, Guo Xin Zhang, Yi Liu
Abstract: A hybrid prediction model based on the simulation of the complete process in high arch dams is proposed because of capacity shortage in the prediction of and early warning for deformation and stress in such dams during the first impounding stage. An early warning system for dam body deformation as well as dam heel and dam toe stress is established in this model. The warning thresholds are also clarified. Applications in the first impounding stage of the Xiaowan Arch Dam show that the model is practical and effective, and can provide highly accurate predictions. Early warning indicator thresholds for deformation and stress are reasonably set to provide warnings for abnormal situations. The model provides accurate predictions and effective warning methods for the safe impounding and operation of high arch dams.
Authors: Zhi Qiang Wang, Wen Biao Liu
Abstract: The brittle failure finite element method is widely used in arch dam safety evaluation, but it also has some problems, the concrete strength criterion is different, the dam failure range is different. This article first introduces brittle failure constitutive relation and three strength criterions, then takes a high arch dam as an example to compute, obtains some conclusions that the relative failure range of foundation plane corresponds to blaxial strength criterion is slightly bigger than the result of uniaxial strength criterion, is almost the same as the result of triaxial strength criterion. Because the influence of the third principal stress is compressed stress to the dam crack is taken into account under multiaxial strength criterion, therefore using multiaxial strength criterion is more reasonable.
Authors: Zai Tie Chen, Qing Wen Ren
Abstract: In order to overcome the weakness in traditional high arch dam safety evaluation without considering the randomness, failure mode and risk analysis, it is proposed to apply three indexes namely failure probability, economic loss and life loss to high arch dam safety evaluation. On the basis of the analysis of accidents and on-site measured data, expert discussion as well as analytical analogy and by means of Fault Tree Analysis, a probe is made into the four major failure modes and the causes of high arch dam failure, namely destabilization collapse, shear-slipping collapse, excess cracking and man-caused destruction. Based on the calculating of the probability of high arch dam shearing-slipping failure, the computational method and procedures are established by means of Second Moment Method for the calculation of the occurrence probability of the major failure modes of high arch dam. A study is made of the degree of correlation between the major failure modes and of the method for calculating the high arch dam failure probability under multi-failure-modes.
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