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Xing L.,Large Dam Safety Supervision Center | Zhou J.,Large Dam Safety Supervision Center
Advances in Science and Technology of Water Resources | Year: 2013

Based on introducing the general situation of ultra-high dam construction in China, the operational characteristics of ultra-high dams in China and some operational accidents in the world are analyzed in details. The key technologies for the long-term safety operation of ultra-high dams include the following topics: establishment of safety evaluation system, rapid detection and diagnosis of stability of high slopes near dams, discharge atomization and countermeasures, systematic researches on durability of materials, repair and reinforcement technology in deep water, risk management and emergency treatment.

Ding Y.,East China Investigation and Design Institute | Zheng Z.,Large Dam Safety Supervision Center
Advances in Science and Technology of Water Resources | Year: 2013

In order to ensure the safety and reliability of CFRD's plinth placed on the bank slope of completely weathered bedrock, this paper analyses four key technical issues, including the bearing capacity of foundation, the seepage control of foundation, the stability of plinth, and the differential settlement of plinth. With the engineering example of Vietnamese Tuyen Quang CFRD, some appropriate engineering measures were proposed, which include improving the bearing capacity of foundation, strengthening the connection between plinth and completely weathered bedrock, ensuring the seepage stability of foundation and setting plinth expansion joints in different bedrock junctions. The dam safety monitoring results show that the seepage volume of Tuyen Quang CFRD is small, and the deformation regularity of the dam is normal. By application of the engineering measures proposed in this paper, placing the plinth on completely weathered bedrock is safe and feasible.

Li F.,Zhejiang University | Wang Z.,Zhejiang University | Wang Z.,Large Dam Safety Supervision Center | Liu G.,Zhejiang University | And 2 more authors.
Structure and Infrastructure Engineering | Year: 2015

Based on the idea that time-effect deformation can be regarded as a state vector indicating the characteristics of concrete dams, a hydrostatic seasonal state (HSS) model is proposed for improving the accuracy of the data analysis of concrete dams. According to the theory of non-stationary time series, the state equation of the HSS model is represented for objectively extracting the time-effect deformation from monitoring data of total deformation and to interpret its evolution accurately. In this study, the HSS model is applied to an arch dam case, and it is estimated by using the expectation-maximisation algorithm. The results illustrate that the HSS model can efficiently estimate the time-effect deformation from monitoring data of total deformation. Compared with the hydrostatic seasonal time model, the proposed HSS model shows an improvement in fitting precision and prediction ability. © 2015, © 2014 Taylor & Francis.

Zhang D.,Nanjing University | Cui H.,Nanjing University | Cui H.,Large Dam Safety Supervision Center | Shi B.,Nanjing University
Optics and Lasers in Engineering | Year: 2013

As a key parameter of distributed optical fiber sensing (DOFS), spatial resolution has a significant influence on the quality of measurement, which is verified by the constant tensile test and strain distribution comparison at different spatial resolution. Two common calibration methods for distributed optical fiber temperature measurement, including 10%-90% Step-Function and Hot-Spot method, as well as their applicability were discussed. A new calibration method, Dissimilar-Fiber-Splicing method, which means two free fibers with variant initial peak frequency were alternately spliced in series with different length, was recommended. And the experimental results by using Dissimilar-Fiber-Splicing method was shown. © 2012 Elsevier Ltd. All rights reserved.

Kong W.,Hohai University | Wang Z.,Hohai University | Wang Y.,Large Dam Safety Supervision Center | Zhu J.,Large Dam Safety Supervision Center | And 3 more authors.
Advances in Science and Technology of Water Resources | Year: 2013

In order to study the rheology of rockfills and its influence on the stress and deformation of the concrete face, the monitoring deformation data of the Gongboxia Concrete-Faced Rockfill Dam was analyzed. The viscoelastic rheological model Merchant was applied to determine the relevant rheological parameters of the rockfills by back analysis. The stress and deformation of the dam during the operation were calculated using the obtained rheological parameters. The results show that the rheology of rockfills is relatively obvious and the computed results agree well with the measured values. The rheology of rockfills has great impact on the stress and deformation of concrete faces, vertical joints and peripheral joints. The rheological model and parameters obtained by back analysis are reasonable, and can be used to predict the development of axial stress and the cracks occurring trend in the concrete face.

Fu C.,Large Dam Safety Supervision Center | Yao X.,Zhejiang University | Li T.,Large Dam Safety Supervision Center | Shen H.,Large Dam Safety Supervision Center | And 2 more authors.
KSCE Journal of Civil Engineering | Year: 2014

The investigation of abnormal increases in uplift pressure can lead to the discovery of seepage paths that may cause damage to concrete arch dams. A new methodology has been developed in this study in order to analyze the causes of abnormally high uplift pressure increases and their influence on the structural safety assessments of dams. A series of borehole video tests were performed on an area of the Huaguangtan Dam and its foundations in order to investigate seepage phenomena under different working conditions. The reasons for the existence of the seepage paths causing abnormally high uplift pressures were identified by examining stresses on the dam, using a detailed three-dimensional numerical model. The results from the monitoring and on-site inspection showed that the high uplift pressure did not constitute a direct threat to the dam's safety. However, grouting treatment of the existing cracks was recommended so as to prevent them from developing further within the dam's foundations and to ensure the long-term stability of the foundation seepage. It was concluded that the methodology in this study could be used to solve practical engineering problems effectively as well as acting as a frame of reference for similar projects. © 2014 Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg.

Shen Z.-Z.,Hohai University | Nie B.-S.,Hohai University | Xu L.-Q.,Hohai University | Yang L.,Large Dam Safety Supervision Center | Wang N.,Pan China Construction Group Co
Applied Mechanics and Materials | Year: 2014

The stability of high rock slopes under the flood discharge atomization and rainfall is an in-negligible problem especially for the hydropower station with high head during the flood discharge. According to the complicated geological conditions of a high rock slope with the flood discharge problem in China, the method of the saturated-unsaturated unsteady seepage if used, thus the finite element model for the high rock slope in the downstream of the power station is set up. Based on the model, the distribution regularities of the unsteady seepage field of the rock slope is studied under the different discharge atomization and rainfall intensity. Moreover, based on the theory of continuous-discontinuous deformation, the finite element model is set up to analyze the stability of the slope, thus the deformation law of slopes under the flood discharge atomization and rainfall is studied and the safety of the slope is evaluated, and what's more, the engineering measures for improve the stability of the stability of the slope is put forward. © (2014) Trans Tech Publications, Switzerland.

Xu B.,Hohai University | Xu B.,China Institute of Water Resources and Hydropower Research | Liu B.,Large Dam Safety Supervision Center | Zheng D.,Hohai University | And 5 more authors.
Science China Technological Sciences | Year: 2012

Based on the internal temperature variation of a dam lagging behind the ambient temperature variation, the ambient temperature of continuous variation is disctetized, and the functional expression of the thermal displacement component of the dam caused by single instantaneous temperature variation is obtained. Considering the temporal and spatial distribution law of the ambient temperature and its relation with air and water temperature, the function is expanded into a Taylor series. As a result, the improved thermal displacement component expression for a dam monitoring model is obtained. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg.

Yang G.,Hohai University | Yang G.,Large Dam Safety Supervision Center | Zhu S.,Large Dam Safety Supervision Center | Zhu S.,Hohai University
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2016

The random finite element method (RFEM), which incorporates simulation techniques of random fields with the finite element method, is proposed to analyze the seismic response of rockfill dams. In order to consider the spatial variability of dam materials, a Local Averaged Subdivision method is used to simulate the random physical and mechanical property fields. Moreover, to lower the cost of obtaining statistical information of mechanical properties of materials, it is suggested to adopt constitutive equations which connect mechanical properties with physical ones. Then, the random seismic response and deformation of a real rockfill dam is simulated via RFEM, in which the dry density, void ratio, median grain size, uniformity coefficient, initial internal friction angle and shear modulus coefficient of the rockfill materials are modelled as random fields. The simulated results show that: (1) The randomness of dam materials will induce unneglectable dispersion in the performance of dams; (2) It is very likely that the response of dams will be underestimated if the randomness of dam materials is overlooked; (3) Some dynamic performance indicators may follow neither the normal nor the lognormal distribution. © 2016, Editorial Office of Chinese Journal of Geotechnical Engineering. All right reserved.

Qiu L.,Hohai University | Zhang L.,Hohai University | Zhou R.,Hohai University | Shen Z.,Hohai University | Yang L.,Large Dam Safety Supervision Center
Energy Science and Applied Technology - Proceedings of the 2nd International Conference on Energy Science and Applied Technology, ESAT 2015 | Year: 2015

Shangmo Reservoir is located on the Jinjiahe River in the west of Tianshui in Gansu Province, China. It is a loam core, sandy gravel dam with a maximum height of 50.0 m. The in situ drilling and geological prospects show that the rock masses under the dam and reservoir area have a good permeability and the deep riverbed fault fracture zones are difficult to cut off completely by the impervious curtain. Thus, a seepage scheme namely “dam surface geomembrane reservoir bottom geomembrane bank concrete protection (gunite)” is applied for this project. Based on the establishment and calculation of the three-dimensional finite element seepage model, the analysis and comparison among three different horizontal seepage control measures was made. The results show that, in comparison with other schemes, the whole reservoir basin anti-seepage scheme have distinct advantages such as seepage-control effectiveness and operational stability. Besides, the seepage gradient of each structure is also within an allowable range. Therefore, the whole reservoir basin anti-seepage scheme is recommended for the Shangmo Reservoir Project. The achievement and experience of this horizontal seepage prevention design should be taken into consideration for other similar projects. © 2016 Taylor & Francis Group, London.

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