古城控导工程16号坝断坝重大险情分析

1998年7月16日13时,黄河下游花园口站发生4700m^3/s 流量的洪峰。洪水期间,河南省封丘县古城控导工程16号坝造成断坝,过水口门宽26m(距坝根34～60m),最大过水深4m。在没有出现横河、斜河的情况下发生如此重大险情,实属罕见。1 工程概况古城控导工程始建于1930年,共修建了16道坝、20座垛、8段护岸,工程长度达3101m。其中16号坝于1995年修建,属旱地施工的块石结构,靠溜后多次抢险,坝下有一生产堤破除口门。

Study on equivalent strength for crack directors of RCC arch dam based on size effect rule

The size effect rule of roller compacted concrete (RCC) fracture toughness was reached on the analysis of fracture toughness of RCC specimens, which have been done by project team. And then the rule was applied to the calculation formula of equivalent strength of crack director in the RCC arch dam, thus a simple and useful formula was reached. The study shows that the equivalent strength of crack directors increases with the increasing intensity of concrete, but the surplus rate of strength of crack directors section decreases with the increasing intensity of concrete and the distance between centers of adjacent crack directors, and that bilateral interval crack directors are more efficient in weakening the strength of section than unidirectional interval crack directors in the case of the same distance between adjacent crack director centers. A good design for crack directors of RCC arch dam is proposed via the rule.

Research on Present Activity Characteristics of Heizi Fault and Discussion of Its Relative Problems

Based on other previous researches, we recalculate the micro-displacement along the Heizi fault with recent deformation data of the Heizi reservoir. The result shows that activity characteristics of Heizi fault has changed greatly since 1973 and have experienced four phases. The third phase is characteristics of normal fault, and others characteristic of reverse faults. Constructing the reservoir dam and reservoir sluice has important effect on present activity of the fault, even changed the activity characteristics of faults in some phases. Seismicity has some effect on deformation data and fault activity.

Information fusion diagnosis and early-warning method for monitoring the long-term service safety of high dams

Analyzing the service behavior of high dams and establishing early-warning systems for them have become increasingly important in ensuring their long-term service.Current analysis methods used to obtain safety monitoring data are suited only to single survey point data.Unreliable or even paradoxical results are inevitably obtained when processing large amounts of monitoring data,thereby causing difficulty in acquiring precise conclusions.Therefore,we have developed a new method based on multi-source information fusion for conducting a comprehensive analysis of prototype monitoring data of high dams.In addition,we propose the use of decision information entropy analysis for building a diagnosis and early-warning system for the long-term service of high dams.Data metrics reduction is achieved using information fusion at the data level.A Bayesian information fusion is then conducted at the decision level to obtain a comprehensive diagnosis.Early-warning outcomes can be released after sorting analysis results from multi-positions in the dam according to importance.A case study indicates that the new method can effectively handle large amounts of monitoring data from numerous survey points.It can likewise obtain precise real-time results and export comprehensive early-warning outcomes from multi-positions of high dams.

Abnormality diagnosis of cracks in the concrete dam based on dynamical structure mutation

A method of the fuzzy cross-correlation factor exponent in dynamics is researched and proposed to diagnose abnormality of cracks in the concrete dam. Moreover, the Logistic time series changing from period-doubling bifurcation to chaos is tested first using this method. Results indicate that it can distinguish inherent dynamics of time series and can detect mutations. Considering that cracks in the concrete dam constitute an open, dissipative and complex nonlinear dynamical system, a typical crack on the downstream face of a concrete gravity arch dam is analyzed with the proposed method. Two distinct mutations are discovered to indicate that the abnormality diagnosis of cracks in the concrete dam is achieved dynamically through this method. Furthermore, because it can be directly utilized in the measured crack opening displacement series to complete abnormality diagnosis, it has a good prospect for practical applications.

On-line diagnosis method of crack behavior abnormality in concrete dams based on fluctuation of sequential parameter estimates

Research on on-line diagnosis method of crack behavior abnormality in concrete dams can provide support for timely grasping abnormality state of the crack itself and achieving real-time monitoring of the dam safety.Considering that samples of crack effects in concrete dams increase actually over monitoring time,a superiority criterion for the on-line diagnosis is determined so as to detect the abnormality moments timely and reliably.By integrating the safety monitoring statistical model of crack effect variable with change point theory,a fluctuation method of regression coefficients is established for the on-line diagnosis.In addition,each abnormality moment is detected by the cumulative sum of regression model residuals.Results indicate that abnormality of crack behavior in concrete dams can be characterized by structural instability of crack monitoring model.And causes of crack behavior abnormality can be analyzed by the established method,which will play an important role in dam safety monitoring.Further,taking the crack in a concrete gravity-arch dam as an example,the scientific rationality and validity of the established on-line diagnosis method are confirmed.

Singular value diagnosis in dam safety monitoring effect values

Based on the principal component analysis, principal components that have major influence on data variance are determined by the energy percentage method according to the correlation between monitoring effects. Then principal components are extracted through reconstructing multi effects. Moreover, combining with the optimal estimation theory, the method of singular value diagnosis in dam safety monitoring effect values is proposed. After dam monitoring information matrix is obtained, single effect state estimation matrix and multi effect fusion estimation matrix are constructed to make diagnosis on singular values to reduce false alarm rate. And the diagnosis index is calculated by PCA. These methods have already been applied to an actual project and the result shows the ability of the monitoring effect reflecting dam evolution behavior is improved as dam safety monitoring effect fusion estimation can take accurate identification on singular values and achieve data reduction, filter out noise and lower false alarm rate effectively.