Research On Models And Indexes Of Safety Monitoring Of Lijiaxia High Arch Dam

The engineering geologic conditions within Lijiaxia Arch Dam area of the Yellow River are quite complicated , of which the stability of faults such as f20 and F26 in the left bank ,as well as F27 in the right bank is one of the important factors that affects the safe operation of the hydro-electric station. So the Lijiaxia Arch Dam on the Yellow River is used as the prototype in this dissertation. Based on the data collected from the dam's monitoring system, the aim of the research is to establish the project's monitoring models and monitoring indexes, and to make a real time and comprehensive evaluation on the working and safety condition of the dam and its foundation, as well as make stage alarm, so as to ensure the hydro complex's safe operation.By use of the finite element software of ANSYS, a 3-D finite element model has been established, which encompasses the arch dam and its surrounding region. And many of the materials have been simulated. The analyses of whole process simulation of the abutment stability under different load levels have been made, which include the procedures of excavation, foundation treatment in shallow and deep layers, as well as application of high-tonnage prestressed anchorage cables. The comprehensive and detail analyses of the mechanical mechanism of application of the high-tonnage prestressed anchorage cables and their effects on enhancement of abutment's safety have been made.The monitoring data ,such as plumb-line displacements of the dam's arch crown, the left and right one fourth arch of the dam, water levels of the reservoir, air temperature, temperatures at different levels of the dam's arch crown, etc. have been collected and analyzed.By use of the deterministic model, displacements at different levels under different parameters and loading conditions have been calculated, which show us that the dam's safe operation can be ensured.By use of the artificial neural network, the back calculation of the parameters of the dam and its foundation has been finished. And the real parameters have been obtained.In accordance with the known prototype monitoring data, two kinds of statistical models, which are separately based on the air temperatures and the dam's monitored temperatures, and the hybrid model have been set up. And it is more practical to use the hybrid models which have been established by use of the back calculated parameters as monitoring models.The multi-points monitoring models of the dam's deformation have been set up by use of BP neural network, which are of high fit goodness.The genetic regressive monitoring models of the dam's deformation have been set up by use of the improved Genetic Algorithms (GA), so as to improve the precision of prediction.The monitoring models which are based on Wavelet analysis have been set up.By use of the analytical method of structural calculation, monitoring indexes at three different levels have been presented, which can give great help to the safety decision of the dam.