Feedback Analysis And Monitoring Forecasting Study On Monitoring Data Of Longtan Underground Powerhouses

Geotechnical engineering safety monitoring is the whole process carrying on systemic regular measure to the significant parameters of job and surroundings by using monitoring instruments and equipments and making judgment from the measured data that having been analyzed. As the particularity and complexity of geotechnical engineering, it is difficult to make a evaluation and feedback for the safety of construction by applying primal data directly. Varies of monitoring data feedback analytic methods applied in geotechnical engineering are reviewed in this thesis, some methods are used to carry out the feedback analysis and forecast on the safety of Longtan underground power hydraulic project.The main study work focus on the following several aspects:1. Judging the safety status of underground caverns through trimming analyzing and explaining the monitoring data gotten from the three main equipments: multi-extensometer cable stress measure and anchor force measure. At the same time numerical computable methods are adopted to carry out the feedback and comparison, which the feedback analysis results show that the whole stability of caverns are better, and the local must be intensified timbering and encrypt monitoring. Safety monitoring criterion is made a discussion in the thesis. Numerical computable results are defined as the lower limit of total displacement index, at the same time, the multi-extensometer and anchor force measure fitting results are defined as the upper limit of total displacement index. The lower and upper index combining with displacement velocity index supervise the practical monitoring job which can ensure the construction carry out freely. It also shows safety monitoring criterion has engineering practical significance.2. The equivalent modulus of wall rock by Kelvin-Voigt model . displacement monitoring data and displacement -time fitting curves in arbitrary time, then we can get parameters of Kelvin-Voigt model by different temporal equivalent modulus, then thelong-term equivalent modulus (Et)_∞ =0.77E₀ of Longtan underground powerhouse inaccordance with Kelvin-Voigt model is gained, which shows that rheological characteristic of wall rock is more distinct. Rheological characteristic related to the long-term steady needs to investigate further. The displacement forecasting with equation between equivalent modulus and displacement is carried out in this paper, and the forecasting results are in good agreement with fitting displacement, which can be applied to engineering practice.3.The time series data mining system of SAS/ETS is used to conduct tendency forecasting of displacement of Longtan underground powerhouse project. According to the forecasting analysis results, the displacement of rock mass is mainly in a steady rheology state. But the high rock wall's rheological characteristic is very remarkable. The rheological phenomenon will continue a long time, therefore it is suggested to intensify timbering in the important part in order to avoid accelerated rheological phenomenon, which is helpful to keep caverns steady.The above mentioned application and studies are integrated with Longtan underground powerhouse project. The thesis has specific project background. Studies show that the feedback analysis and monitoring forecasting have vital position in geotechnical engineering safety monitoring.