Application Of Gray System Theory In Discharge Tunnel Schedule Control At Pubugou Hydropower Station

Construction schedule control in hydropower engineering is critical for the project to go smoothly. However, there are lots of uncertain factors during implementation, no absolute effective method can solve the problems arisen from schedule control yet. In this paper, a new concept of gray system method used for construction schedule control will be introduced, based on discharge tunnel excavation control at Pubugou Hydropower Station Gray system theory has been applied newly in construction schedule control research. Sequence prediction method in gray system theory is presented in this paper, a GM(1,1) Model established on origin observation information during construction, can predict the schedule, analysis the factors having influences on construction progress, meanwhile decide the sequences according to the degree so as to make certain of influence degree of the factors, at last adjust and control the follow-up activities in a dynamic way with the prediction results.The conclusion has been made as follows in this paper :i. Traditional schedule deviation analysis method can analyze the schedule of completed activities only, no measurable prediction can be made, so it can not control the schedule actively. Compared with traditional one, the schedule deviation analysis method with gray system theory in this paper has certain advantages, it is a new concept to control the schedule actively and dynamically.ii. It is the first time that gray associated analysis method in combination with consequence-sequence method has been applied in schedule deviation reason analysis. Some examples can demonstrate that both methods have complementary actions on each other so as to make theresults close to actual conditions, which overcome the difficulties in the uncertain factors analysis with traditional method.iii. The example of excavation schedule control for discharge tunnelinlet/outlet slope at Pubugou Hydropower Station has demonstrated thatGM(1,1) Model in gray prediction method has considerable precision inschedule prediction used for high slope excavation in hydropowerengineering and is an effective way for schedule early-warning.iv. GM(1,1) Model in gray prediction method has a certain range ofapplication, having the smoothness requirements for the origin data. Incase of origin data overjumping and unsmoothness of data sequence,the precision of prediction result will be influenced, then furtherimprovement will be done for the Model in the follow step.There are a few of gray system theory application experiences inhydropower engineering at present, its application and research in dischargetunnel excavation schedule control at Pubugou Hydropower Station state thatthe gray system theory applied in hydropower schedule deviation analysis anddeviation factors analysis can control the schedule actively and dynamically, italso can be used for schedule control of the relevant hydropower projects.