COMPARISON OF TBM PERFORMANCE PREDICTION WITH ACTUAL TBM OPERATION RESULTS IN HEADRACE TUNNELS NO.1 AND NO.3 OF JINPING II HYDROPOWER STATION

Tunnel boring machine(TBM)performance prediction has played an important role in the selection of construction method,project planning,construction planning and management.Headrace tunnels No.1 and No.3 of Jinping II Hydropower station were excavated respectively by two tunnel boring machines.On the base of the obtained information of rock masses conditions and rock masses environmental conditions,such as in-situ stress and groundwater condition along the tunnel alignments,the rock mass was sectioned according to the influence of key factors on TBM excavation.NTNU and rock mass characteristic TBM performance prediction models were used to predict the penetration rate.And NTNU cutter life mode and CAI value were used to predict the cutter wear.By comparing the results of in-situ TBM penetration tests with the prediction penetration rates,the applicability and errors of these penetration rate prediction models were discussed.During TBM construction process,the rock mass conditions,TBM operation parameters,TBM operation results were collected and analyzed.The actual rock mass conditions and excavation results were compared with the rock mass conditions obtained for TBM performance prediction and predicted TBM performance results.The reasons of making the difference were studied.Generally,the penetration rate prediction is reliable in most cases.But in the condition of high in-situ stress,these TBM penetration rate prediction models need to be modified.Due to the influence of the high in-situ stress and rock bursts,the abnormal cutter failure is too much.Thus,the predicted results for cutter life are not good.