Research On The Wear Characteristics And Prediction And Early Warning Methods Of TBM Disc Cutters

With continuous innovation and development of tunnel engineering technology,China has achieved fruitful results in the development of water conservancy,hydropower,highways,railways and other projects.TBM,as the preferred equipment for tunnel engineering construction,is gradually developing and improving towards integration and intelligence.As the core component of TBM,the performance and service life of the disc cutter directly affect the construction efficiency and cost.Based on several domestic TBM construction projects,this thesis summarizes the wear characteristics of TBM disc cutters under different influencing factors,and establishes methods for predicting cutters loss and warning of abnormal damage,which provides a valuable reference for similar projects in the future.Firstly,the cutter consumption under construction with different geological data and equipment parameters were counted to obtain the failure distribution and causes of disc cutter in different projects.The results show that rock grading,lithology,cutterhead diameter,cutter type,and cutter installation and maintenance all affect the performance of cutters in specific projects.Based on the proportion of normal cutter replacement,the cutter performance was divided into three levels: excellent when the proportion is ≥80%,good when the proportion is between 70% and 80%,and poor when the proportion is <70%.Most project cutter performances were evaluated as good.In addition,the utilization rates of each project were calculated,and it was discovered that the time for inspecting and replacing cutters accounted for 7%～15%of the total construction time in most cases,with individual extremely hard rocks reaching more than 25% and most projects around 10%.the higher the rock integrity and compressive strength,the more the tool inspection and replacement time accounts for.Furthermore,the comparative analysis of cutters loss law based on multiple factors in multiple projects shows that rock integrity,compressive strength and abrasiveness are the most important factors affecting cutters wear.The results of the field application tests of narrow cutter and standard cutter for extrahard rock conditions show that narrow cutters can achieve greater penetration and digging speed,increasing the construction speed by about 17.2%,while the consumption of narrow cutters also increases significantly,exceeding that of standard cutters by about26.8%,but the increase in the number of cutters changes of narrow cutters does not delay normal digging,and has minimal impact on the utilization rate of TBM digging operations.However,it is estimated that the benefits of narrow cutters through increased construction speed are much greater than the increased tool costs.Therefore,it is more advantageous to use narrow cutters in extremely hard rock conditions over120 MPa.To estimate the overall cutters consumption for the entire project,the surrounding rock was classified based on TBM construction conditions,and a correlation between different rock grades and cutters consumption was established.A regression fitting method was used to provide an empirical formula for cutters consumption prediction.Combining previous theoretical models,the formula was improved by introducing cutterhead and disc cutter diameters,further expanding the accuracy and scope of the prediction model.It was verified that for Class II and III surrounding rocks with good integrity,the prediction error of the model could be controlled within 10%;for Class III and IV surrounding rocks with poorer integrity,the prediction error could be controlled within 20%.In addition,statistics on the consumption of other parts of the cutter,and cost conversion to get,TBM per kilometer of boring tool cost total cost of about 3.509 9 times the cost of the removable ring.Finally,for the abnormal damage of the cutter during the TBM digging,an intelligent algorithm model based on DE-ELM algorithm to predict the penetration index FPI is established,and an early warning method to identify the abnormal damage of the cutter by comparing the predicted FPI with the actual FPI is proposed,and different warning levels are divided.When the deviation between the predicted FPI and the actual FPI is in the range of 20%～50%,it belongs to a low-level warning;when the deviation exceeds 50%,it is a high-level warning.And provided different handling measures based on different warning levels to detect abnormal cutter damage in a timely manner without delaying the construction.