Analysis on TBM cutter consumption based on the particle size distribution of rock debris

The rock debris is produced by rock-machine interaction during TBM excavation.The rock debris and its particle size distribution are crucial and effective indexes to evaluate TBM geological adaptability,tunneling efficiency and cutter consumption.In terms of the problem of cutter consumption evaluation of double shield TBM in water conveyance tunnel of Lanzhou water source construction project,the in-situ measurement and screening tests of TBM rock debris for different rock mass conditions were carried out.The measured data of rock debris particle size distribution were statistically analyzed and fitted with the theoretical distribution function.The characteristics of TBM cutter consumption was summarized.On above basis,the relationships between TBM cutter consumption under different rock mass conditions and some particle size distribution parameters of rock debris,i.e.coarse index (CI),particle gradation coefficient and category ratio were discussed.The results show that the cutter consumption is closely related to rock mass and geological conditions.The higher the rock strength and abrasiveness,the more the cutter consumption.TBM cutter consumption in the surrounding rocks of class II and IV is significantly higher than that in the surrounding rocks of class III.The cutter diameter has a certain influence on the cutter consumption,large diameter cutters can reduce the consumption under the same surrounding rock conditions.For different lithology conditions,the particle size distribution of rock debris is uneven,which is generally well graded.The particle size distribution of rock debris conforms to the Rosin-Rammler function,and the Rosin-Rammler function can be used to calculate the particle size distribution parameters of rock debris.The correlation between cutter consumption and rock debris curvature coefficient is not obvious,while there is a good quadratic function relationship between cutter consumption and rock debris inhomogeneity coefficient,and the correlation coefficient is 0.875.Meanwhile,there is a significant quadratic function relationship between cutter consumption and the coarse index of rock debris,and the correlation coefficient is 0.87.When the coarse index is higher than 430,the higher the coarse index of rock debris is,the higher the TBM tunneling efficiency is,and the smaller the cutter consumption is.The cutter consumption is positively proportional to the average particle size of rock debris including geometric average particle size and R-R function average particle size,and the correlation coefficients are 0.84.The cutter consumption is closely related to the proportion of debris shape and its content.The higher the rock chip content is,the smaller the cutter consumption is.When the content of flaky debris is more than 40%,the decrease rate of cutter consumption decreases faster.When the content of rock blocks and powder increase,the cutter consumption also increase.When the content of block debris is more than 40%,the increase rate of cutter consumption is faster.The research results establish an effective relationship between TBM tool consumption and rock slag particle size distribution.