Study On Tool Wear Law And Tunneling Performance Evaluation In TBM Construction Of Hard Rock Mass

TBM has special advantages in tunneling speed,safety and environmental protection compared with other tunnel construction methods,so it has been widely used in the construction of tunnels and underground projects in China.The tool on the TBM cutter head is the core component for performing excavation.In the construction of hard granite formations,the tool is worn by the rock on the one hand,and the rock is also destroyed on the other hand.The wear and failure of the tool will directly affect the driving efficiency and construction safety.Taking the TBM construction project of the Yangtaishan hard granite tunnel in the section between Dalang station and Shiyan station of the section 6101 of Shenzhen Metro Line 6 under construction as the research background,based on the data statistics and analysis of the tracking site construction,the TBM tool’s wear rule and the evaluation of tunneling performance in the hard granite formation are analyzed and studied.The main work and research results are as follows:(1)Based on the characteristics of the Yangtai Mountain tunnel project,the surrounding rock conditions of the tunnel and the construction arrangement,a suitable double shield TBM model for the hard granite formation is determined;based on the design parameters of the TBM model,the driving parameters of TBM driving in hard granite strata such as TBM driving thrust,hob torque,overturning moment and cutter torque under different surrounding rock conditions are determined;the analysis of the tunneling application is carried out in the tracking construction,and the evaluation problems of cutterhead hob wear and TBM adaptability of hard granite stratum in the hard granite stratum tunneling of the Yangtaishan tunnel are proposed.(2)Follow the TBM construction of the Yangtaishan Tunnel,the wear of the TBM disc hob in the hard granite formation is analyzed statistically,three main forms of TBM tool failure in the hard granite formation are carried out,and the corresponding relationship between the different wear failure modes of different tool positions on the cutter head,the number of hobs and the amount of wear are analyzed.It is found that in hard granite formations,the closer the TBM is to the center of the cutter head,the smaller the cumulative wear of the hob when driving the same length;but in terms of the amount of wear per unit track length,the wear of the center hob is relatively large,the wear of the front hob and edge hob is relatively small,and it is basically maintained at the same wear level which is independent of the distance from the center of the cutter head.(3)According to the influence of different factors on the wear of TBM hob in hard granite strata,based on the analysis of the statistical data of the Yangtaishan tunnel,it is carried out from four aspects: the strength of the surrounding rock,the grade of the surrounding rock,the depth of the tunnel and the TBM driving speed.According to the research,it is found that the strength of the surrounding rock has the most significant effect on the wear of the double shield TBM hob,the grade of surrounding rock is next.The influence of the tunnel depth on the hob is not obvious.At the same time,in terms of the influence of the driving speed on the wear of the hob,because the driving speed needs to be kept relatively stable during the construction process,the influence of the driving speed is relatively weak.On this basis,the mechanical management and maintenance recommendations of the double shield TBM cutters in the hard granite stratum are proposed,and the construction of the Yangtaishan Tunnel is guided.(4)In order to study the tunneling performance of the double shield TBM in hard granite formations,taking the TBM penetration index FPI as the reference index,based on the correlation analysis,the fitting relationship between FPI and the uniaxial compressive strength USC and the rock mass integrity coefficient Kv of the surrounding rock is established.And the fitting relationship between FPI and the thrust force F and penetration P of the TBM cutter head is also established.On this basis,the tunneling performance of the double shield TBM of the Yangtaishan Tunnel is evaluated.