Coupling Analysis Of TBM Cutterhead And Rock Based On Energy Method And The Layout Optimization Of Cutters

The development of economy is inseparable from the improvement of infrastructure,and road construction,especially tunnel construction is an important part of infrastructure construction.Tunnel boring machine(TBM)plays an increasingly important role in tunnel construction because of its high efficiency,economy and safety.Cutterhead is the key part of TBM.It is very important to analyze the coupling between cutterhead and rock in the process of rock breaking for optimizing the arrangement of hob on cutterhead and improving the performance of TBM.In this dissertation,the relationship between the breaking characteristics and energy of TBM rock is analyzed.Based on the previous studies on the mechanism of rock energy failure,the energy components involved in TBM rock failure are discussed,and the energy conversion process is analyzed.Furthermore,the relationship between the dissipation energy and the size of rock fragmentation,and the relationship between the residual elastic strain energy and the severity of rock fragmentation are analyzed.It provides a basis for subsequent layout optimization of cutters.The optimization method of cutter polar diameter based on the stability constraint of the face is proposed.Firstly,the cutterhead is divided into two parts: positive cutter area and edge cutter area,and the relationship between the radius of cutter and the residual elastic properties of each rock area is deduced.In this process,the influence of in-situ stress is considered.According to the residual elastic energy of each rock area,the degree of rock breaking intensity is proposed to measure the stability of the face,and the maximum stability of the face is used to optimize the pole diameter of the cutters.An optimization method of cutter polar angle based on the constraint of impact energy balance distribution of cutter head is proposed.According to the splashing phenomenon of rock after rock breaking,the concept of rock impact energy is put forward.the offset of the impact energy equivalent action point of rock on the cutter head is given,and the traditional indexes such as the center of mass offset of cutters,overturning moment and radial unbalanced force are considered.The optimization of cutters polar angle is carried out based on the weighted average minimum of four indexes.The weight of each index is determined by using critical method and combining with the original data of Qinling tunnel project and TB880 E cutter head.An example of optimization method based on energy principle is analyzed.Taking Dahuofang engineering and MB264-311 TBM cutterhead as examples,the rationality and effectiveness of the optimization method are verified.the results show that the average value of rock breaking intensity in the positive cutterhead area after optimization is reduced by 1.55%,the variance of rock breaking intensity in the side cutterhead area is reduced by 1.68%,and the weighted comprehensive index of impact energy offset,overturning moment,center of mass offset and radial unbalanced force of the cutter head decreases by 24.62%.The size of each component of TBM rock breaking energy system in Dahuofang project is calculated.The influence of different burial depth on the residual elastic strain energy is analyzed.