| With the rapid development of China’s economy,more and more attention has been paid to the utilization of underground space.Shield tunneling has the characteristics of high efficiency,fast,green and environmental protection.It is the mainstream method of underground construction.However,China has a vast territory and different stratum conditions.High abrasion stratum is a major problem faced by shield construction.By analyzing the characteristics of Wuhu tunnel stratum,the stratum not only has high abrasion resistance,but also is a composite stratum.Shield tunneling will face the problems of uneven force on cutter head and severe cutter wear.Therefore,this paper studies the stress of shield cutter head,the wear of shield cutter and the optimization of shield cutter layout.By consulting a large number of literatures at home and abroad,the rock-breaking mechanism of hobs is analyzed and summarized.The rock-breaking mechanism of hobs is the combined action of tensile failure theory,shear failure theory and unloading theory.The rock breaking force calculation model of hob is analyzed,and its application scope is discussed.The motion equation of cutting point of disc hob is established by means of kinematic analysis of spatial mechanism.The formation characteristics are studied and analyzed,and the abrasion property of the formation is expounded.Based on CSM hob rock breaking force calculation model,the formulas for calculating unbalanced force and overturning moment of shield cutter head are established.A program for calculating the unbalanced force and overturning moment of shield cutter head in composite stratum is compiled by LabVIEW.When shield tunneling in composite strata with different soft rock ratio,the simulation calculation of cutter head unbalance force and overturning moment is carried out,and the variation law of cutter head unbalance force and overturning moment is obtained.Starting from the wear mechanism of cutter,adhesive wear and abrasive wear are the main ways of hob wear.Based on the wear mechanism,hob structure and tunneling parameters,the prediction model of hob wear is established.LabVIEW is used to compile a program for calculating the wear of hobs,and an example is given.The calculated wear of hobs is consistent with the actual wear.It shows that the prediction model is correct and provides a basis for the prediction of hob wear.The genetic algorithm of MATLAB is used to optimize the layout of cutter.Taking the installation radius and polar angle of hob as design variables,the unbalanced force of cutter head,the overturning moment of cutter head and the standard deviation of cutter wear as objective functions,the optimization model of cutter layout is established.The cutter layout optimization of positive hob and edge hob is carried out respectively.After optimization,the unbalance force and overturning moment of the cutter head decrease greatly.It provides a basis for cutter head design and cutter layout of shield machine. |
